US residential solar · 2026 data

Solar Panels for a 3-Bedroom House

Q: How do I calculate the number of solar panels from my electric bill?

Add up 12 months of kWh from your bills, then divide by (panel kW × local peak sun hours × 365 × 0.86). For a 0.4 kW panel at 4.5 sun hours that is 565 kWh per panel per year, so 10,400 kWh needs 19 panels. Get local sun hours from NREL PVWatts.

Q: Is there still a federal tax credit for solar panels in 2026?

Not for homeowners who buy with cash or a loan. The 30% residential credit (Section 25D) ended for expenditures after December 31, 2025 under the One Big Beautiful Bill Act. Third-party-owned lease and PPA systems may still use the commercial credit under current law, subject to deadlines. State and utility incentives may still apply.

Q: How much does a solar system for a 3-bedroom house cost in 2026?

Roughly $19,800 to $26,600 for a 7.6 kW system before state incentives, based on about $2.60 per watt (EnergySage marketplace average) to $3.50 per watt (Lawrence Berkeley National Laboratory's 2024 cash-purchase median). Your price depends on installer, equipment, roof complexity and location, so compare at least three quotes.

Q: How long does it take for solar to pay back without the federal credit?

Our model shows about 10 to 13 years for a 7.6 kW system: $19,760 or $26,600 upfront, first-year savings near $1,700 at 16.5 cents per kWh, 3% yearly rate growth and 0.5% yearly panel degradation. Higher local rates and full retail net metering shorten it; low rates and export-credit limits lengthen it.

Est. net savings

$38,600

Over 25 Years (low-cost case) · no federal credit

$19,760 Cost, no federal credit

10.3 yrs Payback (low-cost case)

7.6 kW System size

Typical result:

About 19 panels (400W)
7.6 kW system
$19,800–$26,600 before state incentives
10–13 year modeled payback

✓ EIA rates & NREL sun data ✓ 2026 federal policy applied ✓ Open methodology

Updated September 29, 2026 · 9 min read ·By Green Energy Calculators Editorial Team

Calculate My System Size View State Data

25 years without solar vs with solar

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

Without solar

25-year utility bills

$58,400

Rates rise ~3% per year

With solar

System cost + remaining bills

$19,760

Installed cost, no federal credit

Difference

Estimated 25-year net

+$38,600

Before any state or utility incentives

Author Green Energy Calculators Editorial Team

Editorial policy No paid placements

Last updated Sep 29, 2026

Data approach EIA rates · NREL sun hours · 2026 federal policy · methodology

A typical US home needs about 19 solar panels rated at 400W (7.6 kW) to cover its yearly electricity use, but the range runs from roughly 13 panels in Phoenix to 23 in Seattle. Three things set your number: how much electricity you use, how much sun your roof gets, and how much of your bill you want to offset. Bedroom count is only a loose proxy for the first one.

This guide uses the average US household figure from the U.S. Energy Information Administration (EIA): about 865 kWh per month in 2024, or roughly 10,400 kWh per year, at an average residential price of 16.5 cents per kWh (EIA). A 3-bedroom home is a common size for that average, but EIA does not publish usage by bedroom count. Electric heating, heat pumps, air conditioning and EV charging can push a home well above it, so use your own bills.

Important 2026 change: the 30% federal tax credit for homeowner-owned solar ended for expenditures after December 31, 2025. Many older guides still show “after tax credit” prices that no longer apply to cash or loan purchases. Every cost figure below is before any federal credit.

Last updated September 29, 2026. Figures are US-based; the sizing formula works anywhere if you use local sun-hour data (in Europe, the EU’s PVGIS tool serves the same purpose as NREL’s PVWatts).

How Many 400W Solar Panels Does a 3-Bedroom House Need?

Divide your annual electricity use by the yearly output of one panel, then round up.

Panel output (kWh/year) = 0.4 kW × peak sun hours × 365 × 0.86

The 0.86 factor is the default system derate in NREL’s PVWatts calculator (about 14% lost to inverter efficiency, wiring, heat and soiling). At 4.5 peak sun hours, one 400W panel makes about 565 kWh a year, so 10,380 kWh ÷ 565 = 18.4, which rounds up to 19 panels (7.6 kW).

Sun hours vary a lot by city. The table applies the same 10,380 kWh household to each location for an apples-to-apples comparison (aiming for 100% offset):

400W Panels Needed by Location, 10,380 kWh/Year Home (2026)

Location	Peak sun hours/day (approx.)	kWh per panel per year	Panels for 100% offset	System size
Phoenix, AZ	6.5	816	13	5.2 kW
Dallas, TX	5.4	678	16	6.4 kW
Atlanta, GA	5.0	628	17	6.8 kW
Boston, MA	4.6	578	18	7.2 kW
Chicago, IL	4.2	527	20	8.0 kW
Seattle, WA	3.7	465	23	9.2 kW

Peak sun hours are rounded annual averages derived from NREL solar-resource data; published figures differ slightly by dataset and source. Enter your address in NREL PVWatts for a site-specific number. Panel counts are our own calculation from the formula above.

