Solar Panel Calculator
Enter your monthly electricity usage and location to get the recommended system size, number of panels, roof space required, estimated annual savings, and payback period. Based on NREL peak sun hour data by climate zone.
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Top PickSolar Panels (400W) — Amazonfrom $149/panel* Affiliate links — we may earn a commission at no cost to you.
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How to Use This Calculator
- 1Enter your measurements in the fields above. Use the units shown next to each field (ft, in, etc.).
- 2Click Calculate to get your material estimate instantly.
- 3Review the highlighted result — it shows the key quantity you need to order.
- 4Use Copy Results to save your estimate, or bookmark the URL — your inputs are encoded in the link.
Pro tip: Always add 10% to your material order to account for waste, cuts, and defects.
Frequently Asked Questions
How many solar panels do I need for a 1,500 sq ft house?
A 1,500 sq ft home uses roughly 600–900 kWh/month. At 5 peak sun hours and 80% system efficiency, a 100% offset system requires 5–7 kW = approximately 13–18 standard 400W panels.
What is the 30% federal solar tax credit?
The Residential Clean Energy Credit lets you deduct 30% of your total solar system cost from your federal income taxes. On a $20,000 system, that's a $6,000 tax credit. The credit applies to panels, inverters, labor, and battery storage installed through 2032.