Best Practices for Installing a Solar-Ready Low Slope Roof PVEL is one of the solar industry's world-acclaimed reliability and performance testing labs. As an independent laboratory, PVEL samples and tests solar modules from leading solar manufacturers as part of its Product Qualification Program (PQP), and publishes the annual PV Module Reliability Scorecard based on these test results. The PV Module Reliability Scorecard is recognized as one of the most comprehensive publicly available comparisons of solar module reliability and performance, and the title of Top Performer - granted to high-ranked companies - is considered throughout the industry an esteemed mark of product quality and reliability.