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Authors: Shravan K. Chunduri, Michael Schmela
Cell & Module Technology Trends 2025
Key Developments In TOPCon, HJT & BC
Solar Cells and Modules
Cell & Module Technology Trends | TaiyangNews 3
Executive Summary
Today’s PV technology landscape reects an
ecosystem where multiple technologies coexist.
While TOPCon has emerged as the standard,
its contemporaries – heterojunction (HJT) and
the more advanced back contact (BC) structure-
are also in high-volume production, with notable
progress across all. Although some innovations
remain technology-specic, others – especially at
the module level – are increasingly applicable across
platforms. This report offers a high-level overview of
such developments.
Starting upstream, an important innovation in ingot
production is LONGi’s proprietary TRCZ process,
which offers precise resistivity control from seed
to tail while maintaining RCZ’s cost advantages.
TaiRay wafers made via TRCZ also enable better
gettering. Regarding wafer specications, BC is the
most demanding, followed by TOPCon, while HJT
is the most forgiving, particularly in terms of oxygen
content.
In TOPCon, one major advancement is laser-assisted
contact formation, which decouples metal contact
recombination from contact resistivity. Deposition
methods like LPCVD and PECVD now deliver
comparable performance, having overcome earlier
limitations. PVD is also emerging as a viable third
option. Another notable trend is edge passivation,
addressing defects from slicing large wafers into
halves. Simultaneously, vendors are developing
tools tailored to half-cell processing, a practice long
established in HJT. Meanwhile, patent disputes have
created uncertainty in some markets, prompting
shifts away from TOPCon – especially in the U.S.
Looking ahead, Several TOPCon manufacturers are
exploring rear poly – ngers – borrowed from BC
designs – to reduce parasitic absorption and boost
efciency by applying polysilicon only beneath rear
metal contacts
For HJT, the foundational structure has already
undergone a key shift from doped amorphous
silicon to microcrystalline silicon, which has become
a standard. The next frontier lies in metallization
cost reduction. Manufacturers are moving in 3 key
directions: increasing the number of busbars and
eventually eliminating them through zero-busbar
(ZBB) designs; lowering the paste laydown by
reducing the nger width and reducing the silver
consumption by lowering the silver loading; and
ultimately going silver-free. Companies are also
focusing on high mobility TCO material used in HJT
processing.
BC technology is more opaque compared to
its peers due to the proprietary nature of its
development. However, insights from industry
leaders like LONGi, AIKO, and SPIC reveal shared
themes. BC is a platform that can be based on
various cell architectures. However, the majority of
manufacturers are using bipolar passivated contacts.
Laser technology plays a vital role in BC solar cell
manufacturing, particularly in enabling the rear-side
structuring that denes this architecture. While there
have been some growing pains with lasers in the
beginning, today’s laser can very well support the
throughput as well as quality requirements of BC cell
makers. When it comes to metallization, all major BC
manufacturers are actively exploring ways to reduce
or replace silver, with a clear focus on copper-based
solutions. And adopting ZBB is a common strategy
to reduce silver consumption.
At the module level, the industry is witnessing a shift
from a ‘one-size-ts-all’ approach to products to
application-specic designs. Module manufacturers
are now tailoring their BOMs to meet the diverse
demands of different climates, installation
environments, and system congurations. As a
result, almost every traditional component – be
it glass, encapsulant type, backsheet, or frame –
has an alternative, enhancing the application and
integration spectrum of PV.
t Enjoy reading our Cell & Module Technology Trends 2025
Shravan K. Chunduri
Head of Technology, TaiyangNews
shravan.chunduri@taiyangnews.info
+91 996 327 0005
Hyderabad, India
Michael Schmela
Managing Director, TaiyangNews
michael.schmela@taiyangnews.info
+49 173 15 70 999
Duesseldorf, Germany
Cell & Module Technology Trends | TaiyangNews 5
www.aikosolar.com
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Contents
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© TaiyangNews 2025
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Cell & Module Technology Trends 2025
ISBN 978-3-949046-30-8
The text, photos and graphs in this report are copyrighted (cover photo credit:
JinkoSolar, AIKO, Huasun, LONGi ). TaiyangNews does not guarantee reliability,
accuracy or completeness of this report's content. TaiyangNews does not accept
responsibility or liability for any errors in this work.
Publisher:
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01
Introduction 711
02
TOPCon
03
Heterojunction (HJT) 25
• Wafers
• Cells
• LONGi p. 2
• AIKO p. 4
• JA Solar p. 6
• JinkoSolar p. 10
• DMEGC Solar p. 14
• Trinasolar p. 19
• VON ARDENNE p. 22
• GCL p. 28
• Tongwei p. 31
• Risen Energy p. 34
• DAS Solar p. 38
• HANGZHOU FIRST p. 41
• DKEM p. 44
• Solamet p. 49
• Cybrid p. 51
• Huasun p. 55
• Wafers
• Cells
05
Modules 45
• Efciency & Power
• Zero BusBar
• Innovations in BOM
04
Back Contact (BC) 35
• Wafers
• Cells
• Modules
9783949 046308
Cell & Module Technology Trends | TaiyangNews 7
It’s remarkable how much the solar landscape
has transformed in just 5 years. What was once
a PERC-dominated world has now evolved into
a dynamic ecosystem led by TOPCon, with HJT
and back-contact (BC) technologies also in the
fray, backed with multi-GW scale capacities. And
it’s not just about new cell architectures – each
of these technologies is advancing at a steady
clip. Meanwhile, the module side – often seen
as conservative – is also increasingly becoming
innovative. We are now seeing application-specic
designs and tailored bills of materials (BOM), with
almost every conventional component facing an
alternative. Innovative interconnection processes
are also helping to debottleneck cell-level limitations
– for example, reducing silver usage. Behind the
scenes, manufacturing processes and production
equipment are being continuously rened to keep
pace with these shifts.
At TaiyangNews, we’ve been tracking these
technological shifts closely through our in-depth
reports and insightful virtual conferences, providing
a front-row view of the PV industry’s development.
These publications and forums take a deep dive into
the relevant aspects of each technology, providing a
comprehensive understanding of their developments
and impact.
This report offers a bird’s-eye view of overall
technology developments, focusing on key
advancements across each mainstream PV
technology. The TaiyangNews Cell & Module
Technology Trends 2025 report distils the core
trends driving the advancement of TOPCon and HJT,
the 2 front-running next-generation technologies.
And while BC remains largely proprietary, we
examine its dening characteristics and highlight the
recent advancements shaping its future role in high-
efciency solar.
1.1 Market Shares of Different Technologies
Before going into the details, here is a quick peek
into the market shares of PV technologies. The
graph below summarizes the market share estimates
for different solar cell technologies as projected by
ITRPV, CPIA, and research rm Exawatt.
1. Introduction
0
10
20
30
40
50
60
70
80
90
100
CPIA
Exawa
ITRPV
S&P Global
Exawa
CPIA
ITRPV
Exawa
CPIA
Exawa
CPIA
ITRPV
Exawa
CPIA
Exawa
ITRPV
CPIA
ITRPV
ITRPV
202420252026202720282029203020322035
Market Share (%)
PERC TOPCon HJT XBC Tandem
Source: CPIA, Exawatt; ITRPV, S&P Global
TOPCon is the mainstream: The market share prediction from various sources, highlighting the
continuing dominance of TOPCon in the near term, the gradual rise of XBC, and then HJT with the
phase-out of PERC, and tandem only to enter in about 4 years.
Market Share Comparison by Source and Technology
8 TaiyangNews | Cell & Module Technology Trends
It is well known that TOPCon is the workhorse of
the industry, and all sources unanimously agree
that TOPCon will dominate the cell technology
landscape. In 2025, CPIA and Exawatt forecast
TOPCon to capture around 80% of the market share,
while ITRPV estimates it slightly lower at close to
70%. This leadership is expected to persist through
the decade, according to both CPIA and Exawatt,
before gradually declining to 60% (CPIA) and 54%.
ITRPV estimates the technology to peak in 2029, but
still at around 70% and then decline to 42% by 2035.
HJT is steadily gaining traction, with all 3 sources
forecasting a gradual rise. In 2025, its estimated
share ranges from 4% according to Exawatt to 8%
according to ITRPV. The technology is seen growing
slowly but surely, reaching 10% by 2028 in Exawatt’s
view, and 20% by 2030 according to CPIA. ITRPV,
in contrast, projects higher initial market capture –
10% already in 2027, but more conservative growth
thereafter, peaking at 14% in the next 5 years and
slightly declining to 12% by 2035.
Although it sounds counterintuitive, the technology
envisioned to take the second spot in market share
is XBC, not HJT. The outlook for XBC (back-contact
technologies), including TBC (TOPCon-based) and
HBC (HJT-based), is more dynamic. Starting from
an 8% to 10% share in 2025, all sources agree on
an upward trajectory for this technology. Exawatt
is especially bullish, projecting a dramatic rise to
35% by 2029. On the other hand, ITRPV is the most
conservative in estimating the technology to reach
a little short of this level in the next 10 years. CPIA’s
projection is also on the conservative side, but still
signals growth, reaching close to 20% by 2030.
Tandem technologies, such as silicon-perovskite
stacks, are expected to remain niche in the near
term, with negligible market presence before 2027.
This technology is expected to be rst be detectable
on the technology radar in 2029, according to both
ITRPV and Exawatt, with a share of about 3%. In
contrast, CPIA maintains a cautious outlook with just
1% in 2030.
1.2 Innovations in Upstream
As market shares shift among cell technologies,
upstream advancements are setting the stage for
broader performance gains across all architectures.
LONGi’s TaiRay wafer, introduced last year,
earns a mention here. The key aspect of this
wafer, according to LONGi, is advancement in
silicon wafer technology, aligning closely with
the evolving needs of high-efciency solar cell
manufacturing, underscoring that wafer and cell
development are inseparably linked. This new ingot
growing technology results in wafers that address
performance and cost challenges. Traditionally,
the ingot production evolved from the standard
Czochralski (CZ) process to Recharge Czochralski
(RCZ) to Continuous Czochralski (CCZ) methods,
each aiming to optimize cost, resistivity control,
and material purity. However, challenges remained,
particularly with CCZ, where increased oxygen
content and metal impurity accumulation lead to
compromised lifetime and process yields, especially
in n-type wafers.
To address this issue, LONGi developed a new
pulling approach: Trailblazing Recharge Czochralski
(TRCZ) technology. TRCZ preserves the productivity
and cost advantages of RCZ while considerably
improving resistivity uniformity and wafer quality
across the ingot. This innovation led to the
introduction of the TaiRay wafer, which has been
available commercially since late last year.
This wafer offers several breakthroughs. It achieves
exceptional consistency in bulk resistivity from
the seed to the tail ends of the ingot, maintaining
variation within a tight 1.1–1.2 ratio. This uniformity
ensures that module production achieves higher
efciency yields, improved EL uniformity, and better
reliability. Moreover, TaiRay wafers are compatible
with all mainstream cell technologies, including
TOPCon, HJT, and BC architectures. The wafers
are offered in different geometries and thicknesses,
meeting the demands of various cell vendors.
One of the standout features of the TaiRay wafer is
its optimized dopant engineering. By using antimony,
LONGi has reduced the migration activation energy
of intrinsic metal impurities, making them easier to
remove during the gettering process. This advantage
is especially critical for sensitive technologies
like HJT. Tests demonstrated that even tail-end
wafers maintain high performance after gettering,
outperforming benchmarked standard silicon
substrates.
Mechanical strength has also been improved. TaiRay
Cell & Module Technology Trends | TaiyangNews 9
Source: LONGi
Tight resistivity distribution: One of the major technical advancements with TaiRay wafers from
LONGi is the tight resistivity distribution along the ingot length.
wafers show enhanced bending resistance, opening
possibilities for thinner wafer applications without
compromising module durability.
Performance trials across multiple technologies
validate TaiRay’s advantages. In TOPCon production
lines, TaiRay wafers showed clear pathways to
higher cell efciencies by better matching resistivity
to process requirements. In TBC and HBC lines,
preliminary results suggest a signicant uplift in
performance potential. In HJT applications, where
lifetime uniformity is crucial, TaiRay demonstrated
notable improvements, even across longer ingot
runs.
Cell & Module Technology Trends | TaiyangNews 11
As discussed above, TOPCon has rmly established
itself as the mainstream technology in today’s
PV production landscape. While the transition
from PERC to TOPCon came with its own set
of challenges, these have been progressively
addressed through the concerted efforts of the solar
industry – ranging from materials and equipment
suppliers to cell and module manufacturers. This
chapter outlines the most important technological
advancements that have supported TOPCon’s
rise, starting with developments at the wafer level,
followed by innovations in processing that have
enabled its rapid industrial adoption.
