When rooftop is the right call
You own the home, plan to stay 8+ years, have a south- or west-facing roof in decent condition, pay 15¢/kWh or more, and your state has net metering or a fair export rate. Even without the federal credit, a 7 kW system in California or the Northeast returns its cost comfortably within its warranty period, and it is the only option that can cover a whole home's usage.
When plug-in is the right call
You rent, own a condo, have a shaded or aging roof, are not sure you will stay, or simply want to spend under $1,000 to see what solar does for you. It also makes sense as a first step: the kit keeps working if you later go rooftop (check your interconnection terms), and the habit of watching production tends to cut consumption too.
The 2026 twist: no federal credit
The residential clean energy credit is gone for anything placed in service after December 31, 2025. For rooftop that removes $6,000 to $12,000 of support and pushes payback out by years. Plug-in kits were never meaningfully helped by the credit (most never qualified), so their economics are unchanged, which is one reason interest spiked in 2026. Third-party-owned systems (leases, PPAs) can still use commercial credits, so expect more of those offers; read the escalator clause before signing.
Can you combine them?
Technically yes. Legally it depends on your interconnection agreement, which typically lists the generating equipment you are allowed to connect. In a state with a plug-in law, a certified kit under the cap is exempt from interconnection rules on its own, but the combined system may still exceed what your net-metering tariff allows. Ask your utility before adding a kit to a rooftop system.
Run both scenarios with your own rate in the calculator, then check your state's rules.