Temperature-dependent influence of a-Si:H cell degradation on the energy delivered under realistic reporting conditions

Various environmental effects such as variable irradiance, temperature and spectral distribution of the irradiating light cause considerable deviations in the efficiency of any PV system from its name plate rating efficiency (measured at SRC). An a-Si:H solar cell module will additionally suffer some losses through light-induced degradation. These various losses in the energy delivered by an a-Si:H solar cell operated outdoors are separated. Furthermore, the authors investigate whether an improvement in the energy output is possible when the cell is operated at higher temperatures (in which case long term degradation losses should be smaller). An estimate reveals a possible gain of up to 5% when the a-Si:H module´s average operating temperature is increased by 5 K. In order to obtain these results, a complete description of the performance of a-Si:H solar cells is required. This includes the knowledge of both the cell´s behaviour under realistic reporting conditions (in terms of irradiance, temperature and spectrum) and a degradation model (dependent on irradiance and temperature as well)