Grade A panels have no defects, 100% power compliance, and come with a 25-year original factory warranty; Grade B panels often have scratches or color differences, the power is usually 3-5% lower, and there is no official warranty. Classifying solar panels into categories A and B typically revolves around multiple critical factors. Efficiency: Class A panels generally boast higher efficiency ratings, significantly outperforming Class B variants in converting sunlight to energy. V-shaped: Not allowed for Class A. These grades are typically assigned during or after the panel manufacturing and testing process, particularly during electroluminescence (EL) testing. The primary standards used for these tests in the United States are set by Underwriters Laboratories (UL). Specifically, UL 1703 is the standard for flat-plate PV modules and panels, evaluating their fire.
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