US residential solar · 2026 data

Solar Panels for 600 kWh/Month

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

Not for homeowners who buy. The 30% Residential Clean Energy Credit (Section 25D) ended for systems placed in service after December 31, 2025. Leased or PPA systems may still qualify for the business credit (Section 48E) claimed by the owner, and any savings reach you only through pricing. Some states, including New York and Massachusetts, offer their own credits, so check DSIRE.

Q: How much does a 600 kWh per month solar system cost?

At about $2.60 per watt (EnergySage's early-2026 marketplace average), a 5.2 kW system costs roughly $13,500 before incentives. The range for 4.0 to 6.8 kW is about $10,400 to $17,700. Small systems usually cost more per watt, and quotes run higher at $3.00 per watt or more. Get at least three quotes.

Q: How long does it take for solar to pay for itself at 600 kWh per month?

It depends mostly on your electricity rate. Using 2025 EIA residential averages and no incentives, a 5.2 kW system at $2.60 per watt pays back in about 4.6 years in Hawaii, 6.2 in Massachusetts, 7.1 in New York, 12.1 in Texas, and 14.9 in Louisiana. Real results shift with your rate structure, export credits, and system price.

Q: Does my roof direction or shade change how many panels I need?

Yes. A south-facing, unshaded roof is best. East- or west-facing roofs typically produce roughly 10–20% less, which usually means one to three more panels for the same 600 kWh. North-facing roofs and shaded roofs can lose considerably more. Microinverters or optimizers can reduce partial-shade losses, and PVWatts lets you model your exact tilt and azimuth.

Est. net savings

$12,700

Over 25 Years (Texas example, no incentives) · no federal credit

$13,500 Cost before incentives

4.6–14.9 yrs Payback range

5.2 kW System size

Typical result:

10–17 panels (400W)
5.2 kW reference system
~$13,500 before incentives
4.6–14.9 year payback by state

✓ 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

$26,238

Rates rise ~3% per year

With solar

System cost + remaining bills

$13,520

Installed cost, no federal credit

Difference

Estimated 25-year net

+$12,718

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

To offset 600 kWh per month, most US homes need 10 to 17 solar panels rated at 400W, or about 4.0 to 6.8 kW, depending on local sunlight. In a sunny market like Phoenix, one 400W panel produces about 62 kWh per month; in cloudy Seattle, about 36 kWh. That gap is why location is the biggest variable in any sizing calculation.

2026 update: The 30% federal tax credit for homeowners who buy solar (Section 25D) ended for systems placed in service after December 31, 2025. Any 2026 quote that subtracts 30% from the price of a system you own is out of date. See the cost section for what still applies.

Key takeaways

Panels: 10 to 17 (400W), with 13 panels (5.2 kW) as a middle-of-the-road case.
Cost: about $13,500 for 5.2 kW at $2.60 per watt, before incentives.
Payback: roughly 4.6 to 14.9 years, driven mainly by your local electricity rate.
Best next step: run your ZIP code through NREL’s PVWatts calculator and compare at least three installer quotes.

Three factors drive almost everything: your local peak sun hours (roughly 3.5 in the Pacific Northwest to 6.5 in the Desert Southwest), the wattage of the panels you install (residential panels today are commonly in the 380W to 440W range), and your roof’s orientation and shading. Get these three right and the math is straightforward.

How Many Panels Do You Actually Need to Offset 600 kWh/Month?

The formula is simple: divide your monthly usage by your panel’s monthly output.

A 400W panel in a location with 5.0 peak sun hours per day produces roughly:

0.4 kW × 5.0 h × 30 days × 0.80 system efficiency = 48 kWh/month

To hit 600 kWh/month: 600 ÷ 48 = 12.5, so 13 panels (5.2 kW). The 0.80 factor is a rounded allowance for inverter, wiring, temperature, and soiling losses; PVWatts uses a default loss assumption of about 14%, so real results will differ slightly.

Solar Panel Count by City — 400W Panels, 600 kWh/Month Target (2026)

Location	Approx. Peak Sun Hours	kWh/Panel/Month	Panels Needed	System Size
Seattle, WA	3.7	35.5	17	6.8 kW
Chicago, IL	4.2	40.3	15	6.0 kW
Dallas, TX	5.2	49.9	13	5.2 kW
Miami, FL	5.5	52.8	12	4.8 kW
Denver, CO	5.8	55.7	11	4.4 kW
Phoenix, AZ	6.5	62.4	10	4.0 kW

Calculated with the formula above (400W, 0.80 efficiency, 30-day month). Peak sun hours are rounded planning values; confirm yours with PVWatts using your ZIP code.

