The efficiency of photovoltaic modules can decline in the event of a voltage difference between the solar cells and the grounded frame. Conventional modules are made to be resistant to this so-called potential-induced degradation (PID). With the current increase in the system voltage from 1,000 to 1,500 volts, however, the question of PID resistance has cropped up again.

Now, in the context of the SolarEraNet research program, ZSW in Stuttgart has developed an extreme test in collaboration with the companies Specialized Technology Resources España and CS Wismar which goes beyond the standard test and simulates an operating life of several decades. It shows that solar modules with a polyolefin elastomer (POE) embedding material lose hardly any power through PID even after the equivalent of 60 years of operation.

For investors, banks, manufacturers and project developers, such long-term forecasts are important when it comes to assessing the cost-effectiveness of solar projects. “With our new test, we will be able to determine PID resistance more accurately in future than has been possible previously,” says Peter Lechner, head of the ZSW photovoltaic test laboratory SOLAB. “The embedding material of the solar modules has a big influence on PID resistance. Modules with POE are extremely stable in this respect.”