Best Home Battery for Backup in California (2026): Buyer’s Guide
Straight answer: the best backup battery is the one whose three published numbers clear your house — usable kWh (how long), continuous kW (how much at once) and motor-start LRA (whether the air conditioner or well pump starts). Of the batteries we’re asked about most, a single Tesla Powerwall 3 or FranklinWH aPower 2 publishes the highest motor-start rating, 185 LRA; Enphase’s IQ batteries grow in 5 or 10 kWh steps and list 48 A and 90 A per unit. Below, the datasheet numbers are mapped to backup goals and one house is run through four quotes.
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- For backup, three published numbers decide the fit: usable kWh (how long), continuous kW (how much at once) and motor-start LRA (whether a compressor or pump starts). A brand name decides none of them.
- One Powerwall 3 (13.5 kWh, up to 11.5 kW, 185 LRA) or aPower 2 (15 kWh, up to 10 kW, 185 A LRA at its top setting) carries the highest motor-start rating here; Enphase grows in 5 or 10 kWh steps with 48 A or 90 A LRA per unit.
- Multi-day outages are decided by solar recharge, not battery size: one 13.5 kWh unit covers about 1.7 days of critical loads with no sun, and a recharge-capable array refills it on sunny days.
- 2026 money: the 30% federal credit is gone and SGIP’s general-market rebate is closed; only income-qualified SGIP budgets remain.
Three numbers decide a backup battery
Usable energy (kWh) sets how long your backed-up loads run. Makers do not all quote it the same way: Tesla lists the Powerwall 3 as 13.5 kWh of AC energy, FranklinWH lists 15 kWh of usable AC system energy, and Enphase lists usable capacity (5.0 kWh for the IQ Battery 5P, 10.0 for the 10C). Continuous power (kW or kVA) sets how much can run at the same time — and the Powerwall 3 and aPower 2 are each commissioned at one of four output settings (5.8 to 11.5 kW and 5 to 10 kW), so the proposal should state which one you are getting. Motor-start capability (LRA) is the brief surge a compressor or pump needs to spin up; if the battery’s rating is below what the motor draws at start, the motor will not start however many kWh are stored. The motor’s own figure is the LRA (locked-rotor amps) on the nameplate of the air conditioner’s outdoor unit or the pump.
Batteries are now the norm on new California solar: 57% of new residential installs in the state were paired with storage in 2024, up from 14% in 2023, and the median battery was 13.5 kWh (LBNL). For a spec-by-spec comparison of the same products at matched storage, see Powerwall vs Enphase vs FranklinWH; this page maps those numbers to backup jobs.
| Backup goal | What decides it | What the datasheets show |
|---|---|---|
| Essentials for a day or two (fridge, lights, Wi-Fi, furnace fan, a medical device, a small pump — about 7.2 kWh a day) | Usable kWh | Days with no sun, 10% reserve held: Powerwall 3 1.7; aPower 2 1.9; IQ Battery 10C 1.25; two IQ 5P 1.25; three IQ 5P 1.9 |
| Starting central air or a well pump | Motor-start rating vs the motor’s nameplate LRA | Powerwall 3 185 LRA; aPower 2 185 A LRA at its 11.5 kVA setting; IQ 10C up to 90 A; IQ 5P up to 48 A per unit |
| Running much of the house at once | Continuous kW across the system | One Powerwall 3 up to 11.5 kW; one aPower 2 up to 10 kW (11.5 kVA); three IQ 5P 11.52 kVA; one 10C plus one 5P 10.92 kVA |
| Growing later | Expansion step and ceiling | Tesla: up to four Powerwall 3 plus three Expansion units, seven in total; FranklinWH: 15 kWh steps, up to 15 per aGate (225 kWh); Enphase: 5 kWh steps |
| New solar at the same time | Solar inverter in the battery | Powerwall 3 takes direct DC solar input up to 20 kW STC in the same unit |
| Adding a battery to existing solar | AC coupling | Enphase IQ batteries and the aPower 2 (with its aGate) are AC-coupled: they carry their own inverters and connect alongside existing solar |
| A generator as a last resort | Generator input | FranklinWH’s aGate manages grid, batteries and a standby generator through an optional generator module |
| Daily cycling plus backup | Warranty term, cap and capacity floor | Tesla: 10 years, 70% at year 10, unlimited cycles for self-consumption and backup; Enphase: 15 years or 6,000 cycles, 70% at year 10; aPower 2: 15 years or 60 MWh, 70% at the end |
Sources: Tesla Powerwall 3 datasheet · Tesla warranty · Enphase IQ Battery 5P · Enphase IQ Battery 10C · Enphase warranty · FranklinWH aPower 2 · FranklinWH aGate · FranklinWH warranty. Days = usable kWh less a 10% reserve, divided by 7.2 kWh a day — Cali Energy calculation.
