Solar panels in Joliet: what they cost and what they make
A typical Joliet home needs 16 solar panels. They would make about 8,558 kWh a year and cost $17k to $25k before incentives. At today's electricity prices they pay for themselves in about 19.9 yrs.
See panels on your own Joliet roof
Type your address. You get your roof from above, the panels that fit, a month-by-month forecast and a battery test. No phone number.
What solar costs in Joliet
At $3.00 a watt, the median price cash buyers pay nationally, a 6.7 kW system costs about $20,100. Quotes in Joliet will usually fall between $16,750 and $25,125. Complex roofs, main-panel upgrades and financing push prices up.
The 30% federal tax credit no longer applies to systems homeowners buy. This estimate includes no state or utility incentives; check with your utility before you buy.
The number that decides whether solar pays in Joliet is what your utility pays for the power you send back. Illinois ended full retail net metering for new systems on Jan 1, 2025 (supply-only netting); a $300/kW DG rebate applies. Under full payback is about 12.1 yrs. Under net billing it is about 19.9 yrs, because only the ~42% of solar a typical home uses as it is made saves the full retail price.
Cash purchase, prices rising 2.5% a year, panels losing 0.5% a year, $25/kW a year for upkeep. No federal credit for homeowner-owned systems.
Every way to pay for a 6.7 kW system in Joliet
Change any number →| Way to pay | Day one | Monthly payment | Monthly net, year 1 | Ahead after 25 years |
|---|---|---|---|---|
| Pay cash Full price on install day | $20,100 | $0 | +$67 | $7,000 |
| Credit-union loan 8% APR, 20 years, no dealer fee | $0 | $168 | −$101 | −$13k |
| “1.99%” solar loan 1.99% APR, 25 years, 25% dealer fee | $0 | $106 | −$39 | −$4,900 |
| Lease $70/mo, +2.9%/yr | $0 | $70 | +$11 | $1,000 |
| Power purchase (PPA) 9.7¢/kWh, +2.9%/yr | $0 | $69 | +$12 | $3,300 |
Under net billing, the usual rule for new customers here, at 19.2¢/kWh rising 2.5% a year. The “1.99%” loan’s $5,025 dealer fee is included in its payments. Lease and PPA prices are typical offers, not quotes.
How much sunshine Joliet gets
kWh per kW, 25° southJul is the best month for solar in Joliet, and Dec the weakest: a Dec day makes 42% of a Jul day. A 6 kW system would make about 355 kWh in Dec and 847 kWh in Jul.
On June 21 the sun rises at 5:18 am and sets at 8:30 pm, 15 hours 11 minutes of daylight. On December 21 it is up from 7:16 am to 4:25 pm, just 9 hours 10 minutes.
Peak sun hours in Joliet, month by month
| Month | Flat ground | Panels at 36° | kWh per kW |
|---|---|---|---|
| Jan | 1.7 | 2.8 | 66 |
| Feb | 2.6 | 3.8 | 82 |
| Mar | 3.6 | 4.5 | 111 |
| Apr | 4.7 | 5.1 | 124 |
| May | 5.4 | 5.2 | 131 |
| Jun | 6.1 | 5.6 | 135 |
| Jul | 6.2 | 5.8 | 141 |
| Aug | 5.4 | 5.5 | 132 |
| Sep | 4.5 | 5.4 | 121 |
| Oct | 3.0 | 4.2 | 98 |
| Nov | 2.0 | 3.3 | 73 |
| Dec | 1.4 | 2.5 | 59 |
| Year | 3.9 | 4.5 | 1,273 |
A peak sun hour is one hour of sunlight at 1,000 W per m². Why sites disagree.
The best angle and direction for panels in Joliet
| Roof faces (6/12 pitch) | Output vs south | kWh per kW |
|---|---|---|
| South | 100% | 1,273 |
| Southeast | 95% | 1,209 |
| Southwest | 95% | 1,209 |
| East | 83% | 1,057 |
| West | 83% | 1,057 |
| North | 61% | 777 |
Face panels south and tilt them 36° for the most energy over a year. East and west roofs keep about 83% of that. A north-facing roof keeps 61%, which is rarely worth the money. Try other angles.