2.1 Wafers
One of the key ingredients of most advanced cell
architectures beyond PERC has been the change
of wafer type, from p-type to n-type. Even within
n-type, there are a few special requisites for every
cell technology. The wafer quality requirements for
TOPCon are somewhat in the middle of HJT and BC.
Electrical Parameters
The preferred resistivity for n-type wafers used in
TOPCon is typically between 1 to 3 Ω·cm, which
provides a good balance between minimizing
recombination losses and maintaining adequate
conductivity. Carrier lifetime is another key parameter,
with high-performance lines targeting bulk lifetimes
above 1,000 µs, while it is even exceeding 2,000 µs
in a few cases, aspiring for high Voc. The next item
in the list is the oxygen content, which is generally
kept below 10-12 ppm. Additionally, carbon content
is also monitored, typically maintained below 1 ppm,
as excessive carbon can lead to unwanted defect
complexes during high-temperature processing.
These electrical quality metrics collectively form the
foundation for reliable and efcient TOPCon cell
manufacturing.
Physical Parameters
While wafer thickness may come to mind rst among
the physical parameters, it is not the hot topic in the
case of TOPCon. The average wafer thickness is
between 125 µm and 140 µm, which is expected to
go down to 110 µm in the next 5 years according to
CPIA’s roadmap. What matters more for TOPCon is
the dimensions of the wafer.
Rectangular Wafers
In recent years, wafer dimensions have again
become a focal point in PV manufacturing. Now it
is not about increasing the size, but rather moving
away from the traditional square or pseudo-square
to rectangular sizes. This is facilitated by the fact that
every PV module is built on sliced silicon substrates.
Thus, rather than cutting a wafer or cell into 2
equal parts, dividing them into asymmetrical pieces
still enables them to meet the required module
dimensions and corresponding power ratings for
different applications. This also gives module makers
the freedom to achieve the voltage and power
requirements for a specic application by carefully
selecting the size and count of cell strips.
Companies are also nding their own sweet spot
for a wafer dimension. A few companies are even
adopting more rectangular wafer dimensions than
2. TOPCon
Typical Wafer Specications for TOPCon
Parameter n-type TaiRay wafer (LONGi) n-type TOPCon wafer
Doping Element Antimony Antimony Phosphorus
Resistivity (Ω·cm) 0.7–1.4 0.7–1.4 0.6–1.6
Minority Carrier Lifetime (μs) ≥1000 ≥1000 ≥1000
Interstitial Oxygen (ppma) ≤12 ≤12 ≤12 ≤12
Substitutional Carbon (ppma) ≤1 ≤1 ≤1 ≤1
Source: InfoLink
Balanced resistivity: The resistivity for TOPCon wafers typically range from 1 to 3 Ω·cm, striking a
balance between low recombination losses and sufcient conductivity.
12 TaiyangNews | Cell & Module Technology Trends
one to build modules for different applications. For
example, Astronergy uses dimensions of 182 × 210
mm (commonly referred to as 210R) for its modules
aimed at utility applications and 182.2 × 191.6 mm
(191R) for DG application modules. JA Solar noted
that at least 3 different wafer sizes are required to
cater to the industry mainstream 54, 66, 72, and
78 cell module layouts. JA Solar tackled this issue
smartly by using only one wafer size, i.e., 182 × 199
mm. The specialty of this wafer is that it can be cut
in different ways to create modules of different sizes
while maintaining the same width of 1,134 mm. For
example, when the wafer is cut along the longer
side, it can be used to create a 72-cell module with
dimensions of 2,465 × 1,134 mm. When the same
wafer is cut into 2 asymmetrical pieces of 105 mm
and 94 mm, it can be used to create 66, 72, and 54
cell modules with dimensions of 2,382 × 1,134 mm,
2,333 × 1,134 mm, and 1,762 × 1,134 mm.
Quoting an internal market study report, Trinasolar
shared insights into the global cell capacity and
estimated production gures, focusing on wafer
dimensions for 2023 and 2024 at the TaiyangNews
High Efciency Solar Technologies Conference.
The study highlighted that the major rectangular
cell dimensions are 210R, 191 × 182 mm (191R),
and 199 × 182 mm (199R). By the end of 2023,
Source: JA Solar
One size ts all: JA Solar smartly uses one wafer size of 182 × 199 mm to produce 3 different sizes
of rectangular wafer sizes that, in turn, allow it to make 5 different module congurations.
JA Solar’s Different Module Formats Derived from One Wafer Size
Wafer Size Module Layout Module
Length Half Cell Size Module
Power
Dimensions
(mm)
182 × 199 mm
72-Cell 2,465 mm 99.5 × 182 mm 630 W 2,465 × 1,134 mm
66-Cell 2,278 mm 99.5 × 182 mm 580 W 2,278 × 1,134 mm
182 × 188 mm
72-Cell 2,333 mm 94 × 182 mm 595 W 2,333 × 1,134 mm
54-Cell54-Cell 1,762 mm1,762 mm 94 × 182 mm94 × 182 mm 450 W450 W 1,762 × 1,134 mm1,762 × 1,134 mm
182 × 210 mm182 × 210 mm 66-Cell66-Cell 2,382 mm2,382 mm 105 × 182 mm105 × 182 mm 610 W610 W 2,382 × 1,134 mm2,382 × 1,134 mm
Source: TaiyangNews 2025
Cell & Module Technology Trends | TaiyangNews 13
global rectangular cell production capacity was
expected to hit 84 GW, with 14.5 GW of it reected
in actual production. Looking ahead at that time, the
capacity was projected to surge to 420 GW in 2024,
accounting for over 80% of the cell market share.
Rectangular cell production was expected to range
between 200 GW and 300 GW in 2024. And as
expected, most of the leading suppliers introduced
modules based on rectangular wafers in 2024.
2.2 Cells
More than being based on n-type wafers, the crux
of the TOPCon cell structure lies in a true and next-
level passivation. Apart from covering the surface
passivation requirements, it is also aimed at
Wafer Size Variants by Leading PV Manufacturers
Company Wafer Size (mm)
Astronergy 182 × 210; 210 × 210; 182.2 × 191.6; 182 × 182
DAS Solar 182.2 × 191.6; 182 × 210
JA Solar 182 × 199
JinkoSolar 182.3 × 183.5; 182 × 186.8182.3 × 183.5; 182 × 186.8
LONGi 182.2 × 191.6
RisenRisen 210 × 210210 × 210
TongweiTongwei TOPCon: 210 × 210; 182 × 210; 182 × 183.75; HJT: 210 × TOPCon: 210 × 210; 182 × 210; 182 × 183.75; HJT: 210 ×
210210
TrinasolarTrinasolar 182 × 210; 210 × 210182 × 210; 210 × 210
Source: TaiyangNews 2025
Length and Wafer Dimensions Across Module Layouts
Manufacturer HSAT DAT
54-Cell 1,722 mm
182 × 182 mm
182 × 183.75 mm
182 × 185.3 mm
48-Cell48-Cell 1,762 mm1,762 mm
182 × 186.8 mm182 × 186.8 mm
182 × 210 mm182 × 210 mm
66-Cell66-Cell 2,384 mm2,384 mm 182 × 210 mm182 × 210 mm
72-Cell72-Cell
2,278 mm2,278 mm
182 × 182 mm182 × 182 mm
182 × 183.75 mm182 × 183.75 mm
182 × 185.3 mm182 × 185.3 mm
2,333 mm2,333 mm 182 × 186.8 mm182 × 186.8 mm
78-Cell78-Cell 2,465 mm2,465 mm
182 × 182 mm182 × 182 mm
182 × 183.75 mm182 × 183.75 mm
182 × 185.3 mm182 × 185.3 mm
Source: TaiyangNews 2025
Unity in diversity: Companies are nding a different rationale to narrow down to a particular
wafer dimension that led to different wafer sizes, but they all agreed to stick to a set of module
dimensions
14 TaiyangNews | Cell & Module Technology Trends
www.dmegcsolar.com
Series modules
• Increased performance and efficiency
• Extended stress test: lEC TS 63209-1
• TÜV Rheinland Bankability Programme
• Enhanced hail resistance VKF
• Outstanding aesthetics ABT
•
• Transparent supply chain
• Green product
Infinity Power,
Infinity Future
Cell & Module Technology Trends | TaiyangNews 15
www.dmegcsolar.com
Series modules
• Increased performance and efficiency
• Extended stress test: lEC TS 63209-1
• TÜV Rheinland Bankability Programme
• Enhanced hail resistance VKF
• Outstanding aesthetics ABT
•
• Transparent supply chain
• Green product
Infinity Power,
Infinity Future
addressing one main shortcoming associated with
prior-art cell structures. Metal contacts formed in the
predecessor architectures are highly recombination-
active and cause losses. This can be avoided by
electronically separating contacts from the absorber
by inserting a wider bandgap layer. TOPCon is
nothing but adapting this technique to the rear side
of the cell.
Efciency
The effort is worth it. It’s astonishing to look at the
number of announcements made about efciency
progress by leading manufacturers at several
of TaiyangNews' virtual events; the table below
provides a nice overview. Several companies had
already announced reaching efciency levels of
close to 25.5% by H1-2023, close to 26% by the
end of 2023, and beyond the 26.5% level by the end
of 2024. However, these high efciency levels may
not be equivalent to international calibrated values.
A senior technology leader at a leading production
house said there is at least a 0.56% overestimation
of efciency in China, especially due to the
calibration method. On the other hand, companies
are using the cell efciency metric only for internal
evaluation and benchmarking, and module efciency
is considered the true metric for evaluation.
However, ITRPV and CPIA give an estimate for
stabilized cell efciencies. As shown in the graph,
CPIA estimates that the average TOPCon cell
efciency has increased from 25.4% in 2024 to
25.7% this year, and is expected to improve by 0.9
percentage points in the next 5 years to 26.6%. A
little on the conservative side, ITRPV estimates that
the efciency for 2025 is at 25.5% and will take only
2 years to improve by 0.5 percentage points to reach
26% in 2027, but another 8 years for the next 0.5%
absolute improvement.
TOPCon Processing
How did the technology get there? The essence
of the TOPCon process centers on passivation,
specically focusing on the rear surface engineering
of an n-type base wafer. This involves applying
an optimal passivation scheme, which includes
a nano-scale tunneling oxide layer topped with
a polysilicon layer that is then doped. For front
surface passivation, TOPCon cells require a layer of
aluminum oxide covered by silicon nitride. The rear
passivation stack is typically applied using either
low-pressure chemical vapor deposition (LPCVD)
or plasma-enhanced chemical vapor deposition
(PECVD), while some processes also utilize physical
vapor deposition (PVD). Additionally, the cell
Efciency Announcements for TOPCon
Parameter
H1-2023 H2-2023 H2-2024
Lab Level
Mass Pro-
duction
Average
Lab Level
Mass Pro-
duction
Average
Lab Level
Mass Pro-
duction
Average
JinkoSolar 26.40%26.40% 25.40% 26.89%26.89% 25.80%25.80% - - - -
DAS Solar 26.24%26.24% 25.30% 26.33%26.33% 25.90%25.90% - - 26.60%26.60%
Trinasolar 26.20%26.20% 25.50% - - - - 26.58%26.58% - -
Astronergy --25.60%25.60% - - 26%26% - - 26.90%26.90%
JA Solar - - 25.30%25.30% - - 26%26% - - 26.80%26.80%
JolywoodJolywood 26.70%26.70% - - - - 26%26% - - - -
SolarSpaceSolarSpace - - - - - - 25.30%25.30% - - - -
Tongwei SolarTongwei Solar - - 25.50%25.50% - - 26.10%26.10% - - 26.90%26.90%
JTPVJTPV - - - - - - - - 26.09%26.09% - -
Source: TaiyangNews 2025
Fab surpasses lab in 2 years: Within just 2 years, mass production efciencies for TOPCon have
exceeded their lab-level performance.
16 TaiyangNews | Cell & Module Technology Trends
25.6
25.3 25.3 25.4 25.5 25.5
26 25.9 26
25.8
26
25.3
26.1
26.9
26.6
26.8 26.9
24.5
25
25.5
26
26.5
27
27.5
Astronergy
DAS Solar
JA Solar
Jinko Solar
Tongwei
Trina Solar
Astronergy
DAS Solar
JA Solar
Jinko Solar
Jolywood
SolarSpace
Tongwei
Astronergy
DAS Solar
JA Solar
Tongwei
H1-2023 H2-2023 H2-2024
Efficiency (%)
Source: TaiyangNews 2025
High claims: Though cell efciencies are only used for internal evaluation, the claimed levels of
TOPCon are very high, close to 27% as of the end of last year.
