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Safety-critical fault · Growatt Error 04

Growatt Error 04 — Insulation Fault: Causes, Safety, and Diagnosis

DC insulation resistance has fallen below the safe threshold (typically 1MΩ for UK G98). This is a genuine safety event requiring immediate isolation. Most common cause: MC4 connector water ingress on older installations. This guide covers every diagnostic step.
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  • Written from field diagnostic experience
  • Applies to all Growatt models — MIN, MOD, SPH, MIC
Error 04 — What happens now?

Your inverter has detected an insulation fault and shut down as a safety measure. Work through this diagnostic guide to identify the cause. Most cases can be narrowed down remotely, and we can advise on whether a site visit is required.

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Safety: Isolate the system at the consumer unit. Do not restart or override the fault.

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Keith Ballard · Apr 2026

Absolutely wonderful support. I have a GivEnergy system that was installed in 2022, and a firmware update was flagged in the app, so I proceeded to update the software .... and immediately regretted it, as my inverter came up with an error, and was not working at all! With no GivEnergy support available, and my installer saying there was nothing he could do, I googled help, and found Ron. What a stroke of good luck! Submitted an on line enquiry late morning, and received phone call just after 5 pm, and later that evening Ron was able to supply me with old firmware no longer available on the GivEnergy web site. I was then able to update the firmware using a GivEnergy youtube video as reference, and hey presto the system was back up and running. One further slight adjustment by Ron and we are back normal. What a relief. I have no hesitation in recommending Solar Tech Support if you have a problem. Great service! And if you are a GivEnergy system owner, whatever you do, DO NOT UPDATE FIRMWARE!

Neill Ginn · Jul 2026 Google

Ronald was able to organise a brilliant electrician with extensive experience of GivEnergy systems local to me in the SW. I have now got a fully functioning system and suspect that my electricity bill will be substantially reduced or in credit over a year. Also when said electrician discovered an overvoltage in the my local grid, Ronald prepared a very lucid and comprehensive report of the situation which I have now supplied to my local grid. Cannot recommend Ron and Dan enough.

Ian Macmillan · Jul 2026 Google

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)

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Diagnosis steps

6-step diagnostic process

Error 04 has four main root causes. Work through these steps in order to narrow down which is affecting your system.

1

Isolate immediately at consumer unit and DC string isolator

Error 04 is a safety fault. Switch off the main AC isolator at your consumer unit and the DC string isolator near the roof-mounted array. Do not touch any DC connections on the roof. Do not repeatedly restart the inverter in an attempt to clear the fault — this will not fix it and only risks exposure to live voltage.

2

Check ShineServer for when the fault first appeared and weather pattern

Log into ShineServer and navigate to Fault Logs. Note the exact date and time Error 04 first appeared. Check the weather on that date — if it appeared in the morning during wet or rainy weather, MC4 connector water ingress is almost certainly the cause. If it appeared after weeks of dry weather, a gradual cable or panel degradation is more likely.

3

Visually inspect MC4 connectors for water ingress

This step requires safe roof access. Inspect all MC4 connectors between the solar panels and the inverter. Look for: water droplets visible inside the connector housing, corrosion or whitish crystalline deposits, discoloured or corroded connector pins, or physical cracking of the connector body. Pre-2018 installations are most vulnerable — connectors degrade and lose weatherproofing over time. If you see water ingress, the connector must be replaced.

Safety: Only perform this check if you can safely access the roof. Do not work at heights if you are not confident. A qualified engineer can perform this inspection as part of a site visit.
4

Inspect DC cable for UV damage or physical damage

Check the DC cable that runs from the roof array down to the inverter. Look for: cracks or splits in the cable insulation (often appear as fine white lines from UV exposure), physical damage from installation work or weather, crushed sections, or discolouration. Damaged cable insulation is the second most common Error 04 cause. Check the full cable run from roof to inverter.

5

Check individual panel junction boxes for cracks or failure

A failed or cracked junction box on a specific panel can cause localized insulation loss. If you can safely view the back of the panels (during a site visit), inspect the junction boxes for visible cracks, discolouration, or separation from the panel. A single faulty panel can often be isolated from the string by repositioning the string combiner input.