Panels of 400W needed to offset 600 kWh/month, by city (calculated). Values come from the formula and table above.

Chart summary: Sunlight changes the panel count by up to 7 panels (70%) across these six cities. Phoenix homeowners need about 10 panels, while Seattle homeowners need about 17 for the same 600 kWh. If you are between two counts, round up: it is cheaper to add a panel now than after installation.

Panel wattage and degradation. With 440W panels, multiply the output above by 1.1, which usually removes one or two panels from the count. Panels lose a small amount of output each year (many manufacturers warrant roughly 0.5% per year or less), so a system producing 600 kWh in year one could produce about 570 kWh in year ten. Adding around 5% headroom is a reasonable hedge.

Roof direction. A south-facing roof is best in the Northern Hemisphere. East- or west-facing roofs typically produce roughly 10–20% less, and north-facing or heavily shaded roofs can lose considerably more. Use our solar system size calculator or PVWatts to model your exact roof.

Run the numbers for your state

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What Does a Solar System Cost to Offset 600 kWh Per Month in 2026?

A system sized for 600 kWh/month typically runs 4.0 kW to 6.8 kW. EnergySage reports an early-2026 marketplace average of about $2.60 per watt before incentives, with other 2026 surveys showing a wider range of roughly $2.40 to $3.30 per watt. Small systems often cost more per watt than large ones, so treat the figures below as estimates and not quotes.

Estimated Cost Before Incentives — 600 kWh/Month Sizing (2026)

System Size	Cost at $2.60/W	Cost at $3.00/W	Monthly Loan Payment at $2.60/W*
4.0 kW (10 panels)	$10,400	$12,000	$118
5.2 kW (13 panels)	$13,520	$15,600	$154
6.8 kW (17 panels)	$17,680	$20,400	$201

*Illustrative 10-year loan at 6.5% APR with no down payment. Actual solar loan rates and terms vary by lender.

Estimated system cost before incentives at $2.60/W and $3.00/W (calculated). Values come from the table above.

Chart summary: Cost rises in a straight line with system size, and every $0.40 per watt of price difference adds about $2,100 to a 5.2 kW system. That is why comparing quotes in dollars per watt is the fastest way to spot an overpriced bid.

What happened to the federal tax credit? The 30% Residential Clean Energy Credit (Section 25D) was ended by the One Big Beautiful Bill Act, signed July 4, 2025. It applies only to systems placed in service on or before December 31, 2025. What may still be available in 2026:

Leases and PPAs: the company that owns the system can claim the business credit under Section 48E if it meets the law’s timing rules, and any benefit reaches you only through lower pricing.
State and local programs: New York and Massachusetts, among others, offer state tax credits, and some utilities offer rebates. Check the DSIRE database for current programs in your state.

Use our solar tax credit calculator to see incentives that apply to your state. This is general information, not tax advice.

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

$26,238

Total solar cost (installed + remaining bills)

$13,520

Net savings

+$12,718

Avg. monthly difference

+$93/mo

See my savings →

How Fast Will a 600 kWh/Month Solar System Pay Back?

Payback is your system cost divided by your annual savings. Offsetting 600 kWh/month means 7,200 kWh per year, so your savings equal 7,200 times your electricity rate. Using 2025 residential averages from the U.S. Energy Information Administration (EIA), the 5.2 kW reference system ($13,520) pays back like this:

Simple Payback by State — 5.2 kW System, 600 kWh/Month, No Incentives (2026)

State	2025 Residential Rate (¢/kWh)	Annual Savings	Simple Payback
Hawaii	40.59	$2,922	4.6 yrs
California	32.54	$2,343	5.8 yrs
Massachusetts	30.48	$2,195	6.2 yrs
New York	26.39	$1,900	7.1 yrs
Texas	15.47	$1,114	12.1 yrs
Louisiana	12.57	$905	14.9 yrs

Source for rates: EIA Electric Power Monthly (March 2026), 2025 annual residential averages, as compiled by the U.S. Chamber of Commerce. Assumes the system offsets all 600 kWh at the full retail rate, no state or utility incentives, flat electricity prices, and no panel degradation. California’s net billing pays less than the retail rate for exported power, so real California payback is likely longer.

Simple payback in years by state for a 5.2 kW system (calculated). Values come from the table above.

Chart summary: Payback is roughly inversely proportional to your electricity rate. Hawaii’s rate is more than three times Louisiana’s, and its payback is about a third as long. In lower-rate states, solar can still work if you plan to stay in the home for well over a decade, but the margin is thinner.

