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Brand support · Fox ESS

Fox ESS Support — Grid Faults, Battery Comms & EPS

Independent help with Fox ESS inverters and batteries, from current H1-G2 and H3 systems to first-generation models: grid alarms, battery and BMS faults, EPS not working and Fox Cloud offline. We diagnose Fox ESS systems remotely using portal data and error logs. Remote-first, but WiFi isn't remote work: if the datalogger needs reconnecting to your WiFi, we can set it up on site, from £195. Independent from Fox ESS and your installer.
Free remote diagnostic £125 only if we fix it remotely
Book Fox ESS DiagnosticSee Fox ESS faults
  • Not affiliated with or endorsed by Fox ESS
  • All Fox ESS models
  • Current and older batteries
Not sure where to start?

Battery alarm, grid fault, EPS not working: we diagnose Fox ESS systems remotely in a single session. Fox Cloud offline? Follow our Fox Cloud offline guide, and if the datalogger needs reconnecting to your WiFi, we can set it up on site, from £195.

Book your free remote diagnosticFox Cloud offline guide

Safety: do not open inverter or battery enclosures. Smoke, fire or a burning smell? Do not go near the equipment. Get everyone out, call 999 and tell them there is a solar battery.

5.0
Rated 5.0 on Google Read all 151 reviews

Called back within a day and gave good advice.

Rob and Sue Dempster · Jun 2026 Google

Great service. Got our Givenergy battery back online remotely when others said it needed an onsite visit. Ron resolved the issue within about an hour of my email. Brilliant service.

adam mitchinson · Jul 2026 Google

Diligent and reliable service.

Samuel Jakovljevic · Jul 2026 Google

My 3-year old GivEnergy Solar/Inverter/Batteries installation went down with all generated electricity going to the grid and absolutely no help available from the Administrators! Thankfully, I found Solar Tech Support and Ron, who used to be a GivEnergy installer. His knowledge and ability are phenomenal and he sorted everything out remotely. I cannot recommend him more highly and a really pleasant guy to deal with! Very many thanks Ron!!

Jerry Robson · Aug 2026 Google

Ron was Absolute God send . After 6 months of nightmares with the installer who messed up in every single aspect of the install... Ron came investigate and provide me with a detailed report and standing behind his words for my case His knowledge and understanding are simply exceptional. I can not express how happy I am to have the luck to deal with him

Boris Rusev · Oct 2026 Google

I contacted Solar Tech Support because I had a problem with my legacy GiveEnergy installation. within 24 hours they had diagnosed the problem and offered advice on resolution. Because they were unable to fix the problem there was no charge! This despite numerous time consuming emails. I am currently trying to engage with the original installer but if that is unsuccessful I will go back to Solar Tech Support and ask them to repair the system with a retrofit. Very knowledgeable and responsive. I highly recommend them.

Tim Hatt · Aug 2026 Google

Written by · Independent Solar Engineer Last updated

Fox ESS Faults

Fox ESS problems we diagnose

Pick the fault that matches what you're seeing for its guide, or book a diagnostic if you're unsure.

Inverter & Grid
Grid Fault
Grid faults (Grid Volt Fault, Grid Freq Fault, Grid Lost)

The inverter has raised a grid alarm because the voltage or frequency it measured was outside its allowed range, or the supply was lost. A wrong country setting, which the installer checks at start-up, is one possible cause and a high or weak supply is another. G98 applies to a system of up to 16 A per phase of total registered capacity (3.68 kW single-phase), and G99 applies above that, with an application to the network operator before installing.

See diagnostic guide
Solar
No solar production

Inverter powered but generating no power. It could be a solar-side fault, a DC isolator switched off or a grid alarm. Check the Fox Cloud app and the inverter display for the alarm name before anything else.

See diagnostic guide
Performance
System underperforming

Inverter generating below expected output. It may be a solar-side problem, soiled panels or a settings fault. We review Fox Cloud historical inverter data by date (PV power, battery power, load and grid) to identify loss patterns.

See diagnostic guide
Earth
Ground Fault or Iso Fault

Ground Fault is an earth alarm and Iso Fault is a solar-side insulation alarm, and Bms Insul Fault is a separate battery-side alarm. Don't keep clearing any of them. Call an engineer.

See diagnostic guide
Meter
Meter Lost Fault or CT fault

Meter Lost Fault means the link between the meter and the inverter is interrupted. Code 240 means the CT or meter isn't detected, and a firmware mismatch after a battery change can cause it too. The meter and CT wiring is an engineer's job.

See diagnostic guide
Fault Codes

Fox ESS fault code index

Seeing an alarm in Fox Cloud or on the inverter? Our guide explains what the alarms mean and the safe next steps, by Fox's own alarm names.

Browse Fox ESS fault codes How to read fault codes All STS services

Fault code categories

Services

What we do for Fox ESS owners

All services

Remote Fox ESS Diagnostic

We review Fox Cloud data, inverter settings, and alarm history to identify the fault remotely.

  • Alarm code root-cause analysis
  • Fox Cloud data review
  • Written engineer summary
Book remote diagnostic

Fox Cloud Portal Recovery

Portal access lost or monitoring never set up? We get access through an account transfer (£95) or your login, shared with your permission, and reconfigure the system.

  • Account access recovery
  • Settings reconfiguration
  • On-site WiFi setup, from £195
Start recovery

On-Site Fox ESS Repair

BMS cable checks, grid settings if requested, EPS circuit checks and component replacement. A targeted visit, led by the evidence and quoted in writing before we start. For a warranty claim, if your Fox ESS installer has gone bust, we can be the Local Installer you appoint to make the claim.

