Your panels make power at noon. SDG&E charges you the most at 6pm.

That sentence is the entire reason home batteries exist in San Diego.

A south-facing array in Mira Mesa hits its production peak somewhere around solar noon and is winding down by four in the afternoon. That is exactly when your household starts using power — the AC catches up, the oven goes on, everybody's home, the EV gets plugged in. SDG&E's on-peak period runs 4 p.m. to 9 p.m., every day of the week, and it is priced accordingly.

Under the old net metering rules that mismatch didn't matter much. You banked midday exports at nearly retail value and spent them back in the evening. That arrangement is gone for anyone who interconnected after April 15, 2023. New solar customers are on net billing — the Solar Billing Plan — where exported kilowatt-hours are credited at the CPUC's avoided-cost values, hour by hour, and those values sit well below what you pay to buy power back. Sending energy to the grid at noon and buying it back at 6 p.m. is now a losing trade.

A battery is how you stop making that trade.

What SDG&E actually charges, and why the spread is the whole argument

Here are the current total residential rates on Schedule TOU-DR1, SDG&E's standard residential time-of-use plan, effective August 1, 2026:

In summer, the gap between on-peak and super off-peak is about 31.7 cents a kilowatt-hour. Every kilowatt-hour you shift out of 4–9 p.m. and into a cheaper window is worth roughly that much. That is the arithmetic a battery runs, hundreds of times a month.

Two honest footnotes. First, TOU-DR1 applies a baseline adjustment credit of $0.10702/kWh on usage up to 130% of your baseline allowance, so your effective rate is lower than the table until you exceed it — heavy evening users are the ones the table describes best. Second, these rates change. SDG&E refiles them multiple times a year; the January 2026 summer on-peak rate was $0.69654 and the June 2026 rate was $0.68459. Treat any number on any contractor's website — including this one — as a snapshot, and check the current tariff table before you sign anything.

SDG&E's super off-peak window is now 12 a.m.–6 a.m. and 10 a.m.–2 p.m. on weekdays, and 12 a.m.–2 p.m. on weekends, year-round. The midday portion used to run only in March and April. That expansion matters: it means a battery has a genuinely cheap window to charge from the grid in, on the days your panels can't fill it themselves — winter, marine layer, a week of gray in May.

Sizing to your 4–9 p.m. load, not to a brochure

Most battery quotes in this county are sized to whatever the salesperson's supplier had in the warehouse. That is not sizing. That is inventory.

The only number that matters is how many kilowatt-hours your house actually consumes between 4 p.m. and 9 p.m., separated by season, on your worst days rather than your average ones. A Scripps Ranch house with a heat pump, two EVs, and a pool pump has a completely different evening curve than a 1,400 sq ft Clairemont bungalow with a gas furnace and no AC. Same neighborhood, same roof pitch, batteries that should differ by a factor of three.

Before we quote, we ask you to pull your Green Button hourly data from SDG&E's My Energy Center and send it over. It's free, it takes about five minutes, and it turns the conversation from a guess into a measurement. We look at your evening consumption, your seasonal swing, what your existing array actually produced last year if you have one, and what you're planning to add — an EV, a heat pump water heater, a second AC zone. Then we size to that.

If the data says a battery won't pay for itself at your usage level, we'll tell you. Some houses genuinely don't have enough of an evening load to justify one yet. Come back when you buy the EV.

Backup and bill management are two different products

People walk into this thinking they're buying one thing. They're usually buying one of two, and the difference decides the design.

Bill management means the battery's job is economic: soak up midday solar, discharge across 4–9 p.m., avoid buying at on-peak rates. It cycles daily. It can be sized fairly tightly to your evening load, and it doesn't necessarily need to back up your whole panel.

Backup means the battery's job is to keep things running when the grid is down — a Public Safety Power Shutoff, a transformer failure, a storm. That requires different hardware: an automatic transfer switch or a backup gateway, and usually a critical loads subpanel so the battery isn't trying to carry your entire house. Refrigerator, a few circuits of lighting, internet, a bedroom AC, medical equipment, the garage door. Whole-home backup is possible but it costs materially more, both in battery capacity and in electrical work, and for most San Diego homes it's not the right trade.

The good news is one system can do both. The design just has to be intentional about it — reserve capacity held back for outages is capacity not earning you money on peak shaving, and that reserve percentage is a decision you should make on purpose rather than have made for you at commissioning.

Adding a battery to solar you already own

If you interconnected before April 15, 2023, you're on NEM 1.0 or NEM 2.0, and that tariff is worth protecting. The CPUC allows customer-generators to remain on their legacy tariff for 20 years from their original interconnection date. Nobody should talk you out of it.