Where the sun goes over Joliet
The noon sun is lower in winter, which is why the best winter tilt (64°) is steeper than the best summer tilt (12°).
Joliet's homes
Joliet has 51,055 households. 73.7% own their home, and 36,054 of those owners live in single-family houses, the kind of home that usually gets rooftop solar.
The median home here was built in 1985. Many roofs that age are due for replacement. Replace the roof first, then add solar: taking panels off and putting them back later costs thousands.
12.1% of homes heat with electricity and 86.1% with gas. If you switch to a heat pump or an electric car, plan for more panels or leave room on the roof.
Source: U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates.
If the power goes out in Joliet
Solar panels alone shut off in a blackout. Add a battery and they keep going. One Tesla Powerwall 3 (13.5 kWh) running a fridge, freezer, furnace fan, lights, Wi-Fi, TV and microwave (6.9 kWh a day):
Change the appliances, the battery and the weather in the battery calculator.
Questions people ask about solar in Joliet
How much do solar panels cost in Joliet?
A 6.7 kW system — enough for the average Illinois home — costs about $16,750 to $25,125 before incentives, based on $2.50–$3.75 per watt. The 30% federal credit no longer applies to systems homeowners buy.
How many solar panels does a house in Joliet need?
About 16 panels of 420 watts for a home using 693 kWh a month, the Illinois average. Each kilowatt of panels here makes about 1,273 kWh a year on a south-facing roof.
Is solar worth it in Joliet?
Over 25 years, solar power here costs about 12.1¢ per kWh, against 19.2¢ from the grid today. Payback is about 12.1 yrs if your utility credits exported power at the full retail rate, and 19.9 yrs if it pays about 30% of retail. Most new customers in Illinois are on the lower rate.
How many peak sun hours does Joliet get?
4.5 a day on panels tilted to 36°, and 3.9 on flat ground. The best month is Jul; the weakest is Dec.
What is the best angle for solar panels in Joliet?
36° for the most energy over a year, facing south. 64° is best in winter and 12° in summer. On a normal pitched roof, anything within 15° of 36° gives you about 95% of the maximum.
How long would a home battery last in a Joliet power outage?
A Tesla Powerwall 3 running a fridge, freezer, furnace fan, lights, Wi-Fi, TV and microwave (6.9 kWh a day) lasts about 43 hours with no sun. With 7 kW of solar to recharge it, it gets through a three-day outage even in overcast January.
Solar near Joliet
| City | Miles | kWh per kW | Sun hours |
|---|---|---|---|
| Plainfield, IL | 8 | 1,294 | 4.5 |
| Bolingbrook, IL | 12 | 1,290 | 4.5 |
| Naperville, IL | 16 | 1,291 | 4.5 |
| Orland Park, IL | 16 | 1,283 | 4.4 |
| Tinley Park, IL | 18 | 1,282 | 4.4 |
Joliet shares a weather-data neighbourhood with Aurora; their sunshine numbers differ by less than our data can resolve. Housing, prices and outage figures are specific to Joliet.
Cities with the same sunshine as Joliet
These far-away cities get almost exactly as much solar energy per panel.
- New Brunswick, NJ 1,294 kWh per kW
- Missoula, MT 1,295 kWh per kW
- Boston, MA 1,297 kWh per kW
Snow: NASA records about 16 cm of snow on the ground here in an average January. Covered panels make little until it slides off, and these figures (like PVWatts') don't subtract that.
Sources: NASA POWER 2001–2020 monthly climatology (grid cell 29 km from Joliet's Census point), our PV model (within 1.6% of NLR PVWatts® on average), U.S. EIA prices and use, U.S. Census 2025 population estimates and ACS 2020–2024. Estimates for an average home, not a site survey. How we calculate.