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 home using 1,000 kWh per month needs about 23 solar panels (400W each, a 9.2 kW system) at the U.S. planning average of 4.5 peak sun hours. Depending on where you live, that can be as few as 18 panels (Phoenix) or as many as 29 (Seattle). At about $2.75 per watt the system costs roughly $25,300 before incentives, and simple payback is about 11–12 years.
For context, EIA reports that U.S. residential customers used an average of 865 kWh per month in 2024, so 1,000 kWh is about 16% above average. Three variables decide your panel count: your location’s peak sun hours, the wattage of the panels, and overall system efficiency (inverter losses, wiring, heat, and shading). Here is how to size it.
⚡ System Size
How to Calculate Solar Panels for 1,000 kWh/Month
The calculation takes three steps:
Convert to daily use: 12,000 kWh per year ÷ 365 = 32.9 kWh per day.
Find the required system size: daily kWh ÷ (peak sun hours × system efficiency).
Divide by panel wattage to get the panel count.
Using 4.5 peak sun hours and an 80% efficiency factor (a conservative allowance for inverter, wiring, temperature, and soiling losses):
Required system size = 32.9 kWh ÷ (4.5 h × 0.80) = 9.1 kW
At 400W per panel, that is 9,132 W ÷ 400 W = 23 panels (9.2 kW). The table below shows how wattage and location change the count.
Panels needed for 1,000 kWh/month (80% system efficiency)
Location (approx. peak sun hours)
Required kW
350W panels
400W panels
440W panels
U.S. planning average (4.5)
9.1
27
23
21
Seattle, WA (3.6)
11.4
33
29
26
New York, NY (4.2)
9.8
28
25
23
Dallas, TX (5.0)
8.2
24
21
19
Miami, FL (5.1)
8.1
24
21
19
Denver, CO (5.2)
7.9
23
20
18
Phoenix, AZ (5.9)
7.0
20
18
16
Peak sun hours are approximate annual averages, set within the ranges published for each city; your roof’s tilt, direction, and shading change them. Enter your address in NREL’s PVWatts Calculator for a site-specific estimate, or use our solar system size calculator.
Size for your annual average, not your worst month. Where full-retail net metering exists, summer surplus offsets winter shortfall; where export credits are lower, a closely matched system makes more sense.
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💰 System Cost
What Does a 9.2 kW Solar System Cost in 2026?
Published 2026 residential pricing runs about $2.50–$3.30 per watt before incentives, with EnergySage reporting an average quote near $2.75 per watt. For a 9.2 kW system, that works out to roughly $23,000–$30,400, or about $25,300 at the average.
Data visualization
9.2 kW system cost at three 2026 price points. About $25,300 at the $2.75-per-watt average; totals are price per watt times 9,200 W, before incentives. Source: EnergySage, NREL-based 2026 price guides.
Chart summary: a 9.2 kW system costs about $23,000 at the low end of 2026 pricing, about $25,300 at the $2.75-per-watt average, and about $30,400 at the high end. The $7,000-plus spread is why getting at least three installer quotes matters more than almost any other cost decision.
Equipment, labor, permitting, and installer overhead all affect price; NREL identifies “soft costs” as the largest and most persistent part of residential pricing. Larger systems usually cost less per watt, and prices vary by state. Check DSIRE for state, local, and utility incentives that may lower your net cost.
Solar vs utility company · 25-year comparison
25-year totals: 3%/yr rate increases, 0.5%/yr degradation, no federal credit. Methodology
For homeowner-purchased systems placed in service after December 31, 2025, yes. The residential clean energy credit (Section 25D) was ended by the One Big Beautiful Bill Act signed July 4, 2025. Systems placed in service by December 31, 2025 can still claim the 30% credit on a 2025 return using IRS Form 5695, and unused credit can carry forward to later years.
What this means for a 1,000 kWh/month system installed in 2026 or later:
Plan on the pre-incentive cost (about $25,300 at average pricing), not a 30%-reduced figure.
State, local, and utility programs may still reduce cost; availability changes, so verify in DSIRE.
If you are considering a lease or power purchase agreement, ask the provider how any incentives are handled and have a tax professional review it.
⚡ System Size
How Peak Sun Hours Change Your Panel Count
Peak sun hours measure how much usable sunlight your location receives each day, expressed as hours of full-intensity sun (1 kW/m²). A sunnier location needs fewer panels for the same output. For more on this topic, see our guide to How Many Solar Panels for 400 kWh/Month?. For more on this topic, see our guide to How Many Solar Panels for 1,750 kWh/Month?.
Data visualization
400W panels needed for 1,000 kWh/month, by city. Ranges from 18 panels in Phoenix to 29 in Seattle; each count is 32.9 kWh per day divided by peak sun hours times 0.80 efficiency and 0.4 kW per panel, rounded up. Source: NREL PVWatts sun-hour ranges, our calculations.
