STS-Certified publishes a Statistical analysis of PV module quality in mass production

STS Certified, a leading provider of quality assurance services, mass-production scale testing and certification solutions, announces the publication of a statistical analysis based on the results of the tests of tens of thousands of PV modules performed by the company between January and September 2013. The report is available for download free of charge at

By performing tests at a module level in mass-production scale, STS reveals the actual quality level of PV module manufacturers in the most representative and comprehensive way. The report offers a detailed perspective on which quality defects are the most present in PV modules, and at which frequency, so that PV module buyers and PV projects stakeholders can better anticipate the required actions to prevent failure of PV modules. Going beyond quality assurance services offered to PV buyers, STS also aims at supporting PV module manufacturers improve quality management processes to reach stable quality at mass-scale production.

The results notably reveal an overall rate of defective panels of 25.2%, representing an increase of 88% from the 13.4% defect rate observed by STS-Certified in 2012. Defects in solar cells (e.g. micro-cracks) account for the majority of defects (58.9%) detected during the tests. Most defects (77%) were classified as major defects, hence putting the PV modules’ performance at risk in the short to long term.

Thibaut Lemoine, General Manager at STS-Certified, comments this new publication: “Thanks to our proprietary testing process, we are able to perform tests on PV modules at large scale and therefore have access to data that virtually no other laboratory has ever been able to compile. For the period from January to September 2013, we observed a sharp increase in defects on solar panels compared with our data compiled in 2012, which is rather a negative signal for the solar industry. Although we have observed a positive learning curve for manufacturers whose products are frequently tested by STS, for many it remains challenging to maintain stable quality at mass production. It is too often assumed that manufacturers commercializing products certified against IEC or UL standards are delivering compliant or quality products. The methods of testing and inspection developed by STS are rather unique in the solar industry and provide an objective solution towards quality improvements at mass-scale.”

The report is available for download free of charge on

About STS Certified

STS-Certified is a leading provider of quality assurance services, mass-production scale testing and certification solutions. More than testing, inspecting and certifying products, STS helps the PV industry stakeholders from manufacturers to authorities and regulation agencies make certain that the projects they are taking part to will perform properly on the long course.


Thibaut Lemoine
General Manager