  • Evidence-led targeted checks
  • Safety-focused report
  • Repair or replacement path
Discuss visit
Documents

Fox ESS datasheets and manuals

Datasheets, user manuals and quick installation guides for Fox ESS inverters and batteries. Self-hosted copies, kept as Fox ESS supplied them. Check Fox ESS for the newest issue.

Browse Fox ESS documents All brand documents

About Fox ESS systems: what you need to know

Fox ESS is a Chinese manufacturer. The H1 hybrid inverter series (single phase, 3 to 6kW in the UK) combines solar MPPT, battery management, and grid connection in one unit. Fox's three-phase range is the H3 series. The H1 pairs with Fox's high-voltage batteries: the current EP, EQ and CQ ranges, and the older ECS modules, which stack to add storage. The AC1 is an AC-coupled battery inverter in the same 3 to 6kW range as the H1. It has no solar input and is used to add a Fox battery beside an existing solar inverter.

The Fox Cloud portal and app provide monitoring and configuration. The inverter's country or grid-standard setting is made at commissioning. EPS (the backup output) needs the protected circuits wired to the EPS output and EPS switched on in the inverter settings, both by the installer. A BMS Lost or Bms Ext Fault alarm means the inverter has lost contact with the battery, and Fox's action for it is a check of the BMS cable, which is an installer's job.

We help with grid alarms (voltage, frequency or a lost supply), EPS wiring or settings (backup not working), BMS communication faults (the inverter has lost contact with the battery) and Fox Cloud connectivity (a lost datalogger connection or broadband loss). If you're searching for Fox ESS repair UK, Fox ESS battery not charging, Fox ESS grid code fault, Fox Cloud offline, or Fox ESS EPS not working, STS provides independent diagnostic and repair support across the UK. We're not affiliated with or endorsed by Fox ESS. We cover all Fox ESS models, current and older.

Current Fox ESS ranges

H1-G2 and AC1-G2, KH and KA, H3 Smart and H3 Pro inverters, the Evo and PowerQ (PQ1) all-in-ones, MiniQube, and EP, EQ and CQ batteries. The H3 Plus is a commercial range.

Older Fox ESS ranges

First-generation H1, AC1, H3 and AC3 inverters, and ECS and HV2600 batteries.

Related problem pages

Useful guides

New to your system?

Case studies

We also support

STS supports all major inverter and battery brands, not just Fox ESS. If you have a mixed-brand system or are comparing options, visit the brand hub.

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Explore

More Fox ESS help

Fox ESS problems & faults

Fox ESS fault guides: battery not charging, BMS comms, grid faults, EPS backup, ground fault and Fox Cloud offline. Not affiliated with or endorsed by Fox ESS.

See Fox ESS problems & faults
Fault codes

Fox ESS inverter and battery alarms by name: Grid Volt Fault, BMS Lost, Iso Fault and more. What each means, what Fox advises, and where app numbers come from.

See fault codes
Documents & downloads

Download Fox ESS datasheets and manuals for the H1 (G2), H3, EVO and the EP, EQ and ECS batteries, plus quick installation guides for the H3 and H3 Smart.

See documents & downloads
Fox ESS warranty

Fox ESS UK warranty terms by product, the 120-day Fox Cloud rule and who can claim, from the 2026 policies. If your installer's gone bust, we can claim.

See Fox ESS warranty
FAQ

Fox ESS questions answered

We cover all Fox ESS models: hybrid and AC-coupled inverters, three-phase systems, all-in-ones, and current and older batteries. To work on your system we need access to it in Fox Cloud. That is either an account transfer (£95), or you share your login with us, with your permission. Grid settings can be changed if you request it.
The remote diagnostic is free. A remote fix is £125, only if we fix it remotely. On-site WiFi setup is from £195, an on-site repair visit is from £295, and on-site work is quoted in writing before we start.
Remote diagnostics have same or next-day availability, Monday to Friday, 09:00–19:00. Tell us what's happening and any alarm name you can see, and we'll come back with the next step. We need access to your system in Fox Cloud before a session can start, so that is worth sorting first.
Your installer does, so contact them first: Fox ESS UK's policies let only the installer or Fox-authorised staff claim, but if your Fox ESS installer has gone bust, we can be the Local Installer you appoint to make the claim in their place. We find the fault in a free remote diagnostic, make and follow up the claim with Fox ESS UK for our £125 claim fee, and fit any replacement Fox approves, as on-site work quoted in writing before we start. If Fox finds no qualifying fault in a returned unit, its policy allows a flat-rate inspection charge or recovery of the replacement's cost, and if we made the claim, whichever Fox asks for is passed on to you. Our Fox ESS warranty guide sets out the terms and Fox ESS UK's contact details.
No. STS Solar Tech Support is independent, not affiliated with or endorsed by Fox ESS. We're independent of your installer too. Fox ESS UK's own contact details are in our Fox ESS warranty guide.
Our order for a Fox ESS system is the battery's power button first, then the AC isolator, then the inverter's DC isolator, and the battery's DC MCB last if it has one, so the MCB is never switched under load. To turn it back on, go in reverse: battery DC MCB, DC isolator, AC isolator, then the battery's power button. Read the full shutdown guide.
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Ready to fix your Fox ESS system?

Tell us what's happening. We'll review your details and come back with a clear diagnosis path, usually the same day.

  • Not affiliated with or endorsed by Fox ESS
  • No fix, no fee covers remote fixes. On-site work is quoted in writing before we start.
  • On-site visits available

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