Analysis of weathered c-Si PV modules

The LEEE-TISO testing centre for PV components has, since 1991, carried out systematic tests, under real operating conditions, on the most important modules currently on the market. PV c-Si modules coming from production shows a typical degradation in performance when exposed to light of up to -5%. This initial degradation of c-Si modules takes place during the first hours of exposure. During the first year of operation some of the tested modules shows almost no further degradation and some a very small degradation. The long term degradation of c-Si modules has been extensively studied on one of the LEEE-TISO plants. In 21 years of service, the Arco solar ASI 16-2300 modules of the 10 kW TISO plant showed several signs of physical degradation. Yellowing of PVB encapsulant and hot-spots affected the module efficiency. Nevertheless, the results of the indoor performance measurements of all plant modules indicate that the ASI 16-2300 modules are still working in a very satisfactory manner.