The Principal Solar Institute aims to provide an unbiased comparison of PV modules by creating a comprehensive PV module rating standard called the PSI Rating. The PSI Rating is based on a module's 25-year lifetime energy production, calculated using seven key characteristics that impact energy output like power at different irradiance levels and temperature coefficients. It analyzes published data for over 10,000 modules and assigns a rating along with a percentile rank to help customers choose the best module for their application.