System size guide
How much does a 15 kW solar system cost?
A 15 kW residential system — about 36 × 425-watt panels — costs roughly $37,500–$50,250 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 21,000 kWh per year in typical US conditions, worth roughly $3,115 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.
15 kW system cost by state
| State | 15 kW cost | Est. annual production | Est. payback |
|---|---|---|---|
| Alabama | $34,500–$45,750 | 21,000 kWh | 12–17 yrs |
| Alaska | $43,500–$58,500 | 14,250 kWh | 15–20 yrs |
| Arizona | $35,250–$46,500 | 25,800 kWh | 10–14 yrs |
| Arkansas | $36,000–$47,250 | 20,400 kWh | 16–22 yrs |
| California | $38,250–$50,250 | 22,650 kWh | 7–9 yrs |
| Colorado | $38,250–$49,500 | 22,350 kWh | 13–17 yrs |
| Connecticut | $42,000–$54,000 | 18,300 kWh | 10–12 yrs |
| Delaware | $39,000–$51,000 | 19,800 kWh | 14–18 yrs |
| Florida | $35,250–$46,500 | 22,200 kWh | 13–17 yrs |
| Georgia | $35,250–$46,500 | 21,000 kWh | 15–19 yrs |
| Hawaii | $43,500–$58,500 | 23,700 kWh | 5–7 yrs |
| Idaho | $36,750–$48,000 | 20,700 kWh | 20–26 yrs |
| Illinois | $39,000–$51,000 | 19,050 kWh | 16–20 yrs |
| Indiana | $36,750–$48,000 | 19,200 kWh | 15–20 yrs |
| Iowa | $37,500–$48,750 | 19,500 kWh | 17–22 yrs |
| Kansas | $36,750–$48,000 | 21,750 kWh | 15–19 yrs |
| Kentucky | $36,000–$47,250 | 19,500 kWh | 17–23 yrs |
| Louisiana | $35,250–$46,500 | 20,700 kWh | 17–23 yrs |
| Maine | $42,000–$54,000 | 17,850 kWh | 11–14 yrs |
| Maryland | $39,000–$51,000 | 19,500 kWh | 13–18 yrs |
| Massachusetts | $42,000–$54,000 | 17,400 kWh | 10–13 yrs |
| Michigan | $38,250–$50,250 | 17,400 kWh | 14–18 yrs |
| Minnesota | $39,000–$51,000 | 18,750 kWh | 17–22 yrs |
| Mississippi | $35,250–$46,500 | 20,700 kWh | 15–19 yrs |
| Missouri | $36,000–$47,250 | 20,250 kWh | 17–22 yrs |
| Montana | $38,250–$50,250 | 19,950 kWh | 19–25 yrs |
| Nebraska | $36,000–$47,250 | 20,700 kWh | 18–23 yrs |
| Nevada | $36,000–$47,250 | 25,050 kWh | 12–15 yrs |
| New Hampshire | $42,000–$54,000 | 17,700 kWh | 10–13 yrs |
| New Jersey | $39,750–$51,750 | 18,900 kWh | 13–17 yrs |
| New Mexico | $36,000–$47,250 | 25,500 kWh | 11–15 yrs |
| New York | $41,250–$53,250 | 17,700 kWh | 11–15 yrs |
| North Carolina | $36,000–$47,250 | 20,700 kWh | 16–21 yrs |
| North Dakota | $37,500–$49,500 | 19,800 kWh | 21–28 yrs |
| Ohio | $36,750–$48,000 | 18,000 kWh | 15–20 yrs |
| Oklahoma | $35,250–$46,500 | 22,050 kWh | 16–21 yrs |
| Oregon | $39,000–$51,000 | 17,400 kWh | 19–25 yrs |
| Pennsylvania | $37,500–$49,500 | 18,300 kWh | 14–18 yrs |
| Rhode Island | $42,000–$54,000 | 18,450 kWh | 10–13 yrs |
| South Carolina | $36,000–$47,250 | 21,000 kWh | 15–20 yrs |
| South Dakota | $36,750–$48,750 | 20,550 kWh | 17–22 yrs |
| Tennessee | $36,000–$47,250 | 20,100 kWh | 17–22 yrs |
| Texas | $35,250–$45,750 | 22,725 kWh | 12–15 yrs |
| Utah | $36,000–$47,250 | 21,750 kWh | 17–22 yrs |
| Vermont | $42,000–$54,000 | 17,250 kWh | 14–18 yrs |
| Virginia | $37,500–$49,500 | 19,950 kWh | 16–22 yrs |
| Washington | $39,000–$51,000 | 15,750 kWh | 25–33 yrs |
| Washington, D.C. | $40,500–$53,250 | 19,500 kWh | 14–18 yrs |
| West Virginia | $36,750–$48,750 | 18,750 kWh | 17–23 yrs |
| Wisconsin | $38,250–$50,250 | 18,300 kWh | 15–20 yrs |
| Wyoming | $37,500–$49,500 | 21,300 kWh | 18–24 yrs |
Assumptions last reviewed September 2026. Broad estimates before incentives — not quotes. See methodology.
Frequently asked questions
How much does a 15 kW solar system cost installed?
At a national assumed range of $2.50–$3.35 per watt, a 15 kW system costs roughly $37,500–$50,250 before incentives. State markets range meaningfully in both directions — see the table on this page.
How many panels is a 15 kW system?
About 36 panels at a typical 425 watts each. Higher-wattage panels reduce the count; smaller panels increase it.
How much electricity does a 15 kW system produce?
Around 21,000 kWh per year at a typical US production factor of 1,400 kWh per installed kW — enough to offset roughly a $320/month electric bill at average rates. Sunnier states produce 10–25% more, cloudier states less.
Is there a federal tax credit for a 15 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 15 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.