The 15 kW line, and what sits on either side of it
Residential systems greater than 15 kW AC in Dominion Energy territory are subject to standby charges. The amount depends on the amount of peak power demand used on site, which means it is driven by your household load rather than by the array.
Below that threshold the arrangement is straightforward: Virginia Code Section 56-594 compensates a residential system of not more than 25 kW one-to-one at the retail rate for electricity exported to the grid.
So there are two caps to design against rather than one. The statutory residential ceiling is 25 kW, but in Dominion territory the practical planning threshold for most households is 15 kW AC, because crossing it introduces a recurring charge that a savings projection has to account for.
Ask your installer directly whether the proposed system is above or below 15 kW AC, and if above, ask them to model the standby charge across a full year and to show the same project designed below the threshold. That comparison is the whole decision.
Sizing, and the annual consumption rule
Systems under Virginia Code Section 56-594 are typically sized not to exceed the customer's annual consumption. That makes your last twelve months of electricity bills the right starting point for a design rather than a generic household profile.
Ask every installer to work from your actual bills and to show the calculation. It is the single most effective way to compare two quotes on the same basis, and it is also how you find out whether a proposal was designed for your household or for your roof area.
If your consumption is about to change, say so early. An electric vehicle, a heat pump replacing gas heating, a pool pump or an additional occupant all move the number, and designing for a load you know is coming is easier and cheaper than expanding later.
Net metering provisions have been under revision, so confirm the current terms with your utility before a design is finalised rather than relying on a guide, including this one.
The second income stream
The Virginia Clean Economy Act set a Renewable Portfolio Standard requiring Dominion Energy to reach 100 percent renewable electricity by 2045, and at least 1 percent of Dominion's requirement each year must come from in-state distributed generation resources smaller than 1 MW. That carve-out is what creates demand for certificates from rooftop systems like yours.
To sell them you register your system and work with a broker. Certificates are eligible to be sold for 5 years, and prices move with the market rather than being set administratively.
So treat any SREC income in a savings projection as a forecast rather than a payment. Ask what price the model assumes, where that figure came from, and ask to see the projection with SREC income removed entirely.
That last figure is your floor: what the system is worth on net metering alone. A project that only works on optimistic certificate prices is a more fragile purchase than it looks.
Ask your locality about the property tax exemption
Virginia Code Section 58.1-3661 allows any county, city or town to exempt or partially exempt certified solar energy equipment from local property taxes by adopting an ordinance. This is the detail most often got wrong about Virginia solar, because it is a local option rather than a statewide rule.
So a guide that tells you Virginia exempts solar from property tax is only right where the locality has actually adopted an ordinance, and it may be a partial exemption rather than a full one. Ask your county or city commissioner of the revenue directly whether an ordinance is in place and what it covers.
Where adopted, the exemption is effective beginning in the next succeeding tax year and is permitted for a term of not less than five years. Ask what term applies locally, since that is the horizon you can actually count on.
On the federal side, the 30 percent 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, and confirm with a tax advisor.