Assumes 3%/yr rate increases, 0.5%/yr panel degradation and no federal tax credit (the 30% §25D credit ended for systems installed after Dec 31, 2025). How we calculate
Data approachEIA rates · NREL sun hours · 2026 federal policy · methodology
Quick answer: A typical US home uses about 10,800 kWh of electricity per year (EIA), and reaching net-zero with solar takes roughly 6 to 10.5 kW of panels, or about 16 to 27 panels at 400 W each. Where you fall in that range depends mostly on local sunshine, then on how much electricity you cut before sizing. In 2026 you should also plan without the federal 30% tax credit, which ended for systems bought after December 31, 2025.
Key facts at a glance
Sizing formula: system kW = annual kWh ÷ (peak sun hours × 365 × 0.80)
Typical home: about 10,800 kWh per year, or about 900 kWh per month
Typical net-zero system: about 8.2 kW (21 panels) at 4.5 peak sun hours
Typical 2026 price: about $2.60–$3.30 per watt before incentives
Federal credit: none for homeowner-purchased systems in 2026
Last updated October 2, 2026. Prices, incentives and net-metering rules change often, so confirm current terms with your installer and utility.
⚡ System Size
How Many Solar Panels Does a Net-Zero Home Need?
A net-zero home produces at least as many kilowatt-hours (kWh) per year as it uses. It does not mean the house runs on solar every hour. The meter simply nets out over twelve months, which is why annual kWh is the starting point for sizing.
The U.S. Energy Information Administration reports that the average US residential customer bought 10,791 kWh in 2022, about 899 kWh per month. Usage varies widely by state, from about 6,178 kWh in Hawaii to about 14,774 kWh in Louisiana. Your own bill is a better input than any average.
How to size a net-zero solar system in 4 steps:
Find your annual kWh. Add up 12 months of bills, or use your utility’s online usage history.
Apply the formula. System kW = annual kWh ÷ (PSH × 365 × 0.80).
Convert to panels. Divide system watts by panel wattage, then round up.
Worked example. A home using 10,800 kWh per year at 4.5 peak sun hours needs 10,800 ÷ (4.5 × 365 × 0.80) = 8.2 kW. With 400 W panels, that is 8,200 ÷ 400 = 20.5, so 21 panels.
The 0.80 factor is a planning derate for real-world losses such as inverter efficiency, wiring, dirt, heat and shading. PVWatts assumes about 14% system losses by default plus roughly 96% inverter efficiency, which works out to about 0.82. This guide rounds down to 0.80 to stay conservative. Skipping losses entirely leaves a system that falls short of net-zero.
If your roof is not ideal. East- or west-facing roofs and partly shaded roofs produce less per panel than an unshaded south-facing roof, and the size of the loss depends on your tilt and location. Model your actual roof in PVWatts. If production is 10% to 20% lower, scale the system up by about 11% to 25% (1 ÷ 0.90 and 1 ÷ 0.80). For the 21-panel example, that means roughly 2 to 5 extra panels. Also consider headroom for panel degradation and future loads such as an EV or heat pump.
The savings calculator loads your state's average electricity rate, sun hours and net-metering rule. Then enter your own bill and installer quote.
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💰 System Cost
How Much Does a Net-Zero Solar System Cost in 2026?
Solar is priced per watt: system cost = system watts × price per watt. In 2026, installed prices before incentives generally fall between about $2.60 and $3.30 per watt. EnergySage marketplace quotes averaged about $2.58 per watt in early 2026, while SEIA market data runs closer to $3.30. The gap reflects different data sources and quote types, so treat the range as a planning band rather than a quote.
Data visualization
An 8 kW solar system costs about $20,800 to $26,400 before incentives in 2026. Low case uses $2.60 per watt and high case uses $3.30 per watt. Source: EnergySage and SEIA price-per-watt data 2026, author calculation.
Chart summary: An 8 kW system, close to the 8.2 kW net-zero example above, costs about $20,800 (blue) to $26,400 (orange) before incentives. Each additional 2 kW adds roughly $5,200 to $6,600. Larger systems usually cost less per watt, so the 10 kW and 12 kW bars slightly overstate real prices.
