Prompt and useful support regarding my Sunsynk system lack of performance. Ronald simplified the technical issues to make them understandable. Many thanks, looking forward to follow up.
Patrick Keenan · May 2026
Fault code reference · AlphaESS SMILE inverter & battery
AlphaESS Error Code Reference
Every AlphaESS SMILE inverter error code and battery alarm — the numeric code, what triggered it, and whether you need an engineer or can resolve it yourself. Look up your code below or browse by system area.
Free remote diagnostic · pay only if we fix it — from £75 if remediable remotely
- Sourced from official AlphaESS SMILE5 maintenance manual
- Covers SMILE5, SMILE-S5, and SMILE-BAT series
- Includes inverter errors (100xxx) and system alarms (110xxx)
AlphaESS error code you can't resolve?
If your AlphaESS inverter is flashing red or showing a numeric error code and you're unsure what to do next, a remote diagnostic identifies the root cause from your Alpha Cloud data — typically within 30 minutes.
Book free AlphaESS diagnosisHow diagnostics workMassively massively recommended. We had a big battery array (49kW across three phases) put in four years ago. c £35k cost. It’s been a total nightmare for many reasons, not least 1. our installer being totally useless and unresponsive and 2. Givenergy, our battery supplier, going bust. Long story short it had never worked anywhere near properly despite countless hours on phones and emails; the best we’d achieved was one third of the batteries working. Rather than write it off, I asked a PM friend to try to source someone who could come on site and review and revive the system. He found Solar Tech Support and Ron. Ron assured us he was the man to get it going again. After so many years of pain, I was not convinced but, true to his word, five hours later it was up and running. Lovely chap, super knowledgeable with a support team to lean on who are also clearly super technical. I honestly didn’t think there was much chance of getting this array going ever again so was absolutely delighted when Ron and team pulled it off. Bravo!
Will Wynne · 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
Our 3 year old GivEnergy batteries froze. They were showing 0% on the app, but they were fully charged. Some how Ron took over our inverter and remotely cured the problem. We live in King’s Lynn, he is in Leeds I believe. Very grateful.
David Lewin · Jul 2026 Google
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
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
How to find your error code. On the inverter LCD, press ENT → Status to view active faults. In Alpha Cloud (cloud.alphaess.com), open My System and check alarm history. AlphaESS uses numeric codes — 100xxx codes are inverter errors (the system has stopped or limited operation), while 110xxx codes are alarms (warnings that may self-clear). Note the full number before searching this index.
Grid & AC faults
Fault codes triggered by mains supply conditions — voltage deviations, frequency shifts, grid loss, and relay failures. The inverter disconnects from the grid automatically when these protections activate.
100010 — Grid_relay_faultInverter error — grid relayThe grid relay inside the inverter has failed its self-test. If it occurs occasionally due to a short-term grid abnormality, the inverter recovers automatically. If it recurs frequently and the grid supply is normal, the internal relay may be damaged — contact AlphaESS support or book a diagnostic.
110004 — dc_power_alarmAlarm — grid overvoltage deratingThe inverter has entered a derating state due to high grid voltage. Check the grid voltage reading on the LCD or Alpha Cloud — if it is consistently above 253V, the issue is with the mains supply. Contact your DNO. Confirm the Level 1 overvoltage protection threshold with AlphaESS support if needed.
110021 — Grid Loss AlarmAlarm — no grid detectedNo mains supply detected. The inverter will resume automatically once the grid returns. If the alarm persists, confirm the AC breaker is on, the AC cable connections at the inverter are tight, and the consumer unit breaker for the solar circuit has not tripped. If the mains supply is present but the alarm continues, the inverter AC input circuit may be faulty.
