Five years operation results of different crystalline-Si PV systems and analysis of the degradation rate in the field

“HOKUTO Mega-Sola” is in operation since 2008. Seventeen different kinds of crystalline-Si based PV modules are installed in the first phase. The typical array capacity and the inverter capacity of the systems are 10kW. Overall performance is evaluated using performance ratio. Performance losses or gains of the systems are quantitatively calculated using Sophisticated Verification (SV) method. Annual performance ratios of the crystalline silicon technologies are around 82% in average. Performance ratios were higher in winter seasons and lower in summer seasons mainly due to the temperature effect. Annual degradation rate of the systems was −0.71%/year in average.