Photovoltaic Module Performance for Six Years After Hail Damage

Outdoor modules that have experienced golf-ball sized hail are characterized by flash testing and photoluminescence, electroluminescence, and thermal imaging. These measurements were performed immediately after the hailstorm and then again every two years for another six years in the field. The modules experienced different ranges of hail damage with some having cracks on approximately half of the cells within the module and some having few to no cracked cells. We compare two modules with no cell cracking to five modules with the worst cell cracking. Flash testing shows that the hail-damaged modules with the most cracked cells have 3 to 4% less power than those with the least damage due to the hail-induced cell cracks. After six more years in the outdoor climate of Golden, Colorado since the hailstorm, all of the modules still exhibit similar power outputs and trends in degradation. These modules are on fixed, open-air mounts and experience thermal cycling day-to-day and due to climate but no tracker movements or associated mechanical stresses. The results here suggest that the hail damage has initially reduced power but has not yet increased the degradation rate.