110022 — Grid Volt AlarmAlarm — grid voltage out of rangeGrid voltage is outside the acceptable operating window. Check the grid cable connection is secure. Restart the inverter and monitor whether the alarm returns. If the grid supply is consistently high or low, contact your DNO — the inverter is protecting itself correctly. Grid overvoltage guide →
110023 — Grid Freq AlarmAlarm — grid frequency out of rangeGrid frequency has drifted outside the permitted range (typically 47.5–52Hz). The inverter disconnects as required by G98/G99 protection settings and will resume when the grid stabilises. If the alarm recurs frequently, contact your DNO. After obtaining permission, AlphaESS support can adjust the inverter grid protection parameters via the app.
110024 — 10min Grid Volt AlarmAlarm — sustained voltage deviationThe 10-minute sliding average of grid voltage has exceeded the allowable range. This is a more persistent overvoltage or undervoltage condition than a momentary spike. Check the grid voltage and the sliding average voltage protection settings in the inverter configuration.
110027 — LN Reverse Alarm Wiring fault — do not ignoreThe mains live and neutral wires are reversed at the inverter AC connection. This is a wiring fault that must be corrected by a qualified electrician — do not operate the system until the L/N polarity is corrected at the AC terminal block.
110059 — grid waveform abnormal alarmAlarm — waveform distortionThe grid AC waveform is distorted beyond acceptable limits. This is typically a short-term grid supply anomaly and the inverter will resume automatically. If it occurs frequently, contact your DNO and ask AlphaESS support to review the grid protection parameter settings via the app.
Solar / PV faults
Codes related to the DC input from solar panels — insulation resistance, string polarity, overvoltage from too many panels in series, and input detection failures.
100007 — Insulation_faultInverter error — insulation resistancePV string insulation resistance is below the safe threshold. Often caused by moisture on panel cables or junctions — check whether conditions are wet or humid. If the alarm occurs in dry weather, disconnect strings one at a time and power on to isolate the faulty string. Use a megohmmeter to test each string (normal reading is in the megohm range). Persistent insulation faults indicate degraded cable insulation or a damaged panel junction box.
100012 — PV_Reverse Polarity reversed — do not touch DCPV string cables are connected with reversed polarity. The positive and negative DC connectors are swapped. Switch off the PV isolator and do not touch DC cabling — a qualified engineer must reconnect the cables in the correct orientation.
110014 — Pv over voltageAlarm — PV string voltage too highThe open-circuit voltage of the PV string exceeds the maximum MPPT input voltage. Calculate the maximum open-circuit voltage at the lowest expected local temperature and compare it with the MPPT rating. If the string has too many panels in series, one or more panels will need to be removed or the string reconfigured.
110048 — No Pv Input AlarmAlarm — no solar generationNo PV input detected. If this occurs in weak light (early morning, dusk, heavy cloud) it is normal — the string voltage is simply too low to activate the MPPT tracker. If it occurs in good light, check for a short circuit or open circuit in the panel string connections. Verify the PV isolator is switched on and the string insulation resistance is adequate.
110049 — Input Power Limit AlarmAlarm — PV input power limitedPV input power has reached the inverter's maximum input capacity and is being clipped. This is normal behaviour in peak generation conditions — no action required. The inverter limits input power to protect its components.
Battery & BMS faults
Codes from the battery management system and the inverter's battery interface — covering overvoltage protection, undervoltage shutdown, communication loss, and overcurrent events during charging or discharging.
100025 — BAT_OVPInverter error — battery overvoltageBattery voltage has exceeded the safe upper limit. During initial installation, confirm the battery voltage is within the allowable range for the inverter model. If this occurs during normal operation, it may indicate a charging fault or BMS communication anomaly — check that battery wiring is secure and BMS communication is intact. A loose connection can cause voltage spikes that trigger this protection.
100026 — BAT_UVPInverter error — battery undervoltageBattery voltage has dropped below the minimum safe threshold. Confirm the battery voltage is within the allowable range and that both the inverter breaker and the battery switch are closed and on. If the alarm occurs during operation, check whether the breaker has tripped and whether the battery BMS is reporting any alarms of its own.
100027 — Battery_loseInverter error — battery not detectedThe inverter cannot detect the battery. Check that the battery DC wiring is connected correctly and securely, the DC switch is closed, and the BMS communication cable (RS485 or CAN) is in place. If the battery is powered on and the connections are correct, the BMS may have entered a lockout state — power cycle both the inverter and battery.
