Tesla Battery
Tesla Powerwall, 13.5 kWh of storage with whole-home backup.
Warranty you can read
- 10 year warranty on the unit
- Retained capacity guaranteed, not just that it powers on
- Unlimited cycles for solar self-consumption use
Sized for a real house
- 13.5 kWh usable, roughly an average household evening and overnight
- Enough continuous power to run the whole house, not a single circuit
- Stackable if your usage grows, an EV or a heat pump for instance
Clever about tariffs
- Charges from cheap overnight electricity on a time-of-use tariff
- Prioritises your own solar first, exports only the surplus
- Modes for self-powered, time-based control and backup reserve
Backup and safety
- Backup gateway option keeps the house running through a power cut
- Sealed, weather-rated unit, indoor or outdoor mounting
- Monitored remotely by us as well as by you
A battery does not make you more energy. It moves energy you already generated from the middle of the day, when the house is usually empty, to the evening when you are cooking, washing and charging things. The Powerwall is the most common home battery in the world, and the case for it is less about peak specification than about the software and the support around it being mature.
What it does in a day
Solar covers the house first. Surplus charges the Powerwall. Once it is full, the rest exports. In the evening the house runs off the battery until it is empty, then falls back to the grid.
13.5 kWh usable is, for most households, the evening and the overnight base load. In summer you will often wake up with charge still in it. In December it will be doing a different job.
What it does on a time-of-use tariff
The second trick, and in winter the more valuable one, is charging from the grid overnight at the off-peak rate and running the house from that stored cheap energy through the expensive part of the day.
That means the battery earns money even in the months when there is not enough sun to fill it, which is exactly when a solar-only system is doing least for you.
Power cuts
With a backup gateway fitted, the Powerwall disconnects from the grid and keeps the house running when the street goes dark. Without one, the system shuts down safely like any other grid-tied installation.
You choose a backup reserve, a percentage the battery will not spend on ordinary evenings so it is there when you need it.
If something goes wrong
State of charge, cycle count and health are visible remotely, to you in the app and to us in our monitoring. Degradation is gradual and expected; a fault is not, and it stands out against the trend.
You call us. We hold the install records and raise the warranty claim.
The honest downsides
A battery has the longest payback of anything in a domestic system. If the gap between your import and export prices is small, it may never pay for itself on arithmetic alone.
It takes wall or floor space, usually a garage, utility room or plant space, and it needs clearance around it.
Capacity fades with cycles. Plan on the warranted retained capacity, not the day-one figure.
Whole-home backup needs a gateway and a bit of switchgear work, which is not included unless we have said so.
Two minutes, three questions. No sales calls unless you ask for one.