How to read inverter fault codes brand-by-brand guide for UK solar systems
Inverter fault codes tell you exactly what is wrong with your solar system — but only if you know where to find them and what they mean. This guide covers every major UK brand: where the fault log is, how to read severity levels, and which codes require urgent action versus a simple reset.
A remote diagnostic reads your fault log directly and identifies the root cause — usually within 30 minutes. Covers all major UK inverter and battery brands.
Book a diagnostic — £75 → How diagnostics workWhat are inverter fault codes?
Fault codes are alphanumeric references generated by the inverter's firmware when it measures a value outside its acceptable operating range. They are your system's language for telling you what is wrong.
The inverter generates a code when a measurement crosses a threshold — grid voltage too high, battery temperature out of range, DC isolation resistance too low. The code tells you which threshold was crossed, not necessarily why. An F01 (grid over-voltage) might indicate a real grid problem, an export limiting misconfiguration, or a faulty voltage sensor. The code is the starting point, not the final answer.
The inverter display only shows the most recent active fault. But the monitoring portal stores every code ever generated, with timestamps. This history is invaluable — it shows whether a fault is recurring (likely an active problem) or was a single event that self-cleared (often a transient grid disturbance).
There is no universal fault code standard across inverter manufacturers. Code 24 on a Growatt is a grid fault. Code 24 on a Sunsynk relates to bus voltage. Code E024 on a SolarEdge means something else entirely. Always look up codes using the correct brand reference — the brand-by-brand sections below show where to find each manufacturer's fault code documentation.
Most brands use a tiered severity model. Warnings are advisory — the system keeps running but something is marginal. Faults mean the inverter has throttled output or shut down, but will retry automatically. Critical errors require manual intervention — the inverter will not restart until the fault is cleared by an engineer or a specific reset procedure is followed.
Where to find inverter fault codes
There are three places fault codes appear: the physical inverter, the monitoring app, and the web portal. Each shows different information.
Most hybrid inverters have an LCD or LED display showing operating state and any active fault. The display shows the current fault code (e.g. "F01", "Grid Fault", "E012") and usually a brief description. It does not show historical codes — only what is active right now.
Every major UK brand has a smartphone app showing the fault/alarm log. Here is where to find it in each app:
Most inverter brands have an installer-level portal that shows a more detailed event log than the homeowner app — including raw fault timestamps, system state at fault time, and in some cases automatic fault descriptions. If your installer has connected your system, they can pull this log remotely. If you cannot access the app or the log is limited, ask your installer to retrieve the fault history from the portal. This is often the fastest route to a full picture of what the inverter has been doing.
Reading GivEnergy fault codes
GivEnergy inverters (Gen 1, Gen 2, Gen 3, and AIO) use a prefix-based code system. Codes are visible in the MyGivEnergy portal and on the inverter LED/LCD display.
F-codes indicate the inverter has stopped generating in response to a measured fault. Most will auto-retry after a delay. Common F-codes on GivEnergy systems:
E-codes typically indicate internal system issues or communication failures rather than grid or solar input faults.
The full GivEnergy fault code reference — including all F and E codes with descriptions and recommended actions — is available in the GivEnergy fault code index. For GivEnergy-specific problems, the GivEnergy hub page covers the most common faults and fixes.
Reading Growatt fault codes
Growatt inverters (MIN, SPH, MOD, MIC series and the Growatt SPH battery systems) display faults as "Error" followed by a number. Fault history is in the ShinePhone app under Device → Fault Alarm.
The 1–25 range covers grid-side issues. These are the most frequent fault codes on UK Growatt systems, given the variability of UK grid voltage:
The higher number range covers DC input and battery/BMS issues:
The full Growatt error code reference is in the Growatt fault code index. For common Growatt problems, visit the Growatt hub page. If ShinePhone shows no data or the plant is offline, see the monitoring offline guide.
Reading Sunsynk fault codes
Sunsynk hybrid inverters (3.6kW, 5kW, 6kW, 8kW, 12kW) display faults on the front LCD and in the SunsynkConnect app under Plant → Alarms. The LCD also shows a fault bitmap — a set of binary flags that each represent a different fault condition.
