Skip to content
07944 877 329 hello@solar-tech-support.co.uk
Alectrona Get a quote
Fault code index · SolaX X-Hybrid all models

SolaX Fault Code Index

Every SolaX X-Hybrid inverter and T-BAT / Triple Power battery fault code — 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.
Free remote diagnostic £125 only if we fix it remotely
Book SolaX diagnosisAll fault codes
  • X1-Hybrid, X3-Hybrid, X1-Boost & X3-Mega
  • T-BAT & Triple Power battery codes included
  • Sourced from SolaX technical documentation
SolaX fault you can't resolve?

If your SolaX inverter or battery is showing a fault code and you need expert diagnosis, a remote diagnostic reviews your SolaX Cloud data and identifies the cause — usually within 30 minutes.

Book free SolaX diagnosisHow diagnostics work
5.0
Rated 5.0 on Google Read all 151 reviews

We decided to treat ourselves to an upgrade to our existing solar system, and after a little searching, it became evident that Ron and his team provide the service and support we required. Decommissioning and recommissioning our new SunSynk inverter and a wall-mounted Fogstar battery (which is of substantial size and weight compared to the original) was completed swiftly and competently. The installation was perfectly executed, and all upgraded paperwork for the increased battery export capacity was handled by Ron. I have no hesitation in recommending this team of support technicians to you.

Iain Donkin · Sep 2026 Google

Ronald at Solar Tech Support was very quick and knowledgeable in helping me restart my GivEnergy solar electric battery. I would highly recommend his services.

Thomas Croke · Aug 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

Ron was very knowledgeable and patient as we worked through the cause of Givenergy Hybrid Inverter suddenly failing (with 0W grid). He was able to quickly identify the probable cause, and point me in the right direction to identify the ‘burnt out’ AC isolator switch & piece of cable, which I was able to find a local electrician to replace. The best £95 I have spent. Thanks Ron.

Martin Smith · Aug 2026 Trustpilot

Our SolarEdge PV system with LG batteries had its first hiccup after 8 years of hard work. The Inverter failed. Fortunately I found Solar-Tech-Support who diagnosed the problem very quickly, ordered a replacement unit and fitted it shortly after we received the unit from SolarEdge. Very thorough and professional approach. Thank you, a solid 5 star recommendation.

Les Bennett · Jun 2026 Google

What an absolute star. Ron went well beyond what i would have hoped for. His attention to detail was incredible, even making good the work of others.

Miles Gladson · Sep 2026 Google

Written by · Independent Solar Engineer Last updated

How to find your fault code. SolaX fault codes appear on the inverter LCD display and in the SolaX Cloud app under the fault or alarm history. Grid and inverter faults use short names (Grid Volt, PLL Lost, Isolation). Battery charger faults are prefixed with C1 (e.g. C1 CAN, C1 TEMP). BMS faults use the BMS_ prefix. Match your code to the categories below.

Grid & AC faults

Fault codes triggered when grid voltage or frequency is outside safe limits, or the grid connection is lost. The inverter disconnects as required by UK grid codes G98/G99 and reconnects automatically when conditions normalise.

Grid Volt / E012 Most common
Grid voltage outside the inverter's UK protection limits. Almost always overvoltage during peak solar export: a 10-minute average above 253V, or above 262.2V for 1 second. The inverter reconnects automatically when voltage drops. If recurring every sunny afternoon, this is a network issue — report to your DNO and consider export limitation.
Grid FreqGrid frequency error
Grid frequency outside the safe range (47.5Hz–52Hz). Caused by grid instability, not an inverter fault. The inverter reconnects automatically when frequency normalises. Single events after storms or outages are normal. Recurring events suggest a weak grid connection.
Grid Lost / IE02No grid connection detected
Inverter cannot measure grid voltage at all. Check: AC isolator is on, consumer unit breaker for the solar circuit has not tripped, AC cable connections at the inverter are tight. If mains power is present and all connections are secure, the internal grid relay may be faulty.
PLL LostGrid sync failure
The inverter lost synchronisation with the grid frequency — it could not maintain a stable phase lock. Often occurs during grid instability after storms or power cuts. Usually clears within minutes. If persistent, check AC wiring and neutral connections.
AC5M VoltVoltage out of range 5 min
Grid voltage has been outside the acceptable range for more than five consecutive minutes. The inverter has shut down to protect itself. More serious than a brief Grid Volt trip — suggests a sustained grid voltage problem. Check SolaX Cloud for the voltage reading and contact your DNO.
AC10M VoltVoltage out of range 10 min
Grid voltage has been outside specification for more than ten minutes. The grid at your property is persistently unstable. This requires DNO investigation — the distribution network may need reinforcement or the transformer tap may need adjusting.
Grid RelayInternal relay fault
Internal grid relay switch malfunction. Can be caused by a poorly connected neutral line or three-phase unbalance on X3-Hybrid systems. Try a full power cycle first. If the fault returns, the relay or inverter may need replacement — contact an engineer.

