Solar Panel Calculator
Free solar panel calculator — estimate the system size you need, number of panels, upfront cost, monthly savings, and payback period based on your electricity usage and location.
Short answer: Solar Panel Calculator — Estimate solar system size, cost, savings & payback. Free solar panel calculator — estimate the system size you need, number of panels, upfront cost, monthly savings, and payback period based on your electricity usage and location. It answers “how many solar panels do i need calculator”. Who it is for: Homeowners sizing a solar system from their electricity bill; Buyers comparing quotes from solar installers; Anyone checking payback years before signing. It runs entirely in your browser — no sign-up, no account, no email and no upload — and every result can be exported as a dated PDF report.
- ✔ Price: free, unlimited use, no rate limits
- ✔ Sign-up: not required
- ✔ Privacy: all math runs client-side, nothing is uploaded
- ✔ Export: one-click PDF report (2026 rates)
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Who is this tool for?
- ✔ Homeowners sizing a solar system from their electricity bill
- ✔ Buyers comparing quotes from solar installers
- ✔ Anyone checking payback years before signing
- ✔ Households weighing a battery with panels
- ✔ Renters and owners learning how panel count is worked out
How to use Solar Panel Calculator
- Enter your average monthly electricity usage in kWh.
- Set peak sun hours per day for your location (typical 4–6).
- Adjust panel wattage, cost per watt, and electricity rate.
- Read system size, panel count, cost, monthly savings, payback years, and 25-year savings.
Frequently asked questions
How many solar panels do I need for a 2000 kWh/month home?
For 2000 kWh/month with 5 peak sun hours, you need roughly a 13 kW system — about 33 panels at 400W each. This calculator does the math for your exact usage.
How much does a 10 kW solar system cost in 2026?
Roughly $2.50–$3.50 per watt installed before incentives — so about $25,000–$35,000 gross. Federal and state tax credits typically cut this by 30%+.
What is a good solar payback period?
7–10 years is typical in the US and much of Europe. Under 7 is excellent, over 12 usually means the sizing or price assumptions need revisiting.
How do I calculate peak sun hours for my area?
Peak sun hours are the equivalent hours of full 1000 W/m² sunlight per day. US averages: 4 (Pacific NW) to 6.5 (Southwest). Look up NREL PVWatts for exact values.
Do solar panels work in cloudy weather?
Yes — panels still produce 10–25% of rated output under heavy clouds. Peak sun hours already factor in your local weather average.
Is this solar calculator accurate?
It gives a solid ballpark within ~10% for a well-oriented residential rooftop. Get a site-specific quote before purchasing.
How many solar panels do i need calculator?
Use the Solar Panel Calculator above: Estimate solar system size, cost, savings & payback. Free solar panel calculator — estimate the system size you need, number of panels, upfront cost, monthly savings, and payback period based on your electricity usage and location.