The most important aspect of any photovoltaic module is its yield – which refers to the amount of kilowatt-hours per kW of installed power are generated by the system and flow to the inverter. And it is exactly this question of yield that PHOTON laboratories attempt to answer with their solar module field testing.

In 2009 Photon conducted their first test, installing 16 different photovoltaic solar modules on a property in Germany that was free of any shadowing, with each module facing south at a 28° angle and mounted about 2.5 m above the ground. PHOTON monitored the outputs of each using an elaborate and accurate testing system with measurement tolerances of +/- 1.85 percent.

In addition to data derived from the photovoltaic modules themselves, the PHOTON also measu­re solar irradiation as well as other climate data such as ambient tem­perature, wind speed, precipitation and barometric pressure. All this data is then correlated and a final yield value is arrived at, enabling the PHOTON laboratory to then rank the efficiency of solar modules.  

Apollo recommends using only the panels that score highly in the photon tests to guarantee you get the best possible returns from your system. The number 1 performing panel in 2010 was made by Siliken, closely followed by the one made by Kioto. So far the number 1 performing panel in 2011 is made by REC.

2010 PHOTON test results graph

2011 PHOTON test results