Use our solar system size calculator to enter your ZIP code and monthly bill for a local estimate.

400W panels needed for a 10,380 kWh/year home (100% offset). Calculated with 0.4 kW × peak sun hours × 365 × 0.86. Sun hours from NREL-derived annual averages; usage from EIA 2024.

Chart summary: The same home needs 13 panels in Phoenix and 23 in Seattle, about 77% more, purely because Seattle receives roughly 3.7 peak sun hours a day versus 6.5 in Phoenix. If your home uses more or less than the national average, scale the panel count in proportion.

Run the numbers for your state

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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What Does a Solar System for a 3-Bedroom House Cost in 2026?

A 7.6 kW system (19 × 400W panels) costs roughly $19,800 to $26,600 before state or local incentives, with no federal credit for cash or loan purchases. That range comes from two published benchmarks:

About $2.60 per watt is the average price on the EnergySage quote marketplace in 2026, or about $19,760 for 7.6 kW (EnergySage).
About $3.50 per watt is the national median for cash-purchased residential systems in Lawrence Berkeley National Laboratory’s Tracking the Sun data for 2024, or about $26,600 for 7.6 kW.

Prices per watt vary by state, installer, equipment and roof complexity, and larger systems generally cost slightly less per watt. Equipment is only part of the total: EnergySage estimates that required solar equipment, including supply-chain costs and sales tax, is about 46% of the system price, and the panels alone are about 12%. The rest is labor, permitting, overhead and installer margin, which is why quotes for identical systems can differ widely. Compare at least three.

What happened to the tax credit? The 30% Residential Clean Energy Credit (Section 25D) covered systems completed by December 31, 2025, and the IRS states it is not available for property placed in service after that date (IRS). Homeowners who lease a system or sign a power purchase agreement (PPA) may still benefit indirectly, because the company that owns the system can claim the commercial credit (Section 48E) under current law, subject to deadlines and sourcing rules (SEIA). Read any lease or PPA terms carefully, including escalators and transfer clauses.

State, local and utility programs (rebates, property tax exemptions, performance payments) can still reduce your cost. Search your state in the DSIRE incentives database.

Estimated cost of a 7.6 kW system (before state incentives). Left: 2025-style net cost with the 30% credit at $2.60/W, shown for comparison only. Middle and right: 2026 price with no federal credit at EnergySage’s ~$2.60/W average and LBNL’s ~$3.50/W 2024 median.

Chart summary: At the same $2.60-per-watt price, losing the 30% credit raises the net cost of a 7.6 kW system from about $13,800 to about $19,800, a difference of roughly $5,900. At the higher $3.50-per-watt benchmark the cost is about $26,600. The 2025 bar is arithmetic for comparison, not a current offer.

Solar vs utility company · 25-year comparison

25-year totals: 3%/yr rate increases, 0.5%/yr degradation, no federal credit. Methodology

Total utility payments

$58,400

Total solar cost (installed + remaining bills)

$19,760

Net savings

+$38,600

Avg. monthly difference

+$129/mo

See my savings →

How Long Until Solar Pays for Itself on a 3-Bedroom Home?

In our model, a 7.6 kW system pays for itself in about 10.3 years at $2.60/W and 13.3 years at $3.50/W, with no federal credit and no state incentives. Your result will be shorter with higher local electricity rates or a state rebate, and longer with low rates or limited export credits.

Model assumptions (all editable in our payback calculator):

19 panels produce about 10,700 kWh a year at 4.5 peak sun hours; we credit only the 10,380 kWh the home actually uses.
Electricity price starts at 16.5¢/kWh (EIA 2024 US average), so year-1 savings are about $1,713.
Electricity prices rise 3% a year (an assumption; actual rates vary by utility and year).
Panel output falls 0.5% a year (a commonly cited median degradation rate).
Every kWh produced offsets a kWh you would have bought at the full retail price. This holds under full retail net metering or if you use most of your solar power at home.
No financing costs, maintenance, or inverter replacement (string inverters often need replacing once during a 25-year period, which would lengthen payback).

Modeled Results, 7.6 kW System (2026)

Installed price	Upfront cost	Year-1 savings	Payback	25-year net
$2.60/W (EnergySage avg.)	$19,760	~$1,713	~10.3 years	~$38,600
$3.50/W (LBNL 2024 median)	$26,600	~$1,713	~13.3 years	~$31,800

Export credits matter. Some utilities now credit exported solar power at less than the retail rate (California’s Net Billing Tariff is one example), which lowers savings unless you use more of the power yourself or add a battery. Check your utility’s current net metering or net billing rules before you sign, using our net metering calculator.

Modeled cumulative net cash flow for a 7.6 kW system, no federal credit. Assumes 16.5¢/kWh rising 3% a year, 0.5% yearly panel degradation, full retail offset of 10,380 kWh/year, no financing or inverter replacement.

Chart summary: Both lines cross zero (break-even) between year 10 and year 14: about year 10.3 for the lower-cost case and year 13.3 for the higher-cost case. By year 25 the modeled net gain is roughly $38,600 or $31,800. These are model outputs based on the stated assumptions, not guarantees.

