Solar Panel Cost Calculator

Estimate system size, total cost, federal tax credit, and payback period based on your monthly electric bill and location.

$2.50$3.50
System Size
4.4 kW
11 x 400W panels
Gross Cost
$13,200
at $3.00/watt
Federal ITC (30%)
-$3,960
tax credit
Net Cost
$9,240
after incentives
Annual Production
7,066 kWh
estimated output
Annual Savings
$1,915
$160/month
Payback Period
4.8 years
then free electricity
25-Year Net Savings
$38,635
lifetime profit
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How It Works

This calculator estimates your solar panel system cost in three steps:

  1. System sizing: Your monthly electricity usage (kWh) is derived from your bill and local electricity rate, then divided by peak sun hours and a system efficiency factor (80%) to determine the required system size in kW.
  2. Cost estimation: The system size is multiplied by your selected cost per watt. The 30% federal Investment Tax Credit (ITC) is then applied to calculate your net cost.
  3. Savings and payback: Annual energy production is calculated from system size and local sun hours, then multiplied by your electricity rate to determine annual savings. Payback period is net cost divided by annual savings.

Frequently Asked Questions

How much do solar panels cost in 2025?

The average cost of a residential solar panel system in 2025 is $2.50 to $3.50 per watt installed. For a typical 8 kW system, that is $20,000 to $28,000 before the 30% federal tax credit, which brings the net cost down to $14,000 to $19,600.

What is the federal solar tax credit (ITC)?

The federal Investment Tax Credit (ITC) allows you to deduct 30% of the total cost of your solar panel system from your federal income taxes. This credit is available through 2032 and then steps down to 26% in 2033 and 22% in 2034.

How long does it take for solar panels to pay for themselves?

The average payback period for residential solar panels is 6 to 10 years, depending on your electricity rates, sun exposure, system cost, and available incentives. After the payback period, you essentially get free electricity for the remaining 15 to 20 years of the system warranty.

Are there additional state incentives for solar?

Many states offer additional incentives beyond the federal ITC, including state tax credits, rebates, performance-based incentives, and net metering programs. Check your state energy office or use our calculator to estimate your specific savings.

Does roof size affect solar panel cost?

Yes, roof size determines how many panels you can fit. A typical 400W panel takes about 20 square feet. If your roof is too small to fit enough panels to cover your energy needs, you may need higher-efficiency (and more expensive) panels or a ground-mounted system.