You do not have to give it up to add storage. SDG&E's Schedule NEM-ST treats paired energy storage as an addition or enhancement to the existing generating facility, and the schedule's own language preserves the eligible customer-generator's right to remain on the tariff as it existed at their original application, for 20 years from the original year of interconnection. What does put a legacy system at risk is enlarging the generating capacity — adding panels — beyond the allowed threshold. That's a separate decision from adding a battery, and it's one we walk through explicitly before anyone touches a roof.

The practical work is: confirm your existing interconnection agreement and tariff, design the storage addition to stay inside the paired-storage rules, file the interconnection paperwork correctly, and don't guess. We handle that filing. If your situation is unusual — a system you inherited with the house, an installer that's out of business, missing paperwork — say so early, because that's the part that adds weeks.

→ Read our full explanation of NEM 1.0, NEM 2.0, and net billing

The roof comes first, and we're the ones who can say that

This is where most battery companies go quiet, because they can't help you.

If your roof is in the last stretch of its service life, mounting a new array on it is a mistake you'll pay for twice — once now, and again when you have to pay somebody to detach and reset every panel to reroof underneath them. And if you already have panels on an aging roof, the reroof has to happen through the array, which is a job most roofers won't touch and most solar companies aren't licensed to do. California's C-46 solar classification bars a licensee from performing other building trades except as required to install a solar system — a solar-only contractor cannot legally re-roof your house.

McKay has been roofing San Diego County since 1981. We do both trades, with our own crews, and we sequence them in the right order: roof first if the roof needs it, array and battery after, one warranty covering the assembly instead of two companies pointing at each other when something leaks.

There's a warranty dimension to this most homeowners never hear about. Owens Corning's Platinum Protection warranty explicitly excludes damage to the roofing system caused by alterations made after the roof is completed, including solar panel installation. OC sells a separate product — Platinum Solar PROtect — that requires a contractor certified in both trades. If somebody puts panels on your new OC roof and they weren't the roofer, you may have quietly voided the roof warranty.

→ Reroofing under existing solar panels: detach and reset

Equipment

What we can tell you without knowing your brand preference: any battery we install will be UL 9540 listed, because the City of San Diego requires that listing on the submittal, and we will show you the listing before installation rather than after.

Incentives: what's real as of August 2026

We'd rather lose a sale than let you sign based on a credit that doesn't exist.

The federal residential credit is gone. Internal Revenue Code §25D — the residential clean energy credit, which covered both solar and battery storage of 3 kWh or more — was terminated by Public Law 119-21. The statute now reads that the credit "shall not apply with respect to any expenditures made after December 31, 2025." The IRS treats an expenditure as made when the installation is completed, so a 2025 deposit on a 2026 installation preserved nothing. If a salesperson tells you your home battery qualifies for a 30% federal credit in 2026, they are either misinformed or lying, and either way you should not let them wire your house.

SGIP is effectively closed in our territory right now. California's Self-Generation Incentive Program is administered here by the Center for Sustainable Energy. As of the program's own metrics dashboard on August 20, 2026, both residential storage budgets in the CSE territory — Small Residential Storage and Residential Solar and Storage Equity — show a status of Closed, with trivial remaining funds. SGIP has historically reopened in steps, and the equity budgets in particular have been refunded before, so this is worth checking rather than writing off. We check it before every proposal. What we won't do is put an SGIP line item in your quote as if it were money in hand.

Business and commercial properties are a different story. The commercial §48E investment credit remains available, on a schedule. If this is a rental property, a commercial building, or a mixed-use situation, that changes the analysis significantly.

→ Commercial solar and storage

Demand response. SDG&E runs a residential Emergency Load Reduction Program that pays participating customers for reducing grid draw during declared events, and battery owners are natural participants. Enrollment and compensation terms are SDG&E's, not ours, and they change — we'll point you at the program, we won't quote you a number for it.

Permits, code, and what actually happens at your house

In the City of San Diego, batteries fall under the electrical permit. The city's residential rooftop solar permit allows a self-issued permit with no plan review for an energy storage system of up to 38.4 kWh total, with no single unit exceeding 20 kWh, installed alongside a qualifying rooftop PV system. Most residential designs land well inside that, which is why a straightforward battery job doesn't need to wait in the plan-check queue.

