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
$131,300
Rates rise ~3% per year (EIA avg.)
With solar
Net system cost
$34,400
After 30% federal ITC
Your savings
Difference
+$96,800
Estimated lifetime advantage
A $300/month electric bill in the US typically needs 41 solar panels (16.4 kW) at national average electricity rates and sun hours — $34,400 after the 30% ITC with 11.0-year payback. State-by-state, system size ranges from 4.9 kW in Hawaii to 27.8 kW in Washington, and payback spans 3.3–18.7 years.
Start here: National $300/month guide · Solar savings calculator · 3,500 sq ft by state
| Metric | US average ($300/mo bill) |
|---|---|
| Est. monthly usage | ~1,840 kWh |
| System size | 16.4 kW |
| Panels (400W) | 41 |
| Net cost after ITC | $34,400 |
| Simple payback | 11.0 years |
| 25-year savings | $96,800+ |
Formula: kW = Annual kWh ÷ (Peak sun hours × 365 × 0.82)
| Fastest payback | Slowest payback | |
|---|---|---|
| State | Hawaii | Washington |
| System | 4.9 kW · 13 panels | 27.8 kW · 70 panels |
| After ITC | $10,300 | $58,500 |
| Payback | 3.3 yrs | 18.7 yrs |
High electricity rates (e.g. Hawaii, California, Massachusetts) often beat sunny low-rate states for $300/month payback.
| State | System | Panels | After ITC | Payback |
|---|---|---|---|---|
| Alabama | 16.9 kW | 43 | $35,600 | 11.4 yrs |
| Alaska | 16.6 kW | 42 | $34,800 | 11.1 yrs |
| Arizona | 14.0 kW | 36 | $29,400 | 9.4 yrs |
| Arkansas | 20.2 kW | 51 | $42,500 | 13.6 yrs |
| California | 7.1 kW | 18 | $14,800 | 4.7 yrs |
| Colorado | 15.4 kW | 39 | $32,300 | 10.3 yrs |
| Connecticut | 11.5 kW | 29 | $24,300 | 7.7 yrs |
| Delaware | 18.1 kW | 46 | $37,900 | 12.1 yrs |
| Florida | 15.6 kW | 40 | $32,800 | 10.5 yrs |
| Georgia | 17.8 kW | 45 | $37,400 | 11.9 yrs |
| Hawaii | 4.9 kW | 13 | $10,300 | 3.3 yrs |
| Idaho | 21.9 kW | 55 | $45,900 | 14.7 yrs |
| Illinois | 17.5 kW | 44 | $36,800 | 11.7 yrs |
| Indiana | 19.1 kW | 48 | $40,100 | 12.8 yrs |
| Iowa | 22.5 kW | 57 | $47,200 | 15.1 yrs |
| Kansas | 18.2 kW | 46 | $38,300 | 12.2 yrs |
| Kentucky | 22.9 kW | 58 | $48,200 | 15.4 yrs |
| Louisiana | 19.5 kW | 49 | $41,000 | 13.1 yrs |
| Maine | 12.7 kW | 32 | $26,700 | 8.5 yrs |
| Maryland | 17.6 kW | 44 | $36,900 | 11.8 yrs |
| Massachusetts | 11.7 kW | 30 | $24,500 | 7.8 yrs |
| Michigan | 16.5 kW | 42 | $34,600 | 11.1 yrs |
| Minnesota | 18.1 kW | 46 | $37,900 | 12.1 yrs |
| Mississippi | 19.0 kW | 48 | $39,800 | 12.7 yrs |
| Missouri | 19.7 kW | 50 | $41,400 | 13.2 yrs |
| Montana | 20.0 kW | 51 | $42,100 | 13.4 yrs |
| Nebraska | 22.0 kW | 55 | $46,200 | 14.7 yrs |
| Nevada | 13.1 kW | 33 | $27,400 | 8.8 yrs |
| New Hampshire | 13.1 kW | 33 | $27,500 | 8.8 yrs |
| New Jersey | 15.5 kW | 39 | $32,600 | 10.4 yrs |
| New Mexico | 13.5 kW | 34 | $28,300 | 9.0 yrs |
| New York | 12.5 kW | 32 | $26,200 | 8.4 yrs |
| North Carolina | 18.1 kW | 46 | $37,900 | 12.1 yrs |
| North Dakota | 24.5 kW | 62 | $51,500 | 16.4 yrs |
| Ohio | 19.2 kW | 48 | $40,200 | 12.8 yrs |
| Oklahoma | 19.7 kW | 50 | $41,400 | 13.2 yrs |
| Oregon | 21.2 kW | 54 | $44,500 | 14.2 yrs |
| Pennsylvania | 17.0 kW | 43 | $35,800 | 11.4 yrs |
| Rhode Island | 11.4 kW | 29 | $23,900 | 7.6 yrs |
| South Carolina | 16.8 kW | 43 | $35,300 | 11.3 yrs |
| South Dakota | 21.1 kW | 53 | $44,200 | 14.1 yrs |
| Tennessee | 19.7 kW | 50 | $41,400 | 13.2 yrs |
| Texas | 15.6 kW | 39 | $32,700 | 10.4 yrs |
| Utah | 18.5 kW | 47 | $38,900 | 12.4 yrs |
| Vermont | 14.4 kW | 36 | $30,200 | 9.6 yrs |
| Virginia | 18.4 kW | 47 | $38,700 | 12.3 yrs |
| Washington | 27.8 kW | 70 | $58,500 | 18.7 yrs |
| West Virginia | 23.1 kW | 58 | $48,500 | 15.5 yrs |
| Wisconsin | 16.4 kW | 41 | $34,400 | 11.0 yrs |
| Wyoming | 20.9 kW | 53 | $43,900 | 14.0 yrs |
Estimates use EIA state rates, NREL sun hours, and 0.82 derate. National methodology.
$300/month maps to roughly 3,500 sq ft in national usage intensity — close to our 3,500 sq ft sizing tier.
| Sizing method | Best when you know… | National guide |
|---|---|---|
| Monthly bill (this page) | Utility bill amount | $300/mo |
| Home sq ft | House size | 3,500 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 $300/month electric bill.
Electricity rates and incentives vary — see data for your state.