Performance ratio calculation for solar system
The performance ratio is a measure of the quality of a PV plant that is independent of location and it therefore often described as a quality factor. The performance ratio (PR) is stated as percent and describes the relationship between the actual and theoretical energy outputs of the PV plant. It thus shows the proportion of the energy that is actually available for export to the grid after deduction of energy loss (e.g. due to thermal
losses and conduction losses ) and of energy consumption for operation
Performance of PV systems is calculated as follows:
E = Electricity generation [kWh]
Pp = Installed capacity [kWp]
GPOA = Total global solar irradiation sum on the plane of array [kWh/m²]
GSTC = Global solar irradiance at STC [1 kW/m²]
A performance evaluation is possible only if a pyranometer can be connected to the inverter or a separate monitoring system is used to which the inverter and a pyranometer are connected because the total global solar irradiation sum on the plane of array [kWh/m²] is a basis for any calculation including automatic monitoring systems.