DC & Insulation faults

Fault codes related to the DC solar input — panel voltage, insulation resistance, and PV array configuration. Isolation faults are safety-critical and should not be restarted without inspection.

PV VoltPV voltage error
DC input voltage from the solar panels is outside the acceptable range — either too high (too many panels in series) or too low (insufficient sunlight, DC isolator off, or a broken string). Check the DC isolator is on and MC4 connections are secure. If voltage is above the inverter's maximum input rating, the string design needs reviewing by an installer.
Isolation URGENT — do not restart
Insulation resistance between the DC circuit and earth has dropped below the safe threshold. This is a safety-critical fault — electricity is leaking from the DC wiring. Do not restart the system. Common causes: water ingress at MC4 connectors, damaged cable insulation, or a faulty panel junction box. Contact a qualified engineer for inspection before any restart.
PV Config.PV array configuration error
The PV array configuration in the inverter settings does not match the physical panel connections. This can occur after a panel replacement or if the string configuration was changed without updating the inverter settings. Check MPPT input assignments and PV configuration in the inverter menu.

Internal inverter faults

Fault codes originating from inside the inverter — processor communication, cooling, overcurrent protection, and memory errors. Try a full power cycle first. If the fault returns, the inverter needs professional diagnosis.

SPISPI communication fault
Internal processor communication error. The inverter's internal components have lost synchronisation. Perform a full power cycle — AC off, DC off, wait 60 seconds, DC on, AC on. If the fault returns, the control board may need firmware reflash or replacement.
SCISCI communication fault
Internal SCI serial communication has failed. Similar to SPI — an internal processor issue. Power cycle the system. If persistent, the main control board or DSP may need replacement. This is not user-serviceable.
Bus VoltDC bus voltage out of range
The internal DC bus voltage is too high or too low. This is the voltage on the inverter's internal power conversion stage — not the panel input. Often caused by a grid voltage spike or a transient event. Power cycle first. If persistent, the inverter's power stage may be failing.
Inv OCPOvercurrent protection
Inverter has detected current above the safe limit on the AC output. May self-clear after a brief overload event. If persistent, check for a short on the AC output wiring or an internal inverter fault. Do not keep restarting if the fault returns immediately.
Temp OverOvertemperature shutdown
Internal temperature has exceeded the thermal shutdown threshold. Check ventilation clearances (minimum 20cm all sides), ensure no direct sunlight on the inverter, and clear any dust from cooling vents. If the environment is cool and ventilation is adequate, the internal temperature sensor may be faulty.
Fan1 / Fan2Cooling fan failure
One or both internal cooling fans are not spinning or running at an abnormal speed. The inverter will derate or shut down to prevent overheating. Check for debris blocking the fan intake. If the fan has seized, it needs replacement — this is a common wear item on older X-Hybrid units.
RelayRelay malfunction
Internal relay switch has failed its self-test. The inverter cannot safely connect to the grid. Power cycle first. If the fault returns, the relay has worn out or failed — the inverter needs professional repair or replacement. This is more common on older units with high switching cycles.
RCDResidual current device fault
The inverter's internal RCD has detected a leakage current. This is a safety protection — do not ignore it. It may indicate an earth fault on the AC side. Check AC wiring connections. If persistent, the inverter or the AC wiring needs professional inspection.
Inv. EEPROMInternal memory fault
The inverter's EEPROM memory chip has experienced an error. Settings or calibration data may be corrupted. A firmware reflash may resolve the issue. If the fault persists after a power cycle, the control board likely needs replacement.
SampleDetection circuit failure
The inverter's internal voltage or current detection circuit has failed its self-check. The inverter cannot accurately measure its own output and has shut down as a safety measure. Requires professional diagnosis — the measurement circuits may need recalibration or the control board may be faulty.
TZ ProtectOvercurrent protection triggered
The inverter's internal overcurrent protection mechanism has been activated. Similar to Inv OCP but triggered by the hardware protection circuit rather than the software limit. Power cycle first. If persistent, the output stage or power components may be damaged.
DCI DeviceDC injection device fault
The DC injection monitoring circuit has detected a fault. This safety circuit ensures no DC current enters the AC grid. A power cycle may clear a transient fault. If persistent, the DCI monitoring hardware needs professional inspection.
RTCReal-time clock fault
The inverter's internal clock has malfunctioned. This can cause ForceTime and TOU schedules to run at the wrong time, and SolaX Cloud timestamps to be incorrect. A power cycle and clock resync via SolaX Cloud usually resolves this. If persistent, the RTC battery on the control board may need replacing.

