Fox ESS Fault Code Index
Every Fox ESS inverter alarm from the official H1(G2) manual and Fox Cloud — what the fault code means, the most likely cause, and what to do next. Find your code below or browse by system area. Covers H1, H3, KH, and AC1 series.
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Fox ESS Fault Code Index
- Sourced from official Fox ESS H1(G2)/AC1(G2) user manual V1.0.8
- Linked to full diagnostic guides where available
- Covers H1, H3, KH, AC1, and T-series hybrid inverters
If your Fox ESS inverter is showing a fault code in Fox Cloud or the red LED is lit and you're unsure what to do next, a remote diagnostic identifies the root cause from your monitoring data — typically within 30 minutes.
Book free Fox ESS diagnosisHow diagnostics workI have a GivEnergy system consisting of two batteries, two inverters and a controlling EMS (Energy Management System) which has not worked since Nov 2025. After six months I discovered Solar Tech Support, reached out to them and Ron phoned me back – how often do you get that service? Could not be more helpful – worked directly with me over the phone, outside what I would call normal working hours. Lucid explanations and we were able to discuss the issues and history using camera and email history. As this was a very rare setup, Ron was able to access an EMS expert in the field to confirm the solution. One sunny day in, I am now only paying for standing charge and a few pence for spikes in grid consumption while battery catches up with house demand.
When my GivEnergy system had an issue, I was completely left without support and had honestly lost all hope. Thankfully, I searched online and found Ron, which completely turned things around. After sending him a message, he responded incredibly fast and called me to assure me that he would get the problem fixed. I really admire his dedicated, supportive nature and his determination to find a solution. With this kind of outstanding attitude and customer service, he has absolutely secured a future customer in me.
Ron want out of is way to help, nothing was to much. He was very thorough in what he did Very knowledgeable I would highly recommend Ron and his company He did a fantastic job for me. if you have any problems, he'll do his best to help you out and resolve your problem. I wouldn't hesitate to recommend them
Ron took me through a diagnostic to confirm my GivEnergy Inverter had a fault. A common one as it turns out with the AC Inverter. As GivEnergy is defunct there is no immediate fix, aside from sourcing 2nd hand replacement. It may be that a fix becomes available over the summer which would make a lot of GivEnergy customers happy (Again)
Contacted Ron with a problem and he sorted it out quickly with no problems at all. Very knowledgeable on anything solar/ batteries. I would recommend him to anyone
I've spoken to Ron a couple of times with issues with my Givenergy installation. Such a friendly knowledge guy very highly recommended. Thank you very much for resolving my issues
Contacted Solar Tech Support in desperation. After explaining the issues I had with my system a diagnosis was made and a solution proposed. Fantastic service, even contacted a manufacturer to arrange replacement parts for me. Great communications, explained all they were doing and what I had to do, clearly and precisly. Followed up to confirm all was ok. Excellent service.
After GivEnergy went into liquidation, just my luck, my battery started playing up (internal board crashed). Contacted my installer - not interested! Found Solar tech support on a Google search. Sooo glad I found this company! Ron is extremely helpful and has plenty of experience. He soon confirmed what the fault was, and helped me to get my system up and running again. Now moved my GivEnergy account to Solar tech support, and will definitely use again if I have more issues. Unusual to find such a helpful company in these times, no morons reading scripts, just direct contact with the engineer.
Contacted Solar Tech Support when trying to understand what my Givenergy inverter problem might be and what might be my options. Received good/honest advise which backed up my thoughts.
Ron is a super star. Two months ago my GivEnergy battery failed a firmware upgrade leaving it a brick. My installer couldn't/wouldn't fix it. GivEnergy couldn't/wouldn't fix it. Then they went into administration and all hope was lost. A flurry of emails later and Ron had diagnosed the fault (failed USB flash drive, something I'd suspected) and talked me through resolving it. Two months of nothing resolved in about 3 hours. It's great to work with someone who pays attention to the details, knows that they're doing (not just following a script) and gets stuff sorted without a fuss or up-charging.
