Solar Panel Calculator
Size a solar array from daily kWh usage (or your electric bill), peak sun hours, panel wattage, and losses.
Processed locally in your browser — nothing is uploaded.
Typically 3–4 in northern/cloudy regions, 5–6 in sunny ones.
Inverter, wiring, soiling, temperature — ~14% is a common default.
Results
- Required array size
- 6.98 kW
- Number of panels
- 18
- Estimated production of that array
- 31 kWh/day
Peak sun hours vary by season and latitude; check a solar irradiance map for your location. Shading, roof orientation, and tilt can change output substantially.
About Solar Panel Calculator
Start from your daily kWh (or let the tool derive it from a monthly bill and rate), enter your region's peak sun hours and a panel wattage, and get the array size in kW and the panel count. A default 14% system loss covers inverter, wiring, soiling, and temperature derating.
Peak sun hours are the daily solar energy expressed as hours of full-strength sun: typically around 3–4 in cloudy or northern regions and 5–6 in sunny ones.
Common uses
- Rough-size a rooftop system before talking to installers
- Plan an off-grid cabin or van array around real consumption
- See how panel wattage choices change the panel count
Example
Input
30 kWh/day · 5 sun hours · 400 W panels · 14% losses
Output
≈ 6.98 kW array · 18 panels
Limitations
- Roof orientation, tilt, and shading are not modeled; check an irradiance map for your location's real sun hours.