Peak sun hours in South Dakota
South Dakota averages 4.6 peak sun hours a day across the year, 23rd of the 50 states. At that figure a 400-watt panel produces about 1.42 kWh a day after real-world losses, and covering the 900 kWh average US bill takes about 21 panels. Sioux Falls, the state's biggest city, sits at 4.6 hours, close enough to the statewide figure to use either, though elevation and distance from water still move the number street by street.
solid mid-pack sun: 4.6 of a possible ~6.5 hours
Panel counts for South Dakota bills
Computed at South Dakota's 4.6 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 | South Dakota | System size | US average |
|---|---|---|---|
| 500 kWh/mo | 12 panels | 4.8 kW | 12 panels |
| 750 kWh/mo | 18 panels | 7.2 kW | 18 panels |
| 900 kWh/mo | 21 panels | 8.4 kW | 22 panels |
| 1,000 kWh/mo | 24 panels | 9.6 kW | 24 panels |
| 1,500 kWh/mo | 35 panels | 14 kW | 36 panels |
| 2,000 kWh/mo | 47 panels | 18.8 kW | 48 panels |
What 4.6 hours means in practice
South Dakota is mid-pack American sun: 23rd of 50 at 4.6 peak sun hours, within 2% of the national average. The 900 kWh average bill lands at 21 panels against 22 nationally. At this tier the resource neither makes nor breaks the project, which is what the rate and the seasonal spread below are for.
How a South Dakota year is shaped
The 4.6-hour figure is an annual average, and no month is average. These are the twelve monthly means for South Dakota from NASA's 2001-2020 solar climatology, each as a share of the state's own annual mean, with that share applied to the 4.6-hour planning figure. July and December are marked.
| Month | Share of the annual average | Peak sun hours (est.) |
|---|---|---|
| January | 47% | 2.2 |
| February | 71% | 3.3 |
| March | 94% | 4.3 |
| April | 119% | 5.5 |
| May | 141% | 6.5 |
| June | 159% | 7.3 |
| July | 164% | 7.5 |
| August | 138% | 6.4 |
| September | 108% | 5.0 |
| October | 72% | 3.3 |
| November | 49% | 2.2 |
| December | 37% | 1.7 |
Best to worst in South Dakota is 4.4 to one: July at 164% of the annual average, December at 37%, 7.5 hours a day against 1.7. Four months hold 50% of the year's light. A grid-tied array absorbs that on net metering; a battery bank has to be sized for the December end of it.
Half the South Dakota calendar sits above the annual average and half below: April through September are the six months that beat it, carrying 69% of the year's light. April is already worth about 5.5 hours a day, so the productive half of the year starts earlier than most people expect.
Bills here run above the national line. The average South Dakota household used 994 kWh a month in 2024 against 863 nationally, 15% more, and covering that across a year takes 24 panels at South Dakota's sun. Covering it from December sun alone would take 63, 2.6 times the array, which is the number that decides whether a battery plan is realistic.
South Dakota is more uniform than most. The 20 grid cells sampled across the state span 10%, sunniest in the southwest and dimmest in the northeast, which scales to about 4.8 hours against 4.4. Enough to notice on a production estimate, not enough to change which system you buy. Sioux Falls sits inside that band, not at the edge of it.
What that sun is worth on a South Dakota bill
| EIA, 2024 residential averages | South Dakota | United States |
|---|---|---|
| Average home's monthly use | 994 kWh | 863 kWh |
| Price per kilowatt-hour | 12.86¢ | 16.48¢ |
| Average monthly bill | $127.81 | $142.26 |
| One 400W panel, a year's output | 517 kWh | 506 kWh |
| What that output displaces | $67 | $83 |
Cheap power cuts the other way. South Dakota residential electricity averaged 12.86¢ a kilowatt-hour in 2024, 22% under the national 16.48¢ and 13th cheapest in the country, so the same panel that offsets $83 a year at national rates offsets about $67 here. Nothing is wrong with the sun. There is just less money in each kilowatt-hour it makes.
Here the sun ranking flatters South Dakota. 23rd of fifty for sunlight, but only 38th for what a panel earns in a year, a drop of 15 places, and the reason is entirely the price of the electricity being replaced. Alabama gets the same sun (4.6 hours to South Dakota's 4.6) and pays 15.18¢ against 12.86¢, so one panel is worth about $12 less a year in South Dakota than in Alabama.
Two warnings on those dollar figures. They are displaced electricity and nothing else: no install cost, no incentive, no financing, and no assumption about how your utility settles a surplus, which is the single biggest unknown in the sum. And a state average hides the utility you are actually on; 12.86¢ is every South Dakota residential customer averaged together, and neighbouring territories can differ by more than the gap between two states in the ranking.
Getting a number for your address
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 South Dakota?
About 21 400-watt panels (8.4 kW) for the 900 kWh a month an average US home uses, at South Dakota's 4.6 peak sun hours. For the average South Dakota home specifically, which EIA measured at 994 kWh a month in 2024, it is 24. Your own bill is the variable that matters, and the calculator takes any figure.
Is 4.6 peak sun hours good for solar?
It is solidly workable. South Dakota sits near the national average of 4.5 hours, so panel counts here match the US-typical figures, and project economics turn on your utility's rates and net-metering terms rather than on the sun.
How much is one solar panel worth a year in South Dakota?
About $67. One 400-watt panel at South Dakota's 4.6 peak sun hours makes roughly 517 kWh a year after the 0.77 derate, and South Dakota residential electricity averaged 12.86¢ a kilowatt-hour in 2024 (EIA), which puts South Dakota 38th of the 50 states on this measure against 23rd on sunlight alone. That figure is displaced electricity only. It says nothing about install cost, incentives, or how your utility settles a surplus.
Do peak sun hours change with the seasons in South Dakota?
Yes, by a factor of 4.4 here. NASA's 2001-2020 climatology puts South Dakota's July at 164% of the annual average and December at 37%, so the 4.6-hour figure on this page is the midpoint of a curve running from roughly 7.5 hours a day down to 1.7. Grid-tied homes bank the summer surplus as credit; off-grid designs have to size for the trough, and in South Dakota that means 63 panels for an average local bill instead of 24.