NEM 3.0 Battery Rules: Do You Need a Battery with Solar in California?

California changed the rules for new rooftop solar in 2023, and one change matters most. The electricity your panels send to the grid is now worth far less than the electricity you buy back. The new policy is officially the Net Billing Tariff, widely known as NEM 3.0. It pays you based on what your exported power is worth to the grid, hour by hour, instead of the retail rate you pay. That price gap is why a battery has gone from a nice upgrade to the heart of almost every new California solar design. This guide covers the current NEM 3.0 battery rules, whether a battery affects older NEM 2.0 accounts, and the payback math with labeled assumptions.

NEM 3 Battery Rules: What Is NEM 3.0?

NEM 3.0 is the nickname for the Net Billing Tariff the California Public Utilities Commission (CPUC) adopted in December 2022 in Decision D.22-12-056. It applies to interconnection applications submitted to PG&E, SCE, or SDG&E on or after April 15, 2023. Applications filed by April 14, 2023 stayed on NEM 2.0.

Under NEM 2.0, a kilowatt-hour you exported earned close to the retail rate. Under NEM 3.0, exports are credited at avoided-cost values set by the CPUC’s Avoided Cost Calculator, which is why the policy is called a billing tariff rather than true net metering. It covers the three big investor-owned utilities; municipal utilities like LADWP and SMUD set their own solar rules and are not bound by the CPUC decision.

The tariff survived its 2026 legal challenge: the state Court of Appeal upheld it in March, and the state Supreme Court declined further review in June.

What Do NEM 3.0 Export Rates Pay Compared to Retail Rates?

Before the tariff, the average export credit was roughly $0.30 per kWh. Under NEM 3.0 it fell to about $0.08, a cut of roughly 75 percent, according to industry analysis of the CPUC proposal.

The Avoided Cost Calculator prices every hour of the year differently, by weekday and weekend, by month, and by utility. Most midday hours, when solar floods the grid, pay only a few cents per kWh. A small number of late summer evening hours, when the grid is strained, can be worth several dollars.

Installer-reported retail rates across PG&E, SCE, and SDG&E run roughly 33 to 46 cents per kWh depending on the utility and time-of-use (TOU) plan, with the 4-9 PM peak the most expensive window. Exporting midday solar for a few cents and buying evening power at 30-plus cents is a bad trade.

Do You Need a Battery Under NEM 3.0?

No law requires a battery; the rule is economic. A battery charges on cheap midday solar and discharges during the expensive 4-9 PM peak, so you stop buying power at the highest rates. Under NEM 3.0 the savings come from the power you use yourself, not the power you sell. Households on municipal utilities with their own net metering rules, or homes that use most power during the day, can often skip it.

Will Adding a Battery Cancel Your NEM 2.0 Grandfathering?

The answer is no. Adding a battery does not move you off NEM 1.0 or NEM 2.0, and it does not shorten your 20-year grandfathering clock. SCE’s NEM FAQ confirms that storage added to an approved NEM generator stays eligible, and the CPUC’s NEM paired storage decisions (D.14-05-033, D.16-04-020, D.19-01-030) were written for exactly this.

The rules that actually matter:

• A battery is not generation. It stores and time-shifts solar energy, so its capacity does not count against the expansion limit. Legacy customers can add up to the greater of 1 kW or 10 percent of the original generating capacity without losing grandfathered status. Go beyond that with new panels and the system moves to NEM 3.0.
• Storage under 10 kW of inverter output takes the simple path, with no extra metering required. Most single-battery homes stay under this threshold. Above 10 kW, discharge capacity is generally limited to 150 percent of the solar system’s capacity, with extra metering or certified operating modes.
• The battery should charge from solar, not the grid. NEM export credits require solar-only charging.
• File the right paperwork. SCE requires the interconnection request as a NEM 1.0/2.0 Expansion application type. Filed incorrectly, the account can be moved to the Solar Billing Plan.

For a NEM 2.0 customer, the payoff is different from a NEM 3.0 customer. Your exports already earn near-retail credit, so the battery’s daily arbitrage is worth less. For you, a battery is mainly backup power plus insurance for the end of your 20-year grandfathering window.

How Does the Payback Math Work With a Battery?

