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					</table>India, Laos and the U.S. are among the countries with the highest solar module defect rates, exceeding 8%, due to the rapid expansion of manufacturing capacity, which likely introduced challenges related to quality control, operational stability, and workforce training, according to <a href="https://www.kiwa.com/en/" target="_blank" rel="noopener">Kiwa PI Berlin</a>’s The 2025 PV Module Manufacturing Quality Report.
Common quality findings identified in these factories include insufficient training for the equipment operators, poor equipment conditions, material mishandling, and operational inefficiencies.
Rapid manufacturing capacity expansion in countries like India, the U.S., Laos, and Malaysia highlights the importance of stabilizing operations and enhancing quality systems to mitigate risks.
Conversely, countries with more established manufacturing ecosystems, such as Thailand, Cambodia, and China, demonstrate the advantages of maturity and operational efficiency in solar module producti­on.
India <a href="https://www.mercomindia.com/india-module-manufacturing-capacity-2024" target="_blank" rel="noopener">added</a> 11.3 GW of solar modules and 2 GW of cell manufacturing capacity in the first half of 2024, according to Mercom India’s research report, State of Solar PV Manufacturing in India 1H 2024. As of June 2024, India’s cumulative solar module manufacturing capacity reached 77.2 GW, while solar cell capacity totaled 7.6 GW.
A recent report by the Solar Energy Industries Association said module manufacturing capacity in the U.S. <a href="https://www.mercomindia.com/us-module-manufacturing-hits-50gw-capacity" target="_blank" rel="noopener">surpassed</a> 50 GW, allowing the country to produce enough modules to meet its current demand.
<a href="https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-1.png"><img loading="lazy" decoding="async" class="aligncenter wp-image-76551 size-full" src="https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-1.png" alt="" width="752" height="473" srcset="https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-1.png 752w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-1-300x189.png 300w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-1-650x409.png 650w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-1-624x392.png 624w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-1-600x377.png 600w" sizes="(max-width: 752px) 100vw, 752px" /></a>
Defect Categories
Leading defects identified during 2024 pre-shipment inspections are solar cell metallization and cell cracking, frame material, and assembly defects.
Some of the examples of identified defects are as follows:
<ul>
<li>String-to-string gap: Two cells from adjacent strings in contact can lead to internal short circuits, causing underperformance or safety concerns.</li>
<li>Creepage distance: Defects relating to creeping distance or the distance between the live part (cell) and the glass edge below the minimum specified requirement were also noticed.</li>
<li>Branching cracks: Multiple cells in the module exhibit branching cracks. The likelihood of module degradation and potential fire hazards is increased due to hot spot formation.</li>
<li>Frame corner gap: An open corner gap indicates frame assembly issues, which can compromise the module’s mechanical performance and increase glass breakage risks.</li>
</ul>
<a href="https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defct-2.png"><img loading="lazy" decoding="async" class="aligncenter wp-image-76552 size-full" src="https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defct-2.png" alt="" width="710" height="566" srcset="https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defct-2.png 710w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defct-2-300x239.png 300w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defct-2-650x518.png 650w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defct-2-624x497.png 624w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defct-2-600x478.png 600w" sizes="(max-width: 710px) 100vw, 710px" /></a>
Over 22% of the observed defects in module production were directly related to cells. A key factor contributing to the prevalence of cell-related defects is the industry-wide transition from ‘passivated emitter and rear contact’ to ‘tunnel oxide passivated contact’ cell technology. This shift in cell design and technology has significantly influenced the occurrence of defects, as evidenced by the oversight findings.
Frame defects (defects related to frame damage and frame assembly) represent the second largest defect catego­ry with a rate of 17.82%. This high percentage highlights the critical need for stringent quality control measures for incoming materials and robust handling, packaging, and transportation practices to mitigate damage risks.
Other defects include the presence of foreign materials (12.1%), poor lamination (10.47%), and glass damage (10.06%), which highlight challenges in material quality, process control, and manufacturing practices that significantly impact solar module performance, reliability, and safety.
Contamination during production can lead to issues such as moisture ingress and mechanical degradation. Poor lamination increases the risk of delamination, structural instability, and environmental exposure. Glass damage, including scratches, compromises mechanical strength and resistance to stres­ses like mechanical loads.
<a href="https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-3.png"><img loading="lazy" decoding="async" class="aligncenter wp-image-76553 size-full" src="https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-3.png" alt="" width="1504" height="1073" srcset="https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-3.png 1504w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-3-300x214.png 300w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-3-768x548.png 768w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-3-650x464.png 650w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-3-624x445.png 624w, https://mercomindia.s3.ap-south-1.amazonaws.com/wp-content/uploads/2025/02/Defect-3-600x428.png 600w" sizes="(max-width: 1504px) 100vw, 1504px" /></a>
Addressing these defects requires stringent material quality control, optimized process steps, and regular maintenance and calibration of manufacturing equipment to ensure stable production and long-term module reliability.
The Kiwa Berlin report said stringent inspection criteria are one of the most rigorous ways to screen for defective finished goods. Buyers should negotiate these in supply contracts to steadily improve market and manufacturing standards.
Increased defect rates are found at newer manufacturing hubs, aligning with production oversight trends. The trend to higher cell-related defect rates indicates the need and benefit of auditing cell-specific production facilities. Benchmarking pre-shipment inspection results at levelized criteria allows buyers to compare and contrast quality from their suppliers.