Announced TOPCon Mass Production Efciencies
25.4
25.7
26
26.2
26.4
26.6
25.5
26
26.5
25
25.5
26
26.5
27
2024202520262027202820302035
Efficiency (%)
CPIA ITRPV
Graph TaiyangNews; Source CPIA, ITRPV
A long-term mismatch: While CPIA and ITRPV projections for TOPCon efciency are close in the
near term, their long-term forecasts diverge signicantly.
Estimated Cell Efciency Progress of TOPCon
Cell & Module Technology Trends | TaiyangNews 17
technology incorporates thermal processing steps,
such as boron diffusion.
Beyond the rear surface engineering, many
leading companies presented their loss analysis
simulation results at several conferences hosted by
TaiyangNews, which indicate areas of improvement
are related to passivation on the front, rear, and bulk.
That essentially indicates optimization requirements
in the area of recombination in contact and non-
contact regions of both p+ as well as n+ surfaces
and p+ hole transport regions. In fact, the major
losses were coming from the front surface. Thus, the
focus naturally shifted to improving the front surface,
which includes emitter surface passivation and metal
contact recombination. This was followed by some
improvements in rear passivation for n+ poly layers.
The rst line of improvement that nearly every
TOPCon manufacturer has taken up is implementing
the laser-doped selective emitter to reduce contact
resistivity. As it is well known, the application of
selective emitters creates a heavily doped metal
contact region and a lightly doped non-metal contact
region with reduced J0, metal that ultimately helps
in increasing ll factor (FF) and Voc. Despite the
additional step adding a little to both CapEx and
OpEx, the efciency boost, which was specied to
be in the range of 0.15% to 0.3%, as reported by
Jolywood and Astronergy in last 2023, lured most
of the companies to implement the selective emitter
in commercial production. Along with the paste
composition, contact optimization was also part and
parcel of the whole optimization process.
Laser-Assisted Contact Optimization
A somewhat revolutionary improvement that played
a big role in the majority of companies claims
achieving the 26% efciency level for TOPCon cells
is laser-assisted contact optimization. At its core, the
process uses laser power to form the front contacts
of TOPCon solar cells. To provide some background,
the emitter in a TOPCon cell is p+, which leads
to the silver ion getting suppressed. The current
practice to overcome this limitation is to use a silver-
aluminum paste on the front side. Though the silver-
aluminum paste solution improves contact resistivity,
it sometimes results in higher recombination. This
can be explained due to the formation of silver-
aluminum spikes at a micron-scale, which damages
junctions. Employing a laser for contact formation
can overcome this limitation. Here, a bias voltage
and strong light injection with high current density
diffuse the silver paste into silicon to form an ohmic
contact. The process essentially decouples the metal
Source: Jinkosolar
High mobility material: Risen has tactfully developed a target material with high mobility that
reduces resistivity not affecting optical properties.
18 TaiyangNews | Cell & Module Technology Trends
Source: Fraunhofer-CSP
A revolutionary process: If there is any ranking in TOPCon development in recent times, LECO
would top the list due to its ability to strike the right balance between contact resistivity and
recombination.
contact recombination and contact resistivity. The
ring process controls J0.m while the laser process
enables good contact formation, which together
mitigates the bottleneck of using Ag-Al metallization
paste in p+ emitter cells. The LEF process pushes
the balance between the Voc and FF to a higher
level.
Cell Engineering (CE), a company specializing
in solar cell technologies, began developing this
process called Laser Enhanced Contact Optimization
(LECO) in 2017 in cooperation with Qcells. This
approach has improved the efciency of TOPCon
as well as PERC cells by 0.2% to 0.5% absolute – a
game changer, especially for TOPCon technology.
In October 2022, Qcells took a signicant step by
acquiring Cell Engineering. As a result, Qcells now
holds 100% ownership of CE and the intellectual
property rights associated with LECO technology.
On the other hand, almost every Chinese PV
manufacturer involved in TOPCon has also
developed a similar process under a wide
variety of abbreviations. As to the questions of
intellectual property (IP), while choosing to remain
anonymous, an executive working very closely
with the technology and its active development told
TaiyangNews that most companies have developed
proprietary approaches on similar grounds, but
they are not the same. Leading paste makers such
as DKEM are offering pastes specically designed
for these applications. The paste with a superior
chemistry of organic and inorganic compounds and
their mix facilitates direct contact with the silicon,
which improves the conductivity and contact quality
between the silver paste and the silicon, according
to DKEM as elaborated in DKEM’s presentation at
the TaiyangNews High Efciency Solar Technologies
Conference 2023. The paste also showed better
printability; while silver-aluminum pastes pose
challenges for screen opening below 13 µm,
DKEM’s special paste for the laser process has
shown relatively better printability in a narrower
screen opening of 11.5 µm already in 2023. Not
only has DKEM successfully tested the reliability
of this front contacting paste, but it is also offering
the complete package, including the paste for rear-
side and busbars, which also require considerable
optimization.
20 TaiyangNews | Cell & Module Technology Trends
Furthermore, Solamet also emphasized that ne-
line printing and low solid content rear-side pastes
are the 2 mature and effective solutions for cost
reduction in TOPCon, as these approaches reduce
the use of silver (Ag). At the TaiyangNews High
Efciency Solar Technologies Conference 2024,
Solamet emphasized that silver particles – a key
component of paste composition along with Ag
powder, glass frit, binder, and solvent – play a critical
role in determining printability. Solamet highlighted
that ne-tuning the surface morphology of Ag
powder particles can signicantly enhance paste
performance and uniformity. In addition, optimizing
the ratio of different Ag particle sizes and carefully
balancing solid content, viscosity, and sintering
density all contribute to improved ne-line printability
and lower grid line resistance. In-house test results
with optimized paste formulation resulted in a
uniform grid morphology with screen openings down
to 9 µm.
Deposition Technologies
As mentioned above, the crux of the TOPCon
process lies in the rear surface passivation scheme,
and deposition technologies play a very crucial role
here. What is required here is forming a thin silicon
oxide-based tunneling lm, polysilicon topping it and
doped subsequently. PECVD and LPCVD are the 2
mainstream technologies for the core of the TOPCon
structure.
The latter, which is a thermal process, has the
longest track record, as most of the early adopters
of TOPCon kickstarted their mass production with
LPCVD. However, LPCVD typically had a few
shortcomings, such as wraparound, low life of the
quartzware, and external doping of polysilicon.
PECVD, in addition to supporting lower deposition
temperatures, also seamlessly integrates doping of
the applied polysilicon layer simultaneously (in situ).
The 2 processes have their own set of advantages
and limitations.
On the topic of PECVD, Leadmicro, a strong
advocate and leading supplier of such tools, offers 2
types of tool platforms. On the all-PECVD platform,
all the steps, including tunneling oxide as well
as polysilicon deposition and in-situ doping, are
accomplished using PECVD alone. The company
also offers a PEALD + PECVD tool platform that uses
Source: Solamet
Silver surface matters: Solamet underscores that the surface morphology and size of silver
particles play a considerable role in the quality of the contact formation.
Cell & Module Technology Trends | TaiyangNews 21
PEALD for tunneling oxide formation and PECVD for
the application of polysilicon and subsequent doping.
ALD results in very conformal coating, enabling the
application of very thin tunneling oxide layers that
favor efciency.
Leadmicro is offering its 5th-generation PECVD
all-in-one PECVD tool that supports a throughput
of 6,800 wafers per hour. The tool features a no-
cooling electrode maintenance solution that enables
maintenance of the electrode without the need
for the tube to cool down. The platform, which
combines PEALD and PECVD in one tool, reaches a
throughput of 7,100 wafers per hour.
Laplace is a leading supplier of LPCVD tools. The
difference between PECVD and LPCVD starts
with the application of tunneling oxide. In LPCVD,
the tunneling silicon oxide layer is grown in situ
thermally, while the lm is deposited in PECVD using
oxygen or N2O plasma. According to Laplace, it is
well known that thermally grown silicon oxide layers
are superior in quality to deposition layers. As for
in-situ doping, Laplace highlights that the thermal
treatment step is still needed to activate the dopant
in the PECVD approach, while in the LPCVD route,
the dopant is induced and activated in one step. In
order to have some control over the wraparound,
LPCVD tools are typically loaded with one wafer per
slot. Then, irrespective of the deposition method, the
post-deposition chemical treatment is inevitable.
However, Laplace made considerable progress
in a few areas quickly thereafter. The company’s
improved product platform supports the processing of
2 wafers per slot, with full control over wraparound.
This doubles the throughput to 8,600 per hour. With
the help of specic recipes and special know-how,
Laplace says it has been able to improve the lifespan
of the quartz boats to 6 months, and 12 months for
quartz tubes as opposed to 4 months in the past.
The thickness of the polysilicon layer has been a
topic of interest. Here, equipment makers follow the
developments in pastes, which currently support
80 nm. Equipment vendors, paste suppliers and
PV manufacturers are all collectively working on
reducing this thickness further.
In addition to these, leading PVD tool maker Von
Ardenne has also stared offering PVD-based solution
for TOPCon. VON ARDENNE says its system
simplies the process ow by sequentially depositing
the tunnel oxide and doped polysilicon layers without
backside wraparound or separate thermal oxidation.
It also allows for front and rear SiNx passivation
within a single tool. Trials conducted on Fraunhofer
ISE’s TOPCon line showed a +0.1% absolute
efciency gain when replacing PECVD SiNx with
sputtered PVD SiNx, alongside improvements
in open-circuit voltage and ll factor, claims the
tool vendor. The PVD process also eliminates the
need for hazardous gases like phosphine, silane,
and ammonia, signicantly reducing permitting
complexity, facility costs, and operational expenses
– an advantage particularly valuable in emerging
manufacturing regions such as the US, India, and
MENA. In addition, the PVD-based setup drastically
reduces equipment count with its undeniable high
production capacity of 1.3 GW with its GigaNova
platform. It also lowers cleanroom requirements,
leading to overall lower total cost of ownership
compared to conventional CVD setups.
As a side note, all the mainstream equipment
makers that are supplying production tools for
TOPCon are already looking beyond. Companies
like Laplace have collected the resources to offer full
production line solutions for BC. Leadmicro is taking
a step ahead and is already offering deposition tools
for tandem technology.
The GigaNova platform from VON ARDENNE
was also highlighted as adaptable for future cell
architectures. The tool’s chambers, designed for
front-side SiNx deposition, could be recongured
to deposit TCO and ETL/HTL layers, requiring
only limited additional investments. In addition
to sputtering, this tool platform also supports
evaporation, which is required for perovskite
technology.
Edge Passivation
Edge passivation is an emerging trend in the
TOPCon area. The aim with this approach is
to eliminate the undesired losses that originate
from cutting cells in half or, as a matter of fact,
several pieces as and when required. For some
background, cutting a fully processed cell in half
creates defects along the cut corners. These defects
act as recombination centers, possibly leading to
slight performance losses. The edge passivation
22 TaiyangNews | Cell & Module Technology Trends vonardenne.com
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Cell & Module Technology Trends | TaiyangNews 23
Source: Leadmicro
Half-Cell Processing: Leadmicro is presenting an innovative half-cell processing tool, which has
so far been exclusive to HJT.
neutralizes these defects and eliminates the losses.
In the process, the passivation layers are precisely
applied to the cut edges without undesirable effects
on the cell surface. The process is only relevant to
TOPCon, as HJT has long adapted to processing
half cells all along the line. Being a batch process,
TOPCon is not exactly compatible with half-wafer
processing. During the process, an aluminum oxide
lm is applied on the laser-cut edges using ALD.
Most leading equipment makers, including Laplace,
Leadmicro, and Ideal Energy, among others, are
offering edge passivation tools. Depending on
the baseline process, different tool vendors and
manufacturers have announced an efciency gain
ranging from 0.1% to 0.3%.
On the other hand, a particularly interesting
development is that Leadmicro has introduced a
thermal and deposition tool platform capable of
supporting half-cell processing for TOPCon. The
most immediate benet is the elimination of edge
losses. Additionally, this approach improves ingot
utilization upstream and supports efforts to reduce
wafer thickness.
Rear Poly-Fingers
Another important trend that is catching up quickly
among the TOPCon suppliers is rear poly-ngers.