100030 — BAT1_discharge_OCPInverter error — battery overcurrentBattery discharge current has exceeded the protection limit. If the battery is over-discharged, reduce the backup load connected to the inverter and restart. Wait five minutes for the fault to automatically clear. If it persists, the battery or inverter may have a hardware issue requiring diagnosis.
110005 — Battery stops running alarmAlarm — battery shutdownThe battery has stopped operating due to a shutdown command. Contact AlphaESS support to restart the inverter and check whether it recovers. If the alarm clears after a restart but returns, unplug the communication module and confirm whether the alarm clears — if so, the communication module may need replacing.
Inverter & DC bus faults
Internal inverter errors related to the DC bus, output stage, and power electronics. Many of these recover automatically from transient grid disturbances — persistent occurrences indicate a hardware fault requiring professional diagnosis.
100005 — BUS_OVP1Inverter error — DC bus overvoltageInternal DC bus voltage has exceeded the safe limit. An occasional occurrence caused by a grid transient will recover automatically. If it persists, the inverter's internal voltage regulation is faulty — contact AlphaESS support for further diagnosis.
100038 — Output_DC_over_currentInverter error — DC output overcurrentDC output current has exceeded the protection threshold. A transient grid anomaly can trigger this — the inverter should recover automatically. If it continues to appear and the inverter cannot generate power normally, the output stage may be damaged. Contact AlphaESS support.
100041 — Output_DC_over_voltageInverter error — DC output overvoltageDC output voltage has exceeded the protection threshold. An occasional occurrence recovers automatically. If it persists and the inverter cannot generate power, the internal circuitry may be faulty — contact AlphaESS support for further investigation.
100046 — DC_Input_DisturbanceInverter error — DC input disruptionDisturbance detected on the DC input from the PV array. Occasional occurrences from grid transients recover automatically. If it persists, check DC cable connections and PV string integrity. Contact AlphaESS support if the fault continues after verification.
100054 — Dc_bus_undervoltInverter error — DC bus undervoltageInternal DC bus voltage has dropped below the operating minimum. An occasional occurrence will self-recover. Persistent faults indicate the inverter's internal power supply or voltage regulation has failed — contact AlphaESS support.
100166 — inverter circuit abnormalInverter error — internal circuit faultThe inverter circuit has failed to start normally or an internal flag is set. Try restarting the inverter. If it does not recover, contact AlphaESS support to remotely upgrade the firmware. As a last resort, fully power off the inverter (all breakers off, wait 5 minutes) and restart. If the fault still persists, the inverter requires professional inspection.
100167 — boost circuit abnormalInverter error — boost converter faultThe inverter's boost converter circuit is not functioning correctly. Contact AlphaESS support to try a remote firmware upgrade. If the inverter does not recover, fully power off, wait 5 minutes, and restart. Persistent faults indicate a hardware issue requiring professional repair.
110040 — Inv Volt Low AlarmAlarm — inverter voltage lowLow component voltage detected inside the inverter. In weak light conditions (dawn, dusk, heavy rain) this is normal and will clear when irradiance improves. If it occurs in good sunlight, check for a short circuit or open circuit in the PV string connections.
Backup / UPS faults
Faults related to the backup (UPS) output — the secondary AC output that powers essential loads during a grid outage. Overload and overvoltage protection events on this circuit.
100042 — Output_shortInverter error — output short circuitA short circuit has been detected on the backup output. Disconnect the backup load and restart the inverter. If the fault clears, the issue is with the connected appliance or the backup wiring — inspect the backup circuit for damage. If the fault cannot be cleared, the inverter output stage may be damaged.
100043 — Output_overloadInverter error — backup overloadedThe load connected to the backup output exceeds the inverter's UPS power rating. Check which appliances are connected to the backup circuit and remove high-draw items such as kettles, heaters, or electric ovens. Reduce the load, then restart the inverter or wait five minutes for the fault to auto-clear. If the fault persists after reducing the load, disconnect the backup load entirely and restart.
