Solar Calculator: Estimate Your Solar Cost, Savings and Payback

Enter your ZIP code and monthly electric bill to see what size solar system you need, what it costs in your state, how long it takes to pay for itself and how much you could save.

FreeNo email neededResults update as you type
1Your home
Which way does most of your roof face?
How much shade does your roof get?
Fine-tune your numbers

Find your electricity price on your bill: divide the total by the kWh you used.

2Your solar estimate
Sample for an average home in Florida. Enter your ZIP code and bill for yours.
You could save about
$0
over 25 years, after paying for the system
System size
0 kW
Price before incentives
$0
Pays for itself in
0 years
when you pay cash
New monthly bill
$0
Get My Exact Price

Free quotes from vetted local installers. No obligation.

Savings over 25 years$0See my results

When solar pays for itself

Your total bill savings compared with the price of the system, paying cash

Total bill savingsSystem price
On this page
  1. 1How the calculator works
  2. 2How to read your results
  3. 3What size system you need
  4. 4How to calculate solar cost yourself
  5. 5Solar cost by state
  6. 6How to get a more exact number
  7. 7FAQs
  8. 8Where our numbers come from
Built by the Top Solar Review Editorial Team. Data updated November 2026.

How our solar calculator works

The calculator turns your monthly bill into a yearly power use, then sizes a solar system to cover it. It uses your state's average electricity price, how much sun your area gets, and current installed solar prices to estimate your cost, your new bill and your savings.

  1. Your power use: your monthly bill times 12, divided by your electricity price, gives the kWh your home uses in a year.
  2. System size: that yearly use divided by how much power 1 kW of panels makes in your state, adjusted for roof direction and shade.
  3. Price: system size in watts times the average installed price per watt in your state.
  4. Savings: the power your panels make, valued at your electricity price, minus a small monthly utility fee you still pay. We assume power prices rise about 2.5% a year and panels lose about 0.5% of their output each year.
Want a real price for your roof? Compare free quotes from local installers

How to read your results

ResultWhat it means
Savings over 25 yearsYour total bill savings over 25 years, minus what you paid for the system. Panels usually last that long or longer.
System sizeHow many kilowatts (kW) of panels you need. Most homes use 400 to 430 watt panels, so 10 kW is about 24 panels.
Price before incentivesThe installed price, including panels, inverters, permits and labor. State or utility rebates can lower it.
Pays for itself inHow many years of bill savings it takes to cover the price when you pay cash. Under 10 years is strong.
New monthly billWhat you would pay your utility in an average month with solar. Most utilities keep a small fixed fee.

What size solar system do you need?

Most homes need between 6 and 15 kW. The two things that matter most are how much power you use and how much sun you get. A home in Arizona needs fewer panels than the same home in Washington because each panel makes more power.

A quick rule: divide the kWh you used in the last 12 months by the yearly power 1 kW makes in your state, shown in the table below. For example, a home using 13,000 kWh a year in Florida, where 1 kW makes about 1,450 kWh, needs about 9 kW.

How to calculate solar panel cost yourself

You can check any quote with simple math. You need three numbers: your yearly power use, how much power 1 kW of panels makes where you live, and the price per watt.

Example for a Florida home with a $169 bill
Yearly use: $169 × 12 ÷ $0.154 = about 13,170 kWh
System size: 13,170 ÷ 1,450 = about 9.1 kW
Price: 9,100 watts × $2.12 = about $19,292 before incentives
Payback: price ÷ yearly savings of about $1,850 = about 10 years

If a quote is well above your state's price per watt, ask what is included. Batteries, roof work, premium panels and dealer fees on loans can all raise the price.

See solar panel prices, payback and incentives in Florida

Solar panel cost by state in 2026

Average installed price per watt before incentives, the cost of a 10 kW system, the average home electricity price and how much power 1 kW of panels makes in a year. The calculator uses these numbers for your state.

