Solar panels in Joliet, IL
Roofs in Joliet get about 1,538 hours of usable sunlight a year — less than 52% of the cities we've measured. Here's what that means in cost, savings and payback, using real rooftop data rather than a national average.
Check your specific roof in Joliet → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.
What a typical Joliet solar system costs
A 21-panel system (8.4 kW) is about right for an average Joliet home using 10,800 kWh a year. It would produce roughly 10,981 kWh annually and offset 100% of that usage.
| System | Size | kWh/yr | Net cost | Saves/yr | Payback |
|---|---|---|---|---|---|
| 8 panels | 3.2 kW | 4,183 | $6,384 | $682 | 9.4 yrs |
| 12 panels | 4.8 kW | 6,275 | $9,576 | $1,023 | 9.4 yrs |
| 16 panels | 6.4 kW | 8,367 | $12,768 | $1,364 | 9.4 yrs |
| 20 panels | 8 kW | 10,458 | $15,960 | $1,705 | 9.4 yrs |
| 26 panels | 10.4 kW | 13,596 | $20,748 | $1,874 | 11.1 yrs |
Notice that payback barely improves as systems get bigger, and eventually gets worse. That's because you can only save money on electricity you were going to buy anyway. Once a system covers your usage, extra panels mostly generate exports at a much lower rate.
Why Joliet gets 1,538 sun hours
That figure comes from Google's analysis of real rooftops across Joliet — it already accounts for shading from trees, chimneys and neighbouring buildings, which is why it's lower than the raw "hours of daylight" figures you'll see elsewhere. An unusually open, unshaded roof in Joliet reaches about 1,591 hours, roughly 3% better than typical.
The numbers behind this page
| Typical usable sunlight | 1,538 hrs/yr |
|---|---|
| Unshaded roof | 1,591 hrs/yr |
| Electricity rate (Illinois avg) | 16.3¢/kWh |
| Installed cost assumed | $2.85/W |
| Panel size assumed | 400 W |
| Federal tax credit | 30% |
| Typical household usage | 10,800 kWh/yr |
| Power used as generated | 34% |
| Paid for exported power | full retail (net metering) |
| Rooftops sampled here | 14 |
| Google imagery from | 2024 |
Nearby cities
See all of Illinois → statewide sunlight, rates, incentives and every city we've measured.
Joliet solar questions
How many solar panels do I need in Joliet?
About 21 panels for an average home. Joliet roofs get 1,538 usable sun hours a year, so each 400W panel produces roughly 523 kWh annually.
Is solar worth it in Joliet?
At 16.3¢/kWh and 1,538 sun hours, a typical system pays for itself in about 9.5 years and returns roughly $27,437 over 25 years. That is a solid return.
How much do solar panels cost in Joliet?
A 8.4 kW system costs about $23,940 before incentives and $16,758 after the 30% federal tax credit. Prices vary by installer, roof complexity and equipment.
Worth reading before you buy
Estimates only, generated 2026-08-22 from Google Solar API rooftop samples and average Illinois electricity rates. Not a quote and not financial advice. Your roof, usage, utility plan and local incentives will change these numbers — get real quotes before buying.