For Fox ESS owners · Beta
ShiftCharge for Fox ESS batteries on Octopus Agile
Tariff-aware battery scheduling for Fox ESS hybrid inverters on Octopus Agile, Cosy and Go. Connect with your Fox ESS API key and the daily plan runs itself.
Start 30 days free30 days free during the beta, then £4.99 a month or £49 a year if you choose to subscribe.
No payment is taken automatically when your free time ends. Battery automation stops unless you subscribe. Paid plans renew until cancelled; cancel any time. Your first payment is covered by our 30-day money-back guarantee.
ShiftCharge connects to your Fox ESS inverter through the official Fox ESS Cloud API and plans your battery around tomorrow’s Octopus Agile prices, your solar forecast, and the way your household actually uses energy.
Fox ESS support is in open beta. You paste one API key from your Fox ESS Cloud account, point ShiftCharge at your tariff, and the plan is set on your inverter each day.
How ShiftCharge talks to Fox ESS
Fox ESS inverters have a Mode Scheduler: a timetable of up to eight periods, each with its own mode. ShiftCharge writes a full day to it, so the inverter knows when to charge from the grid, when to discharge to the grid, when to hold the battery, and when to run on self-consumption.
Because the timetable lives on the inverter, it keeps following the plan even if your internet drops for a while. ShiftCharge checks the timetable after every change and puts it right if something else has altered it.
Hold battery on Fox ESS
When charging is cheap now but the evening will be expensive, the best move is often to keep what is in the battery rather than use it. On Fox ESS, ShiftCharge holds the battery by raising the self-consumption cut-off to its current level: the grid covers the house, and spare solar still tops the battery up.
What you need
A Fox ESS hybrid or AC-coupled inverter with a battery and the Mode Scheduler, such as the H1, H3, KH, AC1, AC3, AIO or EVO ranges.
A Fox ESS Cloud account. Create an API key at foxesscloud.com: open your user profile, choose API Management and generate a key.
A UK smart-meter time-of-use tariff (Octopus Agile, Cosy, Go, or compatible).
What "beta" means here
The integration is wired end to end: live readings, history, charge, discharge and hold. It is built on the official API documentation and the approach the established open-source Fox schedulers use.
Beta means we are still confirming a few behaviours across more real homes, such as how each model handles the hold setting. If something looks wrong, pause automation from the app and tell us.
Common questions
- Which Fox ESS inverters work?
- Fox ESS hybrid and AC-coupled inverters with a battery and the Mode Scheduler. That includes the H1, H3, KH, AC1, AC3, AIO and EVO ranges. Grid-tie-only Fox inverters without a battery have nothing to schedule.
- Will it conflict with the Fox ESS app?
- The Fox ESS app keeps working for monitoring. ShiftCharge owns the Mode Scheduler timetable, so changes you make to it in the Fox app will be replaced by the plan. Pause automation in ShiftCharge first if you want to take over by hand.
- Can I use it alongside Predbat?
- Not on the same inverter. Both tools write the Mode Scheduler, so they would undo each other. Pick one; if you switch to ShiftCharge, turn off Predbat’s inverter control first.
- Does it use up my Fox ESS API allowance?
- Fox allows 1,440 API calls per inverter per day. ShiftCharge uses roughly 600 to 700 on a normal day, leaving room for the Fox app and anything else you run.
Want this running in your home?
ShiftCharge works with Fox ESS today. Connect your battery, point it at your tariff, and let the daily plan do the work. 30 days free during the beta, no card needed.
Start 30 days free