Free solar panel calculator. Estimate system size, number of panels needed, installation cost, payback period, ROI, and environmental impact for residential solar.
You might also find these calculators useful
Going solar is one of the smartest investments for your home. Our solar panel calculator helps you determine the ideal system size, estimate costs with the 30% federal tax credit, and project your long-term savings. Whether you want to offset 50% or 100% of your electricity bill, this calculator provides accurate estimates based on your location and energy usage.
Solar panel sizing depends on your electricity consumption, local sun exposure (peak sun hours), and system efficiency. The calculator divides your annual energy needs by the production capacity of solar panels in your region. Typical residential systems range from 4kW to 12kW, using 10-30 panels depending on panel wattage and roof space.
System Size Formula
System Size (kW) = Annual kWh ÷ (Peak Sun Hours × 365 × Efficiency)Avoid overpaying for an oversized system or underproducing with a system that's too small.
Understand upfront costs, tax credits, payback period, and 25-year savings before committing.
Use your calculations to evaluate installer quotes and ensure you're getting fair pricing.
See exactly how much carbon dioxide your solar system will offset over its lifetime.
Calculate solar before buying to factor energy costs into your budget.
Determine if solar can significantly reduce your $200+ monthly bills.
Size a system to cover both home usage and EV charging needs.
Perfect time to add solar - save on future installation costs.
The average US home uses 900 kWh/month and needs a 6-8 kW system, which is about 15-20 panels (at 400W each). Your specific needs depend on electricity usage, sun exposure, and panel efficiency. Use our calculator with your actual utility bill for accurate results.