Glossary
Peak sun hours
Peak sun hours are the number of hours per day during which solar radiation equals its standard maximum intensity (1,000 watts per square meter). It is not the same as daylight hours: a day can have 13 hours of light and considerably fewer peak sun hours. It is the figure used to calculate how many kWh each installed kW produces in your area.
What peak sun hours are
The sun does not hit with the same strength all day. At dawn and dusk radiation is weak; at midday it peaks. To simplify the math, all the solar energy reaching one square meter over the day is added up and expressed as if it had arrived at maximum intensity for a certain number of hours. That number is the peak sun hours.
The basic design formula is: installed kW × peak sun hours × days × loss factor = kWh produced. Losses include heat, soiling, wiring, the inverter and orientation.
Why it matters in Florida
Florida gets more peak sun than most of the country, but less than the desert Southwest: humidity, afternoon clouds in the rainy season, and heat (which lowers panel output) take their share. The figure also varies within the state and by month: summer has more daylight but also more clouds; winter is shorter but clearer.
A serious design uses radiation data specific to your location (public databases such as NREL’s), not a national average. And it shows production month by month, because your consumption is not flat either.
Common mistake
Assuming “Florida is the Sunshine State” and accepting an optimistic production estimate. Ask the proposal to state which radiation data source it used and which loss factor it assumed. If two proposals for the same roof and the same size show very different production, one of them is using assumptions that do not match your home. More in how many solar panels do I need in Florida.
Full guide: How many solar panels do I need in Florida? Sizing from your real kWh →
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