The electrical power generated by a polycrystalline silicon photovoltaic (PV) module mounted on an unglazed transpired solar collector (UTC) has been studied and compared to that of a PV module without UTC for a quantitative analysis of electrical output and its role in reducing the simple payback periods of photovoltaic electrical systems. A 75 W polycrystalline silicon PV module was fixed on an UTC in front of the ventilation fan, and effectiveness of cooling by means of the forced ventilation at the rate of 160 CFM was monitored. The temperature reduction under forced ventilation was in the range of 3-9 degrees C with a 5% recovery in the electrical output power on a typical day of the month of February 2005. The simulated and measured electrical power outputs are in reasonable agreement with root-mean-square error of 2.40. The life cycle assessment of a hypothetical PV system located at Daejeon, South Korea and consisting of 3 kW PV modules fixed on a 50 m(2) UTC shows that with a possible reduction of 3-9 degrees C in the operating temperatures, the system requires three 75 W fewer PV modules. The simple payback period of PV system is reduced from 23 years to 15 years when integrated into an UTC air heating system.