The test conducted by the independent laboratory of the leading industry magazine Photon, is currently the most recognized yield performance test comparing international module brands over several years.
Since 2005, Photon Lab has operated an ongoing test that monitors the energy yield of solar modules from leading manufacturers. This test compares the energy produced per kilowatt of installed power of the participating modules, under identical conditions. The 2011 test compared three modules each from 45 module manufacturers over a 12-month period from January to December 2011. The tests are carried out at a facility in Aachen,Germany, where they are mounted outdoors well above ground for good rear ventilation, facing south, and free of shadowing . Photon’s custom testing setup records the current-voltage (IV) curve at the module’s output eliminating the possibility of false inverter adjustments. The test module’s yield is fed into the grid via an inverter allowing the modules to operate under real-world conditions. Solar irradiation is recorded along with weather context data such as ambient temperature, wind speed, precipitation and barometric pressure. All the test data is collected in one second intervals and stored in synchronized databases that allow for precise correlation.