Your roof almost certainly needs a sealed structural design
The North Carolina Office of State Fire Marshal published a statewide uniform requirement of inspection procedures for residential rooftop solar photovoltaic systems. Under it, a North Carolina registered design professional must seal the structural design in four situations: when the weight of the PV system exceeds three pounds per square foot, when the roof has more than one layer of asphalt shingles, when the roofing material is of a type other than asphalt shingles or metal, or when the roof is located in a 140 mph or greater wind zone.
That last trigger is the one that matters here, because coastal North Carolina counties including the Wilmington area fall within design wind speed zones of 140 mph or greater. For most Wilmington homes this is not a possibility to check, it is a requirement to plan for.
So the question to ask every installer is direct: is a sealed structural design by a North Carolina registered design professional included in this price, and if so, whose seal. An installer who works the coast regularly will answer immediately, because every job they do here needs one.
Watch for the other three triggers as well, since they stack. A second layer of asphalt shingles, or a tile or slate roof, brings the same requirement even before wind speed is considered. If you are unsure how many shingle layers your roof carries, that is worth establishing early rather than at inspection.
How this changes the way you compare quotes
Two Wilmington quotes can differ by a meaningful amount purely because one has priced the engineering and the other has not. The cheaper one is not cheaper, it is incomplete, and the difference will appear later as a change order at a point when you have already committed.
Ask each installer to itemise the structural engineering separately rather than folding it into a single figure. Then compare the remaining line items against each other. Without that separation you are comparing a complete project against a partial one and calling the partial one better value.
Ask about mounting and attachment too. A design sealed for a high wind zone will specify attachment points and hardware appropriate to it, and that specification is the reason the seal exists. If an installer describes their mounting approach as the same one they use everywhere in the state, that is worth probing.
Finally, ask what happens if the sealed design comes back requiring more attachment points than assumed. Establish in the contract whether that is priced in or billed as an extra, because on a coastal roof it is a foreseeable outcome rather than an unlucky one.
Roof condition is not a detail here
Panels outlast most roof coverings, so a covering within a few years of replacement should be replaced before the array goes on rather than paying later to remove and reinstall it. That advice holds everywhere, and on the coast the sums involved are larger because reinstallation also means re-engineering the attachment.
Salt air, wind-driven rain and hurricane-season loading are harder on a roof here than inland, so an assessment based on the covering's age alone may be optimistic. Ask for a condition assessment rather than an age estimate.
Get the shingle-layer question answered in the same visit, since more than one layer of asphalt shingles is itself a trigger for a sealed structural design under the state procedure. A roof carrying two layers may be worth stripping back before installation for reasons that go beyond the engineering requirement.
Orientation and shading still drive output and cannot be recovered later with better equipment. A south-facing unshaded plane produces the most, east and west planes produce usefully but give up output, and a north plane rarely repays the hardware. Ask for a shading assessment covering the full year rather than the hour of the site visit.
The utility rules and the federal credit have both moved
Wilmington is served by Duke Energy Progress, and Duke Energy no longer offers legacy flat retail net metering to new residential solar customers. New customers go onto time-differentiated net-metering or bridge rate options, so what your generation is worth now depends on when it happens rather than only on how much of it there is.
Ask your installer which specific rate option they have modelled and to show the same system under the alternatives available to you. Then ask Duke directly which options a new residential solar customer can choose between at your address, and what the differences amount to across a full year rather than a sunny month.
The federal position has changed too. The 30 percent residential tax credit under Section 25D applied through December 31, 2025 and is not available for a purchased home system placed in service after that date. A quote applying it is describing an earlier year. If you take a lease or a power purchase agreement instead of buying, the provider may claim the business version of the credit under Section 48E and reflect part of that value in the rate offered, so ask what they claim and what actually reaches you, and confirm with a tax advisor.
North Carolina excludes most of the added assessed home value of a residential active solar system from property tax, which applies whoever your utility is. Both a building permit and an electrical permit are required from the local authority having jurisdiction, so agree in writing who files each.