What a 4 kW solar system costs
About 10 panels, roughly 220 square feet of roof, and $15,000 at the national median of $3.75 a watt. There is no federal credit to subtract from that any more.
The numbers
The same system bought before 31 December 2025 would have cost $10,500 after the 30% federal credit. That credit no longer exists, so this system is $4,500 more expensive than an identical one installed a year earlier. What changed.
A 4 kW system in the states we have local prices for
| State | Per watt | Price | Makes | Saves, year one | Payback |
|---|---|---|---|---|---|
| Massachusetts | $3.74 | $14,960 | 5,052 kWh | $1,540 | 9.0 years |
| New York | $3.98 | $15,920 | 5,020 kWh | $1,501 | 9.7 years |
| Rhode Island | $3.75 | $15,000 | 5,032 kWh | $1,424 | 9.7 years |
| California | $4.36 | $17,440 | 6,408 kWh | $1,508 | 10.5 years |
| Connecticut | $3.75 | $15,000 | 5,112 kWh | $1,235 | 11.0 years |
| Delaware | $3.18 | $12,720 | 5,100 kWh | $942 | 12.1 years |
| Arizona | $3.62 | $14,480 | 6,752 kWh | $1,038 | 12.4 years |
| Wisconsin | $3.73 | $14,920 | 5,024 kWh | $958 | 13.7 years |
| Texas | $3.46 | $13,840 | 5,556 kWh | $882 | 13.8 years |
| Florida | $4.08 | $16,320 | 5,704 kWh | $857 | 16.3 years |
| Oregon | $3.90 | $15,600 | 4,312 kWh | $689 | 18.9 years |
Three competing quotes beat any amount of comparing panel brands
Sales cost and margin are over a third of an installed price, and they are the part that competition removes. A single quote from whoever reached you first is how people end up in the top quarter of what their neighbours paid.
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Prices and rules change. We will tell you when they do
Berkeley Lab publishes installed prices once a year, the EIA updates electricity rates every month, and Congress changed the tax treatment of all of this in 2025. One email when something on this site actually changes, and nothing else.
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