Sunsynk warnings are displayed in the app as yellow alerts. The system continues to generate but with a restriction or advisory condition:
Sunsynk fault codes show as red alerts in SunsynkConnect. Common faults on UK installations:
The full Sunsynk fault code reference is in the Sunsynk fault code index. For Sunsynk-specific problems, see the Sunsynk hub page. Sunsynk's LCD bitmap fault display is explained in the Sunsynk user manual available from the SunsynkConnect portal.
Reading SolarEdge fault codes
SolarEdge inverters (HD-Wave, StorEdge, three-phase commercial) have a more complex monitoring system than most brands. Fault data appears in the mySolarEdge app and the SolarEdge monitoring portal under Site → Events & Alerts. SolarEdge also provides alerts by email if configured.
Unlike most brands, SolarEdge inverters report status codes rather than simple fault numbers. The inverter status is shown as a text string on the monitoring portal (e.g. "Production", "Standby", "Off", "Night mode") plus any active alerts. Alert types include:
SolarEdge is unique in offering per-panel (per-optimiser) monitoring. In the monitoring portal, select Layout View to see each panel's output as a colour heat map. A dark panel (zero or low output) indicates a faulty optimiser, shading problem, or wiring issue on that specific panel. This level of detail is not available on most other brands — it is one of SolarEdge's key advantages for fault diagnosis. See the SolarEdge fault code index and SolarEdge hub page for more.
SolarEdge installers use the SetApp (Bluetooth commissioning app) to configure and diagnose inverters on-site. If your installer needs to attend, they will use SetApp to read detailed fault data not visible in the homeowner portal. If you have a StorEdge battery, the battery management alerts appear separately in the monitoring portal under the battery device — check both the inverter and battery alert feeds.
Fault codes on Solis, Huawei, Fox ESS and Fronius
These four brands each have distinct fault code systems. Here is a quick reference for where to find codes and the most common faults on UK installations.
Solis inverters (RHI, S5, S6 hybrid series) store fault history in SolisCloud under Plant → Fault Record. The display shows faults as text descriptions alongside an error code. Common Solis faults:
Huawei SUN2000 inverters with LUNA2000 battery systems use the FusionSolar app. Alarms appear under Plant → Alarm & Event. Huawei uses a severity classification of Critical, Major, Minor, and Warning:
Fox ESS hybrid inverters (H1, H3, AC1) use the FoxESS Cloud platform. Alarm history is under Device → Alarm History. Fox ESS codes use a combination of text descriptions and numeric codes:
Fronius inverters (Primo, Symo, Primo GEN24, Symo GEN24) use the Solar.web platform with the Messages section for fault history. Fronius uses a state code system with numeric codes:
How to interpret fault code severity
Not all fault codes are equal. Understanding the severity level tells you whether you need to act immediately, monitor the situation, or simply note the event and move on.
A single occurrence of a grid voltage or frequency code, with no pattern of repetition, usually reflects a brief grid disturbance — a nearby load switching on, a DNO tap change on the local transformer, or a brief supply interruption. These self-clear and require no action. If you see five or more in a single day, that becomes a pattern worth investigating.
A fault code that appears daily or multiple times per week, particularly at similar times of day (e.g. midday grid over-voltage on sunny days), indicates a systemic issue. These are not emergencies but will limit generation and may indicate a developing problem. Common causes:
Certain fault codes indicate a safety condition — the inverter has detected something that could cause equipment damage, fire, or electric shock if the system is re-energised without investigation. These codes must not be reset by a non-qualified person:
If a fault code is not in any reference table you can find, it may be a model-specific code, a firmware-version-specific code, or an internal diagnostic code not intended for end-user reference. In this case, a remote diagnostic session allows an engineer to access the full inverter register directly and identify the exact fault — this is the fastest route to a definitive answer for unusual or undocumented codes.
What to do after reading your fault code
Having identified the fault code, here is the decision process for what to do next — in order of escalation.
Before doing anything else, document what you see. Take a photo of the inverter display showing the fault code. Take a screenshot of the fault log in the app. Note the timestamp. This documentation is essential if you need to report to your installer, contact the manufacturer under warranty, or use a remote diagnostic service.
A surprising number of fault calls are resolved by checking the following:
For grid voltage, grid frequency, or communication warning codes that have not self-cleared: turn the AC isolator off, wait 30 seconds, turn it back on. The inverter will restart and retry. If the same code returns within an hour, do not keep resetting — the underlying condition is still present and repeated resets will not fix it. Move to the diagnostic route instead.
