*3.5. Performance Ratio*

This is a quality factor that indicates how much solar energy is efficiently used. It compares the actual and theoretical power production of a PV installation. The closer the PR is to 100%, the more efficient the PV plant. This nondimensional factor is defined in Equation (9) [18] as

$$PR = \frac{\chi\_{\text{final}}}{\chi\_{\text{ref}}} \tag{9}$$

where *Y*final uses the following formula shown in Equation (10) to express the relationship between the total energy produced by an array (EA) and the absolute power produced by a PV panel *PDC* as

$$Y\_{\text{final}} = \frac{EA}{P\_{\text{DC}}} \tag{10}$$

Whereas the "*Yref* " calculated by dividing the amount of insolation (HA) received by a panel over a given time period by the amount of irradiance received over the same time period at STC as shown in Equation (11) as

$$Y\_{ref} = \frac{HA}{G} \tag{11}$$
