Do I need a battery with solar?

Last updated: September 16, 2026

The arithmetic problem

Your panels make the most power at midday. Your house uses the most power in the evening — cooking, laundry, the EV, the lights. Those two curves barely overlap. Before NEM 3 that didn't matter, because exporting at noon and importing at seven was close to a wash.

It isn't a wash anymore. You export at roughly 5 to 8 cents and reimport at 35 cents or more. A battery closes that gap by holding your own midday production until the hours when buying is expensive. That is the entire case for storage — not backup, not independence. Arbitrage against your own utility rate.

What it does to the payback

A battery adds real cost — typically five figures installed, depending on capacity and how much electrical work your house needs. It also lifts the share of your production you actually use, often from somewhere around a third to the large majority.

In most East Bay cases I see, solar plus storage lands on a shorter payback than panels alone, even though it costs more up front. Solar-only projects under NEM 3 tend to stretch out, because so much of what the roof makes gets sold at a few cents. The exact numbers depend on your usage shape, so treat any published range — including that one — as a prompt to check your own bill rather than an answer.

When you don't need one

I talk people out of batteries more often than you'd expect:

• You're genuinely a daytime household. Someone home all day, a home office running, a pool pump on a midday schedule, an EV that charges in the driveway at noon. If you already consume most of what you produce, storage has less to capture.
• Your bill is modest. There's a floor below which neither panels nor storage earn their keep.
• Your panel can't take it without a major upgrade. Sometimes the electrical work costs more than the battery saves. I'd rather say that than quote around it — see panel upgrades.
• You want it only for outages. That's a legitimate reason to buy one, but it's a different purchase with different sizing. Be honest with yourself about which you're buying, because the right battery for backup isn't always the right battery for bill savings.

Backup is a separate question

Most people assume any battery keeps the whole house running through a PSPS shutoff. It depends entirely on how it's wired and how big it is. A typical residential battery will carry a critical-loads subpanel — fridge, internet, some lights, maybe the furnace fan — for a day or so. Running central air conditioning or an electric range off it is a much larger and more expensive design.

Decide up front what you want to survive an outage, because it changes the sizing, the wiring, and the price. Vague backup expectations are where a lot of disappointment comes from.

What about rebates?

California's Self-Generation Incentive Program still offers meaningful money for storage, but the general-market budget has been oversubscribed and the realistically available tiers are the equity and equity-resiliency ones — aimed at income-qualified households, medical baseline customers, and homes in high fire-threat areas.

If you're in one of those categories the amounts are substantial and worth pursuing. If you're not, plan your budget without it and treat anything that comes through as a bonus. I'll tell you honestly which side of that line you fall on. Note too that the federal credit that used to apply to batteries for homeowners ended with the rest of it on January 1, 2026.

How I'd size it

From your evening usage, not from a brochure. Pull your hourly data from PG&E, look at what you draw between 4pm and 10pm, and size to cover that window rather than to a round number of kilowatt-hours. Most homes need less than the first proposal they're shown, which is worth knowing before you're quoted a second unit you don't need.