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
$54,700
Rates rise ~3% per year (EIA avg.)
With solar
Net system cost
$14,300
After 30% federal ITC
Your savings
Difference
+$40,300
Estimated lifetime advantage
A $125/month electric bill in the US typically needs 18 solar panels (6.8 kW) at national average electricity rates and sun hours — $14,300 after the 30% ITC with 11.0-year payback. State-by-state, system size ranges from 2.0 kW in Hawaii to 11.6 kW in Washington, and payback spans 3.3–18.7 years.
Start here: National $125/month guide · Solar savings calculator · 1,800 sq ft by state
| Metric | US average ($125/mo bill) |
|---|---|
| Est. monthly usage | ~767 kWh |
| System size | 6.8 kW |
| Panels (400W) | 18 |
| Net cost after ITC | $14,300 |
| Simple payback | 11.0 years |
| 25-year savings | $40,300+ |
Formula: kW = Annual kWh ÷ (Peak sun hours × 365 × 0.82)
| Fastest payback | Slowest payback | |
|---|---|---|
| State | Hawaii | Washington |
| System | 2.0 kW · 6 panels | 11.6 kW · 30 panels |
| After ITC | $4,300 | $24,400 |
| Payback | 3.3 yrs | 18.7 yrs |
High electricity rates (e.g. Hawaii, California, Massachusetts) often beat sunny low-rate states for $125/month payback.
| State | System | Panels | After ITC | Payback |
|---|---|---|---|---|
| Alabama | 7.1 kW | 18 | $14,800 | 11.4 yrs |
| Alaska | 6.9 kW | 18 | $14,500 | 11.1 yrs |
| Arizona | 5.8 kW | 15 | $12,300 | 9.4 yrs |
| Arkansas | 8.4 kW | 22 | $17,700 | 13.6 yrs |
| California | 2.9 kW | 8 | $6,200 | 4.7 yrs |
| Colorado | 6.4 kW | 17 | $13,500 | 10.3 yrs |
| Connecticut | 4.8 kW | 13 | $10,100 | 7.7 yrs |
| Delaware | 7.5 kW | 19 | $15,800 | 12.1 yrs |
| Florida | 6.5 kW | 17 | $13,700 | 10.5 yrs |
| Georgia | 7.4 kW | 19 | $15,600 | 11.9 yrs |
| Hawaii | 2.0 kW | 6 | $4,300 | 3.3 yrs |
| Idaho | 9.1 kW | 23 | $19,100 | 14.7 yrs |
| Illinois | 7.3 kW | 19 | $15,300 | 11.7 yrs |
| Indiana | 8.0 kW | 20 | $16,700 | 12.8 yrs |
| Iowa | 9.4 kW | 24 | $19,700 | 15.1 yrs |
| Kansas | 7.6 kW | 19 | $15,900 | 12.2 yrs |
| Kentucky | 9.6 kW | 24 | $20,100 | 15.4 yrs |
| Louisiana | 8.1 kW | 21 | $17,100 | 13.1 yrs |
| Maine | 5.3 kW | 14 | $11,100 | 8.5 yrs |
| Maryland | 7.3 kW | 19 | $15,400 | 11.8 yrs |
| Massachusetts | 4.9 kW | 13 | $10,200 | 7.8 yrs |
| Michigan | 6.9 kW | 18 | $14,400 | 11.1 yrs |
| Minnesota | 7.5 kW | 19 | $15,800 | 12.1 yrs |
| Mississippi | 7.9 kW | 20 | $16,600 | 12.7 yrs |
| Missouri | 8.2 kW | 21 | $17,300 | 13.2 yrs |
| Montana | 8.4 kW | 21 | $17,500 | 13.4 yrs |
| Nebraska | 9.2 kW | 23 | $19,200 | 14.7 yrs |
| Nevada | 5.4 kW | 14 | $11,400 | 8.8 yrs |
| New Hampshire | 5.4 kW | 14 | $11,400 | 8.8 yrs |
| New Jersey | 6.5 kW | 17 | $13,600 | 10.4 yrs |
| New Mexico | 5.6 kW | 15 | $11,800 | 9.0 yrs |
| New York | 5.2 kW | 14 | $10,900 | 8.4 yrs |
| North Carolina | 7.5 kW | 19 | $15,800 | 12.1 yrs |
| North Dakota | 10.2 kW | 26 | $21,500 | 16.4 yrs |
| Ohio | 8.0 kW | 20 | $16,800 | 12.8 yrs |
| Oklahoma | 8.2 kW | 21 | $17,300 | 13.2 yrs |
| Oregon | 8.8 kW | 23 | $18,600 | 14.2 yrs |
| Pennsylvania | 7.1 kW | 18 | $14,900 | 11.4 yrs |
| Rhode Island | 4.7 kW | 12 | $9,900 | 7.6 yrs |
| South Carolina | 7.0 kW | 18 | $14,700 | 11.3 yrs |
| South Dakota | 8.8 kW | 22 | $18,400 | 14.1 yrs |
| Tennessee | 8.2 kW | 21 | $17,300 | 13.2 yrs |
| Texas | 6.5 kW | 17 | $13,600 | 10.4 yrs |
| Utah | 7.7 kW | 20 | $16,200 | 12.4 yrs |
| Vermont | 6.0 kW | 15 | $12,600 | 9.6 yrs |
| Virginia | 7.7 kW | 20 | $16,100 | 12.3 yrs |
| Washington | 11.6 kW | 30 | $24,400 | 18.7 yrs |
| West Virginia | 9.6 kW | 25 | $20,200 | 15.5 yrs |
| Wisconsin | 6.8 kW | 18 | $14,300 | 11.0 yrs |
| Wyoming | 8.7 kW | 22 | $18,300 | 14.0 yrs |
Estimates use EIA state rates, NREL sun hours, and 0.82 derate. National methodology.
$125/month maps to roughly 1,800 sq ft in national usage intensity — close to our 1,800 sq ft sizing tier.
| Sizing method | Best when you know… | National guide |
|---|---|---|
| Monthly bill (this page) | Utility bill amount | $125/mo |
| Home sq ft | House size | 1,800 sq ft |
Use both: if your bill differs from the sq ft estimate, trust your kWh usage from the utility statement.
Direct answers for US homeowners — sized for a $125/month electric bill.
Electricity rates and incentives vary — see data for your state.