Peak sun hours in Wisconsin
Wisconsin averages 4 peak sun hours a day across the year, 40th of the 50 states. At that figure a 400-watt panel produces about 1.23 kWh a day after real-world losses, and covering the 900 kWh average US bill takes about 25 panels. Milwaukee, the state's biggest city, sits at 4 hours, close to the statewide figure, though microclimates and elevation still move the local number.
modest sun: 4 of a possible ~6.5 hours
Panel counts for Wisconsin bills
Computed at Wisconsin's 4 hours with 400W panels and the 0.77 derate; the US-average column shows what the same bill takes at 4.5 hours, so you can see what your state's sun is worth in hardware.
| Monthly usage | Wisconsin | System size | US average |
|---|---|---|---|
| 500 kWh/mo | 14 panels | 5.6 kW | 12 panels |
| 750 kWh/mo | 21 panels | 8.4 kW | 18 panels |
| 900 kWh/mo | 25 panels | 10 kW | 22 panels |
| 1,000 kWh/mo | 27 panels | 10.8 kW | 24 panels |
| 1,500 kWh/mo | 41 panels | 16.4 kW | 36 panels |
| 2,000 kWh/mo | 54 panels | 21.6 kW | 48 panels |
What 4 hours means in practice
Wisconsin runs 11% below the national solar average, 40th of 50 at 4 hours. That is workable sun, not bad sun: the 900 kWh bill takes 25 panels here versus 22 nationally, 3 more. Germany built the world's densest solar fleet on worse. What matters at this tier is the winter-summer swing; annual averages hide December, and December is where off-grid plans in Wisconsin go wrong. Grid-tied with net metering, the year evens out.
For a location-exact figure, run your address through NREL's free PVWatts; it uses measured weather for your grid cell and will also model roof tilt and direction, which statewide numbers cannot. Then compare its annual kWh against a quote's promise before you sign anything.
Questions people ask
How many solar panels do I need in Wisconsin?
About 25 400-watt panels (10 kW) for the 900 kWh a month an average US home uses, at Wisconsin's 4 peak sun hours. Your bill is the variable that matters: the table on this page covers 500 to 2,000 kWh, and the calculator takes any figure.
Is 4 peak sun hours good for solar?
It is below the 4.5-hour national average but far from disqualifying. Panel counts run about 13% higher here for the same bill, and the December-January trough deserves respect in any off-grid plan. Grid-tied systems ride through it on net metering.
Do peak sun hours change with the seasons in Wisconsin?
Yes, everywhere: the figure on this page is the annual average of a curve that peaks in June and bottoms out in December. At Wisconsin’s latitude and cloud cover the winter trough is deep, often a third of the summer figure or less. Grid-tied homes bank summer overproduction as credit; off-grid designs must size for the trough, not the average.