Localized rear ngers is a concept inspired by back-
contact cell designs, where polysilicon is applied
in a ngered pattern on the rear side. The process
involves laser ablation of the rear passivation stack
in non-contact regions, meaning the stack of silicon
oxide and doped polysilicon is etched off in all
open areas on the cell’s rear side except where the
contacts are applied. The technology can benet
from the laser tool ecosystem developed for back-
contact cells. Indeed, several mainstream equipment
vendors in China, most recently Laplace, have also
started developing such laser tools. This approach
reduces the parasitic absorption of poly-layers on the
rear side, improving the bifaciality from 80% to 85%.
These localized rear ngers have the potential to
improve the overall cell efciency from 0.1% to 0.2%
absolute.
Although front-side localized poly could theoretically
provide further benets, its implementation is far
more complex due to alignment challenges and the
sensitivity of front-side emitters, which increases
the risk of shunting and defects. The introduction
of laser-induced metallization (LIM) has already
signicantly reduced front-side recombination,
making localized poly less attractive. Additionally,
24 TaiyangNews | Cell & Module Technology Trends
Source: Fraunhofer-ISE
applying poly ngers on the rear side provides
greater tolerance in patterning, making it easier to
implement. However, this is not unanimous, and the
jury is still out.
Despite these challenges, a few companies have
bifacial poly, essentially implementing poly-ngers
also on the front side. This approach also includes
optimization of contact formation, passivation, and
bulk properties. Paste manufacturers are actively
developing new pastes specically designed for
bifacial poly applications.
IP Conicts
Once a battleground dominated by Western
companies targeting Chinese manufacturers, the IP
landscape in solar cell technology is rapidly evolving.
The spotlight is now on TOPCon, not just for its
performance edge, but for the urry of intellectual
property disputes it’s igniting across borders –
and increasingly within China itself. As seen in the
chart, litigation is no longer a West-versus-East
affair; Chinese rms are now actively pursuing legal
claims against their own domestic rivals, signaling a
maturing and ercely competitive market.
This wave of patent battles is proving to be more
than just courtroom drama. It’s directly impacting
strategic decisions: several companies, particularly
newcomers trying to establish cell production lines,
are opting for older PERC technology instead,
despite its lower efciency, just to steer clear of the
legal uncertainties surrounding TOPCon. The web
of active claims spans the US, EU, and Asia-Pacic
regions, and touches nearly all major players – from
JA Solar, Trina, and Jinko to Maxeon, Qcells, and
Canadian Solar.
As this IP heatwave continues, it underscores a
crucial shift in the solar sector: innovation now
comes with a legal price tag, and navigating the ne
print of patents is becoming as critical as optimizing
cell efciency.
Developments in progress: TOPCon, although mainstream, is also advancing with approaches like
laser-assisted contact formation and edge passivation.
Cell & Module Technology Trends | TaiyangNews 25
Heterojunction (HJT) is a prominent high-efciency
cell technology that has evolved into a serious
contender for mainstream solar production. Built on
the foundation of marrying crystalline silicon with
thin-lm amorphous silicon layers, it stands out as
a unique approach among PV cell technologies
that has been particularly attractive to newcomers
looking to avoid launching yet another ‘me-too’
product. However, despite its promise, HJT has
often remained a contender rather than becoming
mainstream, largely due to its higher costs both
in terms of CapEx and OpEx. Nevertheless, the
technology has secured a loyal group of serious
followers who have established multi-gigawatt-
scale manufacturing facilities, driven by several
undeniable advantages. HJT offers benets such
as low-temperature processing, a reduced number
of process steps, high bifaciality, and a superior
temperature coefcient. Moreover, it is widely
regarded as an ideal platform for the development of
future tandem solar cells. Against this backdrop, we
summarize a range of important developments in the
HJT segment in this chapter.
3.1 Wafers
Like with other commercial advanced cell
technologies, HJT also uses n-type base wafers.
However, compared to its peer technologies, HJT is
most forgiving in terms of wafer quality.
Electrical Parameters
It is already established that in order to address the
requirement for high wafer quality, the industry has
adopted a heat treatment process (annealing) that
mimics gettering, a process of removing metallic
impurities with thermal treatment. As a result, HJT
can now use wafers from different positions of the
ingot and production runs of the crucible.
Annealing is now the standard in the HJT process
sequence. An important development with respect to
wafer requirements for HJT is its compatibility with
low-cost wafers originating from the rechargeable
Czochralski (CZ) technology. In this method, after
the initial silicon melt is depleted during ingot
pulling, the crucible is relled with a new charge of
polysilicon, allowing continuous operation. While
the process results in higher oxygen content, this
is not a concern for HJT. That’s because HJT does
not involve steps involving high temperatures, which
would otherwise activate oxygen-related defects.
Moreover, it also allows the integration of another
low-cost process upstream.
The ingot pulling process can also use the low-
cost granular silicon produced with the uidized
bed reactor (FBR), which results in slightly lower
purity than the standard method, but still aligns well
with the requirements for HJT. Wafer producers like
LONGi (with its new TaiRay wafer technology) have
3. Heterojunction (HJT)
Typical Wafer Specications for HJT
Parameter n-type TaiRay wafer
(LONGi)
n-type HJT wafer -
option 1
n-type HJT wafer - n-type HJT wafer -
option 2option 2
Doping Element Antimony Antimony Phosphorus Phosphorus Phosphorus
Resistivity (Ω·cm) 0.7 - 1.4 0.7 - 1.4 0.3 - 2.1 1 - 7 1 - 7
Minority Carrier Lifetime
(μs) ≥ 1000 ≥ 1000 ≥500 ≥ 1000 ≥ 1000
Interstitial Oxygen (ppma) ≤ 12 ≤ 12 ≤ 14 ≤ 14 ≤ 14 ≤ 14
Substitutional Carbon
(ppma) ≤ 1 ≤ 1 ≤ 1 ≤ 1 ≤ 1 ≤ 1
Graph: TaiyangNews; Source. Huasun, LONGi
Easy on wafers: HJT technology has become more tolerant of wafer specications, accommodating
high oxygen content and enabling the use of low-cost FBR silicon.
26 TaiyangNews | Cell & Module Technology Trends
also raised the bar in overall wafer quality.
The table below lists the typical wafer specs for HJT
cells. HJT wafers come in 2 main resistivity ranges:
0.3–2.1 Ω·cm and 1–7 Ω·cm, with 0.3–2.1 Ω·cm
being the mainstream. The minority carrier lifetime
of HJT wafers varies signicantly depending on
resistivity. In general, HJT wafers have lower lifetime
requirements compared to TOPCon wafers.
When it comes to physical properties, the majority
of HJT producers have adapted to half-wafer
processing. This enables them to improve the ingot
utilization rate by deriving the half bricks from the
slide slabs of the ingot.
An even more compelling topic related to wafers
when it comes to HJT is thickness; to be specic,
the ability to process thin wafers. Huasun Energy,
a leading HJT manufacturer, reported using wafers
around 120 µm thick in mid-2024, with a target
to reach 110 µm by the end of that year. At the
TaiyangNews High Efciency Solar Technologies
Conference held in December 2024, Huasun, as
well as Risen, another HJT leader, announced that
100 µm has already entered production, while a
thickness of 90 µm is being evaluated. However,
companies put an 80 µm cap for wafer thickness
reduction, as any further lowering beyond this would
start affecting efciency.
Both CPIA and ITRPV project a continuous decrease
in wafer thickness, although their forecasts differ in
specic gures and timelines. According to CPIA,
HJT technology has led wafer thickness reduction
efforts, reaching 110 µm last year. This is expected
to further decrease to 105 µm this year and to
100 µm by 2026, although the pace of reduction
is anticipated to slow thereafter, reaching 90 µm
by 2030. In comparison, ITRPV projects relatively
higher wafer thicknesses. According to ITRPV, wafer
thickness is expected to decline from 125 µm last
year to below 120 µm this year, eventually reaching
100 µm by 2032.
Several factors make HJT particularly well-suited
for utilizing thinner wafers. The technology's
symmetrical cell structure, with passivation layers
applied to both sides, helps balance stress and
prevent wafer warpage. Furthermore, the entire HJT
fabrication process takes place at temperatures
below 250°C, avoiding the thermal stress associated
with high-temperature processes typically involved
in contemporary processes. The surface passivation
80
90
100
110
120
130
202420252026202720282029203020322035
Wafer thickness ( µm )
CPIA ITRPV
Lorem ipsum
Continuous thinning: Both CPIA and ITRPV project ongoing reductions in wafer thickness, though
their forecasts differ in the pace and target values.
Wafer Thickness Redcution with HJT
Graph TaiyangNews; Source CPIA, ITRPV
Cell & Module Technology Trends | TaiyangNews 27
of HJT also becomes increasingly advantageous
as wafer thickness decreases, since surface
recombination plays a considerable role in overall
losses for thinner cells. The drive towards thinner
wafers offers multiple benets – most directly, it
reduces silicon consumption.
As for the dimensions, the HJT segment has not
been very active. G12 remained the mainstream
wafer for a long time. At one point, no manufacturer
was offering M10 cell-based HJT modules.
Eventually, leading HJT makers also adapted to
rectangular wafer formats, especially for residential
and utility applications.
3.2 Cells
The most important attribute of HJT is that it is a
fusion of wafer-based solar cell technology and
thin-lm PV, taking the best features from each. It
has the excellent absorption properties of standard
silicon wafer-based cells and superior passivation
characteristics of thin-lm amorphous silicon. The
core HJT structure involves a crystalline silicon
wafer, sandwiched between intrinsic and oppositely
doped amorphous silicon layers on both sides.
This structure has indeed been the backbone of
several world record efciency levels. A signicant
milestone for HJT was LONGi achieving a world
record efciency of 26.81% for an HJT-only cell
structure (i.e., not incorporating back contacts) in
November 2022. This surpassed the long-standing
record held by Kaneka (26.7% on an HBC structure,
which combines HJT with Interdigitated Back
Contacts). As for commercial efciency, Huasun
has been leading with mass production efciency
of 25.5% reached in 2023, 26.1% in mid-2024, and
26.5% by the end of last year. Emphasizing that the
cell efciencies are only for internal assessment
purposes, companies have stopped talking about
cell efciencies, mostly promoting module power and
efciency. However, according to neutral sources
such as CPIA, HJT cell efciency was 25.4% in
2024, which improved by 0.3 percentage points to
25.7% in 2025 and is expected to reach 26.9%,
which is 0.3 percentage points higher than TOPCon
by 2030. On the other hand, ITRPV says the
technology would only reach 25.7% in 2025, then
25.9% in 2027, and will take 10 years from now to
reach 26.6%.
HJT Processing
HJT has been promoted as a technology with fewer
processing steps. After the silicon wafers are etched
25.6
25.9
26.2
26.5
26.7
26.9
25.7
25.9
26.6
25
25.5
26
26.5
27
2024202520262027202820302035
Efficiency (%)
CPIA ITRPV
Difference of opinion: CPIA and ITRPV diverge on HJT efciency forecasts – CPIA expects 26.9%
by 2030, while ITRPV doesn’t project this level even within the next decade.
Estimated Cell Efciency Progress of HJT
Graph TaiyangNews; Source CPIA, ITRPV
Cell & Module Technology Trends | TaiyangNews 29
to remove saw damage and textured, intrinsic
amorphous silicon layers are applied to both sides,
followed by doped amorphous silicon lms with
opposite polarities. Next, a TCO lm is applied to act
as an antireective coating and conductive electrode
for current extraction. A metallic grid is then screen-
printed on top of the TCO and cured to produce the
HJT cell. While keeping these fundamentals intact,
a few technical advancements in the HJT segment
have driven the technology’s progress.
The Shift to Double-Sided Microcrystalline
Silicon
A fundamental evolution within the HJT cell structure
involves replacing the doped amorphous silicon (a-
Si) layers with doped microcrystalline silicon layers.
This transition has taken place sequentially: rst
replacing the doped a-Si layer on the emitter side
(often referred to as HJT 2.0), and subsequently
replacing the layer on the rear side as well, resulting
in a double-sided microcrystalline structure (HJT 3.0).
This architectural shift is motivated by the inherent
material limitations of doped amorphous silicon.
Compared to amorphous silicon, the microcrystalline
silicon exhibits lower parasitic light absorption,
particularly in the shorter wavelength range. This
shift reduces the parasitic absorption losses of HJT
to an extent. Additionally, microcrystalline silicon
has better electrical conductivity than amorphous
silicon, which reduces series resistance losses
within the cell, leading to an enhancement in the
ll factor (FF). It also shares the responsibility for
lateral conductivity with TCO to an extent. The
implementation of microcrystalline silicon layers
requires advancements in deposition equipment
and processes. All leading equipment vendors, such
as Maxwell, have optimized their tool platforms
and these have been implemented at leading HJT
makers. The structure has already been the standard
for some time. The other important developments in
the HJT segment are PIB-based edge sealants and
the adoption of down-conversion encapsulation lms
as standard.