100052 — Backup_ovpInverter error — backup overvoltageOvervoltage detected on the backup output. An occasional occurrence will recover automatically. If persistent, the inverter's backup output voltage regulation may be faulty — contact AlphaESS support for further diagnosis.
110050 — Output Power Limit AlarmAlarm — output power limitedThe inverter's output power has reached its rated limit and is being capped. Restart the system and check whether the fault clears. If the fault cannot be cleared, the inverter output stage may need inspection — contact AlphaESS support.
Safety & protection
Ground fault detection, arc fault protection, insulation monitoring, overtemperature shutdown, and fan failure alarms. These codes indicate safety-critical conditions — some require the system to be isolated before any inspection.
100008 — GFCI_fault Ground fault — isolate systemGround fault current detected. If accompanied by an insulation resistance alarm (100007), follow the insulation fault troubleshooting steps first. If it occurs frequently with other alarms and the inverter cannot connect to the grid, the GFCI circuit inside the inverter may be faulty — do not restart without professional assessment.
100058 — AFCI_check_protectInverter error — arc fault protectionThe arc fault detection circuit has triggered. Restart the system and check whether the fault persists. If it does, a DC arc may be present in the PV string or battery cabling — do not touch DC connectors. Contact a qualified engineer to inspect all DC connections for signs of arcing, melting, or discolouration.
110006 — over_temperature_alarmAlarm — inverter overheatingThe inverter's internal temperature has exceeded its safe operating limit. Check whether the installation is in direct sunlight, whether ventilation is adequate, and whether the ambient temperature exceeds 45°C. If the environment is within limits and the alarm persists, the internal cooling fan or temperature sensor may be faulty — contact AlphaESS support.
110029 — GFCI AlarmAlarm — ground fault warningGround fault current interrupter has triggered at the alarm (warning) level. If accompanied by insulation fault alarms, follow the insulation fault guidance. If it occurs frequently and the inverter cannot connect to the grid, the inverter's GFCI circuit may need replacement — contact AlphaESS support.
110030 — ISO AlarmAlarm — insulation monitoringInsulation monitoring alarm — the system has detected a potential insulation degradation event. Restart the system and check whether the fault persists. If it does, the PV string insulation may need testing by a qualified engineer with a megohmmeter.
110034 — Fan Abnormal AlarmAlarm — cooling fan faultThe inverter's cooling fan is not operating correctly. Check via the Alpha Cloud app whether the internal temperature has reached 60°C — if an external fan triggered the alarm, power off, restart, and observe whether the external fan is running. Inspect the fan for blocked vents, damage, or foreign objects. If an internal fan is faulty, the inverter will require a service visit to replace it.
System & firmware
Internal system errors related to firmware, memory, DSP communication, and the 12V auxiliary supply. These typically require AlphaESS support involvement for remote firmware updates or hardware diagnosis.
100060 — Dsp_selfcheckInverter error — DSP self-check failedThe inverter's internal DSP processors are not compatible. This is a hardware-level fault — the inverter requires professional repair. Contact AlphaESS support to arrange a service or replacement unit.
100122 — EEPROM R/W FailureInverter error — memory read/writeThe inverter's EEPROM memory has failed a read/write operation. If a remote firmware upgrade was recently performed and the inverter is operating normally, this is a normal transient result of the upgrade process. If it persists or the inverter is not operating, contact AlphaESS support.
100123 — DSP communication failureInverter error — DCDC module commsCommunication between the inverter and its internal DCDC module has been lost. Contact AlphaESS support to attempt a remote DCDC module firmware upgrade. If that does not restore communication, fully power off the inverter for 10 minutes and restart. Persistent faults require professional inspection.
100145 — 12V auxiliary power FaultInverter error — 12V supply failedThe inverter's internal 12V auxiliary power supply has failed. An occasional occurrence may recover automatically. If it continues to appear, the 12V supply board inside the inverter is faulty and will require a hardware repair or replacement — contact AlphaESS support.
