This article presents a new dual purpose technique to improve photovoltaic (PV) array efficiency and has a great effect for the net power saving. To realize the first aim, the forced-air cooling technique with the optimal flow rate for PV array is designed and implemented. The decreasing rate in cell temperature has a direct proportional relation with PV efficiency. At the same time, the output hot air is very useful for air conditioning houses and for heating water systems, especially in remote areas. The electrical performance of PV modules also was studied. Finally, the effect of power saving was cleared and the economical results were achieved.