Add panels. Keep your NEM rate.
What a legacy NEM rate is worth, and how to add panels without losing it.
If your system got permission to operate under NEM 1.0 or 2.0, you keep that rate for 20 years from that date. Adding panels the ordinary way can end it early. Kilo designs expansions meant to keep the original agreement grandfathered, within your utility’s rules and subject to its approval.
How NEM grandfathering works.
What NEM is
Net energy metering sets what your exported solar is worth. NEM 1.0 and 2.0 credit exports near the retail rate, which is why older systems often zero out a bill. The Net Billing Tariff, called NEM 3.0, replaced it for new systems on April 15, 2023 and pays a fraction of that.
What grandfathering is worth
Your tariff runs 20 years from the permission-to-operate date. Over a system’s life, the gap between a grandfathered rate and today’s tariff adds up. It does not freeze fixed charges, but it protects what your exports earn.
How people lose it
An expansion filed as a simple size increase can move the whole system onto the current tariff. A small addition filed the wrong way can cost the whole system its rate, which is why add-on work needs a design, not just more panels.
How we expand without breaking it
Depending on your utility’s tariff, new capacity can sometimes be set up separately from the original system, for example metered under its own tariff or designed not to export. Which options exist, and whether yours qualifies, is the utility’s call. We confirm both before any work is agreed.
The program keeps shrinking
NEM 3.0 pays far less for exports than NEM 2.0 did. In 2025, AB 942 as introduced would have ended legacy agreements when a home sells; that provision was removed, but the direction is clear. Savings that depend on the export rate depend on policy holding still.
The protection you own outright
Nobody can legislate away the power you use in your own home. A battery moves your solar from exports to self-consumption: charge at midday, run the house when rates spike, keep the lights on in an outage. It is what keeps a bill offset after a legacy agreement expires.
Updated November 4, 2026
Rules vary by utility and project; we work with all of California’s major utilities. References: PG&E NEM2 tariff (opens in a new tab), SCE net energy metering (opens in a new tab), SDG&E net energy metering (opens in a new tab), and the CPUC net-metering overview (opens in a new tab). Educational overview, not legal or financial advice.
What we check
- Your utility and current tariff
- Permission-to-operate date
- Current capacity and the planned addition
- Interconnection requirements
Key terms.
- NEM 1.0 and NEM 2.0
- California’s earlier net metering tariffs. Exports earned close to the retail rate. Closed to new customers; existing agreements run 20 years from permission to operate.
- Net Billing Tariff (NEM 3.0)
- The tariff for systems interconnected since April 15, 2023. Exports earn a much lower avoided-cost value, which is why storage matters on NEM 3.0.
- Grandfathering
- Keeping the tariff you enrolled under after the program changes. It follows the system’s permission-to-operate date, not the homeowner.
- Permission to operate (PTO)
- The utility’s written authorization to switch a system on. The PTO date starts the 20-year legacy period.
- Non-export addition
- New capacity designed so it does not send power to the grid. Whether it affects the original agreement depends on the utility’s rules.
- Multi-tariff arrangement
- Where a utility allows it, new capacity on the current tariff alongside an original array that keeps its legacy status, each credited separately.
Net-metering questions.
Will adding panels kick me off my current net-metering plan?
No, not when the expansion is designed within your utility’s rules, subject to the utility’s approval. Protecting that rate can be worth more than the new panels.
What does NEM grandfathering mean?
Homeowners already enrolled when the rules changed kept the deal they signed up under: NEM 1.0 or 2.0 rates for 20 years from permission to operate. Those programs credit exports at far better rates than today’s Net Billing Tariff.
Is net metering going away in California?
For new customers, it already has. The Net Billing Tariff replaced NEM 2.0 on April 15, 2023, and existing agreements keep their rate for 20 years from permission to operate. A battery protects you after that.
Is a battery the same as adding panels?
No. Batteries and added panels have different interconnection rules. We confirm your utility’s program rules before the design is final so your tariff stays in place.
Will the new equipment have the same warranty?
Your original equipment keeps its manufacturer warranty, and the new equipment carries its own. The installer documents where one system ends and the other begins.
Is a battery worth it on a legacy NEM rate?
Yes for most homes. On time-of-use billing you save by using stored power when rates spike, and you get outage backup. If the math doesn’t work for your home, we tell you.