100165 — data storage errorInverter error — data storageAn error has occurred in the inverter's internal data storage. An occasional occurrence recovers automatically. If persistent, the inverter's storage hardware is faulty — contact AlphaESS support for diagnosis and potential replacement.
110036 — FLASH ID AlarmAlarm — flash memory IDFlash memory identification error. Restart the system and check whether the fault persists. If it does, contact AlphaESS support — the flash memory chip may require replacement or the firmware may need to be reflashed.
110037 — ReadFlash AlarmAlarm — flash memory readThe inverter cannot read from its flash memory correctly. Restart the system. If persistent, contact AlphaESS support for a firmware reflash or hardware inspection.
110039 — Machine Type AlarmAlarm — firmware model mismatchThe firmware loaded on the inverter does not match the physical hardware model. This typically occurs after an incorrect firmware update has been applied. Contact AlphaESS support to load the correct firmware version for your inverter model.
Code not listed here?
AlphaESS may release new error codes with firmware updates, and different SMILE hardware generations can have additional codes not shown here. Share the exact numeric code from your LCD or Alpha Cloud alarm history and we'll identify it. AlphaESS also maintain support via cloud.alphaess.com.
AlphaESS fault code questions
Fault codes appear on the inverter LCD display and in Alpha Cloud. On the SMILE5, press ENT to enter the menu, then navigate to Status to view active alarms. In Alpha Cloud (cloud.alphaess.com), open My System and check the alarm history for timestamped error codes. Each code has a numeric identifier like 100007 or 110021 that you can look up in this index.
Many 110xxx alarm codes clear automatically once the triggering condition resolves — for example, a Grid Volt Alarm clears when mains voltage returns to normal. For persistent 100xxx error codes, a full power cycle (switch off the AC breaker, battery breaker, and PV isolator, wait five minutes for capacitors to discharge, then restore power in reverse order) can clear transient faults. If the same code returns after a power cycle, the underlying issue requires diagnosis rather than repeated restarting.
A red fault LED on the SMILE inverter indicates an active hardware or protection fault. The LCD screen shows the specific numeric error code. Common causes include grid relay faults, insulation resistance failures, battery communication loss, and DC bus voltage problems. Note the code from the display and look it up in this index before taking any action — some codes indicate conditions where the system should not be touched without a qualified engineer present.
STS offers remote diagnostic assessments from free. Our engineers can access your Alpha Cloud monitoring data remotely to analyse fault history, system performance, and configuration without visiting site. The diagnostic identifies the root cause and recommends whether a settings change, firmware update, or on-site repair is needed — saving you the cost of an unnecessary callout.
Error 100007 (Insulation_fault) is one of the most common AlphaESS alarm codes and is typically caused by moisture on PV panel cables or junction boxes — it often appears during or after rain and clears when conditions dry out. If it occurs frequently in dry weather, the insulation resistance of one or more PV strings has degraded. An engineer can isolate individual strings and test with a megohmmeter to identify the affected circuit. Persistent insulation faults should not be ignored as they indicate a potential safety issue.
Book
AlphaESS error code you need diagnosed?
Share the numeric error code from your LCD or Alpha Cloud alarm log, describe what the system is doing, and when the fault first appeared. We'll identify the root cause and recommend whether it needs a remote fix or an on-site visit.
- Not affiliated with AlphaESS Co., Ltd
- No fix, no fee
- Written report with cause and recommended action
We use cookies to measure traffic and improve our ads — including sharing limited, hashed details with Meta (Facebook) to measure ad performance. Accept, or decline for essential cookies only. Privacy policy
STS Solar Tech Support
Usually replies within minutes
Hi there!
Got a solar fault or need a quick answer? Drop us a message — we usually reply within a few minutes. Mon–Fri, 9am–7pm.
Start WhatsApp Chat
Got a solar fault or need a quick answer? Drop us a message — we usually reply within a few minutes. Mon–Fri, 9am–7pm.
End-to-end encrypted