Water cooking for backsheet and PV module endurance evaluation

Water cooking is applied as an efficient screening tool to evaluate various structures of PV module backsheet from three suppliers against thermal and humidity stressing. Visual appearance, adhesion, yellowing effect, water vapor transmission rate (WVTR) and FT-IR spectral are inspected. De-lamination among layers and PET hydrolysis take place after 600 to 800 hours. Comparing with extended damp heat reliability in P-mono modules with those backsheets, it has well correlation between water cooking to damp heat result. The acceleration factor is around six to eight times faster than damp heat test.