Solar Panel Calculator
Work out how many solar panels you need, what they cost in your state and how fast they pay back, using current prices, electricity rates and NREL solar data.
Your result
Enter your numbers and press the button. Your result appears here.
Solar calculators
Solar cost
- Solar Panel Cost Calculator
- Solar Installation Cost Calculator
- Solar Cost per Watt Calculator
- Cost of a 3 kW Solar System
- Cost of a 4 kW Solar System
- Cost of a 5 kW Solar System
- Cost of a 6 kW Solar System
- Cost of a 7 kW Solar System
- Cost of a 8 kW Solar System
- Cost of a 9 kW Solar System
- Cost of a 10 kW Solar System
- Cost of a 11 kW Solar System
- Cost of a 12 kW Solar System
- Cost of a 15 kW Solar System
- Cost of a 20 kW Solar System
- Cost of a 25 kW Solar System
- Solar Panel Cost for a $100 Electric Bill
- Solar Panel Cost for a $150 Electric Bill
- Solar Panel Cost for a $200 Electric Bill
- Solar Panel Cost for a $250 Electric Bill
- Solar Panel Cost for a $300 Electric Bill
- Off-Grid Solar System Cost Calculator
- Solar and Battery Cost Calculator
- Solar Cost per kWh Calculator
System sizing
- How Many Solar Panels Do I Need?
- Solar System Size Calculator
- How Many Solar Panels for 500 kWh a Month?
- How Many Solar Panels for 750 kWh a Month?
- How Many Solar Panels for 1,000 kWh a Month?
- How Many Solar Panels for 1,250 kWh a Month?
- How Many Solar Panels for 1,500 kWh a Month?
- How Many Solar Panels for 2,000 kWh a Month?
- How Many Solar Panels for a 5 kW System?
- How Many Solar Panels for a 6 kW System?
- How Many Solar Panels for a 8 kW System?
- How Many Solar Panels for a 10 kW System?
- How Many Solar Panels for a 12 kW System?
- Solar Panel Output Calculator
- Solar Panel kWh per Day Calculator
- How Many kWh Does a 300 W Solar Panel Produce?
- How Many kWh Does a 350 W Solar Panel Produce?
- How Many kWh Does a 400 W Solar Panel Produce?
- How Many kWh Does a 450 W Solar Panel Produce?
- Solar Production Calculator
- Solar Inverter Size Calculator
- Solar Roof Space Calculator
- Solar Panels Needed From Your Electric Bill
- Solar Offset Calculator
- Solar Panel Wattage Calculator
Batteries
- Solar Battery Size Calculator
- Battery Backup Time Calculator
- Solar Battery Cost Calculator
- How Many Powerwalls Do I Need?
- Whole-Home Battery Backup Calculator
- Off-Grid Battery Bank Calculator
- 12V Battery Bank Calculator
- 24V Battery Bank Calculator
- 48V Battery Bank Calculator
- What Size Solar Panel to Charge a Battery?
- Battery Runtime Calculator
Panel and system tools
- Solar Irradiance by Zip Code Calculator
- Solar Panel Azimuth Angle Calculator
- Solar Panel Conversion Efficiency Calculator
- Solar Panel Daily Power Generation (kWh) Calculator
- Solar Panel Optimal Tilt Angle Calculator by Zip Code
- Solar Panel Power Calculator by Size
- Solar Panel Voltage Calculator
- How Many Solar Panels to Power a House Calculator
- Maximum Charging Voltage Calculator
- Photovoltaic Array Annual Power Generation Calculator
- Photovoltaic Array Row Spacing Calculator
- Solar Battery Charge Time Calculator
How it works
System size (kW) = yearly kWh ÷ yearly output per kW. Panels = size in watts ÷ panel watts, rounded up.
Example: 865 kWh a month is 10,380 kWh a year. At 1,367 kWh per kW that needs 7.59 kW, or 19 panels of 400 W.
Panels convert sunlight into direct current through the photovoltaic effect. Some energy is lost to heat, dirt, wiring and the inverter, which turns DC into the AC your home uses; NREL's PVWatts model allows 14% for system losses and a 96% efficient inverter by default.
Solar by state
An 8 kW system at each state's average price per watt, electricity price and output. Payback in years, before incentives.
