Net metering & solar export credits

The three dates that reset South Carolina solar

One-for-one net metering closed to new applicants on 1 June 2021. Full-retail grandfathering for customers who applied before 16 May 2019 ran out on 31 December 2025. And the 30% federal residential credit expired for systems placed in service on or after 1 January 2026. Together those reset the arithmetic of a South Carolina system, and a great deal of the advice still online predates all three.

What survived is the 25% South Carolina state credit on Form TC-38, capped at $3,500 in any one tax year and at 50% of your annual state liability, with a ten-year carry-forward. Because of that annual cap most residential systems are claimed across two or three returns, so it behaves like a stream rather than a discount at purchase. Confirm your own eligibility with a tax professional.

Grandfathered status generally attaches to the installation and its interconnection date rather than to the homeowner. If you are buying a house with an existing array, what applies to that system is a question worth asking before closing rather than after.

There is no single South Carolina export rate

South Carolina is served by investor-owned utilities, the state-owned Santee Cooper, and member-owned cooperatives, and each sets terms through a different mechanism. Dominion Energy South Carolina and the two Duke utilities sit inside the state’s net energy metering chapter and under Public Service Commission ratemaking, so their terms are published and reviewable. Santee Cooper’s board sets its own. A cooperative board adopts its own policy and reports it to the Office of Regulatory Staff.

Title 58 Chapter 40 governs entities defined as electrical utilities and exempts any serving fewer than one hundred thousand customer accounts, which places electric cooperatives outside it entirely. That is a structural difference, not a detail: the figure quoted on almost every South Carolina solar page is Dominion’s, and it does not apply on a cooperative meter.

In the Charleston metro the point sharpens further, because Dominion and Berkeley Electric territory interleave. Daniel Island, where our office sits, has both, and two houses on the same street can be on different providers with different export terms. We read the provider off a bill rather than inferring it from an address, because here the address genuinely does not tell you.

What a below-retail export credit changes about your system

When exports are credited below the retail rate, a kilowatt-hour used as you generate it is worth the full retail rate you avoid paying, while a kilowatt-hour exported is worth the export credit. The wider that gap, the less sense it makes to oversize an array to bank credits, because the surplus is sold at a discount you cannot recover.

That turns sizing into a question about your usage pattern rather than your roof area. A household at home during daylight, or with electric water heating, a pool pump or an EV charging in the afternoon, converts far more of its generation at the higher value than one that is out from eight to six. It is usually the largest single difference between two otherwise identical homes.

It also makes storage a genuine economic question rather than an upsell. A battery that keeps a kilowatt-hour on site instead of exporting it captures the difference between the two rates every time it cycles, and where that difference is widest the case is strongest. Where it is narrow, we will say the resilience argument has to carry the decision on its own.

The unglamorous version of the same advice costs nothing: move what you can into daylight. Water heating, pool pumps, laundry and EV charging are all flexible, and shifting them converts power at retail value instead of selling it at export value.

What to check on any South Carolina quote

Whether a federal credit has been applied. It should not be, for any system placed in service on or after 1 January 2026, and this is currently the most common and most expensive error on competitor paperwork.

Whether the state credit has been spread across tax years. A quote showing the full 25% as an immediate deduction is showing a cash position you will not have in year one, given the $3,500 annual cap and the 50% liability limit.

Which utility and which export assumption the savings figure is built on. Two quotes for near-identical hardware can differ by tens of thousands over twenty-five years purely on that assumption and the rate-escalation figure behind it, neither of which is usually stated on the front page.

And the production estimate in kilowatt-hours rather than dollars. A kilowatt-hour figure can be checked against your own bill and against the roof; a dollars-saved headline embeds every assumption above and hides all of them.

One more, which almost nobody asks: what happens if production comes in below the estimate, and what the remedy is. An estimate offered without any stated tolerance is a marketing number rather than an engineering one, and the answer tells you how seriously the modelling was done.

If a quote survives all five questions, you are comparing offers. If it does not, you are comparing assumptions, and the cheaper-looking one is frequently just the one with the more optimistic arithmetic behind it.