I can add to the list of customers who had already 'given up' on GivEnergy due to their appalling customer service, and that was before they went into administration (their Trustpilot reviews don't lie!). So you can imagine my desperation when, having changed my ISP and my Inverter, predictably, proving to be the only device that didn't connect automatically to my new network, I found zero prospect of any customer support with GivEnergy having called in the administrators just five days earlier! The salvation came from Solar Tech Support. My IT advisor stumbled across their web site and some very helpful tips for beleaguered GivEnergy customers, as well as an offer to provide direct assistance. Nothing ventured, I decided to drop them an E-Mail, with very low expectations based on my experience of GivEnergy customer support. Within an hour Ron had responded with some pin point advice, and after a few exchanges of E-Mails he had nailed the problem, enabling the combined efforts of my IT advisor and solar installer to resolve it and reconnect my Inverter. Thank you Solar Tech Support, and Ron in particular, for coming to the aid of a deserted and despondent GivEnergy customer. Expert, razor sharp advice and first class customer service, even though I wasn't officially a customer.
This company are a rare gem, I had a very unusual problem following a failed firmware upgrade on my GivEnergy kit. I then found out GivEnergy were in administration and had dismissed all their support staff! None of the usual fixes to try and restore my inverter comms would work, and I looked everywhere, forums, GivEnergy youtube support videos - even AI couldn't figure it out. My installer was talking about huge sums for system replacements, and being vague / evasive about if they'd even install replacement GivEnergy inverter. Enter Solar Tech Support, reassuring and knowledgeable from the very start, I've learnt loads about my solar system though the friendly chat while my engineer worked as he diagnosed the problem and figured out a fix procedure that I've not found anywhere else - amazing . If you need solar system repairs - especially if you like me have been left high and dry by GivEnergy, I cannot recommend this company enough. Give them a call.
I sent a message on their website regarding a problem I have on my Givenergy system. Although not supplied by Ronald, I thought it was worth an email. Within the hour on a Saturday, he phoned and we discussed the problem. He logged in remotely and gave excellent advice. I'm too far away for his on-site help but he did diagnose the problem and was happy also to chat through my thoughts about an upcoming solar/battery install I'm planning. Great bloke.... if only he was nearer!
I have a GivEnergy system consisting of two batteries, two inverters and a controlling EMS (Energy Management System) which has not worked since Nov 2025. After six months I discovered Solar Tech Support, reached out to them and Ron phoned me back – how often do you get that service? Could not be more helpful – worked directly with me over the phone, outside what I would call normal working hours. Lucid explanations and we were able to discuss the issues and history using camera and email history. As this was a very rare setup, Ron was able to access an EMS expert in the field to confirm the solution. One sunny day in, I am now only paying for standing charge and a few pence for spikes in grid consumption while battery catches up with house demand.
When my GivEnergy system had an issue, I was completely left without support and had honestly lost all hope. Thankfully, I searched online and found Ron, which completely turned things around. After sending him a message, he responded incredibly fast and called me to assure me that he would get the problem fixed. I really admire his dedicated, supportive nature and his determination to find a solution. With this kind of outstanding attitude and customer service, he has absolutely secured a future customer in me.
Ron want out of is way to help, nothing was to much. He was very thorough in what he did Very knowledgeable I would highly recommend Ron and his company He did a fantastic job for me. if you have any problems, he'll do his best to help you out and resolve your problem. I wouldn't hesitate to recommend them
Ron took me through a diagnostic to confirm my GivEnergy Inverter had a fault. A common one as it turns out with the AC Inverter. As GivEnergy is defunct there is no immediate fix, aside from sourcing 2nd hand replacement. It may be that a fix becomes available over the summer which would make a lot of GivEnergy customers happy (Again)
Contacted Ron with a problem and he sorted it out quickly with no problems at all. Very knowledgeable on anything solar/ batteries. I would recommend him to anyone
I've spoken to Ron a couple of times with issues with my Givenergy installation. Such a friendly knowledge guy very highly recommended. Thank you very much for resolving my issues
Contacted Solar Tech Support in desperation. After explaining the issues I had with my system a diagnosis was made and a solution proposed. Fantastic service, even contacted a manufacturer to arrange replacement parts for me. Great communications, explained all they were doing and what I had to do, clearly and precisly. Followed up to confirm all was ok. Excellent service.