Many common fault code scenarios have dedicated diagnosis guides on this site. The problems hub covers the most frequent fault scenarios — inverter not generating, battery not charging, no data in the app, and more. Each problem page walks through the diagnosis process step by step before recommending a diagnostic call.
If the fault is persistent, safety-related, or you cannot identify it from any reference, a remote diagnostic is the most efficient next step. An engineer connects to your inverter's portal, reads the full fault log and live data, and identifies the root cause — usually within 30 minutes. A written report and recommended fix is included. This avoids unnecessary site visits and gives you a clear picture of whether the fault requires an engineer to attend or can be resolved remotely.
Frequently asked questions
An inverter fault code is a reference number generated by the inverter's firmware when it detects a condition outside its normal operating parameters. Codes are categorised as Warnings (the system continues operating, something is marginal), Faults (operation is restricted or the inverter has shut down), or Critical errors (the inverter has tripped on a safety issue and requires manual intervention). The specific meaning varies by brand and model — the same number can mean different things on different inverters.
Yes, this is common with warning-level codes. Many fault codes are advisory — the inverter logs the event but continues operating in a degraded or restricted mode. A grid over-voltage warning may cause the inverter to throttle output by 10–20% without fully shutting down. Battery communication warnings may allow solar-only operation while the battery is bypassed. If the system is generating but a code is present, check whether it is persistent (active for hours or days) or a transient event. Persistent warning codes should still be investigated — they often indicate a developing fault.
Many fault codes self-clear once the fault condition resolves — a grid voltage fault clears when voltage returns to normal. You can also perform a soft reset by switching the AC isolator off for 30 seconds and back on. However, safety-related codes — isolation fault, arc fault, insulation fault, earth fault — should not be cleared without investigation. Clearing a safety code without finding the cause risks re-energising a fault that could damage equipment or be hazardous. If in doubt, contact a qualified engineer before resetting.
Warnings indicate a condition outside optimal parameters but not severe enough to stop operation. The inverter logs the event and may throttle output, but continues working. Faults indicate the inverter has restricted or halted operation in response to a measured condition — grid voltage too high, DC isolation failure, battery overtemperature, etc. Critical faults require manual reset or engineer intervention before the system will restart. The terminology varies slightly by brand — Sunsynk uses Warning and Fault, GivEnergy uses Advisory and Fault, SolarEdge uses Warning and Error.
Midday grid over-voltage is a well-documented issue in UK solar installations, particularly in suburban and rural areas where local grid infrastructure was not designed to handle significant solar export. When multiple solar systems in an area all generate at peak simultaneously, the combined export raises local grid voltage above the 253V threshold set by G98/G99 (the UK grid connection standard). The inverter's protection circuits detect this and shut down or throttle output. Solutions include: requesting your DNO investigate the local network voltage, enabling reactive power control (Q(U) droop) if your inverter supports it, or adjusting export limiting settings. A remote diagnostic can identify which solution applies to your specific setup.
If you don't have app access — for example if the previous owner set up the account or the WiFi dongle has been swapped — you can still read the current active fault from the inverter display. Some inverter models also store a fault log accessible via the inverter's local web interface (accessible on your home network via the inverter's IP address). For GivEnergy, Growatt, and SolarEdge in particular, contacting the manufacturer's technical support with your inverter serial number allows them to pull the fault history directly from their servers. Alternatively, an engineer with the appropriate installer app can connect directly to the inverter via Bluetooth or local network and read the complete fault register.
Related guides, problems and fault code indexes
Step-by-step triage for any solar or battery system fault, from no generation to battery not charging.
Fault codes that indicate generation has stopped — grid faults, DC faults, and safety trips explained.
Battery communication faults, BMS errors, and charge limit issues — what each fault code means.
Complete reference for all GivEnergy F-codes and E-codes with descriptions and recommended actions.
All Growatt error codes for MIN, SPH, MOD and MIC series inverters with full descriptions.
Sunsynk warning and fault codes for all hybrid inverter models with severity guide.
Understanding inverter architecture helps interpret fault codes — grid tie, hybrid, and battery operation explained.
Why midday grid over-voltage faults occur and how export limiting settings can reduce them.
Monitoring communication errors vs actual generation faults — how to tell the difference.
Got a fault code you can't resolve?
If your inverter is showing a persistent fault code — or you can't identify what it means — a remote diagnostic reads the full fault log directly and identifies the root cause. Usually resolved in a single 30-minute session.