High Mobility TCO
A relatively more recent advancement in HJT
processing is high mobility target materials for TCO
from Risen. The TCO layer is critical because it must
balance 2 essential properties: high conductivity and
high optical transparency. To optimize the TCO layer
performance, Risen focused on 3 main directions:
lowering the resistivity of the layer, increasing its
light transmittance, and enabling low-temperature
Source: Risen
High mobility material: Risen has tactfully developed a target material with high mobility that
reduces resistivity not affecting optical properties.
30 TaiyangNews | Cell & Module Technology Trends
deposition for better compatibility with delicate cell
structures, a few of which are counteracting. In
practice, lowering the resistivity of the TCO layer
is the primary goal. Resistivity largely depends on
2 factors: the carrier concentration and the carrier
mobility within the layer. Increasing the carrier
concentration can reduce resistivity, but it also
increases light absorption within the TCO layer
itself. This leads to less sunlight reaching the active
cell area and ultimately reduces the overall cell
efciency. Conversely, improving carrier mobility
reduces resistivity without negatively impacting light
transmittance. Therefore, a careful balance between
carrier concentration and carrier mobility must be
achieved to optimize cell efciency. Risen developed
an optimized target material composition that
enhances carrier mobility – a 29.11% improvement.
This enhancement, while maintaining a favorable
carrier concentration, led to an approximate 0.02%
absolute efciency gain at the single-cell level,
according to Risen.
Metallization
HJT as a technology is more than 2 decades old,
and has always been an efciency pioneer. Until very
recently, HJT always had an edge over its peers;
even now, albeit marginal. But the major bottleneck
of the technology has been its higher costs, mainly
stemming from higher equipment CapEx and, more
importantly, higher manufacturing costs. Metallization
is the key contributor to costs, and if narrowing
down to the microscale, silver paste is the origin.
This is primarily because of the cost associated with
specialized low-temperature silver pastes required
for HJT. The lower conductivity of these pastes
compared to the high-temperature pastes used in
PERC and TOPCon necessitates wider ngers or
higher paste laydown, increasing silver consumption.
Thus, advancements in metallization are crucial for
HJT's cost reduction roadmap.
Leading paste supplier Fusion has provided a nice
overview on the status of the current metallization
scene, recent advancements and outlook.
Metallization costs can be reduced in 2 ways: by
reducing the paste usage and lowering the silver
loading of the paste composition. The reduction in
paste consumption can be achieved differently for
busbars and ngers, and they are also interlinked.
More Busbars to No Busbars
Busbar optimization is a rather low-hanging fruit
in optimizing metallization for HJT. The rst line of
action related to busbars is to increase the number
of busbars. The number of busbars went from 9
to 20 between 2022 and early 2024, as shown
Source: Fusion
From more to none: As shown in this graph, HJT technology — and similarly other cell
architectures — saw an increase in the number of busbars from 9 to 20, before moving toward
entirely eliminating busbars from the cell layout.
32 TaiyangNews | Cell & Module Technology Trends
in the graph below. This increase helped narrow
the screen opening from 50 µm to 27 µm. Toward
the end of 2024, Fusion developed an interesting
version of silver-coated copper paste for busbars,
with 55% silver content, and it quickly entered mass
production. On the other hand, most of the leading
manufacturers had moved away from using busbars
in the metallization layout by then, adopting ZBB
technology. See the Modules section for more details
on the zero busbar approach.
Low on Silver Loading
The cost reduction roadmap for ngers can take
2 parallel paths: reducing the paste laydown and
reducing silver loading. An innovative form of the
latter approach is using silver-coated copper particles
instead of pure silver particles. This technology
is not new, and the industry has been reducing
the silver content of such pastes steadily. The
industry was able to use Fusion’s paste formulation
mentioned above and from other leading paste
vendors with 50% silver content in 2023, followed
by further reductions to 40% in Q2 2024 and 30%
in Q4 2024. These pastes are suitable for use in
both super MBB (SMBB) and ZBB architectures,
and can be applied to both front and rear ngers.
More recently, Fusion developed a new formulation
with just 20% silver, currently recommended only
for rear nger applications. This is mainly to keep
performance parity with pure silver pastes within the
acceptable deviation. The table below summarizes
the performance losses of silver-coated copper
along with the reduction of silver content. A point to
be noted: the reduction in silver does not directly
relate to cost savings, as one also needs to factor in
the processing costs of silver-coated copper into the
costs of silver-coated copper paste. For example,
50% silver content in a silver-coated copper paste
reduces the costs by 35%, and its performance is
comparable to pure silver-based pastes. A paste with
20% silver content reduces costs by 50%, maintains
good reliability, and keeps efciency losses within
0.1%.
Low laydown
The nger provides yet another avenue for
optimization, which is reducing the width, and is
directly proportional to paste usage and costs.
According to Fusion, between 2022 and 2024, silver
consumption in HJT cells remained higher than in
TOPCon. During this period, screen opening widths
were reduced from 22 µm in 2022 to 14 µm in 2024.
As a result, silver consumption decreased from
21 mg/W to 11 mg/W, though still slightly above
TOPCon levels. Risen puts silver consumption at 10
mg/W in 2023, also using silver-coated copper.
In order to reduce the nger width further, which is
necessary to reduce metallization costs, the HJT
segment is moving away from mesh screens to
stencil screens based on either nickel or steel. Since
these screens are free crossover wires of mesh, they
facilitate realizing ngers with higher aspect ratios,
meaning lowering nger widths. According to Fusion,
using these screens has enabled manufacturers
to reduce screen openings to around 10 µm, with
a few going even further. Risen emphasizes that it
has achieved a nger width of 24 µm and an aspect
ratio of 46% with its knotless steel screens. Fusion
also attained a 46% ratio and about a 27 µm nger
thickness with its steel screen. When combined
with ZBB technology and the use of silver-coated
Key Metrics of Silver Coated Copper
Ag % Cu % ReliabilityReliability Cost reductionCost reduction Efciency lossEfciency loss
100 0 OK BL BL
50 50 OK 30-35% ~0.01%
40 6060 OKOK 35-40%35-40% ~0.01%~0.01%
30 7070 OKOK 40-45%40-45% 0.01~0.05%0.01~0.05%
20 8080 OKOK 45-50%45-50% 0.05~0.10%0.05~0.10%
Source: Fusion
Cost-performance balance: Reducing silver lowers both costs and efciency, but achieving a 50%
cost cut with only a 0.1% efciency loss at 20% silver presents a compelling trade-off.
Cell & Module Technology Trends | TaiyangNews 33
copper pastes with just 30% silver content, silver
consumption can be brought down to as low as 6
mg/W. At this level, silver usage is already below that
of TOPCon, and Risen also put a cost tag of 4.4 to 4.8
RMB cents/W.
With ongoing advancements, including further
narrowing screen openings to around 10 µm or
even below, and the adoption of steel plate screens,
some customers have already achieved additional
reductions.
Paste composition
As screen openings become increasingly narrower,
maintaining high-speed printing in HJT cell
production is becoming more challenging. Therefore,
a paste composition that supports both ultra-narrow
screen openings and fast printing speeds is crucial,
and this largely depends on the optimization of the
paste’s organic composition. A typical HJT silver
paste consists of 3 key components. The rst is the
conductive base, typically made of pure silver or
silver-coated copper powder. The second component
is the resin, which is usually an epoxy type. The
third includes organic solvents and additives. Poor
compatibility among these ingredients can lead to
particle aggregation, preventing uniform dispersion
within the system. This, in turn, can lead to printing
defects such as line spreading, broken ngers, or
– in more severe cases – screen clogging due to
high levels of aggregation. The paste formulation
must strike the right balance to ensure smooth and
reliable printing. This means achieving synergy
between optimized particle size and morphology,
a well-matched resin, and effective dispersants –
all tailored to perform according to the demands of
narrow openings and fast production speeds.
Out look
Looking ahead, optimization of metallization is the
key for HJT. The roadmap for how to bring HJT’s
silver consumption HJT at par with TOPCon is clear
– ZBB in combination with 30% silver content of
silver-coated copper paste. In the short term, the
industry’s goal is to make such, or even an ultra-
low 10%, silver consumption a standard in mass
production. Advanced metallization techniques,
such as laser transfer printing, can also help realize
ultra-thin ngers below 20 µm with aspect ratios
above 50%. Additionally, they can help reduce silver
consumption and improve efciency by at least 0.1%,
according to Fusion. But the eventual and ultimate
goal is to replace silver altogether, with several
paste makers already working in this direction. At
the TaiyangNews High Efciency Solar Technologies
Conference, Fusion also showed a glimpse of the
copper paste solutions it is working on.
Source: Fusion
Reduce or replace silver: Future HJT optimization focuses on minimizing silver usage through
ne-line printing and lower silver content in pastes – or replacing it entirely.
Cell & Module Technology Trends | TaiyangNews 35
While the preceding chapters discussed broader
technology trends in cell architectures, it is clear
that the most signicant trend within this space
today is the rise of back contact (BC), particularly in
China. Amid a severe overcapacity situation in PV
manufacturing, especially for TOPCon technology,
virtually all major manufacturers have paused new
expansion plans within China. In this environment,
the only notable capacity building that is happening
revolves around BC technology, albeit still in
relatively modest volumes. Nearly every leading PV
manufacturer is now establishing at least a pilot line
and working on BC development behind the scenes.
However, 4 companies are actively driving the
technology on the commercial front: the pioneer of
back contact technology, Maxeon, along with AIKO,
LONGi, and SPIC. Given the competitive landscape,
much of the innovation and development around BC
remains condential. Nonetheless, TaiyangNews had
the opportunity to engage directly with 3 of these
leading players — AIKO, LONGi, and SPIC — to
gain insights into the evolution of BC. While not all
questions were answered fully, as expected due to
condentiality constraints, the executives provided
valuable perspectives on the current status and the
direction of BC development. Until a dedicated, in-
depth report covering all aspects of BC technology
is published, this chapter summarizes the key
takeaways from our discussions with these industry
leaders and serves as a preface to our upcoming
exclusive report.
Back contact solar cell technology refers to a design
where all the electrical contacts — both positive
and negative — are moved to the rear side of the
solar cell, leaving the front surface entirely free of
metal. This architecture eliminates shading losses
caused by front-side metallization (which is present
in conventional solar cells), allowing more sunlight to
be absorbed and improving the overall efciency of
the cell.
In BC cells, light enters through a clean,
uninterrupted front surface, while the rear side is
carefully structured with interdigitated (alternating)
positive and negative contacts to collect the electrical
current. This structure requires precise engineering,
including advanced passivation layers, laser
patterning for contact separation, and specialized
metallization techniques.
LONGi’s journey toward BC began around 2016–
2017, during a period when the company was
simultaneously investing heavily in multiple cell
technologies, including, PERT, TOPCon, and HJT.
LONGi’s guiding philosophy has always been to
maintain broad R&D exploration while narrowing
production choices based on rigorous scientic
evaluation.
The motivation for prioritizing BC crystallized during
a period when all new world records for silicon-based
single-junction solar cell efciency were achieved
with BC structures. For example, SunPower’s
BC cell with passivated contacts achieved 25.2%
efciency on a fully manufacturable platform, while
Kaneka’s heterojunction-based BC cell reached
a groundbreaking 26.3%. These milestones
were signicantly higher than the commercially
4. Back Contact (BC)
Source: LONGi
Back to front: Back contact solar cells
feature rear-mounted electrodes, leading to
enhanced light capture on the front, leading to
higher efciencies.
36 TaiyangNews | Cell & Module Technology Trends
manufacturable efciencies of PERC cells at the
time. LONGi recognized that while cost reduction is
vital for PV market success, true long-term value lies
rst in achieving higher efciencies, and BC offered
a clear and scalable path for both efciency gains
and future cost optimization. Following an exhaustive
rst-principles analysis, LONGi concluded that
BC technology had vast untapped potential and
that its primary barriers, mostly related to cost,
were technically surmountable through targeted
innovation.
Similarly, AIKO’s decision to focus on BC was the
result of a deliberate evaluation process across
multiple high-efciency technologies. The company’s
R&D efforts included work on HJT, TOPCon, and
BC cells. However, after careful consideration,
AIKO selected BC for mass production, citing
its combination of highest efciency potential,
superior aesthetics with a pure black appearance,
and greater energy yield. According to AIKO, BC
modules not only exhibit a lower temperature
coefcient and better degradation rates compared to
other architectures, but they also demonstrate higher
temperature tolerance and better partial shading
resilience – important traits that enhance real-world
energy generation.
