How to Use This Tool
Turn average plane-of-array irradiance over a duration into equivalent full-sun hours. Convert average solar irradiance and duration into energy per square meter, peak sun hours and equivalent full-sun minutes.
The decision this tool supports
Peak sun hours are an energy-equivalent duration, not the count of daylight hours or hours with clear sky. This page keeps the decision bounded to equivalent peak sun hours and the supporting outputs shown beside it. Peak Sun Hours does not import an account, infer a market rate, or silently substitute an industry average.
Inputs and units
The Peak Sun Hours calculation uses Average irradiance, Duration, Reference peak irradiance. Keep all money values in one currency and all time, distance, mass, energy or volume entries in the unit printed beside the field. Mixing Peak Sun Hours scopes can produce a plausible number with the wrong meaning.
- Average irradiance is entered in W/m².
- Duration is entered in hours.
- Reference peak irradiance is entered in W/m².
Formula and worked check
Incident energy kWh/m² = average W/m² × hours ÷ 1,000; peak sun hours = average irradiance × hours ÷ reference irradiance. 650 W/m² averaged for six hours equals 3.90 kWh/m² and 3.90 peak sun hours at the 1,000 W/m² reference. The Peak Sun Hours default is an executable known-answer case, not a benchmark or recommendation. Change one input and verify that the direction of equivalent peak sun hours still matches the stated relationship.
How to interpret the result
Use irradiance averaged over a known plane and period; system energy still requires area, efficiency, orientation and loss modeling. The additional Peak Sun Hours outputs expose the denominator, comparison, capacity or reverse value needed to audit the primary result instead of presenting one unexplained number.
Assumptions
- Average irradiance and duration refer to the same interval.
- Reference irradiance is user editable and positive.
- The converter does not claim location-specific irradiance.
Save the Peak Sun Hours input values and date with any material decision. A later Peak Sun Hours rerun is reproducible only when the same assumptions and units are available.
Limitations and safety boundary
A single average cannot reproduce hourly temperature, shading, spectral, incidence-angle or inverter effects. Peak Sun Hours is an estimate and cannot replace a contract, local code, licensed professional, calibrated measurement, lender statement or platform report where one governs the decision.
Source and privacy
The Peak Sun Hours definition or rule was checked against NREL — National Solar Radiation Database on 2026-08-26. Recheck NREL — National Solar Radiation Database when a specification or policy behind Peak Sun Hours can change. Peak Sun Hours arithmetic runs in this browser tab; ecech does not receive the values through a calculation API.
Sources & assumptions
Tool Spec v2 · verified 2026-08-26. Platform rules and fees can change; the editable inputs remain authoritative for your account.
Official references
- NREL — National Solar Radiation Database (checked 2026-08-26)
Model assumptions
- Average irradiance and duration refer to the same interval.
- Reference irradiance is user editable and positive.
- The converter does not claim location-specific irradiance.
- A single average cannot reproduce hourly temperature, shading, spectral, incidence-angle or inverter effects.
