The three home batteries we're asked about most in 2026, compared honestly — capacity, expandability, backup power and value.
The contenders
Three systems dominate the conversations we have with customers in 2026: the Sigenergy SigenStor, the Tesla Powerwall 3, and FoxESS’s EP/EQ ranges. All three are LFP chemistry (safe, long-cycle-life), all carry 10-year warranties, and all work with smart tariffs. The differences are in shape, expandability and price.
Side by side
| Spec | Sigenergy SigenStor | Tesla Powerwall 3 | FoxESS EP/EQ |
|---|---|---|---|
| Chemistry | LFP | LFP | LFP |
| Module size | 8 kWh | 13.5 kWh (fixed unit) | 5.2 kWh |
| Max stack | 48+ kWh | 4× units (54 kWh) | ~30 kWh |
| Warranty | 10 yr / ~6,000 cycles | 10 yr / unlimited cycles (self-consumption) | 10 yr |
| End-of-warranty capacity | ≥70% | ≥70% | ≥70% |
| Continuous power | 12–24 kW (stack-dependent) | 11.5 kW | 5 kW (single) / stackable |
| Backup power | Optional gateway | Whole-home included | Optional gateway |
| Inverter | Built into top module | Built-in solar inverter | Separate hybrid inverter (FoxESS matched) |
| Indicative price installed | £6,500 – £11,000 | £8,500 – £11,000 | £5,000 – £8,500 |
| Best for | Growing homes (EV/heat pump) | Whole-home backup | Best £/kWh, new solar bundle |
Prices are the range we typically quote across the North West in 2026 for retrofit or bundled installs. Your actual number depends on siting, cable runs and whether backup is included.
Sigenergy SigenStor — the flexible one
The SigenStor is the battery you’ve seen stacked like a tower of modules. Start at 8 kWh, add modules up to 48 kWh on a single stack, with the hybrid inverter built into the top unit. That expandability is its killer feature: size for today, grow later without redesigning anything. AI-driven tariff optimisation and optional backup power round it out. This is the system we install most.
Tesla Powerwall 3 — the household name
13.5 kWh per unit, an integrated solar inverter, and the best whole-home backup story of the three. The software is polished and the brand needs no introduction. The trade-off is fixed capacity steps — you scale in 13.5 kWh jumps — and a premium price. If backup through power cuts is your priority, it’s hard to beat.
FoxESS — the value pick
FoxESS stackable batteries deliver the lowest cost per kWh of storage of the three, integrate seamlessly with FoxESS hybrid inverters on new solar installs, and have proven reliable across thousands of UK installations. Controls are more functional than flashy, but the fundamentals — cycle life, warranty, efficiency — stand up.
How to actually choose
- Want to start small and expand? SigenStor.
- Backup power is the priority? Powerwall 3.
- Best value on a new solar + battery install? FoxESS.
- Battery-only on a smart tariff? All three arbitrage overnight rates well; sizing matters more than brand.
The honest caveat
The right battery size depends on your usage pattern and tariff, not the brochure. The average home uses 8–10 kWh a day — but a heat pump, an EV or home working changes the maths completely. Get your usage modelled before you buy a single kWh.
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