The federal credit is gone for purchased systems. The 30% Residential Clean Energy Credit (Section 25D) ended for expenditures made after December 31, 2025, under the One Big Beautiful Bill Act. See the IRS residential clean energy credit page for the current rules. Older guides that still show a 30% credit for 2026 purchases overstate the savings by roughly a third of the system price.
Other ways to lower cost still exist:
State and local incentives. Many states and utilities offer rebates, tax credits, performance payments or tax exemptions. Search the DSIRE database for your address.
Third-party ownership. Lease and power purchase agreement (PPA) providers may still be able to claim a federal commercial credit and pass some value through. Ask for the full 25-year cost, because lease payments continue for the contract term and you do not own the system.
Competitive quotes. Get at least three written quotes, and compare them on price per watt, equipment warranties and the production estimate.
Use our solar savings calculator to model net cost after the incentives available in your state.
Solar vs utility company · 25-year comparison
25-year totals: 3%/yr rate increases, 0.5%/yr degradation, no federal credit. Methodology
Cut Load First: How Efficiency Reduces Your Solar System Size
Every kWh you stop using is a kWh you do not need to generate. At 4.5 peak sun hours, each 1,000 kWh per year saved shrinks the required system by about 0.76 kW, roughly two panels.
Annual kWh saved
Smaller system (at 4.5 sun hours)
Fewer 400 W panels
Approx. cost avoided at $2.95/W
500
0.38 kW
1
~$1,100
1,000
0.76 kW
2
~$2,200
2,000
1.52 kW
4
~$4,500
3,000
2.28 kW
6
~$6,700
Calculated as kWh saved ÷ (4.5 × 365 × 0.80), then × $2,950 per kW.
Efficiency upgrades that usually pay off before you size solar:
LED lighting. The U.S. Department of Energy says LEDs use at least 75% less energy than incandescent bulbs.
Heat pump water heater. DOE describes heat pump water heaters as two to three times more energy efficient than conventional electric resistance models.
Heat pump heating and cooling. DOE says heat pumps can cut electricity use for heating by roughly half compared with electric resistance heating.
Air sealing and insulation. These reduce both heating and cooling loads.
One important catch: these savings apply when you replace electric equipment. If you swap a gas furnace or gas water heater for a heat pump, your electricity use goes up (even though your gas use drops), and a net-zero solar system must be sized larger. The same applies to adding an EV. Size solar for the electricity load you will have, not the one you have today.
The federal credits for heat pumps and other efficiency upgrades (Section 25C) also ended for property placed in service after December 31, 2025. Check your utility and state for current rebates.
⚡ System Size
Peak Sun Hours: The Number That Sets Your Panel Count
Peak sun hours (PSH) measure how much sunlight your location receives, expressed as the number of hours per day at an intensity of 1,000 watts per square meter. It is not the same as daylight hours. A location with 5 PSH might have 12 hours of daylight, but the energy received equals 5 hours of full-intensity sun.
The table below applies the sizing formula to a 10,800 kWh per year home. The regional examples are approximate. Actual PSH depends on tilt, orientation, shading and local weather, so run your address through PVWatts.
Peak sun hours/day
Typical regions (approximate)
System size for net-zero
Panels (400 W)
3.5
Cloudier northern and coastal regions
10.6 kW
27
4.0
Parts of the Upper Midwest and Northeast
9.2 kW
24
4.5
Typical national planning value
8.2 kW
21
5.0
Much of Texas, Florida and the Southeast
7.4 kW
19
5.5
Colorado and parts of the Southwest
6.7 kW
17
6.0
Desert Southwest
6.2 kW
16
Data visualization
A home using 10,800 kWh per year needs 10.6 kW at 3.5 sun hours but only 6.2 kW at 6.0 sun hours. Formula: kW = annual kWh ÷ (PSH × 365 × 0.80). Source: EIA average household use 2022, NREL PVWatts method.
