FoxESS EPS Verification Guide

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Method 1: FoxCloud App

Easiest — No hardware access

Check EPS data in the app

1

Open FoxCloud → Analysis tab

Navigate to the data analysis / graph section of the app.

2

Look for "EPS Power" metric

If EPS is wired and enabled, you'll see a specific metric alongside PV, Battery, and Output AC power. If this value stays at 0 W (or is missing entirely), EPS is not providing power.

⚠️

Test with caution: You can simulate an outage by flipping the main grid breaker OFF. If backup circuits stay on and the app shows "Off-Grid" mode with EPS power flowing, your EPS is working. Only do this briefly — flip it back on within 1–2 minutes.

3

Check inverter status changes

During a grid outage, the app should show the inverter switching from "On-Grid" → "Off-Grid" or "EPS Mode".

EPS Power metric visible in Analysis graphs
Inverter status changes to "Off-Grid" during outage
Backup circuits stay powered when grid is off

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Method 2: Home Assistant

Advanced — Via Modbus/API

1

Check sensor.eps_power entity

If the EPS hardware is connected, this entity will register wattage consumed by backup circuits during an outage or off-grid operation.

2

Check inverter operational status sensor

When the grid drops, the state should change from "On-Grid" → "Off-Grid" or "EPS Mode".

💡

Add these to your HA dashboard for live monitoring: sensor.eps_power, sensor.inverter_status, and sensor.grid_connected.

sensor.eps_power entity exists and reads 0W+ (not unavailable)
Inverter status sensor shows "On-Grid" normally
Status switches to "Off-Grid" / "EPS Mode" during outage

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Method 3: Physical Inspection

Hands-on — Visual check

Inverter display

1

Check the inverter front screen

In backup mode, the display shows "EPS Mode" instead of "Grid-Tied." The power flow diagram adjusts to show power routing to the EPS port.

Inverter hardware

2

Look at the bottom of the inverter for the "EPS" port

There's a dedicated port labeled "EPS" next to the "Grid" port. If a thick electrical cable runs from this port to your switchboard, EPS was wired by the installer.

Switchboard

3

Check for EPS Box or internal bypass relay

A proper backup connection requires either:
• An internal bypass relay enabled in the inverter, OR
• An external FoxESS EPS Box installed next to the switchboard

EPS port on inverter has a cable connected to switchboard
EPS Box visible near switchboard (or bypass relay enabled)
Inverter display shows "EPS Mode" during outage

🛠️

Troubleshooting: If EPS Isn't Working

1

Check Mode Scheduler settings

Mode Scheduler may override EPS behavior. Temporarily switch to Self Use mode to test if EPS activates during an outage.

2

Verify battery has sufficient charge

EPS won't work if the battery SoC is below System Min. SOC. Ensure battery is above 20% before testing.

3

Check EPS is enabled in installer settings

Some KH10 configurations require EPS to be explicitly enabled via the inverter's installer menu or FoxCloud settings.

ℹ️

Refer to the KH10 User Manual page 34 for "EPS Connection (Non-Parallel State)" wiring diagrams and the EPS Box User Manual for external bypass setup details.

🔌 FoxESS EPS Verification Guide

Sources