Scenario: a 3,500 sq ft home. 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
A 3,500 square foot home in the US typically needs 35 solar panels (14.0 kW) at national average electricity rates and sun hours — about $42,100 installed with 16.3-year payback. The 30% federal Residential Clean Energy Credit (IRC §25D) ended for systems installed after December 31, 2025, so a solar system you buy and install in 2026 gets no federal tax credit. State-by-state, system size ranges from 9.7 kW in Arizona to 20.3 kW in Alaska, and payback spans 6.0–26.3 years.
Square footage is only a rough proxy for electricity use (about 0.45 kWh per sq ft per month); size a real system from your actual kWh on 12 months of utility bills.
Payback depends more on the electricity rate and on how your utility credits exported power than on sunshine. States with full retail net metering and high rates pay back fastest.
Estimates use EIA state average residential rates, NREL sun hours, typical kWh per sq ft, $3.00/W installed, no federal credit, and a bill-offset share set by each state’s net-metering category. Methodology.
⚡ System Size
How Sq Ft Sizing Compares to Monthly Bill Guides
3,500 sq ft maps to roughly $286/month in utility spend nationally — close to our $300/month bill tier.
Direct answers for US homeowners — sized for a 3,500 sq ft home.
Nationally, a 3,500 sq ft home (~1,573 kWh/month) needs about **35 panels** (14.0 kW) at average US rates and sun hours. State totals range from **25** in Arizona to **51** in Alaska.
**Hawaii** leads at **6.0-year** payback (10.5 kW, $31,500 installed). **Tennessee** is slowest at **26.3 years**, largely because of its net-metering rules and electricity rate.
The US average is about **$42,100** for a **14.0 kW** system, with no federal tax credit for homeowner-owned systems installed in 2026. State costs range from **$31,500** (Hawaii) to **$61,000** (Alaska).
Yes — same end goal, different starting point. 3,500 sq ft maps to roughly **$300/month** nationally. Use this hub for **home size**; use the [$300/month bill hub](/guides/solar-panels-300-month-bill-by-state/) if you know your utility bill.
See the [national 3,500 sq ft guide](/guides/how-many-solar-panels-3500-sq-ft-house/) for roof orientation, panel wattage, and calculator walkthrough. Each state link below adds **local rate & sun hours**.
$300/month electric bill by state
System size and payback vary by electricity rate and sun hours — see your state.
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).
Square footage
Used only as a rough usage proxy: 3,500 sq ft × 0.4495 kWh/sq ft/month. EIA: average US residential customer used about 899 kWh/month (2022). Site assumption: that usage corresponds to a ~2,000 sq ft home (0.45 kWh per sq ft per month). Square footage is only a rough proxy — size from your actual kWh.
Estimates only — not tax, legal or financial advice. Get at least three installer quotes and confirm incentives with your utility and a tax professional.