PV module performance outdoors at PG&E

The 1989 performances of 38 PV (photovoltaic) modules installed outdoors at PG&E´s PV Test Facility in San Ramon, California, are evaluated. Performance improvements with each generation of PV modules indicate the progress of PV. Efficiencies greater than 12% have been measured. Within each PV technology, module performance tends to follow parallel month-to-month trends. Even after initial degradation, amorphous silicon modules have the greatest month-to-month variations. Monthly averaged efficiency is within ±10% of annually averaged efficiency for amorphous silicon modules after initial performance degradation and within ±6% for the single-crystal silicon, polycrystalline silicon, ribbon silicon, bifacial silicon, and concentrating silicon modules evaluated