Replace a tired roof before the array, not after
Panels outlast most roof coverings. If yours is within a few years of the end of its life, replace it first. Removing and reinstalling an array to get at the roof underneath is a cost with no offsetting benefit whatsoever, and it is entirely avoidable while you are still quoting.
Ask for a condition assessment rather than an age estimate, and consider getting it from a roofer rather than only from the company selling you solar. A roofer has no stake in the array going up this month.
Ask how many layers of covering are present and what the structure underneath is, and whether anything needs reinforcement to carry the array. An installer who has not been on the roof cannot answer those questions.
If the roof does need work, coordinating both jobs is usually cheaper and less disruptive than doing them years apart. Ask the roofer and the installer to speak to each other about sequencing and about how the mounting will interact with the new covering.
How it attaches, and who stands behind it
Ask how mounting penetrations are flashed and sealed, and what method the roofing manufacturer approves for your covering type. If the roof is still under a manufacturer or builder warranty, establish the position before work begins rather than during a future claim.
Ask what the workmanship warranty covers on roof penetrations specifically, for how long, and who honours it. This is the warranty that matters most and the one people read least, because the failure it covers arrives years after everyone has stopped thinking about the installation.
Establish who honours each of the other warranties too. Panels, inverter and workmanship are commonly covered by three different parties on three different terms, and a company that has left the market cannot support a workmanship warranty however well drafted.
Get equipment specified by manufacturer and model number rather than by description. Model numbers are what make a warranty enforceable later and what let you compare two quotes on the same basis rather than on adjectives.
What the system earns, and the two limits on it
South Carolina no longer offers simple one-to-one retail net metering to new solar homes. Solar choice metering rates became available to consumers applying for new service on or after June 1, 2021 and are available for ten years, with the value of exported power tied to time-of-use rates.
Existing customers who enrolled earlier continue to receive one-to-one compensation into 2029 depending on when they joined, so treat a neighbour's payback figure as describing a different arrangement.
The state tax credit is the other half of the return. It is 25 percent of total system cost up to $35,000 on Form TC-38, but released at only $3,500 a year or 50 percent of your state tax liability, whichever is less, with a 10 year carryforward.
Ask a tax advisor how much of that you would realistically use, and ask any installer to show the credit year by year as it would actually be received rather than as a single deduction from the price.
The state credit, and how much of it you will actually use
South Carolina offers a state income tax credit of 25 percent of the total system cost, up to a total credit of $35,000, claimed on Form TC-38. That headline is genuinely generous and it is the main reason solar still works here now that the federal residential credit has gone.
The limit that decides what it is worth to you is annual. A taxpayer may use only $3,500 of the credit in a year, or 50 percent of their state tax liability, whichever is less, and the excess for each facility can be carried forward for 10 years.
So a household with modest South Carolina tax liability may not use the whole credit within the carryforward period. That is not a reason to avoid it, but the number in a sales presentation and the number you receive can differ substantially. Ask a tax advisor how much you would realistically realise given your own liability.
The 30 percent federal Residential Clean Energy Credit under Section 25D expired for property placed in service after December 31, 2025, so a cash or loan purchase now receives no federal credit. Section 48E survives at 30 percent for third-party owners under leases and power purchase agreements, so ask any such provider what they claim and what of that value reaches you.