According to a new report from U.S. renewable energy firm Clean Energy Associates (CEA), undetected faults and damage in solar PV modules, such as cracks, manufacturing flaws, and foreign objects, pose “major risks” to the solar industry.
By testing over 300,000 modules across 150 project sites in 16 countries (including the U.S., Canada, Australia, and Western Europe), CEA’s Solar PV Module Quality Risk Report found over 80% of projects had defects.
Invisible “Defects”
The two most common defects were cell cracks and soldering errors, which CEA said can both occur during manufacturing.
For cell cracks, 83% of tested projects had this issue. In manufacturing, moisture ingress, light induced degradation, or stress on cells can ultimately increase internal series resistance and power loss.
Soldering errors are completely attributable to manufacturing processes, found in 78% of projects. CEA said these errors reduce cell efficiency and can even cause hot spots that damage modules.
Complex cracks were found in 76% of tested projects, caused by handling, installation, or extreme weather, leading to widespread module failure and severely impacted performance. 29% of tested projects had ribbon cracks forming at intersections of interconnect ribbons (or wires) and the cell edge. For projects using half-cut cells, the rate of ribbon cracks rose to 81%.
Most strikingly, microcracks saw a “sharp increase” from early 2022 to mid 2023. CEA found the occurrence of cell microcracks and complex cracks in U.S. modules rose 47% since early 2022, a period which saw increased U.S. production and deployment of solar modules after the Inflation Reduction Act (IRA). However, correlation does not imply causation.
All these defects are only visible through electroluminescence testing, which CEA said involves current passed through modules in a dark environment, with infrared light emissions then captured by specialized cameras.
Visible Defects
Foreign objects were the biggest visible defect found in visual inspections, present in 55% of the 29 visual inspection projects in CEA’s report. Next were gaps between cells and glass edges, with 52% having this defect. CEA said these defects can potentially lead to fire risks in extreme cases due to internal arcing.
45% of projects also found glass soiling and encapsulation defects, many due to poor factory workmanship, which can impact module performance and conversion efficiency. 41% of projects found cell misalignment, with uneven spacing between cells.
CEA did not specify which technologies were tested or if differences existed between cell technologies.
Quality Assurance
While defects occur during transport, installation, and extreme weather events, most originate during manufacturing, CEA said. This signals the need for independent third-party quality assurance programs and greater awareness of quality issues across the solar industry. The report did not explicitly state how significant these issues are or quantify specific impacts on module efficiency and performance.
One contributing factor is “quality issues are growing as many module buyers are procuring from new and inexperienced suppliers due to supply chain challenges,” CEA said.
For this, testing center PV Evolution Labs (PVEL) earlier this year published an article on PV Tech outlining new opportunities and risks for module reliability brought by the U.S. IRA, with most of last year’s added production capacity concentrated in the U.S. The IRA and manufacturing boom created ample opportunities for American developers, with PVEL emphasizing that “not all PV modules are created equal, regardless of origin,” in the U.S.
A February report from solar management software provider Raptor Maps estimated poor solar module performance could lead to global losses of $2.5 billion, with reported underperformance events more than doubling since 2019. The number of modules deployed and defects analyzed and detected has also grown significantly since 2019.
In Europe, where internal production capacity is much lower and the market almost entirely imported, the issue exists as well. At last month’s PV Storage Summit 2023 in Birmingham, U.K., John Davies, CEO of British solar consultancy 2DegreesKelvin, said, “We still see lots of concerning manufacturing defects in brand new encapsulated modules from tier 1 producers. Many manufacturing defects actually impact power and get worse over time.”
CEA concluded its report stating: “We need to recognize that quality issues with PV modules are becoming more prevalent. These issues need to be addressed in a timely manner, ideally before project development, to ensure optimum performance.”