Convinced by these advantages, all 3 companies
have built commercial capacities. Leading the trio,
LONGi plans to reach a total BC production capacity
of 50 GW, with with its HPBC 2.0 technology.
AIKO, another major proponent of BC technology,
is also expanding at a rapid pace. The company
currently operates 2 facilities, one with 10 GW BC
cell and module production capacity and another
with 15 GW. AIKO is also adding a new facility with
25 GW capacity, with the module part of it already
operational. SPIC commissioned its initial 200 MW
IBC line in 2019, which has since been upgraded to
TBC (TOPCon Back Contact) with a current capacity
of around 240 MW. Looking ahead, SPIC has plans
to expand further, with new BC production lines
under consideration that could range from 1 GW to 5
GW, depending on funding availability. Additionally,
SPIC maintains about 400 MW of TOPCon
production capacity alongside its BC operations.
4.1 Wafers
As with the other cell technologies, BC also
has a special list of requisites in terms of wafer
specications, perhaps a more demanding one. One
of the most critical differences is in wafer resistivity.
While TOPCon cells typically require wafers with a
resistivity range of around 0.4 to 1.6 Ω cm, BC cells
employ wafers with much higher resistivity, often
Source: AIKO
Beauty also counts: One of the key reasons for AIKO to adopt the back contact architecture is
superior aesthetics with a pure black appearance.
Cell & Module Technology Trends | TaiyangNews 37
greater than 30 Ω cm. According to AIKO, higher
resistivity enables longer minority carrier lifetimes,
which is essential for optimizing the performance of
BC cells. Similarly, LONGi emphasized that its HPBC
2.0 cells use TaiRay wafers – an independently
developed, antimony-doped wafer type – designed
specically with higher purity, lower oxygen and
metal impurity concentrations and, critically, higher
resistivity. This allows BC cells to reach a higher
theoretical efciency limit vis-à-vis TOPCon cells,
which cannot tolerate high-resistivity substrates.
Beyond resistivity, carrier lifetime is another crucial
factor. Both SPIC and AIKO highlighted that
achieving a high minority carrier lifetime is even more
important than resistivity alone. SPIC noted that
BC wafers need to exhibit lower levels of oxygen,
carbon, and metal impurities compared to TOPCon
wafers, contributing to better electronic quality and,
ultimately, improved cell performance. While SPIC
acknowledged that exact specications can vary,
it points out that wafers meeting BC requirements
typically command a higher price than those used for
TOPCon, largely due to stricter quality standards.
In contrast to HJT, which can still tolerate relatively
high oxygen content, BC demands wafers with very
low contamination levels to minimize recombination
losses and ensure superior device performance.
This focus on material quality is in line with BC’s
underlying strategy: achieving extremely high
efciencies by reducing all parasitic losses, including
those stemming from the bulk material itself.
4.2 Cells
Although back contact (BC) technology follows the
common principle of relocating all electrical contacts
to the rear side of the solar cell, there are several
variations.
BC structures
The base variant of the BC structure is diffused
inter-digitated p+ and n- regions. There are also
variations coming from the base wafer – p- or n-type.
Adapting the passivated contact strategy to the
back contact architecture is another variant, and
most BC structures fall into this category. However,
the early BC designs passivated only one polarity
of the contact, but later developments introduced
passivation for both polarities. Additionally, the
HJT structure can also be tweaked into BC, which
liberates the architecture from one of its key
limitations – parasitic absorption of light.
The cell structures adopted by leading manufacturers
also have a few differences in how they balance
light absorption, passivation, and carrier collection.
At LONGi, the BC cell structure is centered on
maximizing optical and passivation performance
at the front, while dedicating the rear side solely
to electrical collection. The ‘sunny’ side is covered
with a uniform, full-area passivating anti-reective
coating that optimizes both surface passivation
and light management without any interruptions
from metal contacts. This avoids shading and
parasitic absorption losses at the front surface – a
clear advantage over conventional structures. The
rear side consists of passivating as well as non-
passivating contact zones. With in the passivating
contact zones, LONGi uses a bipolar passivation
strategy, meaning that both the p-type and n-type
regions employ passivating contacts. LONGi refers
to this careful design approach as a ‘division of
labor,’ where each functional layer is optimized for
Typical Wafer Specications for BC
Parameter n-type TaiRay wafer (LONGi) n-type BC wafer
Doping Element Doping Element Antimony Antimony Phosphorus Phosphorus
Resistivity (Ω·cm) Resistivity (Ω·cm) 0.7 - 1.4 0.7 - 1.4 5 - 25 5 - 25
Minority Carrier Lifetime (μs) Minority Carrier Lifetime (μs) ≥ 1,000 ≥ 1,000 3,000 – 16,000 3,000 – 16,000
Interstitial Oxygen (ppma) Interstitial Oxygen (ppma) ≤ 12 ≤ 12 6 - 11 6 - 11
Substitutional Carbon (ppma) Substitutional Carbon (ppma) ≤ 1 ≤ 1 0 - 0.8 0 - 0.8
Graph: TaiyangNews; Source: Aiko, LONGi
More demanding: Among all mainstream technologies, BC has the highest wafer quality
requirements.
Cell & Module Technology Trends | TaiyangNews 39
either light management, passivation, or carrier
collection.
AIKO calls its BC architecture ABC, abbreviated
for All Back Contact technology. The front side of
the ABC cell features an anti-reection coating
made from a combination of aluminum oxide and
silicon nitride, providing both passivation and
reection control. Meanwhile, the rear side uses
a high-temperature passivating contact structure,
where both p and n regions integrate TOPCon-like
layers for superior carrier selectivity and reduced
recombination. AIKO emphasized that this rear-side
design – combining dual TOPCon-based passivation
– is key to achieving both very high efciency and
strong real-world performance.
SPIC, another early mover in BC technology,
originally based its rst generation of BC cells on
the Zebra structure developed by ISC Konstanz,
using a thermal diffusion process to form an n-type
back surface eld and a p-type emitter without
the need for isolation zones. However, SPIC has
since transitioned to its own in-house developed
TBC (TOPCon Back Contact) structure. In the new
design, TOPCon passivation is employed at the
rear side, but with strict isolation between the p and
n regions to minimize recombination losses. This
evolution marks a shift from the simpler diffusion-
based architecture toward more sophisticated
selective passivation similar to other modern BC
designs.
Efciency
Keeping track of cell efciencies with BC is not
straightforward. Manufacturers tend to be precise
only when reporting laboratory or record efciencies.
For commercial production, however, there is no
accurate characterization method commonly agreed
upon – particularly when zero busbar (ZBB) designs
are involved. As a result, efciency gures at the
cell level are primarily used for internal process
validation rather than industry-wide benchmarking. In
a way, this ambiguity offers some leeway. Otherwise,
it would be surprising to see several BC proponents
claim efciencies approaching 27%, considering
that the certied lab record for crystalline silicon
single-junction cells achieved by LONGi using a BC
architecture is not far apart, at 27.81%. Nonetheless,
both ITRPV and CPIA have published the estimated
efciency progress of BC technology. According
to CPIA, BC technology’s efciency is expected to
improve steadily, starting at 26% in 2024, reaching
26.3% in 2025, and progressively increasing to
26
26.3
26.6
26.9
27.2
27.4
25.9
26.2
27.3
25
26
27
28
2024202520262027202820302035
Efficiency (%)
CPIA ITRPV
Graph TaiyangNews;
Source CPIA, ITRPV
Nearing the ceiling: Slowly but surely, BC is expected to narrow the gap to the theoretical
efciency limit of crystalline silicon.
Estimated Cell Efciency Progress of BC
40 TaiyangNews | Cell & Module Technology Trends
27.4% by 2030. In contrast, ITRPV forecasts a more
cautious trajectory, estimating 25.9% in 2025, 26.2%
by 2027, and only 27.3% by 2035 – 5 years later
than CPIA’s timeline for a similar performance level.
Cell Processing
The manufacturing process for BC solar cells is
an extension of high-efciency cell technologies
like TOPCon, but it involves additional complexity
primarily due to the need for structuring interdigitated
p and n regions on the rear side. SPIC’s rst-
generation IBC cells involved 10 process steps,
while the newer TBC structure expanded the process
to 14 steps. The added complexity stems from the
integration of laser patterning, which is essential
for forming the interdigitated rear-side contacts and
creating precise isolation zones between the positive
and negative electrodes. While not disclosing
its complete process ow due to condentiality,
AIKO conrmed that its BC production line adds 2
extra steps compared to a standard TOPCon line.
These additional steps are also attributed to laser
processing required for structuring the rear-side
contacts.
Laser technology plays a vital role in BC solar cell
manufacturing, particularly in enabling the rear-
side structuring that denes this architecture. While
lasers have long been used in the solar industry,
their application in BC requires addressing different
needs. Across manufacturers, lasers are used for
a range of tasks – from precision patterning to
selective removal of masking layers.
Lasers have been very instrumental since the
early days of BC architecture development. These
patterning tools have achieved minimal substrate
damage and, at the same time, can also attain
ultra-high precision. However, accomplishing these
operations at high speed to support high-throughput
manufacturing at low cost was indeed a challenge
back then, but not anymore. LONGi says it jointly
developed BC laser technology with equipment
manufacturers to solve throughput challenge and
reduce equipment and processing costs signicantly.
AIKO highlighted laser scribing as one of the most
critical steps in its BC process. It is used to precisely
separate the positive and negative regions on the
rear side of the cell. If this step is not done properly,
the cell can suffer from electrical leakage, leading
to poor cell performance. While the company has
successfully integrated laser tools into production,
it acknowledged that laser-induced damage to the
underlying silicon remains a point of concern. AIKO
views this as an area for further optimization rather
than a fundamental obstacle.
Higher
Efficiency
Elegant
Appearance
Source: SPIC
Worth the effort: The latest-generation BC structure involves 14 processing steps, including
complex laser patterning, but the payoff is a high-performance cell with a visually appealing
design.
42 TaiyangNews | Cell & Module Technology Trends
At SPIC, lasers are used more selectively –
primarily for removing masking layers during rear-
side processing. It takes a different route to isolate
the p and n regions, using insulating materials to
physically separate the contacts. The company
emphasizes the criticality of keeping the pulse output
of these tools stable, and this aspect needs continual
improvement.
Metallization in BC Solar Cells: Status and
Outlook
As with any other cell technology, metallization
remains one of the most critical and cost-sensitive
aspects also for BC solar cell manufacturing. While
silver paste-based screen printing is still the standard
today, all major BC manufacturers are actively
exploring ways to reduce or replace silver, with a
clear focus on copper-based solutions. Adopting ZBB
is a common strategy to reduce silver consumption.
For now, screen-printed silver paste remains
the dominant choice across the board. As SPIC
noted, screen printing is still considered the most
straightforward and reliable approach. LONGi says
it has already achieved lower silver consumption per
watt than TOPCon, without having to introduce low
cost base metals yet – a result made possible in part
by adopting ZBB designs that reduce paste usage.
Looking ahead, reducing silver usage is a shared
priority. AIKO currently employs a dual metallization
strategy for its BC cells, using both copper plating
and silver paste screen printing. To reduce costs
associated with silver, the company is exploring
improvements in the screen printing route by
adopting stencil printing, which allows for ner
ngers with less silver consumption. At its Zhuhai
facility, AIKO continues to rene copper plating,
aiming to increase the aspect ratio of metal lines
with a primary focus on improving cell efciency.
Simultaneously, the company is developing copper
paste technology at its new base, with the goal of at
least partially replacing, if not completely eliminating,
silver paste in the future.
LONGi, too, is preparing for a silver-free future.
While its current process is still silver-based, the
company emphasized that it has developed a
comprehensive strategy for both silver-lean and
silver-free metallization.
BC structure, unlike TOPCon, which, is not that
susceptible for various reasons, gives it a natural
edge in adopting cheaper metals like copper or
aluminum. Adopting ZBB is also relatively complex
for TOPCon. The technology uses laser-enhanced
contact optimization on the front, which prevents
it from being silver-free, at least as of now. The
contacts are still present on the front and low-
cost metals with higher resistivity, requiring a
higher contact cross-section to compensate the
conductivity. This increases shading, which is not
ideal. The structure is also not very supportive of
using different contact materials for the front and
rear. Above all, any such optimization requires
additional CapEx, which may not be feasible in the
current context of overcapacity. BC is free from
all these limiations, meaning, it is easier to adopt
the low cost metallization solutions. SPIC is also
exploring the transition to copper paste, although it is
currently limited to R&D. The company views copper
paste as the most viable path forward and expects
it to enter production within the next 2 to 3 years,
depending on industry progress. Plating does not
currently appear to be part of SPIC’s metallization
roadmap.
