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 Kiwa PI Berlin’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 added 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. surpassed 50 GW, allowing the country to produce enough modules to meet its current demand.

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:

• String-to-string gap: Two cells from adjacent strings in contact can lead to internal short circuits, causing underperformance or safety concerns.
• 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.
• 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.
• Frame corner gap: An open corner gap indicates frame assembly issues, which can compromise the module’s mechanical performance and increase glass breakage risks.

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.

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.