One house, four quotes
Here is the check done on one example house. It needs the same critical loads (7.2 kWh a day), it wants the central air to run in an outage (about 4.5 kW together with the essentials), and the nameplate on its outdoor unit reads LRA 90 A. Your numbers will differ; the method will not.
| Quote | Critical loads, no sun | Carries 4.5 kW? | Starts a 90 A LRA compressor? | Verdict |
|---|---|---|---|---|
| 1 × Tesla Powerwall 3 | 1.7 days | Yes, up to 11.5 kW | Yes — 185 LRA | Fits |
| 1 × FranklinWH aPower 2 | 1.9 days | Yes, up to 10 kW | Yes, at the 11.5 kVA setting — 185 A | Fits if commissioned at 11.5 kVA |
| 1 × Enphase IQ Battery 10C | 1.25 days | Yes, 7.08 kVA | At the limit — “up to 90 A” | Not assured on paper |
| 3 × Enphase IQ Battery 5P | 1.9 days | Yes, 11.52 kVA | Enphase lists 48 A per battery; get the figure for three | Confirm in writing |
Two things the table makes plain. First, capacity does not start motors: three 5P units store more than one 10C, yet the start question is answered by the LRA rating, not the kWh. Second, running the air conditioner eats capacity fast — at a steady 4.5 kW, a 13.5 kWh battery with a 10% reserve lasts about 2.7 hours (compressors cycle, so real time runs longer). If cooling through a long outage matters, plan more storage, a larger array, or a generator for the long tail. Size your own loads with the battery sizing calculator and choose the backup scope in whole-home vs critical-loads backup.
Multi-day outages: solar recharge decides it
A battery alone is a countdown; a battery that solar can refill is a cycle. A standard grid-tied inverter must shut off when the grid does, so recharge during an outage only happens when the system is designed to run off-grid (why solar goes dark in an outage). Designed that way, even a small array covers critical loads: on an average December day in Los Angeles, a 2.5 kW array makes more than a 7.2 kWh critical-loads day uses. Model your own array, battery count and month with our multi-day PSPS battery model.
Warranty for a battery that also cycles every day
Under NEM 3.0 a battery set to shift solar into the evening cycles almost every day, so the warranty’s use cap matters as much as its term. Tesla guarantees 70% of 13.5 kWh at year 10 with unlimited cycles when the Powerwall is used for solar self-consumption, time-based control and backup. Enphase guarantees 70% at year 10 and 60% at year 15, within 6,000 discharged cycles (current warranty). FranklinWH guarantees the aPower 2 at 70% when its 15 years or 60 MWh end, whichever comes first — about 11 years at one full cycle a day — with no year-10 checkpoint. The full comparison, with a use-cap calculator, is in Powerwall vs Enphase vs FranklinWH.
Money in 2026
- Federal credit: the 30% Residential Clean Energy Credit ended for expenditures after December 31, 2025 (IRS).
- SGIP: as of September 28, 2026, the small residential storage budget — the general-market rebate — is closed in all four investor-owned utility territories; what remains are income-qualified Residential Solar and Storage Equity budgets, open in some territories and waitlisted in others (SGIP program metrics). The budget LADWP administers has put new applications on a waitlist since November 6, 2025 (SGIP announcements). Details: SGIP guide.
- Price: in 2024 the median paired solar-plus-storage system cost $1.70 per watt more than solar alone (LBNL) — about $9,700 on California’s median 5.7 kW system. Ranges by setup are in what a home battery costs.
- Between outages: on SCE’s Solar Billing Plan a battery also earns its keep by shifting cheap midday solar into the 4–9 p.m. peak; on LADWP’s net metering it is mainly backup.
Before you sign: six things to get in writing
Usable kWh and its basis
Usable capacity for the whole system, and whether it is quoted as AC energy or usable capacity, so two proposals compare like for like.
The power setting
Which output setting the battery will be commissioned at (for example 11.5 vs 5.8 kW on a Powerwall 3) and the breaker that goes with it.
Motor start vs your nameplate
The system’s LRA rating next to the LRA on your air conditioner or pump — with the installer’s confirmation that it starts.
The backup scope
Whole home or a named list of circuits. It drives size, controller and price (compare the two).
Solar during an outage
A plain statement that your panels will keep charging the battery when the grid is down — not only that the battery works.
Warranty cap and placement
The term, the cycle or MWh cap and the capacity floor — plus where the unit will go under code (battery safety & code).
Frequently asked
What is the best home battery for backup in California?