Defect Rates in Indian Solar Modules Among the Highest Globally: Report

<a href="https://www.dupont.com/" target="_blank" rel="noopener noreferrer">DuPont</a> has released its ‘Global Photovoltaic Reliability Report’ with findings from studies conducted on solar modules across the globe to track material degradation and how it affects module performance.
The 2020 field report tested around 3 GW worth of solar installations comprising over nine million solar panels from 551 installations and found that defects were exhibited by around 30% of the solar modules and 16% of the backsheets. The previous years’ report <a href="https://mercomindia.com/solar-module-defect-up-dupont/" target="_blank" rel="noopener noreferrer">found</a> total module defects of 34%, total backsheet defects of 14%.
The DuPont Global Photovoltaic Reliability Program identified different types of defects in modules which included:
<ol>
<li>Backsheet defects: outer-layer (the side exposed to the air) and inner-layer (the side facing the cell) cracking, delamination, yellowing</li>
<li>Cell and interconnect defects: corrosion, hot spot, snail trails, broken interconnect, cracks, burn marks</li>
<li>Encapsulant defects: discoloration, browning, delamination</li>
<li>Other defects: glass defects, loss of anti-reflective (AR) coating, junction box</li>
</ol>
The company said that it identified a rapid increase in cracking in polyvinylidene fluoride (PDVF) backsheet, noting that the overall outer layer cracking rate of PDVF backsheets increased by over three times compared to the previous year. These defects directly affect the module’s power generation capacity and can cause other issues like delayed inverter starts, ground faults, and even fires.
<a href="https://mercomindia.com/wp-content/uploads/2020/05/Backsheets-defects-by-degradation-mode.png"><img loading="lazy" decoding="async" class="aligncenter size-full wp-image-19332" src="https://mercomindia.com/wp-content/uploads/2020/05/Backsheets-defects-by-degradation-mode.png" alt="Backsheets defects by degradation mode" width="397" height="261" srcset="https://cms.mercomindia.com/wp-content/uploads/2020/05/Backsheets-defects-by-degradation-mode.png 397w, https://cms.mercomindia.com/wp-content/uploads/2020/05/Backsheets-defects-by-degradation-mode-300x197.png 300w" sizes="(max-width: 397px) 100vw, 397px" /></a>
It said the PVDF outer-layer cracking defect rates rose from 5% to 23% between the fourth and ninth year of installation of the solar modules in countries like China, Europe, India, and North America. Deeper backsheet cracks have led to backsheet delamination, exposing the core layer, and in some cases, leading to inverter tripping and ground faults.
“Delamination and cracking were observed in multiple double glass module installations,” according to Kaushik Roy Choudhury, senior scientist and global technology leader at DuPont Photovoltaic Solutions, the solar wing of DuPont.
“Delamination appears to originate near edges of a module or at individual cells, while cracks likely originate at scratches or chips on glass surfaces and edges or at stress risers introduced by the racking system,” he added.
Mercom has previously reported on how the inferior backsheets can <a href="https://mercomindia.com/inferior-backsheets-will-cut-life-solar-projects/?s=backsheet" target="_blank" rel="noopener noreferrer">cut</a> the overall life of solar projects. Due to the pressure of low tariffs, the quality of components used in solar projects is usually the first casualty. Most of the cost of building a project still goes towards procuring solar modules, and this is where the price is prioritized over quality.
The study, which covered different regions across North America, Europe, Asia, and the Middle East, also identified that climate and cracking were not correlated as cracking was observed in all kinds of weather conditions.
In a recent webinar conducted by Mercom, experts discussed PV module quality deficiencies identified from field installations, penetration of new PV technologies in the Indian space, and their advantages. You can view the webinar <a href="https://mercomindia.com/ensuring-investor-confidence/" target="_blank" rel="noopener noreferrer">here</a>.
Last year, Mercom interviewed Rajaram Pai, Business Leader, E&amp;C South Asia, at DuPont India, who explained the importance of backsheets in solar projects. Read the full interview <a href="https://mercomindia.com/quality-consciousness-solar-mixed-bag-dupont/" target="_blank" rel="noopener noreferrer">here</a>.