StatePrice per watt10 kW systemPower pricekWh per kW a year
Alabama$2.65$26,50016.3¢1,380
Alaska$2.80$28,00029.4¢865
Arizona$2.16$21,60015.1¢1,750
Arkansas$2.62$26,20014.4¢1,400
California$2.80$28,00029.8¢1,620
Colorado$2.68$26,80017.2¢1,535
Connecticut$2.95$29,50024.5¢1,205
Delaware$2.72$27,20018.7¢1,225
District of Columbia$2.95$29,50026.0¢1,200
Florida$2.12$21,20015.4¢1,450
Georgia$2.48$24,80015.9¢1,435
Hawaii$2.70$27,00047.2¢1,610
Idaho$2.56$25,60013.4¢1,230
Illinois$2.82$28,20019.3¢1,125
Indiana$2.60$26,00017.0¢1,135
Iowa$2.80$28,00017.1¢1,185
Kansas$2.56$25,60015.5¢1,440
Kentucky$2.45$24,50013.8¢1,205
Louisiana$2.70$27,00012.9¢1,415
Maine$2.85$28,50032.1¢1,165
Maryland$2.82$28,20021.4¢1,210
Massachusetts$3.35$33,50030.5¢1,160
Michigan$2.78$27,80023.0¢1,100
Minnesota$2.84$28,40017.2¢1,040
Mississippi$2.70$27,00014.4¢1,370
Missouri$2.54$25,40016.0¢1,295
Montana$2.68$26,80015.6¢1,155
Nebraska$2.80$28,00013.5¢1,290
Nevada$2.36$23,60012.7¢1,720
New Hampshire$3.18$31,80027.6¢1,130
New Jersey$2.88$28,80024.6¢1,210
New Mexico$2.44$24,40016.5¢1,700
New York$3.18$31,80028.7¢1,145
North Carolina$2.52$25,20015.0¢1,375
North Dakota$2.75$27,50013.3¢1,135
Ohio$2.58$25,80019.4¢1,090
Oklahoma$2.60$26,00014.8¢1,435
Oregon$2.62$26,20015.9¢1,070
Pennsylvania$2.70$27,00021.8¢1,170
Rhode Island$3.10$31,00028.2¢1,170
South Carolina$2.50$25,00015.8¢1,435
South Dakota$2.70$27,00015.2¢1,390
Tennessee$2.52$25,20013.4¢1,385
Texas$2.24$22,40015.9¢1,460
Utah$2.48$24,80013.3¢1,515
Vermont$3.05$30,50023.8¢1,075
Virginia$2.62$26,20017.6¢1,265
Washington$2.58$25,80014.6¢970
West Virginia$2.60$26,00016.3¢1,095
Wisconsin$2.80$28,00019.4¢1,095
Wyoming$2.70$27,00014.4¢1,400

How to get a more exact number

  1. Use your real bill. Add up the last 12 bills and divide by 12, since summer and winter bills differ a lot.
  2. Open Fine-tune your numbers and enter the electricity price from your bill.
  3. Pick the roof direction and shade that fit the part of your roof where panels would go.
  4. Get quotes. Installers use satellite images of your roof and your utility's exact rates to give you a real price.

Solar calculator FAQs

How accurate is this solar calculator?
It gives a good starting estimate based on state averages for electricity prices, sun and installed prices. Your real price depends on your roof, your utility's rates and the equipment you choose, so use it to set expectations, then compare quotes.
How many solar panels do I need?
Most homes need 15 to 35 panels. Divide your system size in watts by the panel size. For example, a 9 kW system with 410 watt panels needs about 22 panels.
How do I calculate solar panel cost?
Multiply your system size in watts by the price per watt in your state. A 9 kW system at $2.12 per watt costs about $19,100 before incentives.
What is a good payback period for solar?
Under 10 years is strong and 10 to 14 years is common. Payback is shorter where power prices are high and where your utility gives full credit for extra power.
Does the calculator include the federal solar tax credit?
No. The 30% federal credit for homeowners who buy solar ended for systems installed after December 31, 2025. Companies that offer leases and PPAs may still claim a credit on systems they own.
Do I have to give my email to see my results?
No. Your results show instantly and nothing is saved. You only share contact details if you choose to get quotes.
What if my roof faces east or west?
Solar still works well. East and west roofs make about 10 to 15% less power than south roofs, so you may need a few more panels. North roofs are usually the weakest choice.

Where our numbers come from

Electricity prices and average bills come from the U.S. Energy Information Administration (August 2026). Installed prices per watt are based on published 2026 installer pricing by state. Yearly power per kW is based on typical south-facing home systems in each state. Credit for extra power sent to the grid is our estimate for each state, since some states pay less than the full retail price. We update these numbers as prices change.

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