Battery charger faults (C1)

C1-prefixed codes relate to the battery charger circuit inside the X-Hybrid inverter. These affect battery charging and discharging but solar generation to the grid may continue.

C1 CAN Common — battery comms lost
Communication between the inverter and battery via CAN bus has failed. The most common cause is a loose CAN cable, wrong battery type selected in inverter settings (T-BAT vs Triple Power), or a missing termination resistor. See our BMS communication fault guide.
C1 TEMPCharger overtemperature
The battery charger circuit inside the inverter is running too hot. Check ventilation clearances and ambient temperature. If the inverter is in a confined space or exposed to direct sunlight, relocating or improving airflow may resolve the issue. The charger will resume when temperature drops.
C1 FANCharger fan failure
The cooling fan for the battery charger section is not working. Dust or debris may be blocking the fan. If the fan has seized, it needs replacement. Without cooling, the charger will overheat and stop charging the battery.
C1 Bat OVPBattery overvoltage
Battery voltage has exceeded the safe maximum. The charger has stopped to protect the battery cells. This can indicate a BMS fault, a cell imbalance, or incorrect battery settings. Do not keep restarting — the battery needs professional inspection to check cell voltages and BMS health.
C1 Bus OVPCharger bus overvoltage
The internal DC bus voltage in the charger circuit has exceeded the safe range. Often a transient event that clears with a power cycle. If persistent, the charger's power conversion stage may be failing and needs professional diagnosis.
C1 TZCharger protection triggered
Hardware overcurrent protection in the charger circuit has been activated. The charger has shut down to prevent damage. Power cycle first. If persistent, the charger's power components may be damaged — professional repair is needed.
C1 EEPROMCharger memory fault
The charger section's EEPROM memory has experienced an error. Calibration or configuration data may be corrupted. A firmware update may resolve the issue. If the fault persists after a power cycle, the charger control board needs attention.
C1 Temp LowCharger below min temperature
The charger is too cold to operate safely — the ambient temperature has dropped below the minimum operating threshold. Common in unheated garages or outbuildings during winter. The charger will resume when the temperature rises. Insulating or heating the space may help in cold climates.
C1 HCT1 / HCT2Charger current sensor fault
The current measurement sensor in the charger circuit has failed its self-check. The charger cannot accurately measure how much current is flowing to or from the battery. Professional repair needed — the sensor or control board may need replacement.
C1 Charger OCP / Boost OCPCharger overcurrent
Overcurrent detected in the charger or boost circuit. Too much current is flowing through the charging path. This can be caused by a battery fault, a short in the DC battery wiring, or a failing power component in the inverter. Power cycle first — if it returns, professional diagnosis is needed.

Battery BMS faults

BMS (Battery Management System) faults relate to the T-BAT or Triple Power battery itself — communication, isolation, relay, and internal errors. See our dedicated BMS fault guide for full diagnosis steps.

BMS_Lost Common — battery not detected
The inverter cannot detect the battery at all — the CAN bus communication link is completely down. Check the CAN cable at both ends, verify the battery type setting matches the installed hardware (T-BAT vs Triple Power), and check the 120Ω termination resistor is in place. See our BMS fault guide.
BMS_Internal_ErrBMS internal error
Usually caused by a DIP switch misconfiguration on stacked battery modules, or a loose CAN cable at the battery management unit. Check DIP switch positions match the number of modules installed (0 for one, 1 for two, 2 for three). Also check all inter-module RS485 cables on stacked systems.
BMS Relay FaultBMS relay failure
The battery's internal relay has failed. Try resetting the BMU (Battery Management Unit) by power cycling the battery. If the fault persists after restart, the BMU may need replacement. This is not user-serviceable — contact an engineer.
BMS_ISO FaultBattery isolation fault
Insulation resistance within the battery system has dropped below the safe threshold. This is a safety-critical fault — do not restart without professional inspection. Possible causes include water ingress into the battery enclosure, damaged internal wiring, or a failing battery cell.
BMS Circuit FaultBMS internal circuit failure
An internal circuit within the BMS has failed. Try a full battery power cycle — turn off the battery, wait 60 seconds, turn it back on. If the fault returns, the BMS control board needs replacement. This fault typically requires on-site repair.

Monitoring & metering faults

Faults related to the CT clamp, smart meter, EPS (backup) mode, and monitoring connectivity. These typically do not stop solar generation but may affect battery control, export limiting, or monitoring accuracy.