The one whose published numbers clear your house: enough usable kWh for the hours you need, enough continuous kW for what runs at once, and a motor-start (LRA) rating above your air conditioner’s or pump’s nameplate. On datasheets, one Tesla Powerwall 3 (13.5 kWh, up to 11.5 kW, 185 LRA) or FranklinWH aPower 2 (15 kWh, up to 10 kW, 185 A LRA at its 11.5 kVA setting) carries the highest motor-start rating; Enphase’s IQ Battery 5P and 10C grow in 5 or 10 kWh steps with 48 A and 90 A LRA per unit. The answer is the same in any California city; what changes is your loads.
What's the difference between kWh, kW and LRA on a battery?
kWh is stored energy — how long loads run. kW (or kVA) is continuous power — how much runs at the same time. LRA is motor-start capability — the brief surge a compressor or pump needs to start. A battery can have plenty of kWh and still fail to start central air if its LRA rating is below the motor’s.
Will a home battery start my central air or well pump?
Compare two numbers: the LRA printed on the nameplate of the air conditioner’s outdoor unit or the pump, and the battery system’s motor-start rating — 185 LRA for a Powerwall 3, 185 A for an aPower 2 at its 11.5 kVA setting, up to 90 A for an IQ Battery 10C and up to 48 A per IQ Battery 5P. If the battery’s figure is not clearly above the motor’s, get written confirmation from the installer before you sign.
How many batteries do I need for whole-home backup?
Enough for both jobs: continuous kW for everything that runs at once, and kWh for the hours you need. At a steady 4.5 kW with the air conditioning on, one 13.5 kWh battery lasts about 2.7 hours; on 7.2 kWh a day of critical loads it lasts about 1.7 days without sun. Solar that can recharge off-grid extends either. Run your own loads in the sizing calculator.
Which battery warranty guarantees the most capacity after 10 years of daily cycling?
Tesla and Enphase both guarantee 70% at year 10. Tesla’s Powerwall warranty sets no cycle limit for self-consumption, time-based control and backup; Enphase’s current warranty runs 15 years or 6,000 cycles, about 16 years at one a day. FranklinWH guarantees 70% for the aPower 2 only at the end of its 15 years or 60 MWh — about 11 years at one full cycle a day — and sets no year-10 checkpoint. Details: warranty comparison.
Is LFP chemistry better for a home battery?
The Enphase IQ Battery 5P and 10C and the FranklinWH aPower 2 all list lithium iron phosphate (LFP) on their datasheets; Tesla’s Powerwall 3 datasheet does not state a cell chemistry. For backup, chemistry matters less than listing and a code-compliant installation — see battery safety & code.
Does SGIP still help pay for a battery in 2026?
Only for income-qualified households. As of September 28, 2026, SGIP’s general-market residential storage budget is closed in all four investor-owned utility territories; the income-qualified Residential Solar and Storage Equity budgets are open in some territories and waitlisted in others, including the one LADWP administers. The 30% federal credit ended in 2025. See the SGIP guide.
Related reading
Sources & methodology
Figures on this page come from the primary sources below and, where noted, from Cali Energy calculations using the stated assumptions. Rates, incentives, and program terms change; each was verified September 28, 2026.
- Tesla — Powerwall 3 datasheet (13.5 kWh AC, output settings 5.8–11.5 kW, 185 LRA, 20 kW STC solar input, scalability)
- Tesla — Powerwall limited warranty (USA), Rev. 2.6
- Enphase — IQ Battery 5P datasheet (5.0 kWh, 3.84 kVA, up to 48 A LRA, LFP)
- Enphase — IQ Battery 10C datasheet (10.0 kWh, 7.08 kVA, up to 90 A LRA, LFP)
- Enphase — limited warranty, US/Canada, effective 27 December 2024
- FranklinWH — aPower 2 datasheet (15 kWh AC, 10 kW / 11.5 kVA, 185 A LRA at 11.5 kVA, LFP)
- FranklinWH — aGate datasheet (optional generator module, AC-coupled)
- FranklinWH — system limited warranty for end users
- Lawrence Berkeley National Laboratory — U.S. Distributed Solar and Storage 2025 Data Update
- SGIP — Program metrics (budget status)
- SGIP — Public announcements (LADWP RSSE waitlist)
- IRS — Residential Clean Energy Credit
Not sure which battery fits your home?
Tell us what you want to keep running during an outage and we'll size it against the datasheets — usable capacity, the power setting, and whether your air conditioner will start. No brand-pushing, no pressure.
Get a free estimatePrepared by Cali Energy, September 28, 2026. This article is for general educational purposes only and is not legal, tax, financial, engineering, or utility advice. Rates, incentives, codes, permit requirements, equipment specifications, prices, and program terms may change; figures and timelines are estimates, not guarantees. Confirm current requirements with the applicable utility, AHJ, program administrator, manufacturer, or a licensed professional. See our Content Disclaimer. Cali Energy · 19201 Parthenia St, Unit E, Northridge, CA 91324 · CSLB #1032379 (B, C-10, C-39)