Solar Insolation Lookup
Estimate peak sun hours per day for a given latitude and month. Calculate solar insolation for sizing solar arrays and off-grid battery systems.
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Applications
Used by solar installers, off-grid homeowners, RV builders, and renewable energy enthusiasts to estimate solar insolation for sizing PV arrays and battery banks. Critical for determining how many solar panels and batteries you need for reliable power in any location.
Solar Geometry Formula
Solar declination is calculated as δ = 23.45° × sin(360/365 × (284 + n)) where n is the day of year. The hour angle at sunset is h_s = acos(-tan(φ) × tan(δ)). Peak sun hours = (24/π) × [h_s × sin(φ) × sin(δ) + cos(φ) × cos(δ) × sin(h_s)] in kWh/m²/day.
Fun Fact: The Sahara Desert receives about 6-7 peak sun hours per day on average, while Seattle gets only about 3-4 in winter. That's why solar is booming in places like Morocco and the Middle East!
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