Loss factors are computed on a Block by Block basis. A final weighted average is also provided where applicable. The reference points for each of set loss factors quotients are shown in small caps text.

Figure 43. Loss Factor Definitions

 

The non-STC losses (loss due to lower efficiency at lower irradiance levels, and the loss due to the module temperature coefficient), are detailed as follows:

Module Irradiance Loss

Reference: Compute the array P_mp at STC conditions (1000 W/m², 25 °C, air mass 1.5, incidence angle of 90 degrees) and scaled to the effective irradiance. Let this be denoted by P_mp,ηSTC: E.g., @ 200 W/m², energy output shall be defined as 1/5 the energy at STC. In other words, we assume a linear irradiance dependency of module power.

 

Irradiance Loss: Compute the P_mp under actual irradiance conditions but with module temperature fixed at 25 °C. The difference between this P_mp and the previous P_mp will be the energy lost (or gained) due to the module’s response at different radiant intensities.

 

Module Temperature Loss

Temperature loss: Compute the P_mp under real conditions (actual temperature and irradiance). The difference between this P_mp and the previous P_mp will be the energy lost (or gained) due to the modules temperature response; i.e. operation at temperatures other than 25 °C