SAVE
$0+
Over 25 Years
Most homeowners need:
25-year cost comparison for a $300/month US electric bill.
Without solar
25-year utility cost
$57,700
Rates rise ~3% per year (EIA avg.)
With solar
Net system cost
$15,100
After 30% federal ITC
Your savings
Difference
+$42,600
Estimated lifetime advantage
A 1,800 square foot home in the US typically needs 19 solar panels (7.2 kW) at national average electricity rates and sun hours — $15,100 after the 30% ITC with 11.0-year payback. State-by-state, system size ranges from 5.0 kW in Arizona to 10.5 kW in Alaska, and payback spans 3.3–18.7 years.
Start here: National 1,800 sq ft guide · System size calculator · $125/month bill by state
| Metric | US average (1,800 sq ft) |
|---|---|
| Est. monthly usage | ~809 kWh |
| System size | 7.2 kW |
| Panels (400W) | 19 |
| Net cost after ITC | $15,100 |
| Simple payback | 11.0 years |
| 25-year savings | $42,600+ |
Formula: kW = Annual kWh ÷ (Peak sun hours × 365 × 0.82)
| Fastest payback | Slowest payback | |
|---|---|---|
| State | Hawaii | Washington |
| System | 5.4 kW · 14 panels | 8.1 kW · 21 panels |
| After ITC | $11,400 | $17,000 |
| Payback | 3.3 yrs | 18.7 yrs |
High electricity rates (e.g. Hawaii, California, Massachusetts) often beat sunny low-rate states for 1,800 sq ft payback.
| State | System | Panels | After ITC | Payback |
|---|---|---|---|---|
| Alabama | 6.1 kW | 16 | $12,900 | 11.4 yrs |
| Alaska | 10.5 kW | 27 | $22,000 | 11.1 yrs |
| Arizona | 5.0 kW | 13 | $10,500 | 9.4 yrs |
| Arkansas | 6.5 kW | 17 | $13,600 | 13.6 yrs |
| California | 5.6 kW | 14 | $11,700 | 4.7 yrs |
| Colorado | 5.9 kW | 15 | $12,400 | 10.3 yrs |
| Connecticut | 7.7 kW | 20 | $16,200 | 7.7 yrs |
| Delaware | 7.2 kW | 19 | $15,100 | 12.1 yrs |
| Florida | 5.7 kW | 15 | $12,000 | 10.5 yrs |
| Georgia | 6.2 kW | 16 | $13,100 | 11.9 yrs |
| Hawaii | 5.4 kW | 14 | $11,400 | 3.3 yrs |
| Idaho | 6.5 kW | 17 | $13,600 | 14.7 yrs |
| Illinois | 7.4 kW | 19 | $15,500 | 11.7 yrs |
| Indiana | 7.2 kW | 19 | $15,100 | 12.8 yrs |
| Iowa | 7.2 kW | 19 | $15,100 | 15.1 yrs |
| Kansas | 6.5 kW | 17 | $13,600 | 12.2 yrs |
| Kentucky | 7.1 kW | 18 | $14,800 | 15.4 yrs |
| Louisiana | 6.0 kW | 16 | $12,600 | 13.1 yrs |
| Maine | 7.5 kW | 19 | $15,800 | 8.5 yrs |
| Maryland | 7.2 kW | 19 | $15,100 | 11.8 yrs |
| Massachusetts | 7.7 kW | 20 | $16,200 | 7.8 yrs |
| Michigan | 7.9 kW | 20 | $16,600 | 11.1 yrs |
| Minnesota | 7.2 kW | 19 | $15,100 | 12.1 yrs |
| Mississippi | 6.2 kW | 16 | $13,100 | 12.7 yrs |
| Missouri | 6.8 kW | 17 | $14,200 | 13.2 yrs |
| Montana | 6.8 kW | 17 | $14,200 | 13.4 yrs |
| Nebraska | 6.8 kW | 17 | $14,200 | 14.7 yrs |
| Nevada | 5.1 kW | 13 | $10,600 | 8.8 yrs |
| New Hampshire | 7.7 kW | 20 | $16,200 | 8.8 yrs |
| New Jersey | 7.4 kW | 19 | $15,500 | 10.4 yrs |
| New Mexico | 5.2 kW | 14 | $11,000 | 9.0 yrs |
| New York | 7.5 kW | 19 | $15,800 | 8.4 yrs |
| North Carolina | 6.2 kW | 16 | $13,100 | 12.1 yrs |
| North Dakota | 7.2 kW | 19 | $15,100 | 16.4 yrs |
| Ohio | 7.5 kW | 19 | $15,800 | 12.8 yrs |
| Oklahoma | 6.1 kW | 16 | $12,900 | 13.2 yrs |
| Oregon | 7.2 kW | 19 | $15,100 | 14.2 yrs |
| Pennsylvania | 7.7 kW | 20 | $16,200 | 11.4 yrs |
| Rhode Island | 7.5 kW | 19 | $15,800 | 7.6 yrs |
| South Carolina | 6.1 kW | 16 | $12,900 | 11.3 yrs |
| South Dakota | 6.8 kW | 17 | $14,200 | 14.1 yrs |
| Tennessee | 6.5 kW | 17 | $13,600 | 13.2 yrs |
| Texas | 5.8 kW | 15 | $12,200 | 10.4 yrs |
| Utah | 5.6 kW | 14 | $11,700 | 12.4 yrs |
| Vermont | 7.9 kW | 20 | $16,600 | 9.6 yrs |
| Virginia | 6.9 kW | 18 | $14,500 | 12.3 yrs |
| Washington | 8.1 kW | 21 | $17,000 | 18.7 yrs |
| West Virginia | 7.7 kW | 20 | $16,200 | 15.5 yrs |
| Wisconsin | 7.5 kW | 19 | $15,800 | 11.0 yrs |
| Wyoming | 6.5 kW | 17 | $13,600 | 14.0 yrs |
Estimates use EIA state rates, NREL sun hours, and typical kWh/sqft intensity. National methodology.
1,800 sq ft maps to roughly $132/month in utility spend nationally — close to our $125/month bill tier.
| Sizing method | Best when you know… | National guide |
|---|---|---|
| Sq ft (this page) | Home size | 1,800 sq ft |
| Monthly bill | Utility bill amount | $125/mo |
Use both: if your actual bill differs from the sq ft estimate, trust your kWh usage from the utility statement.
Direct answers for US homeowners — sized for a 1,800 sq ft home.
System size and payback vary by electricity rate and sun hours — see your state.
Your target maps to roughly a $125/month electric bill nationally.
$125 $125/month electric bill guide