Simplified life-cycle analysis of PV systems in buildings: present situation and future trends

Abstract

The integration of photovoltaic (PV) systems in buildings shows several advantages compared to conventional PV power plants. The main objectives of the present study are the quantitative evaluation of the benefits of building-integrated PV systems over their entire life-cycle and the identification of best solutions to maximize their energy efficiency and CO2 mitigation potential. In order to achieve these objectives, a simplified life-cycle analysis (LCA) has been carried out. Firstly, a number of existing applications have been studied. Secondly, a parametric analysis of possible improvements in the balance-of-system (BOS) has been developed. Finally, the two steps have been combined with the analysis of crystalline silicon technologies. Results are reported in terms of several indicators: energy pay-back time, CO2 yield and specific CO2 emissions. The indicators show that the integration of PV systems in buildings clearly increases the environmental benefits of present PV technology. These benefits will further increase with future PV technologies. Future optimized PV roof-integrated systems are expected to have an energy pay-back time of around 1·5 years (1 year with heat recovery) and to save during their lifetime more than 20 times the amount of CO2 emitted during their manufacturing (34 times with heat recovery). © 1998 John Wiley & Sons, Ltd.