Calculate the performance ratio of a solar installation against its theoretical output.
The performance ratio separates system quality from site quality, because irradiation is already in the denominator. A well-designed system achieves 80 to 85 per cent regardless of location. Performance ratio is the right metric for diagnosing faults, since a low value cannot be blamed on poor weather.
Solar Performance Ratio
PR = actual generation ÷ (installed kW × irradiation in the array plane)
PR = actual generation ÷ (installed kW × irradiation in the array plane) The performance ratio separates system quality from site quality, because irradiation is already in the denominator. A well-designed system achieves 80 to 85 per cent regardless of location.
Performance ratio is the right metric for diagnosing faults, since a low value cannot be blamed on poor weather.
This calculator takes 3 inputs: Actual generation, System size, Annual irradiation in the plane of the array. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.