6

IR test verification before recommissioning

After the fault source is identified and repaired, a qualified engineer must perform an insulation resistance (IR) test on the DC string. Resistance must be ≥1MΩ as per UK G98 standards before the system can be safely restarted. Do not restart the inverter without documented IR test results.

Location

Where you'll see Error 04

Growatt LCD Display

Inverter screen shows "Error 04" with a red LED indicator. The system stops generating and feeding to grid.

ShineServer Portal

Log into ShineServer → Device → History. Filter by date and look for "Error 04" entries with timestamps.

ShinePhone App

Error history tab shows recent faults including Error 04 with timestamp.

Models

Affected Growatt models

SPH-TL-BH series — hybrid inverters with battery

MIN-TL-X series — single and three-phase string inverters

MOD-TL3-X series — three-phase string inverters

ShineMaster range — older models with insulation monitoring

Costs

Typical repair costs

Most common fix

MC4 connector replacement

Replace the water-damaged connector pair. Quick fix if the fault is isolated to one connector.

£30–50 parts + labour
Cable fault

DC cable replacement

Replace the damaged section of DC string cable. Cost depends on cable run length and roof access.

£50–150 for replacement
Panel fault

Panel junction box

Cracked or failed junction box requires panel replacement. May be covered under panel warranty.

£200–400 for panel replacement
Safety

What NOT to do

✕
Don't keep restarting the inverter

Repeated power cycles do not clear insulation faults. Each restart attempt increases stress on degraded components and may worsen the underlying issue.

✕
Don't touch DC cabling yourself

DC circuits carry lethal voltage even when the inverter is off. Water ingress or damaged insulation create shock hazards. Only a qualified engineer should inspect DC wiring.

✕
Don't assume it will clear itself

Insulation faults caused by moisture or damage are progressive — they worsen over time. A fault that appears occasionally will eventually become permanent.

Context

About Growatt Error 04

Error 04 is the most common Growatt fault code in the UK, particularly on installations from 2015–2022. It affects SPH, MIN, MOD, and older ShineMaster models equally. The inverter detects DC insulation resistance falling below 1MΩ (G98 compliance threshold) and disconnects as a safety measure. This is not a Growatt hardware fault — it is almost always external to the inverter, indicating either connector degradation, cable damage, or a failed panel junction box.

ShineServer logs the exact time the fault appeared, allowing correlation with weather events. Morning appearance in wet weather almost always points to MC4 connector water ingress. Older installations on original equipment are most vulnerable due to connector age.

Root causes in order of likelihood
1. MC4 connector water ingress (especially pre-2018 installations)
2. Damaged DC cable insulation — UV or physical damage
3. Panel junction box failure — cracked or water damaged
4. Inverter internal insulation fault (rare — usually external cause first)
Related pages
Useful guides
FAQ

Error 04 questions answered

Yes. Error 04 indicates DC insulation resistance has fallen below the safe threshold (an insulation / isolation fault). This is a genuine electrical safety event that creates risk of electric shock. The inverter shuts down as a protection mechanism. Do not attempt to override it or restart the system — isolate immediately and identify the fault source before operation resumes.
No. Repeatedly restarting the inverter will not fix Error 04 — it will only restart until the fault is detected again. This does not address the underlying insulation problem and risks electrical shock. The fault must be diagnosed and fixed before safe operation can resume.
Diagnosis varies depending on the cause. Water ingress in MC4 connectors can be identified quickly from ShineServer logs and weather timing. Cable faults require physical inspection. Panel junction box failures may require testing individual strings. Most cases can be narrowed down remotely in a single diagnostic session, but site visits are often needed for repairs.
Repair cost depends on the root cause, and the remote diagnosis to locate it is free. Typical repairs: water ingress at MC4 connectors £30–50 in parts plus labour; damaged DC cable £50–150; a failed panel junction box £200–400 for panel replacement. Because Error 04 is a physical fault it needs an on-site repair (from £295 plus parts) — we pin down the location remotely first and quote before any work.
Weather-dependent Error 04 is a classic sign of water ingress. Moisture in MC4 connectors or junction boxes increases when it's wet or humid, lowering insulation resistance until the inverter trips. This is a slow-developing fault that will eventually fail completely. Book a diagnostic soon — the fault location can often be identified from ShineServer history and weather correlation. (See all Growatt fault codes.)
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