A real cost breakdown for a typical 6kW system in Illinois, not just a national $/watt figure.
Illinois has a fairly typical electricity rate nationally at approximately $0.16/kWh, and a solid, average solar resource at 4.2 peak sun hours a day. Combined with a regional installed-cost estimate of $2.80/watt, a standard 6kW residential system runs approximately $16,800 before any incentives.
| Line item | Estimated cost | Share of total |
|---|---|---|
| Equipment (panels, inverter, racking) | $9,240 | 55% |
| Labor / installation | $5,040 | 30% |
| Permitting & inspection | $2,520 | 15% |
| Total (before incentives) | $16,800 | 100% |
A 6kW system in Illinois costs close to the average across the 50 states we track ($16,872), and the electricity rate it offsets is roughly in line with the 0.16 USD/kWh average across those same states. That combination is what actually determines whether Illinois is a faster- or slower-than-average place to go solar — a lower system cost alone doesn't help if the rate you're offsetting is also low, and vice versa. See how every state stacks up on the Electricity & Solar Rate Tracker.
At $1,177 in estimated annual value from 7,358 kWh of yearly production, this system pays back in roughly 14 years — a longer payback period than the national average. Illinois: Net metering plus separate SREC-style incentive (Illinois Shines). On incentives specifically: Illinois Shines pays an upfront, capped incentive per system on top of standard net metering — a genuinely strong state program. The federal residential tax credit (Section 25D) expired for owned systems after December 31, 2025 — see our 2026 tax credit guide for what that means for your net price.
Same assumptions as above — $2.80/watt installed, 4.2 peak sun hours, 80% system efficiency, $0.16/kWh, no federal credit — scaled to common system sizes. Real quotes usually come in slightly cheaper per watt for larger systems, and the 25-year figure assumes flat electricity prices and 0.5% yearly panel degradation (rate increases would improve it).
| System | Installed cost | Yearly output | Yearly savings | Payback | 25-yr net savings |
|---|---|---|---|---|---|
| 4 kW | $11,200 | 4,906 kWh | $785 | 14.3 yrs | $7,289 |
| 6 kW | $16,800 | 7,358 kWh | $1,177 | 14.3 yrs | $10,933 |
| 8 kW | $22,400 | 9,811 kWh | $1,570 | 14.3 yrs | $14,578 |
| 10 kW | $28,000 | 12,264 kWh | $1,962 | 14.3 yrs | $18,222 |
| 12 kW | $33,600 | 14,717 kWh | $2,355 | 14.3 yrs | $21,867 |
Payback barely changes with system size here, because cost and savings both scale with the number of panels — what moves it is the rate you offset and your price per watt. For a 10-year payback on a 6 kW system at Illinois's $2.80/watt, you would need to be offsetting about $0.23/kWh; the average rate here is $0.16/kWh, which is below that line. Treat the table as a starting point: use the calculator below with your own usage and quotes. To see how your utility's export credit and how much solar you use at home change payback, try the <a href="/tools/solar-payback-export-credit-calculator.html?state=IL">payback calculator with export credit</a>.
A typical 6kW residential solar system in Illinois costs approximately $16,800 installed in 2026, based on a regional estimate of $2.80/watt — equipment usually makes up about 55% of that, labor about 30%, with the rest in permitting.
At Illinois's average rate of $0.16/kWh, a 6kW system pays back in roughly 14 years — a longer payback period than the national average. Your actual number depends on your usage and roof; check it precisely with the Solar Panel Cost Calculator.
A 6kW system in Illinois costs close to the 50-state average of $16,872, while the electricity rate it offsets is roughly in line with the 0.16 USD/kWh average across those states.