Solar Electricity
Solar Performance Ratio Calculator
Calculate performance ratio from delivered energy and reference energy. The default values illustrate the workflow; replace them with measurements or ratings from one documented condition.
Enter values for Performance ratio
Replace the examples with values from the same case.
Performance ratio: calculation method
This page evaluates PR = delivered ÷ reference × 100. Only Delivered energy and Reference energy enter the numerical result.
Using the loaded examples gives 80.00%. Your saved case should identify where each entry came from.
Calculate performance ratio from delivered energy and reference energy. If you also need azimuth-adjusted energy, continue with Solar Azimuth Loss Calculator.
A second scenario
Change Delivered energy from 7200 kWh to 8640 kWh with every other entry unchanged. The result changes from 80.00% to 96.00%.
Do not average the two cases if either could define an operating limit.
Before entering values
Base energy estimates on the limiting season rather than an annual average alone. Do not combine a worst-case value with unrelated nominal data.
At least one field has a positive lower bound because it appears in a denominator. Convert units once, retain the original reading, and verify the converted magnitude. Battery Round-Trip Efficiency Calculator may be useful for the next related quantity.
- Delivered energy
- Default example: 7200 kWh. Enter delivered energy in kWh.
- Reference energy
- Default example: 9000 kWh. Enter reference energy in kWh.
Input quality checks
Mixing nominal and measured data is a common source of error.
Trace an unexpected result back through the raw entries first.
How to use the result
The calculated Performance ratio is meaningful only with its input conditions attached. Compare it with a monthly or seasonal production case.
Label alternate cases rather than overwriting the baseline. Continue with Off-Grid Solar Array Calculator to evaluate required array size.
Checks before using the answer
Define reference energy consistently across comparisons.
The arithmetic intentionally leaves out temperature effects, shading patterns, wiring loss, and equipment availability. Resolve material omissions before selecting a standard size or rating.
Base energy estimates on the limiting season rather than an annual average alone.
Common questions before using the result
Can I change several inputs at once?
Keep unaffected entries fixed so the cause of the difference remains visible. Base energy estimates on the limiting season rather than an annual average alone.
Can I select equipment from this number alone?
No. Compare the value with a monthly or seasonal production case and apply relevant equipment and installation requirements.
How much precision should I keep?
Retain the raw result for comparison and create a separately rounded reporting value if needed.