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EPS / backup fault · Battery inverters

Battery didn't provide backup during power cut

The grid went down and everything went dark — including circuits that should have stayed on from the battery. This is frustrating, especially if backup power was a primary reason for installing the battery.
  • Often a settings issue — easy to fix
  • Not all inverters support EPS
  • EPS typically covers a backup circuit only
EPS configured but still not working?

Wiring faults, firmware issues, and hardware failures can all prevent EPS from working despite correct settings. A remote diagnostic session can identify the cause and advise on the fix.

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Brilliant support to get my solar battery working again. I didn’t expect help on a Saturday but Ron answered the phone, listened and sent me the information I needed to get it going, answered questions etc. A brilliant service I’d happily recommend.

Alison F. Cockerill · Jun 2026 Google

Ron was brilliant. He really tried to help. He spent hours trying to fix our GivEnergy AIO and ultimately it became apparent that it needed parts to fix the BMS management system. As there appears to be no replacement parts available on the market, he gave excellent advice on what options are now available to move forward. He is incredibly helpful and knowledgeable.

Mark Mayson · Jun 2026 Google

Called back within a day and gave good advice.

Rob and Sue Dempster · Jun 2026 Google

Ron was extremely helpful and tried his best to repair/reset our GivEnergy inverter remotely. In the event he was unsuccessful but he couldn’t have been more helpful. If you have problems with a GivEnergy system please contact him. Highly recommended

Neil Crichton · Jun 2026 Google

Big thanks to Ron. He was incredibly patient and helpful over the phone, taking the time to walk myself and the installer through every troubleshooting step. Through lots of testing he figured out the issue was definitely a hardware issue, which allows us to consider our next steps. Support fees are clear and they operate a “no fix no fee” policy. It is rare to find that kind of honesty combined with dedicated phone support nowadays. I highly recommend Ron, if you need help with your solar system don’t hesitate to give him a call.

Steve M · Jun 2026 Google

A superb service from Ron who went beyond the normal service received from other Tech support companies. I live abroad and was badly let down when my givenergy system failed (and the company went bankrupt) and the local supplier ran away from the problem. Ron sorted the problem and even accessed specialist coding for the inverter that would not be available for suppliers. Ron also ran a full diagnostic to insure that all was in good working order afterwards. Without Rons support and patient assistance I doubt I would ever have got the system back up and running. Well done and thankyou and you have a customer for the future.

Philip Davey · Jun 2026 Google

Brilliant support to get my solar battery working again. I didn’t expect help on a Saturday but Ron answered the phone, listened and sent me the information I needed to get it going, answered questions etc. A brilliant service I’d happily recommend.

Alison F. Cockerill · Jun 2026 Google

Ron was brilliant. He really tried to help. He spent hours trying to fix our GivEnergy AIO and ultimately it became apparent that it needed parts to fix the BMS management system. As there appears to be no replacement parts available on the market, he gave excellent advice on what options are now available to move forward. He is incredibly helpful and knowledgeable.

Mark Mayson · Jun 2026 Google

Called back within a day and gave good advice.

Rob and Sue Dempster · Jun 2026 Google

Ron was extremely helpful and tried his best to repair/reset our GivEnergy inverter remotely. In the event he was unsuccessful but he couldn’t have been more helpful. If you have problems with a GivEnergy system please contact him. Highly recommended

Neil Crichton · Jun 2026 Google

Big thanks to Ron. He was incredibly patient and helpful over the phone, taking the time to walk myself and the installer through every troubleshooting step. Through lots of testing he figured out the issue was definitely a hardware issue, which allows us to consider our next steps. Support fees are clear and they operate a “no fix no fee” policy. It is rare to find that kind of honesty combined with dedicated phone support nowadays. I highly recommend Ron, if you need help with your solar system don’t hesitate to give him a call.

Steve M · Jun 2026 Google

A superb service from Ron who went beyond the normal service received from other Tech support companies. I live abroad and was badly let down when my givenergy system failed (and the company went bankrupt) and the local supplier ran away from the problem. Ron sorted the problem and even accessed specialist coding for the inverter that would not be available for suppliers. Ron also ran a full diagnostic to insure that all was in good working order afterwards. Without Rons support and patient assistance I doubt I would ever have got the system back up and running. Well done and thankyou and you have a customer for the future.

Philip Davey · Jun 2026 Google

Important: EPS mode typically powers a dedicated backup circuit — not the whole house. If your installer didn't wire a backup circuit, EPS may be working correctly but not powering anything useful. If the whole house went dark, this may be expected behaviour — check whether a backup circuit was created during installation.

