Peak Sun Hours
Peak sun hours measure usable solar energy at a location, not total daylight time.
What peak sun hours means
Peak sun hours describe how much usable solar energy reaches a location during an average day. One peak sun hour is not one hour of daylight. It is roughly one hour of sunlight at 1,000 watts per square meter.
Solar sizing tools use peak sun hours because panel output depends on sunlight strength, not just sunrise-to-sunset time. In SolarPel planning, start with the Panel Estimator and then compare assumptions against the Solar System Sizing Guide.
How homeowners should use it
- Use local peak sun hour estimates instead of generic national averages.
- Reduce expected output for shading, roof angle, orientation, heat, and inverter losses.
- Treat the result as planning guidance before comparing installer production estimates.
Why it matters
Peak sun hours are one of the main assumptions behind panel count, system size, and production estimates.
Example
If a home uses 30 kWh per day and the site receives 4.5 peak sun hours, a rough starting point is 30 divided by 4.5, then adjusted upward for real-world system losses.