Solar Panel Cost Calculator
Estimate the solar system size you need from your electricity use, the installed cost, your yearly savings and the payback period.
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About the Solar Panel Cost Calculator
This solar panel cost calculator estimates the size of the system you need to offset your electricity use, using your monthly kWh and your location's peak sun hours. It then multiplies by an installed price per watt to estimate cost, subtracts any incentives and shows yearly savings and payback. The federal residential solar tax credit ended for expenses paid after 2025, so enter only incentives you have confirmed, such as state, utility or local programs.
How to use it
- Enter your average monthly electricity use and your electricity rate.
- Enter peak sun hours for your area, the installed cost per watt and any confirmed incentives.
- Press Estimate solar system to see the system size, cost, savings and payback.
Solar sizing formula
System size (kW) = yearly kWh ÷ (peak sun hours × 365 × 0.80). A home using 900 kWh a month with 4.5 sun hours needs about 8.2 kW.
What changes the payback
- Your electricity rate and how fast it rises.
- Net metering or export credit rules in your state.
- Roof direction, tilt and shade.
- Upfront cost, incentives and financing.
- Batteries add cost and change the savings math.
Peak sun hours by region (approximate)
| Region | Peak sun hours per day |
|---|---|
| Southwest (AZ, NV) | 6 to 7 |
| Southeast and Texas | 4.5 to 5.5 |
| Midwest | 4 to 5 |
| Northeast | 3.5 to 4.5 |
| Pacific Northwest | 3 to 4 |
Frequently asked questions
How much does a solar system cost?
Residential systems often cost roughly $2.50 to $3.50 per watt installed before incentives, so a 7 kW system is about $17,500 to $24,500. Prices vary by installer and location.
Is there still a federal solar tax credit?
The residential clean energy credit for homeowners ended for expenses paid after December 31, 2025. Check state, utility and local incentives and ask a tax professional.
How many solar panels do I need?
It depends on your usage and sun hours. A typical home needs about 15 to 25 panels.
How long is the solar payback period?
Often 7 to 15 years, depending on electricity prices, incentives and system cost.
Does solar increase home value?
Owned solar systems often add resale value, but leased systems may not.
Last reviewed: November 2026. Estimates only. Get quotes from licensed solar installers. Incentives change often.