After GivEnergy went into liquidation, just my luck, my battery started playing up (internal board crashed). Contacted my installer - not interested! Found Solar tech support on a Google search. Sooo glad I found this company! Ron is extremely helpful and has plenty of experience. He soon confirmed what the fault was, and helped me to get my system up and running again. Now moved my GivEnergy account to Solar tech support, and will definitely use again if I have more issues. Unusual to find such a helpful company in these times, no morons reading scripts, just direct contact with the engineer.
Contacted Solar Tech Support when trying to understand what my Givenergy inverter problem might be and what might be my options. Received good/honest advise which backed up my thoughts.
Ron is a super star. Two months ago my GivEnergy battery failed a firmware upgrade leaving it a brick. My installer couldn't/wouldn't fix it. GivEnergy couldn't/wouldn't fix it. Then they went into administration and all hope was lost. A flurry of emails later and Ron had diagnosed the fault (failed USB flash drive, something I'd suspected) and talked me through resolving it. Two months of nothing resolved in about 3 hours. It's great to work with someone who pays attention to the details, knows that they're doing (not just following a script) and gets stuff sorted without a fuss or up-charging.
I can add to the list of customers who had already 'given up' on GivEnergy due to their appalling customer service, and that was before they went into administration (their Trustpilot reviews don't lie!). So you can imagine my desperation when, having changed my ISP and my Inverter, predictably, proving to be the only device that didn't connect automatically to my new network, I found zero prospect of any customer support with GivEnergy having called in the administrators just five days earlier! The salvation came from Solar Tech Support. My IT advisor stumbled across their web site and some very helpful tips for beleaguered GivEnergy customers, as well as an offer to provide direct assistance. Nothing ventured, I decided to drop them an E-Mail, with very low expectations based on my experience of GivEnergy customer support. Within an hour Ron had responded with some pin point advice, and after a few exchanges of E-Mails he had nailed the problem, enabling the combined efforts of my IT advisor and solar installer to resolve it and reconnect my Inverter. Thank you Solar Tech Support, and Ron in particular, for coming to the aid of a deserted and despondent GivEnergy customer. Expert, razor sharp advice and first class customer service, even though I wasn't officially a customer.
This company are a rare gem, I had a very unusual problem following a failed firmware upgrade on my GivEnergy kit. I then found out GivEnergy were in administration and had dismissed all their support staff! None of the usual fixes to try and restore my inverter comms would work, and I looked everywhere, forums, GivEnergy youtube support videos - even AI couldn't figure it out. My installer was talking about huge sums for system replacements, and being vague / evasive about if they'd even install replacement GivEnergy inverter. Enter Solar Tech Support, reassuring and knowledgeable from the very start, I've learnt loads about my solar system though the friendly chat while my engineer worked as he diagnosed the problem and figured out a fix procedure that I've not found anywhere else - amazing . If you need solar system repairs - especially if you like me have been left high and dry by GivEnergy, I cannot recommend this company enough. Give them a call.
I sent a message on their website regarding a problem I have on my Givenergy system. Although not supplied by Ronald, I thought it was worth an email. Within the hour on a Saturday, he phoned and we discussed the problem. He logged in remotely and gave excellent advice. I'm too far away for his on-site help but he did diagnose the problem and was happy also to chat through my thoughts about an upcoming solar/battery install I'm planning. Great bloke.... if only he was nearer!
Fault codes triggered by mains supply conditions — voltage out of range, frequency shifts, or total grid loss. The inverter disconnects automatically and attempts to reconnect once conditions return to normal. Grid Lost, Grid Volt, and Grid Freq faults frequently appear together during the same grid event.
Grid Lost Fault
Fox Cloud Error -1 — no AC supply
Grid Volt Fault
Fox Cloud Error 26 — voltage out of range
Grid Freq Fault
Fox Cloud Error 27 — frequency out of range
10min Volt Fault
Fox Cloud Error 28 — sustained overvoltage
Over Load Fault
On-grid overload
Safety-critical fault codes related to insulation resistance, residual current detection, earth connections, and arc faults. These cause the inverter to shut down immediately to protect people and property. Do not repeatedly clear these without investigation.
