A systematic investigation has been made on annual accumulated generated PV power from different solar arrays consisting of three kinds of silicon-based solar cells. To clarify seasonal output power variations with temperature in c-Si and a-Si cells might be an important issue for the operations of PV system. It has been shown from the results that electric output power from a-Si array in summer is 20% larger than that from c-Si. On the other hand, in winter, this scene should be reverted. However, output power from c-Si array is only 5% larger than that from a-Si. The analyzed data also shows that annual accumulated electric power generated from a-Si array corresponds to 90% of its nominal efficiency in the year. While in case of c-Si array, this ratio is about 84%. (C) 2001 Elsevier Science B.V. All rights reserved.