4.3 Modules
Any cell architecture requires a certain degree of
optimization at the module level, but this becomes
especially important in the case of BC cells. Due
to their unique design, BC cells introduce specic
considerations that go beyond standard module
integration practices. While a dedicated chapter
delves into module design and manufacturing in
detail with respect to all technolgies, this sub-chapter
focuses on the aspects of module assembly and
materials specic to BC technology.
One common topic in module making is ZBB. This
approach has several other benets in addition
to savings on silver. By eliminating the busbars
in BC solar cells, the carrier transport path is
signicantly shortened, which in turn helps reduce
series resistance. This design shift also addresses
a specic issue in BC architecture known as the
electrical shading problem. The adoption of a ZBB
layout allows for longer ngers and a larger collection
area, which improves current collection and
minimizes losses caused by shading. Additionally,
this design helps alleviate edge stress, thereby
reducing the risk of microcracks and enhancing the
Cell & Module Technology Trends | TaiyangNews 43
overall mechanical reliability of the cell. Along with
the changes they bring at the cell level, BC cells
also have specic requirements and advantages
in module design and assembly. While many
materials and processes overlap with those used for
conventional cell architectures like TOPCon, BC’s
rear-contact design results in notable differences,
particularly in interconnection, layout, and certain
BOM components.
One of the most apparent differences is in the cell
interconnection process. The absence of front-
side electrodes in BC cells allows manufacturers to
eliminate the Z-shaped soldering used in standard
architectures like TOPCon, which must connect
front and rear sides. Instead, BC modules use linear
soldering, which not only streamlines the assembly
but also helps reduce edge stress by up to 50%,
lowering the risk of soldering-related microcracks,
according to LONGi. In addition, this conguration
supports narrower cell spacing, making BC an ideal
candidate for full-screen module designs, according
to AIKO.
BOM
The requirements for BC modules are similar
in many respects, but there are some specic
differences. AIKO noted that an insulating glue is
required to separate the p and n electrodes. The
absence of front-side metallization also allows
the use of a thinner front encapsulant, while the
rear side, housing both polarities, may require a
thicker or more robust lm. Additionally, since BC
cells eliminate front-side solder ribbons, the rear-
side ribbons can be wider and made of more cost-
effective materials, offering greater exibility in
interconnect design.
Bifacial
Bifacial, which was not even on the BC radar
until recently, is now a buzzword related to BC.
Traditionally viewed as a limitation of the architecture,
given that both contacts are placed on the rear side,
BC is now making steady progress in improving
rear-side light utilization. As manufacturers push BC
modules toward broader adoption, particularly in
utility-scale applications, enhancing bifaciality is seen
as a key enabler. Indeed, BC manufacturers have
made notable progress, reporting bifaciality levels
in the 70–80% range. AIKO, for instance, is pushing
toward 80%, estimating a theoretical potential of
85%. LONGi also highlighted design optimizations
such as rened metallization and patterning to
reduce shading and absorption losses, improving
bifaciality. Across the board, the consensus is clear:
enhanced bifacial performance is essential, and BC
is undergoing optimization to close the gap.
Source: LONGi
Slight BOM adaptation: BC modules require a modied encapsulant – thinner on the front and
thicker on the rear.
44 TaiyangNews | Cell & Module Technology Trends
15 YEARS OF PASTE INNOVATION
CHASING LIGHT INTO THE FUTURE
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TOPCon+ | HJT | xBC Metallization Paste Solutions
Silver-Lean Metallization Paste Solutions
Module Interconnection and Encapsulation Material Solutions
As a global leader in photovoltaic metallization pastes, over the past 15 years,
DKEM® (300842.SZ) has pioneered the domestication wave of photovoltaic silver
pastes in China and spearheaded the technology revolution from p-type to n-type
solar cells. Consistently adhering to the collaborative innovation strategy of
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Cell & Module Technology Trends | TaiyangNews 45
Complementing rapid innovations at the cell level,
a wave of dynamic advancements has also hit
module manufacturing. Today’s module designs are
meticulously optimized to ensure no photon goes
waste, capturing every bit of light that strikes their
surface. At the same time, modules are becoming
increasingly application-specic, with manufacturers
ne-tuning their BOM and offering a wide range of
designs tailored to meet the demands of various
installation scenarios. What were once considered
niche or specialty products are now evolving into
standard offerings across the industry. Interestingly,
innovations initially developed for particular
cell technologies are quickly proving versatile.
Technologies such as zero-busbar interconnection,
rst introduced for HJT, have been successfully
adopted by other architectures, while down-
conversion lms, originally created for HJT, are now
nding relevance in TOPCon modules as well.
5.1 Efciency & Power
Despite this convergence in design and materials,
the core differentiator for modules remains their base
cell technology. As mentioned earlier, cell efciency
is increasingly becoming an internal benchmark for
manufacturers, with module efciency emerging
as the denitive metric for market comparison and
customer evaluation.
Efciency
TaiyangNews has been tracking the commercial
module efciency for each technology from
integrated cell manufacturers for more than 3
years through the monthly column TOP SOLAR
MODULES, and a report analyzing the trends over
a period of time that is published biannually. A
5. Modules
22.8
LONGi
Maxeon
23.6
AIKO
24
AIKO
24.2
AIKO
22.53
Huasun
23.02
Huasun
23.18
Huasun
22.65
JinkoSolar
22.8
Tongwei
22.8
Tongwei
Astronergy 22.8
Tongwei
Astronergy
JA Solar
DMEGC
23
JA Solar
21.7
CSI
LONGi
Risen
21.7
CSI
LONGi
Risen
Tongwei
21.7
CSI
LONGi
Risen
DAS Solar
Tongwei
21.7
CSI
LONGi
Risen
DAS Solar
Suntech
Tongwei
21.7
CSI
LONGi
Risen
DAS Solar
Suntech
21.5
22
22.5
23
23.5
24
24.5
Jan
Feb
Mar
Apr
May
June
Jul
Aug
Sep
Oct
Nov
dec
Jan
Feb
Mar
Apr
May
June
Jul
Aug
Sep
Oct
Nov
Dec
2023 2024
Efficiency (%)
IBC HJT TOPCon PERC
IBC leads: Comparing the commercial efciencies of modules based on different cell technologies,
IBC naturally leads the pack, followed by HJT and then very closely by TOPCon.
Top Solar Module Efciencies for Different Cell Technologies
- IBC, HJT, TOPCon & PERC - 2023 / 2024
Source: TaiyangNews 2025
46 TaiyangNews | Cell & Module Technology Trends
mainstay in all these reports is a graph that provides
an overview of the progress of the top efciencies
of different cell technologies. Below is the graph
from our last report published at the end of last year,
which is still relevant for the most part.
Historically, IBC has always been considered the
efciency leader among the commercially offered
modules – a fact also reected in our list from the
beginning. Thus, the explanation in the above
section about the progress of top efciencies is also
true for IBC efciency. At the beginning of 2024,
AIKO represented the highest efciency of 24%. It
broke its own record in May 2024 by introducing a
module under its Comet series with an efciency
of 24.2%, putting it directly at the top. Going back
to 2023, the top IBC efciency position was initially
held by both LONGi and Maxeon, with both their
modules featuring 22.8% efciency. In March, AIKO’s
module with 23.6% efciency took the lead, with the
company strengthening its position further with a
24% product in June 2023, staying on top through
December 2023.
The top commercial module efciency among
TOPCon products has increased by only 0.35%
absolute over the scope of this report’s timeline.
However, the entire progress essentially took place
in 2024. The top efciency rose from 22.65% to
22.8% in February and further to 23% in November.
At the beginning of the year, JinkoSolar led with a
22.65% efciency product. In February, Tongwei
surpassed this with a module achieving 22.8%
efciency. The very next month, in March, Astronergy
also commercialized a product with the same
efciency, matching Tongwei’s product. In July 2024,
JA Solar and DMEGC joined the race, achieving
22.8% efciency as well. This created a 4-way tie for
the highest efciency in the TOPCon category, with
Tongwei, Astronergy, JA Solar, and DMEGC all at the
top.
The major breakthrough came in November when
JA Solar raised the bar further by launching a
commercial TOPCon module with an efciency of
23%. This was the rst time a listed TOPCon product
reached the 23% benchmark, setting a new record
for the technology. This milestone concluded the
year for TOPCon efciency advancements. In 2023,
JinkoSolar was the TOPCon efciency leader for the
entire year with a 22.65% efciency product, a place
it claimed from Jolywood in September 2022.
In the case of HJT, the top efciency has been
represented by Huasun, the pioneer of this
technology. The top HJT efciency has been
improved by 0.65% absolute over a 2-year period
from 2023 to 2024. The top efciency at the
beginning of 2024 was 23.02%, which was also
one of the top 3. However, it missed the spot in
April 2024. This best efciency for HJT saw its only
improvement for the year in August, when Huasun
again improved its HJT module efciency to 23.18%.
Huasun was also the HJT segment leader in 2023.
Like 2024, the top efciency at the beginning of the
year saw its only improvement in September 2023,
from 22.53% to 23.02%, earning it a place in the top
3 efciencies club.
While not a topic of discussion for this report, PERC
is still part of the TOP SOLAR MODULES listing. The
top efciency for this technology remained at 21.7%
throughout 2023 and 2024; however, the companies
representing this efciency level changed from time
to time.
Power
In the world of solar modules, ‘power’ is the key
selling point. While efciency matters, it’s the rated
wattage that determines the commercial value
of solar modules, as watt is still the sales metric
for solar. Unlike efciency, power has no direct
relevance to the performance of the cell technology.
But it denitely provides insights into technology and
product positioning, especially on the application
front.
As mentioned above, HJT is the power leader,
qualifying it for the rst mention. At the beginning
of 2024, HJT products from Huasun and Tongwei
shared the top position in power with their 715
W products. In August, Huasun raised the bar
by introducing a 720 W module, securing the top
position exclusively through the end of 2024. At the
beginning of 2023, Huasun’s HJT module led both
the HJT segment as well as the entire TOP SOLAR
MODULES listing with a 700 W power rating. In
February 2023, Risen joined in with its own 700 W
module, sharing the top spot with Huasun for the
next 2 months. Huasun commercialized its 715 W
module in September 2023, moving a step ahead to
Cell & Module Technology Trends | TaiyangNews 47
take the lead. However, in December 2023, Tongwei
Solar also commercialized a 715 W HJT module,
sharing the honors with Huasun.
TOPCon represents the second-highest power rating
among PV technologies. However, there was no
change in the top power ratings for this technology
in 2024. Trinasolar’s 700 W TOPCon module led
throughout the year. There, however, were several
ups and downs in 2023. EGing PV’s 685 W TOPCon
module initially led the power ratings in this segment,
retaining its lead till June 2023. But in July 2023,
EGing PV reduced its module power to 580 W,
relinquishing the top spot to the next highest power
value of 625 W, shared by Runergy and Suntech. In
August 2023, DAS Solar and JA Solar surpassed this
by introducing modules with their 630 W modules,
holding the top spot just for that month. In September
2023, Trinasolar commercialized its 700 W TOPCon
module, setting a new record for the technology and
retaining the top spot for the category through the
end of 2024.
Third in line, there was no major change in PERC’s
top power throughout the last 2 years. Canadian
Solar’s 675 W module led the PERC stream power
ratings since the beginning of 2023. In April 2023,
Risen also commercialized a PERC product with
the same power rating, sharing the top spot with
Canadian Solar for the rest of 2023 and throughout
2024.
A leader in efciency, IBC comes last in power
comparison. The top power for this technology
changed only once during 2024, but by the same
company. At the beginning of 2024, AIKO led the IBC
category league with a 620 W product. Introducing
a 655 W module in May, AIKO renewed its lead in
power ratings, with the same module also placing
it at the top of the efciency tables. The story was
slightly different in 2023: LONGi’s 590 W module
led the power ratings at the beginning of the year,
590
LONGi
610
AIKO
620
AIKO
655
AIKO
700
Huasun
700
Huasun
Risen
715
Huasun
715
Huasun
Tongwei
720
Huasun
685
EGing PV
625
Runergy
Suntech
630
JA Solar
DAS Solar
700
Trinasolar
675
CSI
675
CSI
Risen
570
590
610
630
650
670
690
710
730
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2023 2024
Power (W)
IBC HJT TOPCon PERC
Source: TaiyangNews 2025
HJT’s power play: Over the past two years, HJT has led in power output, with Huasun offering a
market-topping 720 W module
Top Solar Module Power for Different Cell Technologies - 2023 / 2024
48 TaiyangNews | Cell & Module Technology Trends
Different Types of ZBB TechnologiesDifferent Types of ZBB Technologies
Type Technological Process Encapsulat-
ing Material Key PointKey Point AlloyingAlloying Advan-
tage Disadvantage Equipment CompanyCompany
SWCT
Copper-coated ribbons are
positioned by a transparent foil.