Chart summary: For identical electricity use, a cloudy-region home (3.5 PSH) needs about 10.6 kW, while a desert-region home (6.0 PSH) needs about 6.2 kW. That is a difference of roughly 4.4 kW, or 11 panels, which makes sunshine a bigger lever than almost any other input.
Roof space can also cap the answer. If your usable roof fits 20 panels (8 kW) but your location needs 24, your options are to reduce consumption first, use higher-wattage panels, add a ground mount, or accept a small residual grid draw.
For many homeowners the answer is yes, but with no federal credit in 2026, your electricity rate and your utility’s net-metering rules matter more than ever. Simple payback is system cost divided by annual bill savings. The model below uses an 8.2 kW net-zero system, a 100% offset of 10,800 kWh per year, flat electricity prices, and no incentives.
EIA data put the average US residential price at roughly 17 to 19 cents per kWh across 2025 and 2026, with large state differences. Hawaii, California and New England sit near the top, and states such as Louisiana sit near the bottom.
Data visualization
An 8.2 kW net-zero system costing $24,190 breaks even in year 11 to 13 with no federal credit. Assumes 10,800 kWh offset at 18¢ per kWh, 0.5 percent yearly panel degradation, and 0 or 3 percent yearly rate escalation. Source: EIA price data 2025-2026, author calculation.
Chart summary: With flat electricity prices (blue), cumulative cash flow turns positive in year 13 and reaches about +$21,500 by year 25. If rates rise 3% per year (orange), break-even comes in year 11 and the 25-year gain is about +$41,900. Both lines include 0.5% annual degradation, and neither includes financing, maintenance or incentives.
Payback by electricity rate. The same 8.2 kW system pays back faster where power costs more. Low case is $2.60 per watt ($21,320) and high case is $3.30 per watt ($27,060), with flat prices and no incentives:
Electricity rate
Annual bill savings
Payback, low case
Payback, high case
12¢/kWh
$1,296
16.5 years
20.9 years
16¢/kWh
$1,728
12.3 years
15.7 years
20¢/kWh
$2,160
9.9 years
12.5 years
25¢/kWh
$2,700
7.9 years
10.0 years
30¢/kWh
$3,240
6.6 years
8.4 years
At the roughly 18¢ national average, payback is about 11 to 14 years across both cost cases.
What can move your payback.
Net-metering and export credits. With full retail net metering, exported kWh offset your bill at the retail rate. Where export credits are lower, as under California’s net billing tariff, a battery or daytime load shifting can improve the math.
Electricity price changes. If your utility’s rates rise, payback shortens. If they fall, it lengthens. This model holds prices flat.
Panel degradation. NREL’s long-term studies report a median degradation rate near 0.5% per year, leaving roughly 88% of output after 25 years. Over 25 years that averages about 94% of year-one production.
Costs not modeled. Financing interest, inverter replacement, roof work and insurance changes are not included.
25-year view (mid-case). An 8.2 kW system at $2.95 per watt costs about $24,200. At a flat 18¢ per kWh with 0.5% annual degradation, it avoids about $45,700 of electricity over 25 years, a net gain of roughly $21,500 before any incentives, financing or maintenance. Higher prices or incentives would improve this result.
Resale value. A 2015 Berkeley Lab study, Selling into the Sun, analyzed about 22,000 home sales across eight states from 1999 to 2013 and found an average premium of roughly $4 per watt for host-owned solar, about $15,000 for a typical 3.6 kW system. The data are dated and the study noted that premiums appeared to decline as systems aged, so treat resale value as an upside, not a guarantee.
Use our solar payback calculator to model the full picture for your address, rate and net-metering terms.
How We Calculated These Numbers (Methodology and Sources)
Annual consumption: about 10,800 kWh, rounded from EIA’s 10,791 kWh average per US residential customer in 2022 (EIA).
System sizing: kW = annual kWh ÷ (peak sun hours × 365 × 0.80). Panel counts assume 400 W modules, rounded up.
Peak sun hours: planning values of 3.5 to 6.0. Regional examples are approximate; verify with NREL PVWatts.
