We install both. They store almost exactly the same amount of energy, both can grow later, and both are fitted by our own MCS certified team. One of them costs £2,000 less than our installed price for a Tesla Powerwall 3, and we are not naming it in our adverts just yet.
The side by side
| Tesla Powerwall 3 | The Mystery Battery | |
|---|---|---|
| Usable storage | 13.5 kWh | 13.68 kWh (14.4 kWh battery) |
| Hybrid inverter | Built in | Built in, 8 kW |
| Add more batteries later | Up to 3 Expansion units | Up to 6 batteries (86.4 kWh) |
| Battery warranty | 10 years | 12 years |
| Inverter warranty | 10 years | 10 years |
| Whole-home backup | With Backup Gateway 2 | Built in, up to 10 kW |
| Solar inputs | Built in | 4 MPPTs, up to 200% oversizing |
| Price | Our installed price | £2,000 less |
Who makes it?
Not a start-up and not a white label. The company behind it was founded in 2004, is publicly listed, turns over more than $400m a year, employs 10,000+ people across seven production centres, has 500+ R&D specialists and 150+ patents, and runs a UK technical support team in Birmingham. Ask us and we will name it, send you both specification sheets and show you exactly how the £2,000 is worked out.
Still like the look of a Powerwall 3?
That is fine. We install Tesla Powerwall 3 too, so we can quote for either and help you pick the one that suits your home.
See the full comparison and ask us what it is or call 01202 985 888.
£2,000 less than our installed price for a single Tesla Powerwall 3, comparing like-for-like single battery installations, October 2026. Prices can change, so we always confirm yours in writing. Specifications are taken from each manufacturer’s published data. Tesla and Powerwall are trademarks of Tesla, Inc. DES Renewable Energy is not affiliated with Tesla.