Yes, South Carolina does give a 25% credit for the purchase of solar energy panels for your home.
The credit is found under South Carolina Deductions and Credits. It is an Other Non-Refundable Credit. Solar Energy Credit.
To claim this credit you must mail your South Carolina return along with form Form SC SCH TC-38 and a certification from the manufacturer. If you have already mailed in this form and received approval, you can apply the credit to this year's tax return without having to re-send the forms. I've attached the SC Sch TC-38: http://www.energy.sc.gov/files/view/TC38_2016.pdf
"Cut the cost of installing solar on your home by a quarter with South Carolina’s state tax credit for solar energy. Residents of the Palmetto State can claim 25 percent of their solar costs as a tax credit – and if you don’t pay enough in taxes to get the full value of the credit in one year, it carries over for up to 10 years."
[From: https://www.energysage.com/solar-panels/solar-rebates-incentives/sc/]