A worked example with labeled assumptions, published by installer Helios Energy Global in September 2026 for a typical SCE household on NEM 3.0:

Assumption	Value
Battery	Tesla Powerwall 3, 13.5 kWh usable
Daily energy shifted (one cycle)	About 11 kWh
Value of midday export given up	About 5 cents per kWh
Peak retail power avoided	About 34 cents per kWh
Net value per shifted kWh	About 29 cents
Annual savings	About $1,150 to $1,250
Installed cost after prepaid lease discount	About $10,150
Simple payback	About 8 to 9 years
With SGIP Equity Resiliency rebate	About 1 to 2 years

Caveats: NEM 2.0 customers get less arbitrage value since their exports already earn near-retail credit, and batteries degrade while rates change, so treat any payback model as an estimate. The CPUC’s own analysis expected about a nine-year payback for standalone solar at $3.30 per watt.

What Battery Incentives Still Exist in California in 2026?

The 30 percent federal residential credit under IRS Section 25D is not available for residential systems placed in service after December 31, 2025, including standalone batteries. Two paths still cut the cost:

• Prepaid lease structures. Some financiers claim the commercial Section 48E credit on a third-party-owned system, pass the savings through as roughly 30 percent off, and transfer ownership to you at the start of year six. Verify the terms before signing.
• SGIP rebates. The CPUC’s Self-Generation Incentive Program (SGIP) pays per kWh of installed storage. General market: roughly $150 to $200 per kWh. Equity (income-qualified): roughly $850 per kWh. Equity Resiliency (high fire-threat districts or qualifying medical needs): roughly $1,000 per kWh, which can cover most or all of a battery’s installed cost. Funding moves in steps and waitlists exist, so check current availability with your installer.

Typical installed battery prices in 2026 run about $11,000 to $16,500 for a standard home battery, with a Tesla Powerwall 3 commonly quoted around $14,500 to $18,500 before incentives.

Who Should Skip the Battery?

A battery is not right for every home. If you are on NEM 2.0 with many grandfathered years left and want bill savings rather than backup, wait. If your municipal utility still pays fairly for exports, or you use most power during the day, a solar-only system sized to daytime use can still pencil. Run the numbers from your actual usage data, not a state average.

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Is a battery legally required under NEM 3.0?

No. But because exported solar earns only a fraction of the retail rate, storing daytime power for the expensive evening peak is where the savings now come from.

How long does NEM 2.0 grandfathering last?

Twenty years from the system’s original interconnection date. The legacy status follows the system, so if you buy a home with grandfathered solar, the remaining years transfer to you. Adding a battery does not reset that clock.

How long are NEM 3.0 export rates locked in?

The decision includes a five-year glide path of ACC Plus adders that lock for nine years from your interconnection date, shrinking by 20 percent each year. Industry guides also report that this nine-year rate lock does not transfer if you sell the home, but that detail is not CPUC-primary verified, so confirm it with your utility.

Did the courts overturn NEM 3.0?

No. The state Court of Appeal upheld it in March 2026 and the state Supreme Court declined review in June 2026, ending the legal challenge.

Can I still get the 30 percent federal tax credit on a battery in 2026?

Not on a purchased residential system. The IRS Section 25D credit is unavailable for property placed in service after December 31, 2025. Third-party-owned systems under a lease or PPA follow different rules.

What are the NEM 3 battery rules for new solar owners?

The NEM 3 battery rules cut export credits to $0.08/kWh, making batteries essential. Under NEM 3 battery rules, a 10-13.5 kWh battery typically pays back in 7-10 years.

Last reviewed: 11 October 2026

Policy-change disclaimer: Utility tariffs and incentive programs change. The rules summarized here reflect sources available on the review date. Verify your tariff, export rates, and rebate availability with your utility or the CPUC before making a purchase decision.

By TheSolarCost Editorial Team

Sources: CPUC Decision D.22-12-056 (via pv-magazine-usa.com coverage); OC Solar, “NEM 3.0 Explained for California Homeowners” (ocsolar.com/resources/guides/nem-3-0-explained); Helios Energy Global, “Add a Battery to Existing Solar in California (2026)” (heliosenergyglobal.com); pv magazine USA, “California Supreme Court declines to hear rooftop solar billing case” (pv-magazine-usa.com/2026/06/10/california-supreme-court-declines-to-hear-rooftop-solar-billing-case); E&E News, “Appeals court upholds California rooftop solar net metering program” (eenews.net); Solar Builder, “California revised NEM 3.0 proposal” (solarbuildermag.com); installer reporting on SGIP tiers (energyscout.org).