How to Calculate Solar Panel Sizing
What is Solar Panel Sizing?
Calculates solar panel capacity needed to meet energy requirements. Accounts for climate, season, and system losses.
Formula
Panel wattage = daily need ÷ insolation ÷ 0.80
Step-by-Step Guide
- 1Daily energy requirement in kWh
- 2Average daily insolation (peak sun hours) for location
- 3Panel efficiency (typically 15-22%)
- 4System losses (inverter 5%, wiring 3%, dirt 2%)
- 5Panel wattage = daily need ÷ insolation ÷ 0.80
Worked Examples
Input
5000Wh/day need, 5 sun hrs
Result
1000W array
Common Mistakes to Avoid
- ✕Not accounting for seasonal variation
- ✕Ignoring system losses (20% penalty typical)
Frequently Asked Questions
How much solar is needed for household?
Average home 5kW system produces 6,000-8,000 kWh/year depending on location.
Does weather affect solar output?
Yes significantly; cloudy days 25-50% output; winter 30-50% of summer; location critical.
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