Enter the actual ready of the plant output and the calculated nominal plant output into the calculator to determine the PV performance ratio.

## PV Performance Ratio Formula

The following equation is used to calculate the PV Performance Ratio.

PR = AO / NO
• Where PR is the performance ratio
• AO is the actual reading of the plant output (kWh)
• NO is the nominal calculated plant output (kWh)

To calculate the PV performance ratio, simply divide the actual output by the nominal calculated output.

## What is a PV Performance Ratio?

Definition:

A PV performance ratio measures the difference between the amount of power generated by a solar energy system and the amount of power expected from the system. This number is expressed as a percentage.

For example, if a solar energy system generates 10 percent more power than expected, then it has a performance ratio of 110 percent. A solar energy system with a performance ratio below 100 percent means that it isn’t performing as well as expected.

A PV performance ratio is independent of location. That means it only measured the performance relative to the expected performance in that area, not relative to areas with more sunlight.