PR (performence ratio)

[Anders]

Could you tell me which factors influence the PR (Performance Ratio) value? -All of them. I have heard about an RP value (Reference Performance / Reference Yield Ratio). Are you familiar with an RP value? Thank you

[hotline_oh]

Dear Anders,

Thank you for your inquiry.

The performance ratio (PR) is the ratio between the actual PV yield Y(PV,actual) and the maximum possible yield Y(PV,max) of the PV system. Thus, the system efficiency is a measure of the energy losses that occur compared to the optimal operating conditions of the system. The maximum possible yield is calculated from the actual annual total solar irradiance on the PV system (G) (in kWh/m²), the area of the PV system (A), and the module efficiency (μ) under standard test conditions.

𝑃𝑅 = YPV,actual / YPV,max = YPV,actual / (𝐺⋅𝐴⋅𝜂)

 

Another useful metric for evaluating yield is the specific annual yield. It is the ratio of the annual output to the installed PV capacity (in kWh/kWp). Due to globally varying solar irradiance, the specific annual yield is highly dependent on the location. For multiple systems at the same location, it is a very good comparative value.