Why backup didn't work

Check these in order — starting with the most common.

EPS not enabled in settings

EPS mode is often disabled by default or was never configured. Check the inverter settings in the app or portal. This is the most common reason — and the easiest to fix.

Battery was below minimum EPS SoC

Most systems require a minimum battery charge (typically 10–20%) before EPS will engage. If the battery was nearly empty when the cut occurred, EPS was inhibited. Check the portal's historical SoC data around the time of the outage.

Inverter doesn't support EPS

Not all solar battery inverters have EPS capability. Basic hybrid inverters disconnect from everything during a grid outage as required by G98/G99. Check the inverter's datasheet or manual for EPS/backup specification.

No backup circuit wired

EPS only powers what is connected to the inverter's backup output. If the installer didn't wire a dedicated backup circuit from the inverter to a backup consumer unit or sockets, EPS has nothing to power.

Firmware reset EPS settings

A firmware update may have reset EPS configuration. Check whether EPS is still enabled in the current settings — some updates revert to factory defaults.

EPS hardware fault

Less common. The EPS relay or transfer switch in the inverter has failed. EPS settings appear correct but the hardware doesn't switch. Requires engineer investigation.

What to check

Work through these in order.

1
Confirm your inverter supports EPS

Find your inverter model name from the label on the unit. Check the manufacturer's datasheet for "EPS", "backup", or "off-grid" capability. GivEnergy hybrid inverters include EPS. Sunsynk and Growatt hybrid models include EPS. Basic string inverters without battery integration do not. If your inverter doesn't support EPS, backup power requires a hardware upgrade.

2
Check EPS is enabled in the settings

Open your inverter's app or monitoring portal and find the EPS or backup power settings. Confirm EPS is enabled. On GivEnergy, this is in the System Mode settings — EPS must be explicitly turned on. Save and confirm the setting has persisted.

3
Check the minimum EPS SoC setting

Find the minimum SoC for EPS in the settings — usually between 10% and 30%. Then check the portal's historical data to see what the battery charge was at the time of the last power cut. If the battery was below the minimum, EPS was correctly inhibited. Consider raising the charge target or lowering the EPS minimum SoC threshold.

4
Identify whether a backup circuit was wired

Ask your installer (or check your installation documentation) whether a backup circuit was wired from the inverter's EPS output to any part of your consumer unit or to dedicated sockets. If no backup wiring was done, EPS has nowhere to supply power to — this is an installation gap that requires an electrician to add a backup circuit.

5
Test EPS with a simulated power cut

With EPS enabled and the battery at a good charge level, you can test the backup function by briefly switching the AC isolator off and watching whether the backup circuit stays live. Wait 2–3 seconds after switching off before checking — the transfer time is typically under 100ms but allow for it.

Only do this if you are comfortable with isolator switches and understand what circuits are and are not on the backup output. Do not do this if the inverter was recently indicating a fault.

FAQ

Frequently asked questions

Most common reasons: EPS mode is not enabled in settings; the battery was below the minimum SoC threshold when the cut occurred; no backup circuit was wired by the installer; or the inverter doesn't support EPS. Check the settings first — it is often that simple.
No. Basic grid-tie inverters must disconnect during a grid outage by law (G98/G99). Only hybrid inverters with a dedicated EPS circuit can provide backup power. Check your inverter's datasheet for EPS capability.
EPS (Emergency Power Supply) is a feature on hybrid battery inverters that allows them to supply power from the battery when the grid fails. The inverter isolates from the grid and switches to an isolated backup output — typically a dedicated circuit, not the whole house — with a transfer time of 20–100ms.
EPS powers a dedicated backup circuit, not the whole house. The inverter must be physically wired to supply specific circuits during an outage. If your installer didn't create a backup circuit, EPS may be working correctly but isn't connected to any load. An electrician can add backup circuit wiring.
A typical low-load standby (lights, router, phone charging, fridge) draws 200–400W. A 5kWh usable battery gives 12–25 hours of that. High loads (kettle, oven) draw 2–3kW and drain a 5kWh battery in 1–2 hours. EPS is best planned around essential circuits rather than whole-house power.
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EPS configured correctly but still not working?

If EPS is enabled, the battery was charged, and a backup circuit is wired — but backup still failed — there may be a wiring issue, relay fault, or firmware problem. A remote session helps pinpoint whether an engineer needs to attend.

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