ABSTRACT
We propose here a performance mode) where the spectral mismatching under overcast conditions is evaluated from an empirical clearness index, which can be easily determined from irradiance data of the site. The model allows to determine the site dependend yields and losses related to the technology of the modules. As an example, a single and a double junction amorphous silicon module is examined. The series connection in the double junction modules leads to a higher loss under low illumination conditions, which results in related yearly losses of 7% instead of 4% for the single junction module. The better spectral matching under real operating conditions than under standard conditions increases the amorphous silicon module performance in Barcelona by about 5%.
