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Fault code index · Sunsynk inverter and battery

Sunsynk Fault Code Index

Every Sunsynk fault code from the inverter display and SolarMan portal — what it means, the most likely cause, and what to do. Find your code in the index below or use the category sections to browse by system area.

Sourced from official Sunsynk fault code document (v1.0) Covers hybrid and battery-only models SolarMan + inverter display codes

Sunsynk Fault Code Index

Every Sunsynk fault code from the inverter display and SolarMan portal — what it means, the most likely cause, and what to do. Find your code in the index below or use the category sections to browse by system area.
  • Sourced from official Sunsynk fault code document (v1.0)
  • Covers hybrid and battery-only models
  • SolarMan + inverter display codes
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5.0
13 Trustpilot reviews
Trustpilot Google

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.

Ian · May 2026 Trustpilot

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.

Sree · May 2026 Trustpilot

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

Dennis Brown · May 2026 Trustpilot

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)

Tony Deacon · May 2026 Trustpilot

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

Phill · May 2026 Trustpilot

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

michael fairhurst · May 2026 Trustpilot

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.

Mr Machin · May 2026 Trustpilot

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.

Keith Ballard · Apr 2026 Trustpilot

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.

Hugh Speirs · Apr 2026 Trustpilot

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.

Christopher · Apr 2026 Trustpilot

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.

customer · Apr 2026 Trustpilot

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.

Andy Thomas · Apr 2026 Trustpilot

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!

Philip · Apr 2026 Trustpilot

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.

Ian · May 2026 Trustpilot

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.

Sree · May 2026 Trustpilot

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

Dennis Brown · May 2026 Trustpilot

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)

Tony Deacon · May 2026 Trustpilot

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

Phill · May 2026 Trustpilot

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

michael fairhurst · May 2026 Trustpilot

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.

Mr Machin · May 2026 Trustpilot

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.

Keith Ballard · Apr 2026 Trustpilot

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.

Hugh Speirs · Apr 2026 Trustpilot

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.

Christopher · Apr 2026 Trustpilot

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.

customer · Apr 2026 Trustpilot

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.

Andy Thomas · Apr 2026 Trustpilot

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!

Philip · Apr 2026 Trustpilot
How to find your fault code. Sunsynk fault codes appear on the inverter LCD display and in the SolarMan (formerly SolarmanPV) portal under Device > Status or in the alarm/event log. The code format is a short alphanumeric string or a description string (e.g. "Grid Lost", "Battery Low Voltage"). Share the exact code text from the screen or portal when booking.
Inverter faults

Fault codes generated by the Sunsynk inverter in response to DC overvoltage, temperature, or relay failures.

F01 / DC_Inversed_Failure ⚠ PV polarity reversed
PV panels or string connected with reversed polarity — DC positive and negative cables swapped. Do not touch DC wiring. Requires engineer to check and correct DC string wiring. This is a safety fault; the inverter will not operate until corrected.
F02 / DC_Insulation_Failure ⚠ Insulation fault
Insulation resistance between the DC circuit and earth is below the safe minimum. Common causes: damaged or degraded cable insulation, water ingress into a junction box or connector, or a faulty panel. Do not touch DC cabling. Requires engineer inspection and insulation resistance testing.
F03 / GFDI_Failure ⚠ Ground fault / leakage current
Ground fault detector interrupt has tripped — excessive leakage current detected on the DC side. Can indicate a damaged panel, connector failure, or cable fault. Do not touch DC wiring. Requires engineer diagnosis.
F04 / GFDI_Ground_Failure ⚠ Ground fault detected
Ground fault confirmed on DC circuit — current flowing through an unintended earth path. Closely related to F03; triggered when the GFDI relay confirms a persistent fault. Do not touch DC wiring. Requires engineer.
F05 / EEPROM_Read_Failure Internal memory fault
Inverter cannot read from its internal EEPROM memory — typically a hardware fault. Try a full power cycle (AC and DC off, wait 2 minutes). If the fault persists the inverter will require a service call or control board replacement.
F09 / IGBT_Failure ⚠ Power module fault
The inverter's IGBT (insulated-gate bipolar transistor) power switching module has failed. This is a hardware fault requiring engineer attendance. The inverter will not operate. A power cycle is unlikely to resolve this — the unit typically requires workshop repair or replacement.
F64 / HeatSink_HighTemp_Fault Inverter over temperature
Heatsink temperature too high. Check ventilation clearances — minimum 20cm from walls, not in direct sunlight, not enclosed in a sealed cabinet. Clear dust from heatsink vents. If ambient temperature is within range and vents are clear, the cooling fan or thermal sensor may be faulty.
Grid / G98 faults

Grid connection codes and events triggered by G98/G99 grid code settings. These are protection functions that disconnect the inverter during grid faults.

