The kit
You buy everything in your own name, fitted by any installer you like. We’ll help you get a good quote, check the spec before you commit, and set up the Brain - a small control unit that plugs into your inverter - once it’s in. Bring whatever battery you want: the Brain talks to the inverter, so it just needs one we support - FoxESS and Solis hybrids today, more coming.
Starting from nothing
| Item | Typical cost |
|---|---|
| FoxESS EP6 battery 5.76kWh nominal capacity. The EP6 used in our savings example. | £1,344 |
| FoxESS H1 hybrid inverter Our simulation uses the 5kW H1 5.0 G2. Your installer confirms grid approval and export limits. | £815 |
| The Brain · Pi 5 Runs the club’s open-source optimiser. Yours outright. | Free |
| Wiring & parts Isolators, breakers, cabling, consumer-unit work. | £315 |
| Installation Qualified electrician, one to two days including sign-off. | £1,100 |
| Grid paperwork DNO notification. | £100 |
| Typical total, installed | ~£3,700 |
| With the £1,000 grant (every member) | ~£2,700 |
With this EP6 and a 5kW inverter, our no-solar simulation saves around £710 a year before membership and wear. After the £15/month membership, the modelled saving is £529 a year, before wear and installation costs.
Already got solar?
The battery can store your surplus too. We check the inverter and metering arrangement with your installer. A supported hybrid inverter gets reused, dropping the price to ~£1,900–2,700 installed with the grant.
See the extra battery saving for a home with existing solar; it keeps the value of your panels separate from what the battery adds.
Already own a battery?
If it sits behind a supported inverter there is nothing to buy - the Brain and the compatibility check are free. Anything else with local control, ask us with your model.
Prices checked July 2026, and move a few hundred pounds with quotes, distance and consumer-unit condition. Where the savings come from: our numbers. To join you’ll need to own a house and be happy on an Octopus half-hourly tariff.