‘Clear and concerning’ rise in PV module defects – Kiwa PI Berlin

Kiwa PI Berlin has been carrying out quality assurance auditing and pre-shipment inspections of modules for over a decade, and in that time said it had witnessed fluctuations in quality as technologies mature and are rapidly adopted by new entrants. 

But in 2025, Kiwa PI Berlin said non-conformance defects identified during module pre-shipment inspections reached their highest-ever record level in over a decade, of 3.36%. This surpassed the high defect rates in 2023 and 2024, as TOPCon replaced PERC as the solar industry’s prevailing PV technology.

Kiwa PI Berlin attributed the 2025 spike in defects to policy uncertainties in the US, including an increased emphasis on supply chain transparency and the rapid expansion of cell and module manufacturing capacity in emerging manufacturing hubs such as the US and Africa.

On the relocation of manufacturing capacity to new regions, Kiwa PI Berlin said evidence suggests that production ramp-ups in these locations have faced “significant challenges” relating to inadequate facilities and infrastructure, shortages of experienced engineers and skilled operators, and persistent supply chain disruptions affecting raw materials and equipment spare parts.

“The uncertainties associated with this shift are expected to persist into 2026 and are likely to continue exerting downward pressure on product quality,” the report said.

Similar pressures have arisen from Chinese manufacturers’ struggles with intense pricing competition. As profit margins have eroded, aggressive cost-cutting has led to the loss of skilled production personnel and their technical expertise. This, combined with unstable production planning, has created further manufacturing risk, the report said.

Overall, of the 85 factories audited by Kiwa PI Berlin in 2025, only 5% achieved an ‘excellent’ rating, with most falling between ‘above average’ and ‘average’. Notably, 21% were rated as ‘below average’ or ‘poor’. This highlights a “persistent risk to long-term reliability that certifications alone may not provide sufficient assurance or fully mitigate”, the testing body said.

New defect patterns

The findings in this year’s report also highlighted new defect patterns emerging in production processes. These include layup precision, lamination integrity and junction box assembly, all issues that directly influence module performance, reliability and safety.

The report also said that batch testing indicates an increase in failures such as potential-induced degradation (PID), highlighting weaknesses in manufacturers’ BOM and process controls.

This finding reflects a similar trend highlighted in sister organisation Kiwa PVEL’s latest module scorecard report, which recorded an increase in BOM testing failures.

“Rising variability in manufacturing processes further compounds these risks. To remain competitive, buyers must strengthen their focus on quality mapping and implement robust controls to ensure their products stand out in the market,” Kiwa PI Berlin noted.

On a more positive note, the report said that cell-related defects in TOPCon production – one of the big concerns over the past two years or so – have decreased to levels similar to those in longer-established PERC technology, reflecting “measurable improvements in quality”.

“These enhancements are attributed to optimised cell-level design, material modifications, and the accumulation of production expertise and knowledge in manufacturing TOPCon cells,” the report said.

Looking ahead, Kiwa PI Berlin said the PV industry’s continued growth and technological advancement will demand even greater diligence in quality assurance.

“It’s a legitimate challenge to manufacture many millions of PV modules in dozens of new and growing factories using hundreds of BOM combinations. By integrating data-driven QA practices into procurement and project execution, stakeholders can not only navigate these complexities but also strengthen PV’s role as a cornerstone of global energy transition,” the report concluded.