Is a 400W Panel the Right Size for a 3-Bedroom Home’s Roof?

For most homes, yes. 400W is a common residential panel rating, and a typical panel of that class covers roughly 20–22 sq ft (about 1.9–2.0 m²), though dimensions vary by model, so check the manufacturer datasheet. On that basis, 19 panels need about 380–420 sq ft (35–39 m²) of unshaded roof, before setbacks required by local fire codes.

Higher-wattage panels reduce the number of panels for the same system size, which helps on small or complex roofs. The table shows panel counts for a system of about 7.6 kW:

Panels Needed for a ~7.6 kW System by Panel Wattage

Panel wattage	Panels needed	Actual system size
300W	26	7.8 kW
350W	22	7.7 kW
400W	19	7.6 kW
450W	17	7.65 kW
500W	16	8.0 kW

Panel wattage does not change how many kWh your home needs. It only changes how many panels, and how much roof, deliver that energy. Price per watt can differ by module type, so ask installers to quote the same system size with two panel options.

How to Get Maximum Output From Your Panels

Four factors matter most: roof orientation, tilt, shading and inverter type.

Orientation: In the northern hemisphere, south-facing roofs generally produce the most energy over a year. East- or west-facing roofs produce somewhat less, and an east-west split can spread production across more of the day. North-facing roofs are usually the weakest option.
Tilt: Tilt close to your latitude generally maximizes annual output, but common roof pitches are usually close enough. Model your actual roof rather than assuming.
Shading: Even partial shade can reduce the output of panels wired in a string. Microinverters or DC optimizers (for example, Enphase or SolarEdge products) let each panel work independently and can reduce those losses on partly shaded roofs.
Modeling: NREL PVWatts is free. Enter your address, system size, tilt and azimuth to see monthly and annual production for your roof.

Over time, panels lose a small amount of output each year. A commonly cited median degradation rate is about 0.5% per year, so a system produces roughly 88–89% of its first-year output in year 25 (in line with what our model assumes).

If your utility offers full retail net metering, excess production in sunny months offsets grid use in winter, so the panel count in this guide holds. If exports earn a lower rate, consider sizing closer to your daytime use or comparing battery options with our battery storage calculator. For a 420W-panel version of this sizing, see How Many 420W Solar Panels for a 3-Bedroom House?.

Sources and Methodology

U.S. Energy Information Administration: average residential electricity consumption (865 kWh/month) and price (16.5¢/kWh), 2024.
IRS: Residential Clean Energy Credit; SEIA: clean energy provisions in the One Big Beautiful Bill.
EnergySage: solar panel cost data (about $2.60/W average in 2026); Lawrence Berkeley National Laboratory, Tracking the Sun (2024 cash-purchase median near $3.50/W).
NREL (now the National Laboratory of the Rockies): PVWatts calculator and National Solar Radiation Database for peak sun hours and the 0.86 default derate.
DSIRE: state and local incentive database.
Panel counts, costs and payback figures are our own calculations from the inputs and assumptions stated above. They are estimates for planning, not quotes, and not financial, tax or legal advice. Confirm current incentives with your installer, utility and a tax professional.

Frequently asked questions

Direct answers for US homeowners — sized for a $144/month electric bill.

How many 400W solar panels does a 3-bedroom house need?

A typical US home uses about 10,400 kWh a year (EIA, 2024) and needs roughly 19 400W panels (7.6 kW) at 4.5 peak sun hours to offset all of it. Sunny Phoenix needs about 13; cloudy Seattle about 23. Bedroom count is only a rough proxy, so size from your own annual kWh.

How do I calculate the number of solar panels from my electric bill?

Is there still a federal tax credit for solar panels in 2026?

How much does a solar system for a 3-bedroom house cost in 2026?

How long does it take for solar to pay back without the federal credit?

Same usage, bill-based guide

Your 3-Bedroom House target maps to roughly a $150/month electric bill nationally.

$150 $150/month electric bill guide Panels · cost · payback · by state →

Popular state solar guides

Electricity rates and incentives vary — see data for your state.

CA California 33.25¢/kWh · 5.8h sun TX Texas 16.06¢/kWh · 5.6h sun FL Florida 15.3¢/kWh · 5.7h sun AZ Arizona 15.44¢/kWh · 6.5h sun NC North Carolina 14.94¢/kWh · 5.2h sun NY New York 29.38¢/kWh · 4.3h sun MA Massachusetts 30.14¢/kWh · 4.2h sun CO Colorado 16.72¢/kWh · 5.5h sun

View all 50 states →

How these numbers were calculated

Electricity rate: 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).
Model: Version 2026.10 · 3%/yr electricity price escalation · 0.5%/yr panel degradation · simple payback = installed cost ÷ year-1 savings
Policy checked: September 29, 2026 · Full methodology · Report an error

Estimates only — not tax, legal or financial advice. Get at least three installer quotes and confirm incentives with your utility and a tax professional.