Iso Fault
⚠ Fox Cloud Error 3 — insulation fault
DCI Fault
⚠ DC component in AC output
Ground Fault
⚠ Earth connection failed
Res Cur Fault
Residual current high — software detection
Res Cur HW Fault
Residual current detection device failed
Fault codes related to the PV string inputs — voltage out of range, overcurrent, and reversed polarity. These typically cause the inverter to stop generating from solar while battery and grid functions may continue.
Pv Volt Fault
PV string voltage out of range
SW Pv Cur Fault
Software — PV input current high
HW Pv Cur Fault
Hardware — PV input current high
PvCon Dir Fault
⚠ PV connection reversed
Fault codes related to the battery management system, battery voltage and current conditions, relay status, and temperature protection. These apply to Fox ESS ECS, HV2600, and compatible third-party batteries connected via the BMS communication bus.
BMS Lost
Fox Cloud Error 14 — BMS comms interrupted
Bms Ext Fault
External BMS communication interrupted
Bms Int Fault
Internal BMS — DIP switch or inter-battery comms
Bat Volt Fault
Battery voltage out of range
SW Bat Cur Fault
Software — battery current high
HW Bat Cur Fault
Hardware — battery current high
Bat Power Low
Battery charge depleted
BatCon Dir Fault
⚠ Battery connection reversed
Bat Relay Open
Battery relay stuck open
Bat Relay Short Circuit
Battery relay stuck closed
Bat Buck Fault / Bat Boost Fault
Battery DC-DC converter MOSFET failure
Internal inverter faults related to the DC bus voltage, AC output current, power electronics, temperature, and firmware. Fox ESS fault codes distinguish between SW (software-detected) and HW (hardware-detected) variants — HW faults are generally more severe.
SW Bus Vol Fault
Software — DC bus voltage out of range
HW Bus Vol Fault
Hardware — DC bus voltage out of range
SW Inv Cur Fault / HW Inv Cur Fault
AC output overcurrent — software / hardware
Temp Fault
Inverter over temperature
Inv EEPROM Fault / ARM EEPROM Fault
Internal memory fault — inverter / manager
MDSP Smpl Fault / RDSP Smpl Fault
Master/slave sample detection circuit failed
Fault codes related to the inverter's internal grid relays and the Emergency Power Supply (EPS / backup) circuit. Relay faults are typically hardware failures requiring professional repair. EPS faults relate to the backup power function during grid outages.
Main Relay Open
Grid relay stuck open
S1 / S2 / M1 / M2 Close Fault
Grid relay stuck closed
Eps Relay Fault
EPS transfer relay failed
Eps Over Load
EPS backup circuit overloaded
Faults related to communication between the inverter's internal control boards, the external electricity meter, and consistency checks between master and slave processors. These are mostly internal hardware faults that require a power cycle followed by professional diagnosis if persistent.
Meter Lost Fault
Fox Cloud Error 242 — meter comms lost
SCI Fault
Fox Cloud Error 11 — master/manager comms
MDSP SPI Fault / RDSP SPI Fault
Master/slave SPI communication failed
GridV / GridF / Dci / Rc Cons Fault
Master/slave measurement consistency
Fox ESS add new fault codes with firmware updates, and some codes vary between H1, H3, KH, and T-series models. If your code isn't listed, share the exact text from the inverter LCD or Fox Cloud alarm log and we'll identify it. The Fox ESS community forum at foxesscommunity.com is also a useful resource.
Full diagnostic — DIP switch, RS485 cable, V1/V2 battery compatibility, firmware updates, and power cycle.
MCB checks, grid voltage readings, DNO voltage issues, and export limit configuration.
System mode, charge schedules, temperature limits, and CT clamp direction.
EPS enable, wiring, backed-up circuits, SOC limits, and overload protection.
Dongle LED, WiFi configuration, data gaps, and meter communication loss.
Fox ESS fault code questions
Got an error code and need it diagnosed?
Share the exact fault code from Fox Cloud or the inverter LCD, describe what the system is doing, and when the fault first appeared. We'll identify the cause and tell you whether it needs a remote settings fix or a site visit.
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- Written report with cause and recommended action
Got a solar fault or need a quick answer? Drop us a message — we usually reply within a few minutes. Mon–Fri, 9am–7pm.