If you gathered solar quotes three years ago and gathered them again this summer, the most visible difference is probably that every proposal now includes storage. That is not a sales fashion. It is a response to how utilities credit the power your system sends back to the grid.
Retail Credit, Net Billing, and Everything Between
Under traditional net metering, a kilowatt hour you export is credited at the same retail rate you would have paid to buy one. Exporting at noon and importing at eight in the evening comes out roughly even, which is what made early solar arithmetic so simple.
A growing number of states and utilities have moved away from that. Under net billing or avoided cost structures, exports are credited at a lower value that reflects what the utility would have paid to generate or buy the power, not what it charges you. The gap between those two numbers can be large. In some territories exported power is credited at a small fraction of the retail rate.
Roughly three dozen states plus the District of Columbia have some form of net metering or net billing on the books, but the label matters far less than the specific tariff your utility applies to new interconnections.
Why This Changes the Hardware
When exports are worth close to retail, the grid acts like a costless battery and there is little reason to buy a physical one. When exports are worth a quarter of retail, every kilowatt hour you export instead of using is value left behind.
Storage closes that gap by holding midday production for evening use, which is also when time of use rates are typically at their highest. That is why proposals in low export markets often show storage improving the payback rather than lengthening it, while proposals in full retail credit markets often show the opposite. Neither is universally true, which is exactly why the numbers should be run both ways for your address.
Grandfathering Is the Detail People Miss
Most net metering arrangements apply the rules in effect when the system is interconnected, and hold them for a defined term. That means a pending tariff change in your state is a timing question, not just a policy question. Homeowners in states with open proceedings sometimes find that interconnecting under the current structure locks in terms that would not be available months later.
The reverse is also worth checking. If your utility has already changed its structure, a proposal modeled on the old one will overstate your savings. Ask the installer which tariff the model uses and confirm it against your utility's published rate schedule.
Questions Worth Asking Any Installer
- Which export tariff applies to new interconnections in my utility territory today?
- Is there a pending change, and what is the expected timeline?
- How long are current terms held once the system is interconnected?
- What does the model assume for the value of an exported kilowatt hour?
- How does the payback change if I install without storage?
- What are the interconnection queue times in this territory?
An installer who works in your area every week will have precise answers to all of these. Vagueness on the export rate is a reasonable reason to seek another quote.
Rate Structure Is Now Part of the Purchase
One consequence of these changes is that going solar often means moving onto a different rate plan, usually a time of use plan. That can shift the economics of things unrelated to solar, such as when you run laundry, charge a vehicle, or cool the house. A good proposal will model your actual consumption against the new plan rather than the one you are on now.
It also means the question of system size has changed. Under full retail credit, oversizing was mostly harmless because surplus banked at full value. Under net billing, an oversized array exports more at a low rate and takes longer to pay back. Sizing to consumption has become more important than sizing to roof space.
Putting It Together
The equipment side of residential solar has become fairly standardized. The variable that decides whether a project makes financial sense is local: your retail rate, your export tariff, your state incentives, and your usage pattern. Two neighbors on different utility territories can get honest proposals with payback periods years apart.
Compare several quotes, ask each installer to show the assumptions rather than only the conclusion, and check the interconnection terms yourself. Our related look at what solar payback looks like without the federal credit covers the rest of that math.
If you are weighing up a solar installation, tell us about your home and we will connect you with installers serving your area. It is free to use, with no obligation to hire.