Solar Panel kWh Calculator
Estimate annual and monthly PV energy (kWh) from array size, peak sun hours, and system losses for commercial planning.
Quick answer
Annual kWh ≈ Array kW × Peak sun hours × 365 × (1 − Loss). Example: 10 kW, 5.0 PSH, 15% loss → about 15,513 kWh/yr. Sized array first? Use the solar panel sizing calculator. Hub: Solar calculator.
Quick PV Energy Production Calculator
Defaults: 10 kW array · 5.0 PSH · 15% system loss.
10 kW × 5.0 × 365 × 0.85.
Advanced PV Energy Production Calculator
Presets
PV Energy Production Results
Engineering disclaimer
Simplified estimate—not NREL PVWatts. Real yield varies with weather year, tilt, shading, and OEM curves. Use for planning screens only.
Results
~15,513 kWh/yr — default example.
Annual kWh by peak sun hours
| PSH | kWh/yr | kWh/month |
|---|
People also ask
- How do I estimate solar kWh? Array kW × PSH × days × (1 − loss).
- Is this PVWatts? No—simplified planning formula with explicit loss %.
- Monthly vs annual? Monthly ≈ annual ÷ 12 for a flat screen; seasonality needs site data.
Planning guidance
- Size first: Get array kW from the solar panel sizing calculator.
- Loss band: 12–20% is common for commercial rooftops before weather uncertainty.
- Cost link: Carry kWh into the energy estimator for tariff screening.
- BOS: Size controllers with MPPT sizing.
- Hub: Solar calculator workflow entry.
Typical scenarios
- 10 kW office roof: ~12–18 MWh/yr depending on PSH and soiling.
- 50 kW warehouse: Scale linearly in this model—confirm inverter clipping separately.
- High-loss site: Dusty / long DC runs—raise loss % before quoting savings.
Formula (quick reference)
Annual kWh = Array kW × Peak sun hours × Days × (1 − Loss fraction)
Monthly ≈ Annual ÷ 12 (flat average). See examples. How to choose loss %: solar system losses & derating.
Frequently Asked Questions
How do I calculate solar panel kWh production?
Multiply array kW by peak sun hours, days per year, and (1 − system loss). Example: 10 × 5 × 365 × 0.85 ≈ 15,513 kWh/yr.
Is this the same as NREL PVWatts?
No. This is a simplified planning estimate with an explicit loss percentage—not a weather-year simulation.
What loss percentage should I use?
Often 12–20% for commercial systems covering inverter, wiring, soiling, and mismatch. See solar system losses & derating for factor bands, then confirm with OEM tools.
How does this differ from solar panel sizing?
Sizing finds required array kW from daily load. Production estimates kWh from a known array size.
What is the next step?
Size MPPT controllers for string current, or screen energy cost with the energy estimator.
How it works
Daily full-sun equivalent hours are scaled across the year and reduced by a combined system loss fraction. The model is linear in array kW—clipping, seasonal PSH, and tilt are out of scope.
Formula and sources
Annual kWh = kW × PSH × Days × (1 − Loss)
Not equivalent to PVWatts. Use for planning screens; confirm with site irradiance and OEM software.
Worked examples
- 10 kW · 5.0 PSH · 15% loss
10 × 5 × 365 × 0.85 = 15,512.5 kWh/yr (~1,293 kWh/month).
- 50 kW · 4.5 PSH · 18% loss
50 × 4.5 × 365 × 0.82 ≈ 67,342 kWh/yr.