Surface polarization effect and recovery process of crystalline-Si photovoltaic modules

Abstract

Surface polarization effect was identified as an important factor that impairs the energy performance of photovoltaic crystalline-Si modules. Such an effect has been experimentally analysed by monitoring a monocrystalline Si-modules based power plant. It has been revealed that the surface polarization effect can reduce the photovoltaic power plant production up to 50 % respect to the expected value. Polarization effects in monocristalline Si-modules are generally caused by an incorrect grounding of the photovoltaic power plant on the DC side. In the present paper such degradation process has been investigated both on the whole plant and on modules. By analysing the I-V characteristics of selected modules, it has been revealed that the degradation rate depends on their position in the string. Finally, different recovery approaches have been experimentally tested on sampled modules and on the whole photovoltaic power plant. The results of the characterization carried out during recovery process are presented.