Fox ESS Hybrid Inverter (H1 / H3 Series)

Fox ESS Hybrid Inverter - Works with BatteryWiz

BatteryWiz was first built around a Fox ESS system. The developer installed a Fox ESS hybrid at home, spent ages trying to find an app that would give proper cost-optimised control over it, and eventually decided to write one. It was the first integration ever built, and it remains the most thoroughly tested one.

H1 and H3 Series

Fox ESS makes a range of hybrid inverters that combine solar PV conversion and battery management in a single unit. The H1 series covers single-phase installations in the 3–6 kW range, which makes it a natural fit for most homes. The H3 series handles three-phase connections and higher-output properties. Both series pair with Fox ESS's own high-voltage ECS battery modules, and both are fully supported by BatteryWiz.

Unlike a plain string inverter, a hybrid unit has a built-in battery controller that decides, moment to moment, whether to charge from solar, discharge to cover your loads, or pull from the grid. BatteryWiz takes that further: instead of relying on fixed rules you set once through the FoxCloud app, it calculates the cheapest possible schedule for your battery across the next 24 hours, and updates it automatically throughout the day.

How the Connection Works

BatteryWiz talks to your inverter through the Fox ESS Cloud API - the same cloud your inverter is already sending data to. There's no hardware to add, no local network connection to configure, and nothing to change at the fuse board. You'll need two things:

• A Fox ESS Cloud account (the same login you use with the FoxCloud app)
• An API key, generated from the FoxCloud portal under API Management

That's it. Enter those in BatteryWiz's settings, and it immediately has a live view of your system.

What BatteryWiz Can See and Control

Once connected, BatteryWiz reads your real-time battery SoC and house load directly from the inverter. On the control side it can:

• Set the minimum SoC - so the battery always keeps a reserve for backup or morning use
• Set the active work mode - switching between Self Use, Force Charge, Force Discharge, and Feed-in as conditions change
• Write time-based schedules - pushing charge and discharge slots into the Fox ESS scheduler for the hours ahead

All of this is driven by a mathematical optimisation model and solver that runs on your device. It uses your electricity tariff (import and export rates by time slot), a solar generation forecast from Solcast, and a machine-learning prediction of your household load. The result is a rolling plan that's recalculated automatically so you never have to think about it.

Getting Set Up

1. Log into foxesscloud.com → click your profile icon → User Profile → API Management → generate an API key
2. Open BatteryWiz → Settings → Inverter → select Fox ESS Cloud
3. Enter your API key in BatteryWiz's Settings page. For a full guide on setting up all fields in the Settings and Tariff page, see the BatteryWiz complete setup guide.
4. Start in Simulation mode: you'll see exactly what the optimiser would do without it touching the inverter

Once you're happy with what you're seeing, flip to Live mode and BatteryWiz will start applying schedules on its own.

Getting the Most Out of It

Fox ESS systems work especially well with BatteryWiz on time-of-use tariffs - anything with a clear, cheap overnight window like Octopus Flux, Intelligent Octopus Go, or Economy 7. The app charges your battery during cheap-rate hours and holds or discharges during peak times, keeping grid import bills as low as possible.

If you have solar panels, BatteryWiz factors in the day's forecast before deciding how much to charge overnight. On a sunny day it'll hold back and let the panels do the work; on a cloudy one it'll make sure the battery is topped up from the grid while rates are low. It also maximises how much you can make through battery arbitrage (i.e. buy cheap, sell high). Either way, you're not leaving money on the table.