Solar panels in Janesville: what they cost and what they make
A typical Janesville home needs 15 solar panels. They would make about 8,181 kWh a year and cost $16k to $24k before incentives. At today's electricity prices they pay for themselves in about 12.0 yrs.
See panels on your own Janesville 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 Janesville
At $3.00 a watt, the median price cash buyers pay nationally, a 6.3 kW system costs about $18,900. Quotes in Janesville will usually fall between $15,750 and $23,625. 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 Janesville is what your utility pays for the power you send back. Under full payback is about 12.0 yrs. Under net billing it is about 19.9 yrs, because only the ~41% 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 6.3 kW system in Janesville
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 | $18,900 | $0 | +$116 | $27k |
| Credit-union loan 8% APR, 20 years, no dealer fee | $0 | $158 | −$42 | $7,800 |
| “1.99%” solar loan 1.99% APR, 25 years, 25% dealer fee | $0 | $100 | +$16 | $16k |
| Lease $110/mo, +2.9%/yr | $0 | $110 | +$20 | $2,200 |
| Power purchase (PPA) 16.2¢/kWh, +2.9%/yr | $0 | $110 | +$19 | $5,100 |
Under net metering, at 19.0¢/kWh rising 2.5% a year. The “1.99%” loan’s $4,725 dealer fee is included in its payments. Lease and PPA prices are typical offers, not quotes.
How much sunshine Janesville gets
kWh per kW, 25° southJul is the best month for solar in Janesville, and Dec the weakest: a Dec day makes 41% of a Jul day. A 6 kW system would make about 356 kWh in Dec and 862 kWh in Jul.
On June 21 the sun rises at 5:18 am and sets at 8:37 pm, 15 hours 19 minutes of daylight. On December 21 it is up from 7:23 am to 4:25 pm, just 9 hours 2 minutes.
Peak sun hours in Janesville, month by month
| Month | Flat ground | Panels at 38° | kWh per kW |
|---|---|---|---|
| Jan | 1.7 | 3.1 | 73 |
| Feb | 2.7 | 4.2 | 91 |
| Mar | 3.7 | 4.8 | 117 |
| Apr | 4.7 | 5.1 | 124 |
| May | 5.5 | 5.3 | 135 |
| Jun | 6.1 | 5.6 | 136 |
| Jul | 6.3 | 5.8 | 144 |
| Aug | 5.4 | 5.6 | 134 |
| Sep | 4.3 | 5.3 | 120 |
| Oct | 2.8 | 4.1 | 95 |
| Nov | 1.9 | 3.3 | 72 |
| Dec | 1.4 | 2.6 | 59 |
| Year | 3.9 | 4.6 | 1,298 |
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 Janesville
| Roof faces (6/12 pitch) | Output vs south | kWh per kW |
|---|---|---|
| South | 100% | 1,298 |
| Southeast | 95% | 1,233 |
| Southwest | 95% | 1,233 |
| East | 82% | 1,064 |
| West | 82% | 1,064 |
| North | 60% | 779 |
Face panels south and tilt them 38° for the most energy over a year. East and west roofs keep about 82% of that. A north-facing roof keeps 60%, which is rarely worth the money. Try other angles.
Where the sun goes over Janesville
The noon sun is lower in winter, which is why the best winter tilt (66°) is steeper than the best summer tilt (13°).
Janesville's homes
Janesville has 28,326 households. 67.3% own their home, and 18,168 of those owners live in single-family houses, the kind of home that usually gets rooftop solar.
The median home here was built in 1972. 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.
21.5% of homes heat with electricity and 74.8% 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 Janesville
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 Janesville
How much do solar panels cost in Janesville?
A 6.3 kW system — enough for the average Wisconsin home — costs about $15,750 to $23,625 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 Janesville need?
About 15 panels of 420 watts for a home using 645 kWh a month, the Wisconsin average. Each kilowatt of panels here makes about 1,298 kWh a year on a south-facing roof.
Is solar worth it in Janesville?
Over 25 years, solar power here costs about 11.9¢ per kWh, against 19.0¢ from the grid today. Payback is about 12.0 yrs if your utility credits exported power at the full retail rate, and 19.9 yrs if it pays about 30% of retail.
How many peak sun hours does Janesville get?
4.6 a day on panels tilted to 38°, and 3.9 on flat ground. The best month is Jul; the weakest is Dec.
What is the best angle for solar panels in Janesville?
38° for the most energy over a year, facing south. 66° is best in winter and 13° in summer. On a normal pitched roof, anything within 15° of 38° gives you about 95% of the maximum.
How long would a home battery last in a Janesville 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 Janesville
| City | Miles | kWh per kW | Sun hours |
|---|---|---|---|
| Rockford, IL | 29 | 1,326 | 4.6 |
| Madison, WI | 35 | 1,331 | 4.6 |
| Waukesha, WI | 45 | 1,296 | 4.4 |
| West Allis, WI | 55 | 1,280 | 4.4 |
| Elgin, IL | 57 | 1,298 | 4.5 |
Cities with the same sunshine as Janesville
These far-away cities get almost exactly as much solar energy per panel.
- Providence, RI 1,325 kWh per kW
- Barnstable Town, MA 1,324 kWh per kW
- Knoxville, TN 1,329 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 45 km from Janesville'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.