A 5 kW solar system costs about $13,900 in 2026, an 8 kW system $20,960, a 10 kW system $25,800 and a 12 kW system $30,720, all before incentives, according to EnergySage marketplace data (cost page updated June 30, 2026). Bigger systems cost more in total but less per watt, from $2.78 at 5 kW to $2.56 at 12 kW. Which size is right depends on what your house uses, not on the lowest price per watt. Here are the numbers for each size, how state prices differ, and how to check whether a larger system earns its extra cost.
Solar Cost by System Size
This table uses EnergySage’s national averages. Annual output comes from EnergySage’s individual system-size pages (updated June and July 2026), and cost per kWh of yearly output is our arithmetic.
| System size | Average cost (EnergySage) | Cost per watt (EnergySage) | Yearly output (EnergySage) | Cost per yearly kWh (our arithmetic) |
|---|---|---|---|---|
| 5 kW | $13,900 | $2.78 | 7,260 kWh | $1.91 |
| 8 kW | $20,960 | $2.62 | 11,614 kWh | $1.80 |
| 10 kW | $25,800 | $2.58 | 14,517 kWh | $1.78 |
| 12 kW | $30,720 | $2.56 | 17,420 kWh | $1.76 |
EnergySage’s 5 kW page quotes $13,750 in its text while its main cost table shows $13,900, so treat 5 kW as about $13,750 to $13,900. EnergySage also lists 6 kW at $16,080 ($2.68 per watt).
The per-watt drop is real, but small. Going from 5 kW to 12 kW adds about $16,800 (our arithmetic) and lowers the price per watt by 22 cents. Fixed costs like permitting, interconnection and the sales process get spread over more panels, but panels, racking and labor still scale with size.
Prices by State
EnergySage’s state figures show how much location moves the total. Texas is the cheapest state in these pages and Massachusetts the most expensive.
| System size | Texas | Florida | Arizona | Massachusetts |
|---|---|---|---|---|
| 5 kW | $10,195 | $10,594 | $11,412 | n/a |
| 8 kW | $16,312 | $16,951 | $18,260 | $23,755 |
| 10 kW | $20,390 | $21,188 | $22,825 | $29,693 |
| 12 kW | $24,468 | n/a | n/a | $35,632 |
Source: EnergySage system-size pages, 2026; “n/a” means we did not find a published figure for that cell. The gap between the cheapest and priciest state for a 10 kW system is about $9,300 (our arithmetic). Higher prices do not always mean worse value, though, because the same states often have much higher power rates. Our solar panel installation cost guide pairs state prices with EIA electricity rates.
What the Federal Credit Status Means for These Prices
Every price above is before incentives, and in 2026 that is also close to the price you pay. The IRS says the Residential Clean Energy Credit equals 30% of qualified costs for property installed from 2022 through December 31, 2025, and “is not available for any property placed in service after December 31, 2025” (IRS page updated July 4, 2026). Check dsire.org for state or utility incentives that may still apply to you.
Which Size Pays Off
Output per dollar is only worth something if you use the power. Here is a simple payback illustration using EnergySage’s national prices and outputs and the EIA’s July 2026 U.S. average residential rate of 18.31 cents per kWh. It assumes every kilowatt-hour offsets a purchase at that rate, with no rate growth, no panel degradation and no financing cost. That is our arithmetic, not a forecast.
| System size | Yearly value of output (our arithmetic) | Simple payback (our arithmetic) |
|---|---|---|
| 5 kW | about $1,329 | about 10.5 years |
| 8 kW | about $2,127 | about 9.9 years |
| 10 kW | about $2,658 | about 9.7 years |
| 12 kW | about $3,190 | about 9.6 years |
The sizes differ by less than a year, so size is not what makes or breaks payback. Your electricity rate is. Using the same 8 kW national price and output, but changing only the rate (our arithmetic): at Massachusetts’s 30.49 cents, payback drops to about 5.9 years, and at Louisiana’s 12.72 cents it stretches to about 14.2 years. For EnergySage’s marketplace-wide payback figures by state, see our solar panel payback period guide.
How to Pick Your Size
Start with your usage, not a price list. Our guide on how many solar panels to power a house walks through the formula. As a rough match using EnergySage’s national output figures:
- 5 kW produces about 7,260 kWh a year, which is about two-thirds of an average 10,791 kWh household (our arithmetic). It suits small homes, a partial offset or a roof with limited room.
- 8 kW produces about 11,614 kWh, enough to cover an average household with a little to spare.
- 10 kW produces about 14,517 kWh. It fits larger homes, heavy air conditioning or electric heat, or a planned EV.
- 12 kW produces about 17,420 kWh. It makes sense only for high usage or added loads. For a typical house it overshoots, and surplus power may earn little.
If your utility pays well below retail for exports, aim for a system that covers your own use and stop there.
Add-Ons That Change the Total
The prices above are for standard grid-tied rooftop systems. Extras move the number:
- A battery is a separate purchase. See our solar battery cost guide.
- A tricky roof, such as tile, steep pitch or several roof faces, tends to cost more, as does an electrical panel upgrade.
- Premium panels or microinverters cost more per watt than standard equipment.
- An old roof should be replaced before panels go on. Our roof replacement cost guide covers that decision.
How to Compare Quotes
Convert every quote to cost per watt, then ask for the estimated yearly kWh. A quote for a larger system is not a better deal just because the per-watt figure is lower. Compare at the same equipment tier, and get at least three bids. EnergySage’s marketplace averages are a benchmark, not a quote.
Bottom Line
Expect roughly $13,900 for 5 kW, $20,960 for 8 kW, $25,800 for 10 kW and $30,720 for 12 kW before incentives, with Texas at the low end and Massachusetts at the high end. Size the system to your usage, because a bigger one only pays if you use or sell the extra power. Then compare your rate: our payback illustration spans about 6 to 14 years for the same system depending on electricity price.
FAQ
How much does a 5 kW solar system cost?
About $13,900 nationally before incentives, per EnergySage (the 5 kW page cites $13,750). By state, EnergySage’s figures run from $10,195 in Texas to $11,412 in Arizona among the states we checked.
How much does a 10 kW solar system cost?
About $25,800 before incentives per EnergySage, or about $2.58 per watt. State prices range from $20,390 in Texas to $29,693 in Massachusetts.
Is a 12 kW solar system too big for a house?
For an average home, usually yes. A 12 kW system makes about 17,420 kWh a year per EnergySage, roughly 1.6 times what an average household uses (our arithmetic). It fits large homes or ones with an EV and electric heating.
Why is solar cheaper per watt on bigger systems?
Fixed costs like permitting, interconnection and sales are spread over more watts. EnergySage’s table shows the price per watt falling from $2.78 at 5 kW to $2.56 at 12 kW.
Can I still get a federal tax credit for solar?
The IRS says the 30% Residential Clean Energy Credit is not available for property placed in service after December 31, 2025. Check your state and utility for programs that still apply.