focus at the collector. They are unable to provide significant power in diffused light conditions. Solar cells are able to provide some output even if the sky becomes cloudy, but power output from concentrating systems drops drastically in cloudy conditions as diffused light cannot be concentrated well. Standards ISO test methods for solar collectors. EN 12975: Thermal solar systems and components. Solar collectors. EN 12976: Thermal solar systems and components. Factory-made systems. EN 12977: Thermal solar systems and components. Custom-made systems. Solar Keymark: Thermal solar systems and components. Higher level EN 1297X series certification which includes factory visits. International Code Council / Solar Rating & Certification Corporation: Testing is performed by independent laboratories and typically includes selection of a collector to be tested from a sample group of at least six solar collectors. ICC 901/ICC-SRCC™ 100: Solar Thermal Collector Standard ICC 900/ICC-SRCC™ 300: Solar Thermal System Standard ICC 902/APSP 902/ICC-SRCC™ 400: Solar Pool and Spa Heating System Standard See also References External links Canadian government ratings of solar collectors Crosbyton Inventory of Records Feasibility of photovoltaic Cells on a Fixed Mirror Distributed Focus Solar Bowl Solar thermal energy Renewable energy pt:Aquecimento solar#Coletor solar