CTCT clamp / smart meter error
The current transformer (CT clamp) or smart meter connected to the inverter is not reading correctly. This affects export limitation accuracy and self-use calculations. Check the CT clamp is clamped around the correct cable, oriented in the right direction, and securely connected to the inverter's meter port. If using a smart meter instead of CT, check the RS485 connection.
AC HCTAC current sensor fault
The inverter's internal AC current sensor has failed. The inverter cannot accurately measure its own AC output. This is an internal hardware fault — the system will shut down as a safety measure. Professional repair or inverter replacement is needed.
Overload (EPS)EPS mode overload
Too much power is being drawn in Emergency Power Supply (backup) mode. The connected loads exceed the inverter's EPS output rating. Reduce the load on the backup circuit — disconnect high-power appliances. If EPS overload occurs during a power cut, the backup circuit may need redesigning to include only essential loads.
EPS RelayEPS relay failure
The relay that switches the inverter into backup mode has failed. The system will not provide backup power during a grid outage. Solar generation and grid-connected operation may still work normally. The EPS relay needs professional replacement.
EPS OCPEPS overcurrent
Overcurrent detected in the EPS output — more current is being drawn than the inverter can safely supply in backup mode. This is similar to Overload but triggered by the hardware protection. Reduce the load on the backup circuit immediately.
DM9000Network DSP fault
The network digital signal processor — responsible for the Pocket WiFi dongle communication — has malfunctioned. SolaX Cloud monitoring may go offline, but the system usually keeps running, so check the inverter's own screen. A power cycle usually clears this. If persistent, the communication module may need replacing.
Explore

More SolaX help

SolaX hub

SolaX fault code, grid frequency fault or BMS lost? Independent engineer decodes faults and fixes ForceTime charging. Free remote diagnostic.

See SolaX hub
All fault codes

Fault code guides for the main UK solar inverter and battery brands: what each code means and what to do next. Find your brand and your code below.

See all fault codes
FAQ

SolaX fault code questions

SolaX fault codes appear in two places: the inverter LCD shows the current fault name, and the SolaX Cloud app logs every fault event with a timestamp in the fault history. Log into SolaX Cloud, select your inverter, and check the fault or alarm history. Codes prefixed C1 relate to the battery charger circuit, BMS codes to battery communication, and Grid Volt or Grid Freq to mains supply conditions.
TZ Protect is the inverter's internal transient and over-current protection tripping. It is most often triggered by a sudden grid disturbance or a DC-side fault rather than the inverter itself. A single event usually clears with a full power cycle — AC off, DC off, wait 60 seconds, then restore in reverse order. If TZ Protect keeps returning, it points to a DC or hardware fault that needs proper diagnosis rather than repeated restarts.
The inverter self-tests its internal grid isolation relay every time it connects, and a Grid Relay Fault means that test failed. A one-off fault often clears on a power cycle and the inverter reconnects normally. A persistent Grid Relay Fault usually means the relay or its drive circuit has failed and the inverter needs a hardware repair — it should not be left running in that state.
C1 codes relate to the battery charger circuit inside the SolaX X-Hybrid. C1 CAN means inverter-to-battery communication has failed — check the CAN cable. C1 TEMP means the charger is overheating. C1 Bat OVP means battery voltage is too high, and C1 Bus OVP means the internal DC bus voltage is outside safe limits. Most C1 codes clear with a power cycle; if the fault returns, professional diagnosis is needed.
Grid faults like Grid Volt and Grid Freq clear on their own once mains conditions return to normal — no restart needed. For internal faults, a power cycle clears transient errors: shut down in this order: battery power button, AC isolator, then the DC/PV isolator. Wait at least 2 minutes, then RESTORE in the reverse order: AC isolator, DC/PV isolator, battery DC isolator, battery power button last. If the same fault returns after a restart it is persistent and needs diagnosis. Isolation (ISO) faults should not be repeatedly restarted without inspection.
A recurring Grid Volt fault on sunny afternoons means the mains voltage at your property exceeds 253V while local solar systems all export at once. The inverter disconnects because UK grid code requires it — correct behaviour, not a defect. Check SolaX Cloud for the voltage at disconnection; if it is consistently above 250V, report it to your Distribution Network Operator and consider configuring export limitation.
The remote diagnostic is free — we pull and interpret your full SolaX Cloud fault log and tell you the root cause. If we can fix it remotely (a settings, grid-code, or configuration issue) it is £125, and you only pay if we fix it. If it is a hardware fault such as a failed relay, charger, or battery module, we quote any on-site work first, from £295.
Usually the same day. Most SolaX faults are confirmed in a single 30-minute remote session — we read your SolaX Cloud fault history and live data while you describe what the inverter is doing. You get a written summary of the cause and the recommended fix straight after the call.

Can't find your SolaX fault code?

Our remote diagnostics service can pull and interpret your full SolaX Cloud fault log, identify the root cause, and provide a clear repair plan — without needing a site visit first.

  • Independent — not affiliated with SolaX Power
  • Full SolaX Cloud fault log analysis
  • Remote diagnosis before any site visit

By submitting you agree to be contacted about your diagnostic request. We don't share your data with 3rd parties.

Call 07944 877 329 Book free diagnostic