| State | Per watt | Electricity | kWh per kW | 8 kW cost | Payback |
|---|---|---|---|---|---|
| Alabama | $3.72 | 16.51¢ | 1,367 | $29,760 | 17.2 |
| Alaska | $2.60* | 27.32¢ | 922 | $20,800 | 10.6 |
| Arizona | $2.25 | 15.36¢ | 1,755 | $18,000 | 8.5 |
| Arkansas | $2.37 | 13.74¢ | 1,373 | $18,960 | 12.9 |
| California | $2.52 | 32.58¢ | 1,677 | $20,160 | 4.7 |
| Colorado | $2.63 | 16.80¢ | 1,595 | $21,040 | 10.0 |
| Connecticut | $2.67 | 27.47¢ | 1,291 | $21,360 | 7.7 |
| Delaware | $2.63 | 17.98¢ | 1,364 | $21,040 | 11.0 |
| District of Columbia | $3.20 | 24.86¢ | 1,391 | $25,600 | 9.5 |
| Florida | $2.12 | 15.32¢ | 1,455 | $16,960 | 9.7 |
| Georgia | $2.50 | 15.48¢ | 1,420 | $20,000 | 11.7 |
| Hawaii | $3.44 | 46.41¢ | 1,622 | $27,520 | 4.6 |
| Idaho | $2.95 | 13.02¢ | 1,468 | $23,600 | 16.0 |
| Illinois | $2.92 | 19.23¢ | 1,308 | $23,360 | 11.9 |
| Indiana | $2.59 | 17.04¢ | 1,332 | $20,720 | 11.7 |
| Iowa | $3.26 | 14.55¢ | 1,367 | $26,080 | 17.1 |
| Kansas | $2.66 | 15.26¢ | 1,526 | $21,280 | 11.7 |
| Kentucky | $2.48 | 14.20¢ | 1,343 | $19,840 | 13.4 |
| Louisiana | $2.31 | 13.27¢ | 1,479 | $18,480 | 12.1 |
| Maine | $2.91 | 30.23¢ | 1,319 | $23,280 | 7.4 |
| Maryland | $2.55 | 21.31¢ | 1,392 | $20,400 | 8.8 |
| Massachusetts | $2.90 | 30.19¢ | 1,302 | $23,200 | 7.5 |
| Michigan | $2.86 | 21.73¢ | 1,291 | $22,880 | 10.4 |
| Minnesota | $3.23 | 16.44¢ | 1,333 | $25,840 | 15.3 |
| Mississippi | $2.29 | 15.06¢ | 1,414 | $18,320 | 11.0 |
| Missouri | $2.49 | 14.28¢ | 1,433 | $19,920 | 12.5 |
| Montana | $2.54 | 14.13¢ | 1,344 | $20,320 | 13.8 |
| Nebraska | $2.60* | 12.92¢ | 1,423 | $20,800 | 14.6 |
| Nevada | $2.35 | 13.36¢ | 1,753 | $18,800 | 10.3 |
| New Hampshire | $2.88 | 26.91¢ | 1,258 | $23,040 | 8.7 |
| New Jersey | $2.60 | 24.09¢ | 1,305 | $20,800 | 8.4 |
| New Mexico | $2.49 | 15.34¢ | 1,779 | $19,920 | 9.3 |
| New York | $2.77 | 29.26¢ | 1,291 | $22,160 | 7.5 |
| North Carolina | $2.44 | 14.94¢ | 1,416 | $19,520 | 11.9 |
| North Dakota | $2.60* | 12.46¢ | 1,294 | $20,800 | 16.8 |
| Ohio | $2.56 | 18.81¢ | 1,296 | $20,480 | 10.8 |
| Oklahoma | $2.57 | 13.81¢ | 1,542 | $20,560 | 12.4 |
| Oregon | $2.40 | 15.46¢ | 1,121 | $19,200 | 14.3 |
| Pennsylvania | $2.60 | 21.13¢ | 1,356 | $20,800 | 9.3 |
| Rhode Island | $2.80 | 29.05¢ | 1,294 | $22,400 | 7.6 |
| South Carolina | $2.57 | 15.90¢ | 1,454 | $20,560 | 11.4 |
| South Dakota | $2.60* | 14.58¢ | 1,409 | $20,800 | 13.0 |
| Tennessee | $3.48 | 13.80¢ | 1,338 | $27,840 | 19.7 |
| Texas | $2.26 | 16.03¢ | 1,421 | $18,080 | 10.2 |
| Utah | $2.60* | 13.19¢ | 1,484 | $20,800 | 13.7 |
| Vermont | $2.78 | 23.93¢ | 1,222 | $22,240 | 9.7 |
| Virginia | $2.56 | 16.95¢ | 1,427 | $20,480 | 10.8 |
| Washington | $2.47 | 14.42¢ | 1,088 | $19,760 | 16.4 |
| West Virginia | $2.60* | 15.58¢ | 1,219 | $20,800 | 14.1 |
| Wisconsin | $3.03 | 19.05¢ | 1,334 | $24,240 | 12.3 |
| Wyoming | $2.60* | 14.01¢ | 1,533 | $20,800 | 12.5 |
* No EnergySage state average published; national $2.60 per watt used.
Common questions
How many solar panels do I need?
Divide your yearly electricity use by the yearly output of 1 kW of panels where you live, then by the panel size. The average U.S. home used 865 kWh a month in 2024 (EIA); at the U.S. average of 1,367 kWh per kW that is about 7.6 kW, or 19 panels of 400 W.
How much does solar cost in 2026?
EnergySage marketplace quotes average $2.60 per watt before incentives, about $20,800 for an 8 kW system. State averages run from $2.12 to $3.72 per watt.
Is there still a federal tax credit?
Not for homeowners who buy their system. The 30% Residential Clean Energy Credit ended for systems installed after December 31, 2025.
How do solar panels make electricity?
Sunlight frees electrons in the silicon cells (the photovoltaic effect), producing direct current. An inverter turns it into the alternating current your home uses; batteries and charge controllers store and manage it.
Sources
- EnergySage, Solar panel cost by state (updated November 6, 2026): https://www.energysage.com/local-data/solar-panel-cost/
- U.S. EIA, Electric Power Monthly, Table 5.6.B (residential price, Jan–Aug 2026): https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_b
- U.S. EIA, Today in Energy: average residential use 865 kWh a month in 2024: https://www.eia.gov/todayinenergy/detail.php?id=65244
- NREL PVWatts v8 (20° tilt, south-facing, 14% losses), state results compiled by TheGreenWatt: https://thegreenwatt.com/average-peak-sun-hours-by-state/
- IRS, Residential Clean Energy Credit: https://www.irs.gov/credits-deductions/residential-clean-energy-credit