Application of Life Cycle Energy Analysis to Photovoltaic Module Design
This paper highlights results from a collaborative life-cycle design project between the University of Michigan, the US Environemtal Protection Agency and United Solar Systems Corporation. Energy analysis is a critical planning and design tool for photovoltaic (PV) modules. A set of model equations for evaluating the life-cycle energy performance of PV systems and other electricity-generating systems are presented. The total PV life-cycle, encompassing material production, manufacturiong and assembly, use and end-of-life management, was investigated.
Three metrics -energy payback time, electricity production efficiency and life-cycle conversion efficiency- were defined for PV modules with and without balance-of-system (BOS) components. These metrics were evaluated for a United Solar UPM-880 amorphous silicon PV module based on average insolation in Detroit, Boulder, and Phoenix. Based on these metrics, a minimum condition for assessing the susteainbility of electricity-generating systems was proposed and discussed. The life-cycle energy analysis indicated that the aluminum frame is responsible for a significant fraction of the energy invested in the UPM-880 module.