System size guide
How much does a 4 kW solar system cost?
A 4 kW residential system — about 10 × 425-watt panels — costs roughly $10,000–$13,400 installed in 2026 at a national assumed range of $2.50–$3.35 per watt, before any state or utility incentives. It would produce around 5,600 kWh per year in typical US conditions, worth roughly $831 in first-year savings at average rates — a simple payback of about 12–16 years.
There is no federal tax credit in these figures: the Section 25D residential credit ended for systems installed after December 31, 2025.
4 kW system cost by state
| State | 4 kW cost | Est. annual production | Est. payback |
|---|---|---|---|
| Alabama | $9,200–$12,200 | 5,600 kWh | 12–17 yrs |
| Alaska | $11,600–$15,600 | 3,800 kWh | 15–20 yrs |
| Arizona | $9,400–$12,400 | 6,880 kWh | 10–14 yrs |
| Arkansas | $9,600–$12,600 | 5,440 kWh | 16–22 yrs |
| California | $10,200–$13,400 | 6,040 kWh | 7–9 yrs |
| Colorado | $10,200–$13,200 | 5,960 kWh | 13–17 yrs |
| Connecticut | $11,200–$14,400 | 4,880 kWh | 10–12 yrs |
| Delaware | $10,400–$13,600 | 5,280 kWh | 14–18 yrs |
| Florida | $9,400–$12,400 | 5,920 kWh | 13–17 yrs |
| Georgia | $9,400–$12,400 | 5,600 kWh | 15–19 yrs |
| Hawaii | $11,600–$15,600 | 6,320 kWh | 5–7 yrs |
| Idaho | $9,800–$12,800 | 5,520 kWh | 20–26 yrs |
| Illinois | $10,400–$13,600 | 5,080 kWh | 16–20 yrs |
| Indiana | $9,800–$12,800 | 5,120 kWh | 15–20 yrs |
| Iowa | $10,000–$13,000 | 5,200 kWh | 17–22 yrs |
| Kansas | $9,800–$12,800 | 5,800 kWh | 15–19 yrs |
| Kentucky | $9,600–$12,600 | 5,200 kWh | 17–23 yrs |
| Louisiana | $9,400–$12,400 | 5,520 kWh | 17–23 yrs |
| Maine | $11,200–$14,400 | 4,760 kWh | 11–14 yrs |
| Maryland | $10,400–$13,600 | 5,200 kWh | 13–18 yrs |
| Massachusetts | $11,200–$14,400 | 4,640 kWh | 10–13 yrs |
| Michigan | $10,200–$13,400 | 4,640 kWh | 14–18 yrs |
| Minnesota | $10,400–$13,600 | 5,000 kWh | 17–22 yrs |
| Mississippi | $9,400–$12,400 | 5,520 kWh | 15–19 yrs |
| Missouri | $9,600–$12,600 | 5,400 kWh | 17–22 yrs |
| Montana | $10,200–$13,400 | 5,320 kWh | 19–25 yrs |
| Nebraska | $9,600–$12,600 | 5,520 kWh | 18–23 yrs |
| Nevada | $9,600–$12,600 | 6,680 kWh | 12–15 yrs |
| New Hampshire | $11,200–$14,400 | 4,720 kWh | 10–13 yrs |
| New Jersey | $10,600–$13,800 | 5,040 kWh | 13–17 yrs |
| New Mexico | $9,600–$12,600 | 6,800 kWh | 11–15 yrs |
| New York | $11,000–$14,200 | 4,720 kWh | 11–15 yrs |
| North Carolina | $9,600–$12,600 | 5,520 kWh | 16–21 yrs |
| North Dakota | $10,000–$13,200 | 5,280 kWh | 21–28 yrs |
| Ohio | $9,800–$12,800 | 4,800 kWh | 15–20 yrs |
| Oklahoma | $9,400–$12,400 | 5,880 kWh | 16–21 yrs |
| Oregon | $10,400–$13,600 | 4,640 kWh | 19–25 yrs |
| Pennsylvania | $10,000–$13,200 | 4,880 kWh | 14–18 yrs |
| Rhode Island | $11,200–$14,400 | 4,920 kWh | 10–13 yrs |
| South Carolina | $9,600–$12,600 | 5,600 kWh | 15–20 yrs |
| South Dakota | $9,800–$13,000 | 5,480 kWh | 17–22 yrs |
| Tennessee | $9,600–$12,600 | 5,360 kWh | 17–22 yrs |
| Texas | $9,400–$12,200 | 6,060 kWh | 12–15 yrs |
| Utah | $9,600–$12,600 | 5,800 kWh | 17–22 yrs |
| Vermont | $11,200–$14,400 | 4,600 kWh | 14–18 yrs |
| Virginia | $10,000–$13,200 | 5,320 kWh | 16–22 yrs |
| Washington | $10,400–$13,600 | 4,200 kWh | 25–33 yrs |
| Washington, D.C. | $10,800–$14,200 | 5,200 kWh | 14–18 yrs |
| West Virginia | $9,800–$13,000 | 5,000 kWh | 17–23 yrs |
| Wisconsin | $10,200–$13,400 | 4,880 kWh | 15–20 yrs |
| Wyoming | $10,000–$13,200 | 5,680 kWh | 18–24 yrs |
Assumptions last reviewed September 2026. Broad estimates before incentives — not quotes. See methodology.
Frequently asked questions
How much does a 4 kW solar system cost installed?
At a national assumed range of $2.50–$3.35 per watt, a 4 kW system costs roughly $10,000–$13,400 before incentives. State markets range meaningfully in both directions — see the table on this page.
How many panels is a 4 kW system?
About 10 panels at a typical 425 watts each. Higher-wattage panels reduce the count; smaller panels increase it.
How much electricity does a 4 kW system produce?
Around 5,600 kWh per year at a typical US production factor of 1,400 kWh per installed kW — enough to offset roughly a $80/month electric bill at average rates. Sunnier states produce 10–25% more, cloudier states less.
Is there a federal tax credit for a 4 kW system in 2026?
No. The 30% federal residential clean energy credit (Section 25D) ended for systems installed after December 31, 2025. Leased or PPA systems may still benefit indirectly through the commercial 48E credit through 2027, and some states offer their own incentives.
Is a 4 kW system the right size for my home?
Size should follow your actual usage, roof space, and your utility’s export rules — not a round number. Our calculator sizes a system from your monthly bill and location in about a minute, with no contact details required.