The short answer
- If you applied to connect before Apr 15, 2023, you keep NEM 1.0 or 2.0 for 20 years from your interconnection date (CPUC).
- You can grow the system by 10% or 1 kW, whichever is greater, and stay on NEM (Resolution E-5118).
- Adding a battery doesn't by itself end NEM 2.0; ask your installer how it will be metered and connected.
- When you sell, a NEM system keeps its legacy term for the next owner. That's the opposite of net billing.
Why NEM 2.0 is worth keeping
Under NEM 2.0, exports offset your use at close to retail value, netted over the year at your true-up. Under the current net billing tariff, exports earn much lower avoided-cost credits (how net billing works). For most homes, NEM 2.0 is the better deal for as long as it lasts.
Adding panels
A NEM 1.0 or 2.0 system can stay on its tariff after a repair or change if it grows by no more than 10% of the original size or 1 kW, whichever is greater (CPUC Resolution E-5118, citing D.14-03-041). Grow it more, and the addition is metered separately on the current tariff, or the whole system moves to it. SCE customers whose systems were destroyed in a disaster may size the replacement to their new needs and keep their tariff.
Adding a battery
A battery charged only from your solar can be added to a NEM system. Your installer files a new interconnection application for it; ask how the battery will be configured (charging from solar only, or from the grid too) and get written confirmation that your NEM status and anniversary date won't change. See adding a battery to existing solar.
Selling the home
NEM systems keep their legacy term when transferred to a new owner at the same location (implementing D.14-03-041). A 2025 bill that first proposed ending legacy NEM on sale (AB 942) didn't become law with that provision. Under net billing the rule is reversed: the 9-year export-rate lock stays with the customer, not the house (D.22-12-056).
When NEM 2.0 ends
Twenty years after interconnection, you move to the then-current tariff. SDG&E says NEM customers move to the Solar Billing Plan at the end of their legacy period (SDG&E).
Checked against official sources on Oct 1, 2026. Sources are linked in the text. Not legal, tax or financial advice.