Solar panel calculator
Estimate solar generation and the number of panels needed for a daily energy target.
Your inputs
Example values are illustrative. Enter your panel specifications and local, seasonal peak sun hours. Results update as you edit.
Calculations run in your browser. Inputs are not saved or sent to analytics.
How it works
- Estimated daily generation = × ÷ 1,000 × × (1 − ÷ 100)
- Estimated period generation = Estimated daily generation ×
- Panels needed for the daily target = ⌈ ÷ Daily energy per panel⌉
Input and formula key
Your result
Complete the inputs to see your result.
Assumptions and limitations
Peak sun hours are equivalent hours at full reference irradiance, not daylight hours. Enter a local seasonal estimate and combined losses including conversion, temperature, dirt and shading. The model repeats one average day across the selected period; it does not fetch location or weather data. It excludes hourly loads, storage, tariffs, incentives, roof suitability and electrical design. Output is an estimate, not guaranteed generation.
Sources
- NLR — PVWatts assumptions and losses Sources reviewed: 2026-10-24
- USAID — photovoltaic systems and peak sun hours Sources reviewed: 2026-10-24
