Three or four positions, decided by dates
In Mon Power and Potomac Edison territory, customers who signed up before December 31, 2024 were grandfathered into the previous, more favourable rates for 25 years. Those installing from January 1, 2025 earn 9.3 cents per kWh for excess.
In Appalachian Power territory, full retail one-to-one crediting required an application by March 1, 2026 and, for residential systems, an order of completion by September 1, 2026. Outside that window, generation earns around 12.4 cents per kWh.
So an existing array could be on old Mon Power terms with decades left, on the 9.3 cent arrangement, on Appalachian Power one-to-one crediting, or on the roughly 12.4 cent rate.
Nothing about the equipment tells you which. It is a documented fact on the account, and it is the first thing to establish.
What to establish before you agree a price
Ask the seller for the application, sign-up and interconnection dates with documentation rather than a recollection, and note which utility serves the property.
Ask which crediting arrangement the account is on today, and get that confirmed by the utility rather than by the seller. A tier is only worth something if the account genuinely carries it.
Ask whether the arrangement transfers to a new owner, what has to be done to effect that, and by when. An arrangement that does not survive the transaction is worth nothing to you.
Ask how many years of grandfathering remain, where applicable. A Mon Power system signed up in 2024 has around twenty-three years of the more favourable terms left, which is a specific and substantial number.
The rest of the checks
Ask for production history rather than a production estimate. An installed system has real data, and real data is worth far more than a model.
Ask for the equipment make and model and what warranty remains on the panels, the inverter and the workmanship. Inverters typically have shorter lives than panels.
Ask about the roof underneath. A system on a roof near the end of its life implies a removal and reinstallation cost that belongs in your purchase arithmetic.
Ask whether the system is owned outright, financed, or on a lease or power purchase agreement. Those are entirely different things to inherit, and only the first is straightforwardly an asset.
Building the number from the meter and the credit
For a new system, the 30 percent federal Residential Clean Energy Credit under Section 25D expired for property placed in service after December 31, 2025, and West Virginia has no state solar tax credit.
Section 48E survives at 30 percent for third-party owners under leases and power purchase agreements.
A new system receives retail value for what you consume as it is generated, and credited generation at the rate applicable to your utility and tier.
For an existing system, start with the dates and whether the arrangement transfers. That single fact changes what the array is worth to you more than anything else about it.