Solar Panel Calculator: Estimate Size, Cost and Savings for Your Home
A free solar estimator tool: enter your ZIP and monthly bill for system size, panels, cost, payback and 25-year savings.
Turn these numbers into a build plan.
- 7.6 kW system
- 19 panels
- 11.1 years payback
Cut list: Solar Panel Calculator: Estimate Size, Cost and Savings for Your Home
- Location4.5 sun hours, $0.17/kWh
- System size7.6 kW
- Panels needed19 x 400 W
- Roof area needed380 sq ft
- Yearly production10,735 kWh (101% of use)
- Installed cost$22,800
- Installed payback11.1 years
- Installed 25-year savings$38,565
- DIY kit cost$11,400
- DIY payback6 years
- DIY 25-year savings$49,965
- First-year bill savings$1,800
- [ ] Solar panels, 400 W19
- [ ] Inverter (AC)about 6.4 kW
- [ ] Racking and flashing19 panels' worth
- [ ] Installed estimate$22,800
- [ ] DIY kit estimate$11,400
- [ ] Inverter, about 6.4 kW AC
- [ ] Racking, flashing and rails
- [ ] Permit and interconnection fees
- [ ] Battery
A 7.6 kW system (19 x 400 W panels) covers about 101% of your use; installed cost $22,800, payback 11.1 years. As a DIY kit with an electrician for the tie-in: $11,400, payback 6 years.
How we estimate: 10,588 kWh a year x 100% / (4.5 sun hours x 365 x 86% after losses x facing and shade) = 7.5 kW, rounded up to whole panels. Savings grow 3% a year with rates and shrink 0.5% a year as panels age.
Save this solar plan to Blueprint: the system size, net cost and payback become a project with a checklist from roof check to permission to operate, a budget, and a place to log installer quotes against $3,000 per kW. Cut the bill first with the energy savings calculator, and check panel capacity with the electrical load calculator.
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Go solar: 7.6 kW system (19 x 400 W panels)
A 7.6 kW grid-tied system in your area making about 10,735 kWh a year, 101% of your use. Installed cost about $22,800; payback 11.1 years. The tie-in, permit and utility interconnection are done by a licensed electrician.
- Materials
- $22,800
- Time
- 2 to 4 months, contract to power-on
- Level
- Easy
- 1
Confirm usage and the roof
Pull 12 months of bills and confirm the annual kWh (this plan assumes 10,588). Have the roof checked: panels last 25+ years, so re-roof first if it is near the end of its life.
- Annual kWh from bills
- Roof age and condition checked
- Shade checked at 9 am, noon and 3 pm
- 2
Get quotes and compare to this estimate
Get three quotes and compare each on price per watt, panel and inverter brand, warranty and production estimate. This plan's benchmark is $22,800 for 7.6 kW.
- Three quotes saved
- Price per watt compared
- Warranties compared
- 3
Check incentives and the utility's rules
Look up state and utility rebates, net metering or net billing rules and any interconnection fee before you sign. Federal tax credit rules have changed; confirm what applies to your install date.
- Incentives listed
- Net metering terms read
- Interconnection application ready
- System
- 7.6 kW
- Panels
- 19
- Payback
- 11.1 years
- Net cost
- $22,800
7 steps · 5 tools · 5 materials
4 more steps, the full tool list and a shopping list you can check off as you go.
Your plan is 60% built. Save it.
3/5Go solar: 7.6 kW system (19 x 400 W panels)
Finished in 2 to 4 months, contract to power-on · $22,800 DIY
Built for your system of 7.6 kW. Your first plan saves free. No card needed.
Or save it with just your email
We send a link; open it and this plan is your first project. Your first plan saves free. No card needed.
Solar estimate example: a $150 bill in Phoenix vs Seattle
Phoenix: 1,000 kWh a month at $0.15/kWh and 6.3 sun hours needs a 6.4 kW system (16 panels), about $19,200 installed, paying back in 9.6 years. Seattle: power is cheaper ($0.13/kWh), so the same bill buys more kWh, and at 3.6 sun hours it takes 12.8 kW (32 panels), about $38,400, with payback of 17.3 years.
