Peak sun hours in South Carolina
South Carolina averages 4.8 peak sun hours a day across the year, 16th of the 50 states. At that figure a 400-watt panel produces about 1.48 kWh a day after real-world losses, and covering the 900 kWh average US bill takes about 21 panels. Charleston, the state's biggest city, runs slightly ahead of the statewide figure at 4.9 hours; treat 4.8 as the midpoint of a real spread rather than a local reading.
solid mid-pack sun: 4.8 of a possible ~6.5 hours
Panel counts for South Carolina bills
Computed at South Carolina's 4.8 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 Carolina | System size | US average |
|---|---|---|---|
| 500 kWh/mo | 12 panels | 4.8 kW | 12 panels |
| 750 kWh/mo | 17 panels | 6.8 kW | 18 panels |
| 900 kWh/mo | 21 panels | 8.4 kW | 22 panels |
| 1,000 kWh/mo | 23 panels | 9.2 kW | 24 panels |
| 1,500 kWh/mo | 34 panels | 13.6 kW | 36 panels |
| 2,000 kWh/mo | 45 panels | 18 kW | 48 panels |
What 4.8 hours means in practice
South Carolina is mid-pack American sun: 16th of 50 at 4.8 peak sun hours, within 7% 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 Carolina year is shaped
The 4.8-hour figure is an annual average, and no month is average. These are the twelve monthly means for South Carolina from NASA's 2001-2020 solar climatology, each as a share of the state's own annual mean, with that share applied to the 4.8-hour planning figure. June and December are marked.
| Month | Share of the annual average | Peak sun hours (est.) |
|---|---|---|
| January | 61% | 2.9 |
| February | 75% | 3.6 |
| March | 98% | 4.7 |
| April | 125% | 6.0 |
| May | 135% | 6.5 |
| June | 139% | 6.7 |
| July | 134% | 6.4 |
| August | 121% | 5.8 |
| September | 105% | 5.0 |
| October | 86% | 4.1 |
| November | 67% | 3.2 |
| December | 54% | 2.6 |
South Carolina has a shallow year by American standards, 2.6 to one between June and December, which still returns 54% of the annual average, around 2.6 hours a day. Only 44% of the light lands in the four best months, against 6.7 hours at the June peak. Nothing here is seasonal enough to change how you size a grid-tied array.
Half the South Carolina calendar sits above the annual average and half below: April through September are the six months that beat it, carrying 63% of the year's light. April is already worth about 6.0 hours a day, so the productive half of the year starts earlier than most people expect.
Set that against what South Carolina homes actually draw. EIA measured 1,050 kWh a month for the average household here in 2024, 22% above the US figure, which is 24 panels at the annual average sun. Hold the same house to a December and the count goes to 44, 1.8 times higher. Net metering is what makes the first number the one that matters.
South Carolina is more uniform than most. The 8 grid cells sampled across the state span 6%, sunniest in the south and dimmest in the northwest, which scales to about 4.9 hours against 4.7. Enough to notice on a production estimate, not enough to change which system you buy. Charleston sits inside that band, not at the edge of it.
What that sun is worth on a South Carolina bill
| EIA, 2024 residential averages | South Carolina | United States |
|---|---|---|
| Average home's monthly use | 1,050 kWh | 863 kWh |
| Price per kilowatt-hour | 14.23¢ | 16.48¢ |
| Average monthly bill | $149.51 | $142.26 |
| One 400W panel, a year's output | 540 kWh | 506 kWh |
| What that output displaces | $77 | $83 |
Cheap power cuts the other way. South Carolina residential electricity averaged 14.23¢ a kilowatt-hour in 2024, 14% under the national 16.48¢ and 22nd cheapest in the country, so the same panel that offsets $83 a year at national rates offsets about $77 here. Nothing is wrong with the sun. There is just less money in each kilowatt-hour it makes.
South Carolina ranks 16th of fifty for sun but 26th for what a panel is worth, 10 places lower, because the power it displaces is cheap. Nebraska gets the same sun (4.8 hours to South Carolina's 4.8) and pays 11.53¢ against 14.23¢, so one panel is worth about $15 more a year in South Carolina than in Nebraska.
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; 14.23¢ is every South Carolina 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 Carolina?
About 21 400-watt panels (8.4 kW) for the 900 kWh a month an average US home uses, at South Carolina's 4.8 peak sun hours. For the average South Carolina home specifically, which EIA measured at 1,050 kWh a month in 2024, it is 24. Your own bill is the variable that matters, and the calculator takes any figure.
Is 4.8 peak sun hours good for solar?
It is solidly workable. South Carolina 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 Carolina?
About $77. One 400-watt panel at South Carolina's 4.8 peak sun hours makes roughly 540 kWh a year after the 0.77 derate, and South Carolina residential electricity averaged 14.23¢ a kilowatt-hour in 2024 (EIA), which puts South Carolina 26th of the 50 states on this measure against 16th 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 Carolina?
Yes, by a factor of 2.6 here. NASA's 2001-2020 climatology puts South Carolina's June at 139% of the annual average and December at 54%, so the 4.8-hour figure on this page is the midpoint of a curve running from roughly 6.7 hours a day down to 2.6. Grid-tied homes bank the summer surplus as credit; off-grid designs have to size for the trough, and in South Carolina that means 44 panels for an average local bill instead of 24.