SOLAR power PERFORMANCE RATIO

[sachidanandam]

The product (GlobInc * Pnom) is numerically equivalent to the Energy which would be produced if the system was always running with its nominal efficiency as defined by the nameplate nominal power [kWh].

HOW DIMENSIONALLY EQUAL

[André Mermoud]

There is often a unit's confusion with the quantity Yr, which may be understood :

- either as the incident energy (with units [kWh/m² / day])

- or as the ideal array Yield according to Pnom (expressed as [kWh / kWp / day]).

This numerical identity results of the STC definition: one kWh/m² of irradiance should produce one kWh/kWp of electricity.

The confusion comes from the fact that the kWh are not the same:

- in the former case [kWh/m² / day], the kWh represent incident irradiance energy (light flux)

- in the latter case [kWh / kWp / day], the kWh mean produced electrical energy !!!