Installed price: $2.60 to $3.30 per watt before incentives, based on EnergySage marketplace data and SEIA market data. Mid-case cost uses $2.95 per watt.
Electricity price: about 18¢ per kWh for the mid-case, based on EIA data for 2025–2026. Sensitivity cases range from 12¢ to 30¢.
Charts: all three charts are direct calculations from the inputs above, not measured or surveyed data. The cash-flow chart uses $24,190 (8.2 kW × $2,950), $1,944 in year-one savings (10,800 kWh × 18¢), 0.5% annual degradation, and two escalation scenarios (0% and 3%); the 3% case is an assumption, not a forecast.
Policy: the end of the Section 25D and 25C credits reflects the One Big Beautiful Bill Act (July 4, 2025). Confirm with the IRS and DSIRE.
This guide is for general information and is not tax, legal or financial advice. Get written quotes and consult a tax professional before buying.
Direct answers for US homeowners — sized for a $200/month electric bill.
A typical US home using about 10,800 kWh per year needs roughly 6 to 10.5 kW of solar, or about 16 to 27 panels at 400 W each. The biggest variable is local peak sun hours: about 6 per day in the desert Southwest versus about 3.5 in cloudier regions. Use this formula: system kW = annual kWh ÷ (peak sun hours × 365 × 0.80), then divide by panel wattage. Your own annual kWh and an NREL PVWatts run for your address give the final number.
No, not for systems you buy with cash or a loan. The 30% Residential Clean Energy Credit (Section 25D) ended for expenditures after December 31, 2025, under the One Big Beautiful Bill Act signed July 4, 2025. Homeowners whose systems were completed by that date, or who carry forward unused credit, may still benefit. Leased or PPA systems may still draw a commercial credit claimed by the provider. Some states, utilities and localities still offer incentives, so check IRS guidance and the DSIRE database before you sign.
Expect roughly $2.60 to $3.30 per watt installed before incentives. EnergySage marketplace quotes averaged about $2.58 per watt in early 2026, while SEIA's national figure runs closer to $3.30. For an 8.2 kW system, a typical size for a net-zero home, that is about $21,000 to $27,000. Cost per watt falls as system size rises and varies by state, roof and equipment, so compare at least three quotes.
At the roughly 18¢ per kWh US average, simple payback for an 8.2 kW system is about 11 to 14 years without a federal credit, based on a conservative model with full offset and flat electricity prices. At 25–30¢ per kWh it drops to roughly 7 to 10 years, and at 12¢ it can exceed 16 years. Full retail net metering, state incentives and rising rates shorten payback, while low export credits lengthen it.
Usually not. Net-zero means your solar produces as many kWh per year as your home uses, but most utilities still charge fixed or minimum monthly fees. Export credits can also be lower than the retail rate you pay, as under California's net billing tariff. Expect a small residual bill, and check your utility's net-metering rules. Batteries or shifting loads to daytime can improve value where export credits are low.
Same usage, bill-based guide
Your Net-Zero Home target maps to roughly a $200/month electric bill nationally.
18.19¢/kWh — US average residential price. Source: EIA Electric Power Monthly, Table 5.6.B (year-to-date through July 2026), residential average retail price (July 2026) (EIA)
Solar production
4.5 peak sun hours/day × 0.82 system derate. Approximate state-average daily solar resource (peak sun hours) based on NREL solar resource data (NSRDB); not location-specific — use NREL PVWatts for an address-level estimate. (NREL PVWatts)
Installed price
$3.00 per watt before incentives. Blended 2026 US residential installed price used by this site; EnergySage marketplace reported about $2.60/W (mid-2026); full-market medians are higher.
Federal tax credit
$0 for homeowner-owned systems installed in 2026 — the 30% §25D credit ended Dec 31, 2025 (IRS)
Net metering
National blend — solar assumed to offset 75% of the bill (87% in full-retail net-metering states, 55–70% elsewhere).
Estimates only — not tax, legal or financial advice. Get at least three installer quotes and confirm incentives with your utility and a tax professional.