Cracking in Solar Backsheets Not Correlated with Climatic Conditions: Report

A recent report based on a survey by <a href="https://www.dupont.com/products-and-services/solar-photovoltaic-materials.html">DuPont Photovoltaic Solutions</a> has found that the overall rate of module defects globally has increased by 34% in 2018. The report points out the failures with various backsheets like PET, polyamide, and highlights issues with glass on glass modules.
The report also highlights the trends in module failures and defects, chronicles backsheet defects by panel age, and provides comprehensive data on backsheet defects by temperature and climate.
DuPont surveyed sites in North America, Europe, Asia, and the Middle East. The team compiled global data from 6.5 million modules, 355 installations, and 1.8 GW of installed solar photovoltaic capacity.
According to DuPont, while there were no defects in the majority of module materials, the following defects were observed:
<ul>
<li>Cell/Interconnect – corrosion, hot spot, snail trails, broken interconnect, cracks, burn marks</li>
<li>Backsheet – outer-layer (airside) and inner-layer (cell side) cracking, delamination, yellowing</li>
<li>Encapsulant – discoloration, browning, delamination</li>
<li>Other – glass defects, loss of AR coating, junction box</li>
</ul>
With 1.8 GW of projects inspected, here’s what they found: total module defects were 34%, total backsheet defects were 14%, backsheet defects increased 47% from 2018 and that cracking comprises 66% of all backsheet defects.
<a href="https://mercomindia.com/wp-content/uploads/2019/06/dupont.png"><img loading="lazy" decoding="async" class="aligncenter size-full wp-image-14015" src="https://mercomindia.com/wp-content/uploads/2019/06/dupont.png" alt="Total Solar Module Defects Up By 34% YoY Globally in 2018: DuPont Survey " width="426" height="350" srcset="https://cms.mercomindia.com/wp-content/uploads/2019/06/dupont.png 426w, https://cms.mercomindia.com/wp-content/uploads/2019/06/dupont-300x246.png 300w" sizes="(max-width: 426px) 100vw, 426px" /></a>
Higher temperatures cause backsheet defects to accelerate. These rates are 75% greater for rooftop installations than ground-mounted, as the roof-mounted systems typically run 15°C higher than ground-mounted. Cracking and delamination can compromise the electrical insulation of the module. Yellowing can lead to mechanical degradation and embrittlement of many backsheet polymers according to the report.
This 2019 report was assembled from inspection and analysis by DuPont teams using a variety of criteria including component, material, mounting, time in service, and climate.
This report could be a matter of concern for some solar developers in India who are already compromising on quality standards by procuring cheap products while the solar tariffs keep plummeting. In the past, Mercom has <a href="https://mercomindia.com/quality-rooftops-suffer-competition-lack-standards/" target="_blank" rel="noopener noreferrer">written</a> about how the lack of regulations for product quality certification, intense competition, and absence of requisite awareness has only emboldened the quality problem in India’s rooftop solar sector.
Until recently, there were no policies or rules for maintaining the quality of projects in India. In <a href="https://mercomindia.com/new-mnre-guidelines-for-solar-manufacturers/" target="_blank" rel="noopener noreferrer">March 2019</a>, the Ministry of New and Renewable Energy (<a href="https://mnre.gov.in/" target="_blank" rel="noopener noreferrer">MNRE</a>) issued a set of guidelines to be followed by solar manufacturers for models of modules that will be utilized in government-owned projects and those set up for the sale of electricity to the government.

Total Solar Module Defects Up By 34% YoY Globally in 2018: DuPont Survey

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