ANNUAL ENERGY-PRODUCTION AND ROOM-TEMPERATURE EFFECT IN SITING FLAT-PLATE PHOTOVOLTAIC SYSTEMS

A method to evaluate the room temperature effect in deteriorating the performance of flat plate PV systems is investigated. The calculations , applied to crystalline Silicon arrays, show a significant energy los s with respect to reference temperature conditions, especially in corr espondence to the sites with highest insolation, in which the effect c an amount up to about 15%. As a consequence, the previous projections about kW h cost for large scale PV power stations should be rectified by introducing a correction factor accounting for thermal effects. The calculations were carried out for 64 zones, particularly suitable for siting PV plants and distributed among 15 countries over a latitude b elt ranging from about 40-degrees North to 15-degrees South. For each zone, it was accounted both for room temperature and insolation histor ical data. The final results show a linear correlation between yearly global sun radiation density and room temperature effect, which appear s quite general, so that, for any other site within the same latitude belt, it is possible to account for thermal effect on PV kW h cost sim ply by knowing the global sun radiation density on horizontal surface (usually the only experimental available datum).