All states / Illinois
Solar in Illinois
At 19.89¢ per kWh and 1308 kWh of production per kW each year, a household paying $200 a month needs a 8.67 kW system. Paid in cash, it returns its $25,841 cost in 11.1 yr.
What we don't know yet
Two prices, two answers
Payback 11.1 yr — at competitive quoted prices ($2.98/W, EnergySage 2026): net cost $25,841, 25-year net $40,755.
LBNL 2023: fewer than 20 observations, so LBNL publishes no median for this state. We show one basis here rather than borrow a neighbouring state's.
Where a second basis exists, the gap between the two is methodology, not staleness: quoted prices are what you get if you shop around for competitive quotes; reported prices are what the average buyer actually paid, as recorded in permit and incentive data. Every table below uses quoted prices. Why we show both.
By monthly bill
| Your bill | Use / yr | System | Panels | Net cost | Payback | 25-yr net (cash) | Lease, year 1 |
|---|---|---|---|---|---|---|---|
| $100/mo | 5,309 kWh | 4.06 kW | 11 | $12,096 | 13.3 yr | $16,124 | $317 |
| $150/mo | 8,326 kWh | 6.37 kW | 16 | $18,969 | 12.2 yr | $28,439 | $497 |
| $200/mo | 11,342 kWh | 8.67 kW | 22 | $25,841 | 11.1 yr | $40,755 | $677 |
| $300/mo | 17,376 kWh | 13.28 kW | 34 | $39,587 | 10.8 yr | $65,383 | $1,037 |
Cash, loan or lease — at $200 a month
| How you pay | 25-year net | Upfront | Year 1 | Payback / cash flow | Federal credit to you |
|---|---|---|---|---|---|
| Cash | $40,755 | $25,841 | $2,106 | 11.1 yr | $0 |
| Loan $200/mo · 6.99% APR · 20 yr | $18,550 | $0 | −$296 | positive from year 18 | $0 |
| Lease / PPA | $18,997 | $0 | $677 | immediate (+$677 in year 1) | $0 |
The 30% federal credit goes to the system owner, not to you. It is reflected in the rate you are offered. The owner claims it at 30% under IRC 48E.
The inputs, and where they came from
| Input | Value | Source |
|---|---|---|
| Residential electricity rate | 19.89¢/kWh | U.S. EIA API v2, electricity/retail-sales, residential sector, 2026-06 |
| Specific yield | 1308 kWh/kW/yr | NLR (formerly NREL) PVWatts v8 API, 1 kW reference system (city:chicago-il) |
| Installed cost | $2.98/W | EnergySage Marketplace real-quote average, as of Sep 2026; page updated 2026-08-28 |
| Export compensation | full retail net metering · 100% | Full retail net metering — not yet verified against the tariff |
| Federal credit, purchase | 0% | IRC 25D (expired) |
| Federal credit, third-party owner | 30% | IRC 48E (Clean Electricity Investment Credit) |
| State incentives | $0 | No upfront statewide credit or rebate for a typical owner-occupier (verified) · Not modelled: Illinois Shines REC contract, Small Distributed Generation 0-10 kW AC |
City-level production on file for: Chicago. The figures above use Chicago.