F35 / AC_NoUtility_Fault Grid absent / no AC supply
No AC grid detected — the inverter has lost its grid supply. Check the AC isolator and consumer unit main switch. If the mains supply is confirmed present at the distribution board, the AC wiring to the inverter or the internal grid relay may be faulty. The inverter reconnects automatically once grid is restored.
F43 / AC_VW_OverVolt_Fault Grid over voltage
Grid voltage above upper threshold. The inverter disconnects to protect itself and comply with G98/G99 requirements. Transient events reconnect automatically after 60–120 seconds. Recurring faults indicate a persistent high-voltage grid issue — contact your DNO.
F44 / AC_VW_UnderVolt_Fault Grid under voltage
Grid voltage below lower threshold. Check AC isolator and connections. If grid voltage is confirmed low from the DNO supply, contact your network operator. Transient dips reconnect automatically.
F47 / AC_OverFreq_Fault Over-frequency disconnect
Grid frequency above limit (typically above 51Hz in the UK). Transient; the inverter disconnects and reconnects automatically when frequency returns to range. Frequent occurrences should be reported to the DNO.
F48 / AC_UnderFreq_Fault Under-frequency disconnect
Grid frequency below limit (typically below 47Hz in the UK). Transient; the inverter reconnects automatically once frequency recovers. Frequent occurrences should be reported to the DNO.
Grid code fault Grid code mismatch
Inverter grid code setting does not match region. The Sunsynk must be set to UK grid code (G98/G99). Requires SetApp or engineer access to reconfigure.
Battery faults

Fault codes related to battery voltage, BMS communication, and battery protection events.

F56 / DC_Bus_Bar_Voltage_Too_Low Battery / DC bus voltage low
DC bus voltage is too low — one of the most common Sunsynk faults in the UK. Usually caused by the battery being fully depleted or the BMS shutting down after a protection event. Ensure the battery is switched on and the DC breaker between inverter and battery is closed. Allow a charge cycle. If voltage doesn't recover, BMS protection may have latched — a full power cycle (battery off at isolator, wait 60 seconds, back on) is often required.
F54 / BAT_HighVolt_Fault Battery over voltage
Battery voltage above safe maximum. The BMS will typically disconnect the battery in this state. Do not attempt further charging. Contact Sunsynk support — this may indicate a BMS calibration issue or a cell imbalance fault.
F58 / BMS_Comm_Fault BMS communication lost
Inverter has lost communication with the battery BMS. Check CAN or RS485 communication cable between inverter and battery — a loose connector is the most common cause. Power cycle inverter and battery (off, wait 60 seconds). Check firmware versions are compatible. If the fault returns after a successful power cycle, the cable or BMS port may be faulty.
Battery over current Current exceeded BMS limit
Charge or discharge current exceeds BMS limit. May indicate a cell imbalance or BMS fault. Requires engineer.
EPS / backup faults

Fault codes related to EPS (Emergency Power Supply) backup function.

EPS over load Load exceeds EPS rating
Load on EPS backup circuit exceeds inverter EPS rating. Remove high-draw appliances from backup circuit. EPS circuit is typically rated at 3–6kW — not suitable for cookers, electric showers, or EV chargers.
EPS under voltage Output voltage low
EPS output voltage collapsed, usually due to overload or a wiring fault on the EPS circuit. Check backup circuit wiring and reduce load.
Communication faults

Faults related to data communication between inverter and monitoring portal, and with system components.

W04 / Meter_Comm_Fail Meter offline
Inverter cannot communicate with the export meter (RS485 meter) or cannot read the CT clamp. Check meter cable connections at both the inverter and meter ends. If using a CT clamp, confirm it is correctly clamped around the incoming supply cable and the cable is intact.
W05 / CT_Wrong_Direction_Warn CT clamp reversed
CT clamp is installed facing the wrong direction. This causes the inverter to misread import and export — it may export when it should import, or vice versa, resulting in wasted energy or grid export when battery should be charging. The CT clamp must be rotated 180° to face toward the consumer unit. Requires engineer correction.
SolarMan data gap Portal not receiving data
Portal shows no data. Check WiFi logger (WLAN-Logger or similar) LED — flashing indicates WiFi disconnection. Reconfigure WiFi via the SolarMan app if needed.
Code not listed here?

Sunsynk releases firmware updates that may introduce new fault codes. If your code isn't listed, share the exact code from your inverter display or SolarMan and we'll identify it.

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FAQ

Sunsynk fault code questions

Sunsynk fault codes appear on the inverter LCD display and in the SolarMan (formerly SolarmanPV) portal under Device > Status or in the alarm/event log. The SolarMan app shows the fault history including timestamps. Note the exact fault code or description text — including the F-code number if shown — before contacting support.
A BMS communication lost fault means the inverter has stopped receiving data from the battery management system. This is commonly caused by a loose or disconnected CAN or RS485 cable between the inverter and battery, a firmware version mismatch, or a BMS fault state after a protection event. Try a full power cycle (inverter and battery off, wait 60 seconds) as a first step. If the fault returns, check cable connections and contact support with the exact fault code.
A grid code fault usually means the inverter's grid code setting doesn't match the local grid requirements. In the UK, Sunsynk inverters must be configured for G98 (systems ≤3.68kW) or G99 (systems >3.68kW). An incorrect grid code setting can cause the inverter to trip off repeatedly. This setting requires a qualified installer or engineer to change — it is not accessible to end users.
Some Sunsynk fault codes triggered during power cuts are temporary and clear once the grid returns. If the code persists after grid restoration, a free remote diagnostic (no fix, no fee) can determine whether there's an underlying issue with your EPS or battery configuration.
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Got a fault code and need it diagnosed?

Share the exact fault code from your inverter display or SolarMan, what the system is doing, and when it started. We'll identify the cause and tell you whether it needs a remote settings fix or a site visit.

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