Seasonal performance of three grid-connected PV systems

The one-year performances of three grid-connected photovoltaic (PV) power systems located at the Florida Solar Energy Center are compared. Three different photovoltaic cell technologies are presented: (1) single junction amorphous silicon (ARCO G4000 modules); (2) tandem junction amorphous silicon (Sovonics P-201 modules), and (3) crystalline silicon (Mobil Ra 180 modules). For the amorphous silicon PV arrays, their operating efficiencies were higher in the summer than in the winter. This is because their efficiency is affected only slightly by operating temperature, the warmer summer months improved the efficiency through annealing, and the spectral irradiance conditions are generally more favorable. Changes in the monthly operating efficiencies of the crystalline silicon PV array were almost entirely dependent on module operating temperatures. Consequently, the operating efficiencies of this PV array were higher in the winter than in the summer