South Carolina pays about 14.5¢ per kilowatt-hour for residential electricity and receives about 4.9 kWh per square metre per day of sunlight — 29th and 14th respectively among the 50 states and DC tracked here. Those two numbers set the ceiling on what rooftop solar returns in South Carolina, and they point in opposite directions.
Where South Carolina sits against the rest of the country
South Carolina is 0.3¢/kWh below the median residential rate across this dataset (14.8¢/kWh) and 0.3 kWh/m²/day above the median insolation (4.6 kWh/m²/day). Under this site's standard assumptions, that combination puts South Carolina 25th of 51 for modeled payback speed, at 13.5 years against a dataset median of 13.5 years.
What actually drives payback in South Carolina
South Carolina is sunlight-led: 14th for insolation but only 29th for electricity price. Swap South Carolina's sunlight for the dataset median and payback moves to 14.2 years (0.7 years of swing). Swap its electricity rate instead and payback moves to 13.3 years (0.2 years of swing). The sunlight swap is the larger of the two, so how much sun the roof gets is the input deciding the outcome in South Carolina.
State incentives on record
Recorded for South Carolina: 25% state tax credit up to $3,500 per year or 50% of tax liability; net billing replaced full net metering under Energy Freedom Act (Act 62) for new customers.
No federal credit is applied above (Section 25D expired 31 December 2025), and export terms often matter more than the headline rate (net metering guide).
The modeled system, in numbers
At South Carolina's sunlight level a 7 kW array produces roughly 9,765 kWh a year, worth about $1,416 in first-year bill savings at 14.5¢/kWh against an assumed $22,400 installed cost. A ten-year payback at this sunlight level would require a residential rate of about 20.5¢/kWh, which is 6.0¢ above what South Carolina households pay today.
States with comparable economics
South Carolina's closest analogues by modeled payback are Kansas (13.5 years), Illinois (13.5 years), Pennsylvania (13.4 years). They arrive there from different rate and sunlight combinations, so their incentive rows are the useful comparison.
- Kansas — modeled payback 13.5 years
- Illinois — modeled payback 13.5 years
- Pennsylvania — modeled payback 13.4 years