The battery brand you pick matters less than one number most quotes don't lead with: usable capacity, not nameplate size. A "10kWh" battery from one brand can deliver meaningfully less real storage than a "10kWh" battery from another, purely because of how much of it is usable versus reserved. Compare on usable kWh, not the headline figure on the box.
Why nameplate capacity is the wrong number to compare
Batteries reserve a portion of their total capacity to protect long-term health — this is normal and expected, but the reserved share (Depth of Discharge, or DoD) varies by brand and chemistry:
| Brand | Typical usable ratio |
|---|---|
| SolaX Triple Power | ~90% DoD |
| GivEnergy (Gen 3 LFP) | Close to 100% |
| Pylontech | ~90–100%, varies by model |
A 10kWh SolaX battery and a 10kWh GivEnergy battery are not the same product once you account for this — the GivEnergy delivers meaningfully more real, usable storage from the same nameplate figure. Always ask for usable kWh specifically when comparing quotes, not nameplate capacity.
Cost comparison, roughly matched for usable capacity
Installed cost for genuinely comparable usable capacity (around 10kWh usable) typically lands in a similar bracket across mainstream brands — roughly £5,500–£9,000 as an add-on to an existing solar install, with brand, installer, and regional labour rates accounting for most of the spread rather than one brand being categorically cheaper than another.
What actually differs between them
- SolaX Triple Power: modular (stack multiple units for more capacity), widely available through UK installers, slightly lower usable ratio than some competitors — factor this into any capacity comparison.
- GivEnergy: strong UK installer network and support ecosystem, near-100% usable ratio, consistently well-reviewed.
- Pylontech: stackable, competitively priced, usable ratio varies by specific model — check the datasheet rather than assuming.
None of these represents a dramatically better or worse choice in isolation — the meaningful differences show up in usable capacity per pound and installer support quality in your specific area, not brand reputation alone.
What to actually ask an installer
- Usable kWh, not nameplate kWh — get this in writing
- Round-trip efficiency — a battery with 95% round-trip efficiency delivers less real energy per charge cycle than the nameplate suggests, on top of the DoD consideration above
- Warranty terms specifically for capacity retention — not just a blanket "10-year warranty," but what capacity is guaranteed at the end of that period
Want your own home's optimal battery size calculated against your actual usage and tariff? Our free calculator works this out for you rather than defaulting to whatever size an installer quotes first.