How many solar panels do I need?
| Monthly use | 3.5 sun hours | 4.5 sun hours | 5.5 sun hours | 6.5 sun hours |
|---|---|---|---|---|
| 500 kWh | 14 panels (5.6 kW) | 11 panels (4.4 kW) | 9 panels (3.6 kW) | 8 panels (3.2 kW) |
| 750 kWh | 21 panels (8.4 kW) | 16 panels (6.4 kW) | 14 panels (5.6 kW) | 12 panels (4.8 kW) |
| 1,000 kWh | 28 panels (11.2 kW) | 22 panels (8.8 kW) | 18 panels (7.2 kW) | 15 panels (6.0 kW) |
| 1,200 kWh | 33 panels (13.2 kW) | 26 panels (10.4 kW) | 21 panels (8.4 kW) | 18 panels (7.2 kW) |
| 1,500 kWh | 41 panels (16.4 kW) | 32 panels (12.8 kW) | 27 panels (10.8 kW) | 23 panels (9.2 kW) |
How we estimate solar size, cost and savings
- Find your yearly use. Add up 12 months of kWh from your bills, or divide your average bill by your rate and multiply by 12.
- Look up your sun hours. Peak sun hours run from about 3.5 a day in the Pacific Northwest to over 6 in the desert Southwest.
- Size the system. kW = yearly kWh / (sun hours x 365 x 0.86 for losses), adjusted for roof direction and shade. Divide by the panel size and round up.
- Price it and find payback. Multiply the watts by the price per watt (about $3 installed, $1.50 for a DIY kit), subtract incentives, and divide by yearly bill savings.
Assumptions: state-average peak sun hours (NREL) and residential rates (EIA, rounded), 14% system losses as in PVWatts, roof factors of 1.0 south, 0.95 southeast or southwest, 0.85 east or west, shade factors of 0.9 light and 0.75 heavy, 0.5% a year panel degradation, 3% a year rate increases, and savings capped at your own use (no credit for exported power).
Peak sun hours by state
| State | Sun hours | Rate |
|---|---|---|
| Arizona | 6.3 | $0.15/kWh |
| Nevada | 6.1 | $0.15/kWh |
| New Mexico | 6.3 | $0.15/kWh |
| California | 5.8 | $0.32/kWh |
| Utah | 5.6 | $0.12/kWh |
| Hawaii | 5.6 | $0.41/kWh |
| Colorado | 5.5 | $0.15/kWh |
| Texas | 5.3 | $0.15/kWh |
| Florida | 5.3 | $0.15/kWh |
| Oklahoma | 5.2 | $0.13/kWh |
| Georgia | 5.0 | $0.15/kWh |
| Kansas | 5.0 | $0.14/kWh |
| South Carolina | 4.9 | $0.15/kWh |
| North Carolina | 4.8 | $0.14/kWh |
| New Jersey | 4.3 | $0.20/kWh |
| Massachusetts | 4.1 | $0.30/kWh |
| New York | 4.0 | $0.25/kWh |
| Illinois | 4.3 | $0.17/kWh |
| Washington | 3.6 | $0.13/kWh |
| Oregon | 4.0 | $0.14/kWh |
Solar cost per watt: DIY vs installed
| System | Installed | DIY kit |
|---|---|---|
| 6 kW | $18,000 | $9,000 |
| 8 kW | $24,000 | $12,000 |
| 10 kW | $30,000 | $15,000 |
Before solar, fix the roof and the waste: check the roof with the asphalt shingle roofing cheat sheet and the roof pitch chart, vent the attic with the attic ventilation guide, and cut use with the energy audit checklist and the energy savings calculator. Shade windows with the window overhang calculator, and read the permit and inspection cheat sheet before you sign.
What you can DIY, and what needs a pro
Sizing, shopping and mounting racking are reasonable DIY work. The utility interconnection, the panel tie-in and the permit sign-off need a licensed electrician and an inspection. Check your service capacity first with the electrical load calculator, and size long wire runs with the voltage drop calculator.
Solar panel calculator FAQ
How many solar panels do I need for 1,000 kWh a month?
Is solar worth it?
Can I install solar myself?
Do I need a permit for solar panels?
What size inverter do I need?
How much roof space do solar panels need?
Do I need batteries?
How accurate is this solar estimate?
Is there still a federal solar tax credit?
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