Battery storage sounds like the obvious next step after solar — but it's not always the right call. Storage adds real cost, and the payback depends on specific factors that vary a lot between California households. Here's a practical framework to decide whether it makes sense for yours.
Start with why you'd add a battery
There are three distinct reasons to add residential storage. They have very different economics, and the right battery size depends on which reason (or combination) applies to you.
Reason 1: Outage protection
Without a battery, most grid-tied solar systems shut off during a utility outage — even when the sun is shining. That's a safety requirement. If you're in a PSPS-exposed area, medically dependent on powered equipment, work from home, or simply can't afford the food loss of a multi-day outage, storage is primarily a resilience purchase. The ROI question is secondary to "do I need this to work when the grid fails."
Reason 2: NEM 3.0 optimization
California switched to NEM 3.0 in 2023, which substantially reduced the credits you get for exporting solar energy back to the grid. Under NEM 3.0, the value of self-consuming your own solar is much higher than exporting it — which is exactly what a battery enables. For new California solar installs, storage is increasingly part of the economics story, not just the resilience story.
Reason 3: Time-of-use arbitrage
California utilities mostly run time-of-use rate plans, where electricity costs more during evening peak-rate windows. A battery charged during midday solar production can discharge during the peak window, effectively shifting your consumption from expensive hours to cheap hours. The savings depend on your rate plan's peak-to-off-peak spread.
The four-question decision framework
Instead of starting from "do I want a battery," start from these four questions. If you answer "yes" to two or more, storage makes sense; if not, you're probably better off skipping it for now.
1. Would a multi-day outage hurt you?
Medical equipment, remote work, food storage, EV charging, septic pumps — any of these mean a sustained outage is expensive or risky. If your answer is "not really, I could deal with a few days," the resilience case for storage is weak.
2. Are you in a PSPS-exposed region?
Public Safety Power Shutoff events have made planned multi-day outages routine in parts of California. Check your utility's PSPS history for your address. If you're in a zone that's been shut off multiple times, that's a meaningful signal.
3. Is your rate plan time-of-use?
If your utility rate plan charges more during 4–9 PM than at midday, a battery can arbitrage that spread. If you're on a flat-rate plan, this benefit disappears. Check your utility bill — the rate structure is always on there.
4. Are you going solar new under NEM 3.0?
If yes, the economics of storage look better than they did under NEM 2.0, because export credits are much smaller now. Self-consuming your own production via storage is often how NEM 3.0 solar makes financial sense.
Powerwall or Enphase? Depends on what you're optimizing for
Tesla Powerwall (details) is larger per unit (13.5 kWh), strong for whole-home backup, and has a polished mobile app. Good pick if you want one or two units to cover most of a home.
Enphase IQ Battery (details) is smaller per unit (5.0 kWh), modular, uses LFP chemistry, and integrates natively with Enphase microinverter systems. Good pick if you want to scale up gradually or if your solar already uses Enphase.
What storage does not do well
Residential storage is not a cash-positive investment the way solar itself often is. The financial payback on storage alone — without the resilience or NEM 3.0 context — is usually 8–15 years, which is long relative to the battery's 10–15 year warranty. Don't add a battery purely because someone told you "it'll pay for itself." Add it for a specific use case you can name.
Adding storage now vs later
If you're installing solar today and you think you'll want storage eventually, adding it during the same install is usually cheaper than retrofitting. Permitting, electrical work, and system integration are done once instead of twice. That said, retrofitting is possible in many cases — your advisor can confirm feasibility based on your inverter architecture and electrical panel.