Chart summary: the same 1,000 kWh/month takes about 29 panels in Seattle but only 18 in Phoenix, an 11-panel gap driven almost entirely by sunlight. Dallas, Miami, and Denver land near 20–21 panels. Peak sun hours are approximate annual averages, so confirm your address in PVWatts.
Other factors that move your number:
Roof direction and tilt: south-facing roofs at a moderate tilt produce the most. East- and west-facing roofs typically produce somewhat less, so plan on a few extra panels; verify the impact for your roof in PVWatts.
Shading: trees, chimneys, and neighboring buildings can cut output sharply; microinverters or optimizers can help.
Net metering: some utilities credit exports at full retail rates, others at much lower rates (California’s NEM 3.0 is a well-known example). Where export credits are low, size close to your actual use and consider a battery.
⚡ System Size
What’s the Payback Period for 1,000 kWh/Month of Solar?
EIA’s short-term outlook puts the average U.S. residential electricity price at about 18.2¢/kWh in 2026. At that price, offsetting 1,000 kWh per month avoids about $182 per month, or $2,184 per year.
Simple payback = $25,300 ÷ $2,184 ≈ 11.6 years.
Payback depends heavily on your local price per kWh:
Data visualization
Simple payback by electricity price for a $25,300, 9.2 kW system. Ranges from 6.3 years in California to 17.6 years in North Dakota; payback is $25,300 divided by 12,000 kWh times the price, with no rate escalation, degradation, or financing. Source: EIA state prices (March 2026) and EIA 2026 forecast.
Chart summary: payback runs from about 6 years in California to nearly 18 years in North Dakota. Electricity price per kWh, not sunshine, is usually the biggest driver of whether solar pays back quickly.
Over the full system life, cumulative cash flow looks like this (before incentives, cash purchase, 0.5% annual panel degradation, 100% of production valued at the retail price):
Data visualization
Cumulative cash flow of a $25,300, 9.2 kW system over 25 years. Net gain reaches $26,146 at a flat 18.2¢/kWh and $49,156 if prices rise 3% per year; assumes 12,000 kWh in year 1, 0.5% yearly degradation, and no incentives. Source: EIA 2026 price forecast, our calculations.
Chart summary: with flat prices the system breaks even in year 12 (11.9 years including degradation) and nets about $26,100 by year 25. If electricity prices rise 3% per year, break-even comes at about 10.3 years and the 25-year net is about $49,200. A 2% annual increase lands between the two (about 10.8 years).
These are simplified models. Real results are lower if your utility pays reduced export rates, if you finance the system, or if the inverter needs replacing during the 25-year period; they are higher if you pay for a quote below $2.75 per watt or qualify for state or utility incentives. Use our solar savings calculator and payback calculator with your own rate and quote.
Our calculations: all panel counts, costs, and payback figures use the stated assumptions (80% system efficiency, 400W panels unless noted, $2.75/W, 12,000 kWh/year, 0.5% annual degradation). They are estimates, not quotes.
Last updated October 3, 2026. Electricity prices, equipment pricing, and incentives change often; confirm current figures before you buy.
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About 23 panels rated at 400W each at the U.S. planning average of 4.5 peak sun hours. The count depends mostly on location: roughly 18 panels in Phoenix, 20–21 in Denver, Dallas, or Miami, 25 in New York, and 29 in Seattle. Using 350W panels adds about 3 panels; 440W panels remove about 2. These figures assume 80% system efficiency, so confirm with NREL's PVWatts for your address.
Roughly 9 kW (9.2 kW with 23 × 400W panels) at 4.5 peak sun hours. The formula is: daily usage (1,000 ÷ 30.4 ≈ 32.9 kWh) ÷ (peak sun hours × 0.80 efficiency) = required kW. At 5.9 sun hours (Phoenix) you need about 7 kW; at 3.6 (Seattle) about 11.4 kW.
Typically $23,000–$30,400 before incentives for a 9.2 kW system, based on $2.50–$3.30 per watt; about $25,300 at the $2.75-per-watt average reported by EnergySage. Prices vary by state, roof, equipment, and installer, so collect at least three quotes. The 30% federal homeowner tax credit no longer applies to systems placed in service after December 31, 2025.
About 11–12 years at the 2026 U.S. average residential price of roughly 18.2¢/kWh: $25,300 ÷ $2,184 of avoided electricity per year ≈ 11.6 years. In high-price states such as California (≈33¢/kWh) it is closer to 6–7 years; in low-price states such as North Dakota (≈12¢/kWh) it is 17–18 years. Annual rate increases shorten payback, while low export credits, financing costs, or inverter replacement lengthen it.
Not for new homeowner-purchased systems. The residential clean energy credit (Section 25D) was ended by the One Big Beautiful Bill Act for expenditures after December 31, 2025. Systems placed in service by that date can still be claimed on a 2025 return using IRS Form 5695, and unused credit can carry forward. State, local, and utility incentives may still apply; check DSIRE. Ask a tax professional about leases, PPAs, or business-owned systems.
Same usage, bill-based guide
Your 1,000 kWh/Month target maps to roughly a $175/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.