If you own an EV you already understand batteries - which is why so many EV owners end up eyeing a home battery. The logic is the same (store cheap energy, use it when energy is expensive) but the economics are tighter. Here is the honest 2026 picture.
What a home battery does
- Tariff arbitrage: charge overnight at off-peak rates, power the house during peak hours. Works with or without solar.
- Solar time-shifting: store midday solar surplus, use it in the evening instead of exporting it for a fraction of its value.
- Backup: keep lights, fridge and internet running through outages (whole-home backup needs the bigger systems and a transfer switch).
- Grid services: in some markets (UK, parts of the US and Australia), batteries earn money by discharging during grid peaks automatically.
What they cost (November 2026)
| System | Usable capacity | Installed price | Best for |
|---|---|---|---|
| Tesla Powerwall 3 | 13.5 kWh | $11,500-$14,000 / £8,500-£10,500 / A$15,000-17,000 | Whole-home backup + solar |
| Enphase IQ 5P | 5 kWh (stackable) | ~$5,000-6,500 per unit installed | Modular builds, Enphase solar homes |
| GivEnergy All-in-One (UK) | 13.5 kWh | £6,500-£8,500 | UK tariff arbitrage + solar |
| Sungrow / BYD (AU) | 10-16 kWh | A$10,000-14,000 | AU solar self-consumption |
Installed prices after typical incentives (US 30% ITC, AU Cheaper Home Batteries Program) from installer quotes, November 2026. Australia's federal battery rebate (from July 2025) cut AU prices roughly 20-30% and pulled paybacks under 7 years in high-tariff states.
When the payback works
- Wide peak/off-peak spreads. UK owners on tariffs like Octopus Flux-style import/export pairings, or Australians on A$0.40+ peak rates, see 5-8 year paybacks.
- Low feed-in tariffs. If exported solar earns 3-7c/kWh while grid power costs 30-45c, storing your own solar beats selling it by a wide margin.
- Outage-prone areas where backup has real value beyond the spreadsheet (California PSPS events, Australian storm season, Texas freezes).
- Stacked incentives: US 30% federal credit, Australia's federal rebate, UK 0% VAT on battery installs - these decide whether the math lands.
Where it does not: flat-rate US markets with 1:1 net metering (the grid is your free battery) and low-tariff regions with cheap overnight power for the EV but no peak spread to exploit.
"My EV is a 60 kWh battery - why buy 13.5?"
Fair question, and the industry agrees with you. Vehicle-to-home (V2H) and vehicle-to-grid (V2G) let the car power the house through a bidirectional charger. In late 2026 the reality is: a handful of EVs support it (mostly CCS/NACS with ISO 15118-20 or CHAdeMO units like the Leaf), bidirectional home chargers cost $3,000-6,000+, and utility approval is still catching up in most regions. It is coming and it will change this whole category - but buying a dedicated home battery today on the promise your next EV will replace it is a bet, not a plan.
Meanwhile, remember the EV already does one battery job perfectly: it stores cheap overnight energy and spends it on transport. Pairing the car's off-peak charging with a house battery's peak-shaving covers most of the value either device offers.
Right-sizing, quickly
- Check your overnight and evening usage on your smart meter data (see what is a smart meter) - 10-13 kWh covers a typical evening-to-morning gap.
- Backup ambition changes everything: whole-home backup with AC or electric cooking needs 20-40 kWh; "keep the fridge and Wi-Fi alive" needs 5-10 kWh.
- Batteries degrade like EV batteries: expect 70-80% capacity at year 10. Warranty terms (usually 10 years / 70%) matter more than headline capacity.
What to read next
- Solar + EV payback math
- Dynamic tariffs: where batteries earn the most
- Heat pump + EV: planning your home's electrical capacity
Sources: manufacturer pricing, installer quotes, US IRS 25D guidance, Australian CER battery program data, UK MCS. Checked November 2026.