Long term reliability of PV modules

Abstract

This paper discusses how BP Solar utilizes long term module exposure data and field return data to determine module lifetimes, expected failure rates and to identify failure mechanisms. Accelerated stress tests are then utilized to test new materials and processes before they are implemented in production. Long term module reliability is assessed using a three pronged approach. 1) A small number of modules have been deployed outdoors for long time periods with periodic measurements of performance in order to establish degradation rates. 2) Field returns are reviewed for both overall return rates and to identify the failure mechanism that caused the return. 3) Accelerated stress tests are utilized to evaluate the present products and all new materials, processes and designs against known failure mechanisms. The data from all three cases indicate that today’s PV modules are extrememly reliable and have projected lifetimes well in excess of the warranties.