There are physical constraints worth knowing before you fall in love with a location. Individual ESS units generally need separation from each other, garage installations need vehicle impact protection, and there are smoke and heat alarm requirements in the adjacent spaces. Poway, Santee, and the unincorporated county each run their own permitting, and their turnaround times differ from the city's. We pull the permit, we meet the inspector, and we schedule around the inspection rather than around our convenience.

What it costs

Battery pricing depends on capacity, backup scope, and the electrical work your panel needs, so we quote it from a site visit rather than a brochure. What we will say is this: the right comparison is payment versus bill, not years-to-payback. Payback calculations assume you know what SDG&E will charge for the next decade, and nobody does — rates have moved several times in the last eighteen months alone. A monthly payment against a monthly bill reduction is a comparison you can actually verify on your next statement.

Talk to us

Send us your Green Button data and we'll tell you what size battery your house justifies — including if the answer is "none yet."

Get a battery quote built from your actual SDG&E usage Call (858) 541-1097 or request a site visit. McKay Roofing & Solar · Nuon Energy LLC · 9520 Padgett St, Suite 107, San Diego, CA 92126 · CSLB License #1130793

FAQ

Will a battery eliminate my SDG&E bill? No, and be suspicious of anyone who says it will. Even with solar and storage you remain an SDG&E customer with fixed charges, and most systems still import power on the worst days of the year. What a well-sized battery does is stop you buying kilowatt-hours during the 4–9 p.m. window when they cost the most — currently about $0.69/kWh in summer on TOU-DR1 versus about $0.37/kWh super off-peak. The realistic goal is a much smaller bill, not a zero one.

How big a battery do I need? It depends almost entirely on how much energy your household uses between 4 p.m. and 9 p.m., which we determine from your SDG&E hourly data rather than from square footage. Houses with EVs, heat pumps, pool equipment, or evening AC need substantially more capacity than houses without. If you want backup capability too, add capacity for the loads you want to keep alive during an outage — those are separate requirements stacked on the same hardware.

Can I add a battery to my existing solar without losing NEM 2.0? Generally yes. SDG&E's Schedule NEM-ST treats paired storage as an addition or enhancement to your existing generating facility, and legacy customers keep their tariff for 20 years from original interconnection. The thing that endangers grandfathering is enlarging the generating capacity — adding panels — past the allowed threshold, which is a different decision. We confirm your existing agreement and file the interconnection paperwork so this is handled correctly rather than hopefully.

Is there still a federal tax credit for a home battery? Not for residential installations completed in 2026. IRC §25D, which covered residential solar and battery storage, was terminated by Public Law 119-21 for expenditures made after December 31, 2025. Because the IRS treats the expenditure as made when installation is completed, a deposit paid in 2025 did not preserve the credit. Commercial and business-use properties are governed by a different section of the code and may still qualify.

What about SGIP — the California battery rebate? As of August 20, 2026, both residential storage budgets in SDG&E's service territory show a status of Closed on the program's own metrics dashboard. SGIP has reopened in funding steps before, particularly on the equity side, so it's worth checking rather than assuming. We check current status before writing any proposal, and we don't include SGIP in a quote unless a reservation is actually obtainable.

Will the battery run my whole house during a blackout? Only if it's designed to, and that costs more. Most residential backup installations use a critical-loads subpanel — refrigeration, lighting circuits, internet, a bedroom AC, medical equipment — so the battery isn't asked to start a 5-ton compressor at 2 a.m. Whole-home backup is achievable with enough capacity and the right gateway hardware. Decide which one you're buying before the design is finalized, because retrofitting from one to the other means redoing electrical work.

Do I need solar to install a battery? No. A battery alone can charge from the grid during super off-peak hours (12–6 a.m., plus 10 a.m.–2 p.m. weekdays) and discharge during the 4–9 p.m. on-peak window, which captures the rate spread without a single panel. It's a smaller savings than a solar-paired system, and the economics depend heavily on your evening usage, but it's a legitimate option — especially for a house with a roof that isn't ready for an array yet.

Do I need a new roof before adding solar and a battery? If your roof is near the end of its service life, yes — because reroofing later means paying to detach and reset every panel, and because a solar-only contractor can't legally reroof your house for you. We'll inspect the roof and tell you honestly which category you're in. Sometimes the answer is that you have plenty of roof left and should proceed. We'd rather say that than sell you a roof you don't need.

Do I need a permit? Yes. Battery storage requires an electrical permit. In the City of San Diego, a system up to 38.4 kWh total with no single unit over 20 kWh can generally be self-issued alongside a qualifying rooftop PV permit without plan review, which keeps the schedule short. Poway, Santee, and the unincorporated county have their own processes. We pull the permits and meet the inspectors.