Estimate peak watts and yearly kWh from array area, efficiency, sun hours, and system loss.
| Peak W | – |
| kWh / year | – |
Use this calculator for a first rooftop or ground-mount sketch when you know roughly how much area you can cover.
Peak watts = 1,000 W/m² (STC) × area × module efficiency. Yearly kWh = (peak kW) × sun hours per day × 365 × (1 − loss). Area can be entered in square metres (m²) or square feet (ft²); it is converted to m² before the formula. Efficiency and loss are fractions (0.2 is 20%; 0.14 is 14% system loss).
Sun hours are peak-sun-hour equivalents, not clock hours of daylight. Shading, tilt, inverter clipping, and soiling still sit inside the loss you type. This is not a PVsyst study.
Array area: Module area facing the sun, in m² or ft².
Efficiency (0–1): Module conversion efficiency as a fraction. 0.2 is a typical silicon panel.
Sun hours / day: Peak-sun-hour equivalents at the site. 4.5 is a temperate-roof ballpark.
System loss (0–1): Combined wiring, inverter, soiling, and temperature loss as a fraction.
Peak W: Nameplate-style DC watts at STC.
kWh / year: Energy after the loss factor.
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