You'll need about
8.3 kW
system size
21
panels
10,950
kWh / year
378
sq ft roof
Quoting a solar install? Turn the system size into a priced proposal — build a free estimate.
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Cómo se calcula
daily use = monthly kWh ÷ 30 · system kW = (daily use × offset) ÷ (peak sun hours × 0.80 derate) · panels = system watts ÷ panel wattage (rounded up).
Annual production = system kW × sun hours × 365 × 0.80. Roof area assumes about 18 sq ft per panel. A real design also accounts for roof orientation, shading, and local incentives.
Es una estimación de planeación: conviene confirmarla siempre con la normativa, las especificaciones y tu proveedor antes de pedir o instalar.
Solar Panel Calculator: FAQ
How many solar panels do I need?
Take your monthly kWh use, divide by 30 for daily use, then divide by (peak sun hours × 0.8 for real-world losses) to get system size in kW. Multiply by 1,000 and divide by your panel wattage for the panel count. A 900 kWh/month home at 4.5 sun hours needs roughly a 9–10 kW system, about 24 panels at 400W.
What are peak sun hours?
Peak sun hours are the equivalent hours per day of full-strength sun for your location — not daylight hours. Most of the US ranges from about 3.5 (Pacific Northwest) to 6 (Southwest). Your solar designer uses a location-specific figure.
Why multiply by 0.8?
Real systems lose energy to inverter conversion, wiring, heat, shading, and panel soiling. An 80% derate factor is a standard planning allowance so the system is sized to actually cover the target, not just on paper.
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