This foil-wire assembly (FWA)
interconnects cells.
Copper-coated ribbons and cells
are rmly combined through
lamination.
Composite
Film+
Encapsulant
Copper wire Copper wire
composite composite
lmlm
LaminationLamination
Strong ad-
hesion,
High
conductivity
Prefabricated cop-
per wire composite
lm, EL testing can
only be done after
lamination
Meyer Burger
Integrated Film Integrated Film
Covering Covering (IFC)
Interconnecting cells by placing
ribbons on their front and rear
sides through IFC. Ribbons and
cells are rmly combined through
lamination.
Skin lm+
Encapsulant Skin lmSkin lm LaminationLamination
Strong ad-
hesion,
No welding
process
Skin lm required,
EL testing can only
be done after
lamination
XN Automa-
tion, Maxwell REC,ASTROREC,ASTRO
DispensingDispensing
Between ngers. Place ribbons
on the cells by dispensing.
Ribbons and cells are rmly
combined through lamination.
PVB/EVA
Skin lm +
EVA/
Gum-printingGum-printing
UV curingUV curing LaminationLamination
Simple
process,
No welding
process
Skin lm and
encapsulant are
needed for
encapsulation-
Insufcient
adhesion
Autowell, AU-
TO-ONE, XN
Automation,
Autowavs,
Lead Intelli-
gent
Risen, Tongwei, Risen, Tongwei,
JinkoJinko
Welding Welding
+ +
Dispensing Dispensing
Welding ribbons to cells (cell Welding ribbons to cells (cell
interconnection and ribbon-cell interconnection and ribbon-cell
combination take place combination take place
simultaneously). Stick ribbons to simultaneously). Stick ribbons to
cells using dispensing.cells using dispensing.
Standard EVAStandard EVA
WeldingWelding
DispensingDispensing
UV curingUV curing
Infrared Infrared
weldingwelding
No need for No need for
load-bearing load-bearing
lm,lm,
Strong ad-Strong ad-
hesion,hesion,
Good hot-Good hot-
spot r spot r
esistanceesistance
High precision High precision
requirements for requirements for
dispensingdispensing
MaxwellMaxwell
Graph: TaiyangNews;
Source: Huasun
Different Approaches: Eliminating busbars at the cell level is straightforward in principle, but requires specic module-level adaptations,
achieved through the methods outlined above.
Cell & Module Technology Trends | TaiyangNews 49
built from 200+ years of innovation DNA and 40+ years of metallization
practice, today, Solamet® has the stronger innovation capability, the
broadest IP and product pofolios, and professional global customer
seice capabilities in photovoltaic metallization area.
Bearing Innovation, Advancing Relentlessly
From n-type to perovskite tandem solar cells, we are making
possibilities into realities.
2024
PV3NL
The world’s rst mass-production TOPCon laser carrier injection metallization paste.
2022
PV43 B
The world's leading ultra-low-temperature paste specically designed for
perovskite tandem solar cells.
PV6NL
TOPCon rear-side low solid content silver pastes continuously redening the
benchmark for cost and peormance.
PV43A
HJT low silver content silver-coated coppper pastes driving cost reduction and
eciency improvements.
Come on stage
2021
2018
2016
2015
2011
2009
1999
1983
Opening a new chapter.
From DuPont Solamet® to Solamet®
Recognizing the contribution of the patented Pb-Te-O technology
to the photovoltaic indust.
ACS Heroes of Chemist Award
PV3Nx/PV6Nx/PVD2x
The world's leading commercialized full package metallization
solution of N-type.
PV76x/PV56x/PV36x
The world's rst commercialized full package metallization
solution for PERC.
PV41x
A novel low-temperature conductive silver paste.
PV145
The world's rst commercialized re-through conductive silver paste.
The world’s rst photovoltaic conductive paste is introduced.
Novel one-paste metallization solution for IBC.
PV93x
Revolutiona silver paste based on the patented Pb-Te-O glass technology.
PV17x
PV36x/PV56x
The world's rst PV-specic aluminum paste/rear
side silver paste.
The world's rst commercialized front side silver-aluminum
paste for N-type solar cells
PV3N1
2023
50 TaiyangNews | Cell & Module Technology Trends
which was also the company’s top efciency product.
Then in March 2023, AIKO’s ABC module series,
featuring even higher power of 610 W, took the title
and improved the top power again to 620 W in June,
which it retained till the end of the year.
5.2 Zero-Busbars (ZBB)
Irrespective of cell technology, the hottest topic in
the module making segment is ‘zero busbars.’ In
principle, the technology is applied at the cell level,
but consequent changes and adaptations must
be made at the module level. What it essentially
means is that the cells have no busbars, meaning
the interconnection wires that establish the series
connection are directly attached to the nger pads.
There are several advantages of ZBB: it reduces
paste consumption, equipment, energy and also
costs, while improving efciency, power and
reliability. Starting with equipment, it eliminates 2
screen printers from the line to apply the busbars at
the front and rear. In terms of electrical gains, ZBB
decreases electrical resistance within the solar cell.
By eliminating the need for centralized busbars,
current can be collected and transported more
efciently across a large number of ne contacts.
This design reduces the distance electrons must
travel, minimizing resistive losses and enabling a
more efcient ow of electrical charge. This helps
in increasing efciency. Huasun also showed that
the ZBB technology improves reliability by reducing
the occurrence of hot spots. It also brings in optical
gains; the metal shadowing area on a ZBB module
is about 16% less on the front and 27% on the
rear, which increases the open area for sunlight
absorption, according to Huasun. The latter also
helps increase bifaciality.
As for its implementation, there are 4 methods
followed for ZBB, all nicely summarized by Huasun.
The HJT maker follows an approach called
Welding combined with Dispensing. In this method,
the ribbons are soldered to the solar cells while
simultaneously applying dispensing techniques
to reinforce the bond. This allows both the cell
interconnection and the ribbon-to-cell bonding to
be completed in a single step. Standard EVA is
typically used as the encapsulant material, with
infrared soldering and UV curing supporting the
process. A major advantage of this approach is that it
eliminates the need for a load-bearing lm, ensures
strong adhesion, and enhances resistance to hot-
spot formation. However, this combined approach
demands high precision during the dispensing
operation to achieve optimal results; Maxwell is a
Source: Nextracker
Solar everywhere: Thanks to the innovations in materials, solar is increasingly nding new
avenues of applications.
Source: LONGi
Source: Cando solar
Source: GoodWe
Source: JA Solar
52 TaiyangNews | Cell & Module Technology Trends
leading equipment provider for this technology. The
other standalone approaches are Dispensing and
Integrated Film Covering (IFC), detailed in the table
below. It also lists SWCT, a Meyer Burger proprietary
approach unavailable in the open market.
5.3 Innovations in BOM
Solar is increasingly becoming versatile and
application-specic. By adapting the materials
used, solar module manufacturers are able to offer
products that meet different application scenarios.
Led by the innovations in materials, today’s solar
modules are suitable for a wide range of installation
sites characterized by extreme temperatures –
both hot and cold –, highly humid and corrosive
atmospheres, or regions with intense UV density.
In parallel, PV applications are expanding in
scope beyond traditional utility-scale and rooftop
systems. Modules are increasingly being deployed
in specialized applications such as Building-
Integrated PV (BIPV), Vehicle-Integrated PV (VIPV),
and Floating PV (FPV). These emerging markets
demand not just electrical performance but also
new considerations like aesthetics, durability, and
integration exibility. From solar modules designed
for agricultural greenhouses and transportation
infrastructure to colored modules that match
architectural styles, PV technology is evolving to
seamlessly blend into various environments. The
examples illustrated below reect how manufacturers
are innovating to meet the growing demand for site-
specic and application-specic solar solutions,
making PV more versatile and adaptable than ever
before.
Polymers
One of the most interesting developments among
the polymer wraps used in module making is the
light conversion lm, also known as down-conversion
lm. It is a technology invented for HJT to protect it
from UVID, a well-known inherent limitation of the
HJT cell structure. One way to overcome poor UV
stability is to use encapsulation lms that cut off UV
light. While this saves the modules from degradation,
it also lowers efciency. The light conversion lm is
an innovation that brings the best of both worlds, or
at least strikes the right balance between the two.
The lm essentially converts the UV light into the
visible band. The underlying mechanism of this lm
works through an orbital electron transition process.
In addition to protecting the module by reducing
UV damage, it also contributes to increased energy
yield, offering the dual benet of improved durability
and enhanced efciency. Cybrid is at the forefront of
Source: Risen
Dual benet: Down-conversion encapsulation lms not only protect the cells from UVID but also
convert harmful light into benign light, which improves overall light absorption.
Cell & Module Technology Trends | TaiyangNews 53
this technology development, with its RayBo brand.
Cybrid has licensed the technology from CHOSHU,
which acquired the IP rights of the technology from
its inventor, Nitto Denko. However, a few other
leading encapsulation suppliers are also offering
such down-conversion lms.
An interesting development in this regard is that
there have been a few reports of UVID also affecting
TOPCon modules in the eld. It can be addressed by
optimizing the upstream processes, especially at the
cell level, with the optimization of passivation layers.
It can also be tackled at the encapsulation level
using down-conversion lms.
Improving the optical gains using polymers is also
gaining traction. Reective black backsheet is
one such development. Backsheet suppliers are
applying special coatings on the cell side of the
black backsheet that, in addition to keeping the
Source: DMEGC
Glass, but no reection: Some module makers are using anti-glare glass as the front cover for
installations in areas like airports and highways.
54 TaiyangNews | Cell & Module Technology Trends
aesthetics intact, also contributes to power gain.
HANGZHOU FIRST, for example, emphasizes that
its reective black backsheet attains over 60%
infrared reectance.
Meanwhile, the industry is developing reective gap
lms to address energy losses through transparent
gaps between cells in bifacial modules. While
screen-printed grid patterns have traditionally been
used, there have been cases of modules cracking
due to uneven heat distribution during processing.
Companies like Cybrid now offer a solution in the
form of reective gap lms, which can be applied
directly to glass or backsheets, avoiding the issues
associated with screen printing. These lms are
available in metallic and more cost-effective non-
metallic versions, both offering similar performance
benets.
Developments in Solar Glass
Innovations in glass are playing an increasingly
important role in enhancing solar module
performance and expanding their range of
applications. To maximize light absorption, solar
glass is now commonly treated with 2-layer anti-
reective (ARC) coatings to reduce the reection to
the maximum extent possible. On the other hand,
polymer-based frontsheets are also replacing glass,
though the spread is rather niche.
In addition to boosting transmittance, some module
manufacturers are adopting anti-glare glass
solutions. Unlike standard glass, which can cause
signicant reection, anti-glare glass is engineered
to diffuse light and minimize glare. This development
has eased the restriction of solar deployment in
sensitive areas such as airports and highways,
where controlling reectivity is critical for safety
reasons. The effectiveness of anti-glare technology
is notable: the reectivity of modules using anti-glare
glass is typically only 20% to 30% of that observed
in standard modules. As a result, anti-glare glass
not only supports better integration into specialized
environments but also helps broaden the overall
application scope for solar energy systems.
Innovations in Frames
Dust accumulation has long been a challenge for
traditionally framed solar modules, particularly along
the lower edges, where settled dirt can block sunlight
and lead to signicant power losses over time. To
address this, several manufacturers have introduced
innovative frame designs aimed at minimizing dust
buildup. A common feature in these new designs is
the inclusion of drain holes on the short sides of the
frame, allowing water and dust to be washed away
more easily. However, design improvements are
not limited to drain holes alone. More sophisticated
frame proles are being developed to promote better
self-cleaning behavior and reduce maintenance
needs, ultimately helping to sustain module
performance over the long term.
Another area of innovation is the exploration
of alternative frame materials. While aluminum
remains the dominant choice due to its lightweight
and corrosion-resistant properties, steel frames
are beginning to gain traction. Steel offers better
mechanical strength and comparable durability,
while also providing advantages in sustainability with
a lower carbon footprint and offering cost benets.
The trade-off is a slight increase in module weight,
but several manufacturers are actively evaluating
steel frame options, with some already introducing
products to the market. Additionally, composite
frames are also being explored as a lightweight
and potentially more sustainable alternative, further
diversifying the options available for advanced solar
module designs.
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