The next chart adds panel degradation of 0.5% per year and holds electricity prices flat, which is deliberately conservative because rates have risen in most states.

Cumulative net cash flow over 25 years for a 5.2 kW system costing $13,520 (calculated). Assumes flat electricity rates, 0.5% annual degradation, no incentives, and full offset of 600 kWh/month at the retail rate.

Chart summary: With degradation included, the system breaks even in year 8 in New York and year 13 in Texas. By year 25 the modeled net gain is about $31,200 in New York and $12,700 in Texas, before any inverter replacement, maintenance, or rate increases. Both are estimates, not guarantees. Use our solar payback calculator to model your own numbers.

For a smaller system, see our guide to how many solar panels to offset 300 kWh per month.

Worked Example: The 600 kWh Sizing Math, Step by Step

This example uses the same formula shown earlier so that you can repeat it with your own numbers.

Find your annual target. 600 kWh × 12 = 7,200 kWh per year. Check your last 12 utility bills, since summer and winter usage often differ.
Find your peak sun hours. Look up your ZIP code in PVWatts. Assume 5.0 in this example.
Calculate one panel’s monthly output. 0.4 kW × 5.0 × 30 × 0.80 = 48 kWh.
Divide and round up. 600 ÷ 48 = 12.5, so 13 panels, or 5.2 kW.
Add headroom. Multiply by about 1.05 if you expect higher usage (an EV or heat pump, for example) or want to offset degradation. 13 × 1.05 = 13.7, so 14 panels.
Check your roof. Confirm that 13 to 14 panels (roughly 250 to 300 square feet in total, depending on panel size) fit on unshaded, favorable roof faces.

If your roof faces east or west, expect to add one to three panels. If part of the roof is shaded, ask installers about microinverters or power optimizers.

Does Net Metering Change How Many Panels You Need for 600 kWh/Month?

It can. Under full retail net metering, surplus power you send to the grid earns credits that offset your later consumption, so you can size the system to your annual usage (7,200 kWh per year). Spring and fall overproduction covers winter shortfalls.

Under net billing or low export rates, exported power earns less than you pay for imported power. California’s Net Billing Tariff (often called NEM 3.0) is the best-known example: exports are credited at avoided-cost rates that are well below retail. In that case, it usually makes sense to size closer to your daytime use and consider a battery, since each exported kWh is worth less.

Net metering rules are set by states and utilities and change often, so confirm your current tariff before choosing a system size. The DSIRE database and your utility’s website are the best starting points. Then run your numbers through our solar net metering calculator.

Living Outside the US?

The same formula works anywhere: panels needed = annual kWh target ÷ (panel kW × local annual yield in kWh per kW). For Europe, the European Commission’s PVGIS tool provides location-specific yield estimates. Note that 600 kWh per month (7,200 kWh per year) is well above typical household use in much of Europe, so check your own bills before sizing.

Methodology and Sources

Panel counts and costs in this guide are calculated with the formulas shown, using the stated assumptions. They are estimates for planning, not quotes or guarantees. Peak sun hours are rounded planning values; use PVWatts for your address.

Electricity rates: U.S. Energy Information Administration, Electric Power Monthly, 2025 annual residential averages, as compiled in the U.S. Chamber of Commerce 2025 Electricity Price Map.
Installed cost: EnergySage solar panel cost data, early 2026 marketplace average of about $2.60 per watt.
Federal tax credit status: IRS Residential Clean Energy Credit information and the One Big Beautiful Bill Act (signed July 4, 2025).
Solar output modeling: NREL PVWatts Calculator.
State incentives and net metering: DSIRE.

Last updated September 29, 2026. This article is general information and not financial, legal, or tax advice.

Frequently asked questions

Direct answers for US homeowners — sized for a $100/month electric bill.

How many solar panels do I need for 600 kWh per month?

Most US homes need 10 to 17 panels rated at 400W, or about 4.0 to 6.8 kW. Phoenix (about 6.5 peak sun hours per day) needs around 10 panels; Seattle (about 3.7) needs around 17. At 5.0 peak sun hours, one 400W panel produces about 48 kWh per month, so 600 kWh takes 13 panels (5.2 kW). Use PVWatts with your ZIP code for a precise count.

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

How much does a 600 kWh per month solar system cost?

How long does it take for solar to pay for itself at 600 kWh per month?

Does my roof direction or shade change how many panels I need?

Same usage, bill-based guide

Your 600 kWh/Month target maps to roughly a $100/month electric bill nationally.

$100 $100/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.