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Fault guide · GivEnergy battery / DC circuit

GivEnergy Battery DC MCB Keeps Tripping

The DC MCB (battery isolator) on your GivEnergy system has tripped. The comms are still connected, so the system can still see the battery, but the breaker has cut the DC power between the battery and the inverter. The battery cannot charge or discharge. The usual causes are poor cable termination at the battery DC connections, buck-boost converter failure inside the inverter and, more and more often, a breaker that is failing early and needs replacing. This guide covers how to tell them apart, and what happens next. For related symptoms, see our inverter not turning on guide.
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DC MCB faults need proper diagnosis

A tripping DC MCB can mean a cable re-termination from £295 or an inverter replacement from £1,495. The fault codes and trip pattern tell us which — we can check remotely before anyone visits site. Send us your fault codes and we'll tell you what you're dealing with.

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Wow!!! I have a Givenergy system. The battery stopped charging and depleted fully. Obviously Givenergy went into administration, so I was working with the reseller / installer to get it fixed. They told me they couldn't resolve it and the best they could do was offer me a replAcement at cost, so basically having to buy a new system. I happened to come across STS when searching for how to fix it myself. Ronald has been a god send, within 2 days all is working perfectly and set up correctly. When it comes to experts. He truly is the expert. If you have issues with your Givenergy system and don't know where to go for good help, give him call. 07944 877329. Thanks Ronald, regards Neil W

Neil · Jul 2026 Trustpilot

Had a fault on a GivEnergy AC coupled 3kW home battery and was getting no joy from multiple companies I contacted, as well as the original installer. Contacted Solar Tech Support and they sorted it really quickly, now working perfectly again, can’t recommend them highly enough, professional and very responsive!

John Jones · Jul 2026 Google

I contacted Solar Tech Support because I had a problem with my legacy GiveEnergy installation. within 24 hours they had diagnosed the problem and offered advice on resolution. Because they were unable to fix the problem there was no charge! This despite numerous time consuming emails. I am currently trying to engage with the original installer but if that is unsuccessful I will go back to Solar Tech Support and ask them to repair the system with a retrofit. Very knowledgeable and responsive. I highly recommend them.

Tim Hatt · Aug 2026 Google

Called back within a day and gave good advice.

Rob and Sue Dempster · Jun 2026 Google

Thank you for your diligence. On this occasion the battery was able to be saved but they have given a route to hopefully arrange a repair from the manufacturer.

David Bateman · Jun 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

Written by · Independent Solar Engineer Last updated

Understanding the DC MCB

What the battery DC MCB does — and why it trips

The DC MCB (miniature circuit breaker) sits between your GivEnergy battery and the inverter. It is the primary safety device protecting the DC battery circuit from overcurrent and short-circuit faults.

NORMAL OPERATION

Closed circuit — handle UP

When the DC MCB handle is in the UP position, the battery is connected to the inverter. DC current flows through the MCB in both directions — charging from the inverter and discharging to the inverter. The rating depends on the battery: GivEnergy's Gen 1 battery manual calls for a 100A breaker, and the breaker built into Gen 3 batteries is rated 125A.

TRIPPED STATE

Open circuit — handle DOWN or mid-position

When the MCB trips, the handle drops to the DOWN position (or a middle position on some models). The comms are still connected, so the system can still see the battery. But the breaker has isolated the DC bus, so no power flows between the battery and the inverter: no charging and no discharging. The battery's own lights may still look normal, because the battery itself is fine.

WHY IT TRIPS

Overcurrent, short circuit or a failing breaker

The DC MCB trips when it detects current exceeding its rating. This is a safety mechanism. Often it is reacting to a real fault: a wiring fault creating a short-circuit path, or an inverter component failure drawing excessive current from the battery. But more and more often we find the breaker itself has failed early. If it keeps tripping and no other fault is found, the breaker needs replacing. That is an engineer job.

The DC MCB is not an AC breaker. Do not confuse it with the MCBs in your consumer unit. The DC MCB is specifically for the battery-to-inverter DC circuit. If the MCB in your consumer unit is also tripping, see our inverter not turning on guide — that is a separate issue affecting the AC side.
Cause 1 — most common
Most common

Poor cable termination — loose or missing ferrules on DC battery cables

The battery DC cables carry up to 100A. If the cable ends were not properly ferrule-crimped during installation, or if the terminal screws have loosened over time, the connections develop high resistance. High resistance at these currents causes arcing, heat build-up, and intermittent overcurrent spikes that trip the DC MCB.

How this happens

→GivEnergy specifies 16mm² tri-rated cable with bootlace ferrules crimped onto the stripped ends before insertion into the inverter DC terminals.
→If the installer stripped the cable and inserted bare copper strands directly into the terminal block, the strands splay and the connection loosens over time with thermal cycling.
→A loose terminal develops micro-arcing under load — especially during high-current events like the battery ramping to full discharge. The MCB sees this as an overcurrent spike and trips.
→The problem is intermittent. The MCB may reset fine and hold for days or weeks before tripping again. This makes it hard to diagnose without a physical inspection of the cable ends.

How an engineer fixes it

→Isolate the DC circuit with a full shutdown in the correct order: battery off first, DC MCB last (see the restart guide)
→Remove the battery DC cables from the inverter terminal block
→Inspect cable ends — look for discolouration, heat damage, or bare strands without ferrules
→Crimp appropriate bootlace ferrules (16mm²) onto each cable end using a proper ratchet crimping tool
→Re-insert the ferrule-terminated cables into the terminal block and torque to manufacturer specification
→Test under load — confirm no further tripping over a monitoring period
How to tell this is your problem: the DC MCB holds after a reset for a period (minutes, hours, or days) before tripping again — typically during a high-draw event like the battery ramping to full discharge in the evening. If the MCB trips immediately when you flip it up, that pattern points to cause 2 below (inverter buck-boost failure) rather than cable termination. A breaker that is failing early can trip in the same holds-then-trips way, so if an engineer finds the terminations sound, the breaker itself is the next suspect.
Cause 2 — inverter fault
Inverter internal fault — requires repair

Buck-boost converter failure — MOSFET short-circuit inside the inverter

The GivEnergy hybrid inverter contains a buck-boost DC-DC converter that regulates voltage between the battery pack and the inverter's DC bus. This converter uses power MOSFETs (transistors) as high-speed switches. When a MOSFET fails short-circuit — which can happen due to a power surge, thermal stress, or manufacturing defect — it creates a direct low-resistance path that draws excessive current through the DC MCB.

How to recognise this fault

→The DC MCB trips immediately when you flip it to the UP position — it will not hold even for a second
→You hear rapid clicking from the inverter (10–12 cycles) as the relay attempts to connect, followed by the MCB tripping to red
→The GivEnergy portal or app shows the fault message Battery short circuit; inverter fail
→The battery LEDs are green when the DC MCB is OFF — the battery itself is healthy, the fault is in the inverter's power electronics

What happens next

→Leave the DC MCB in the OFF (down) position to prevent further damage to the MCB contacts
→The inverter will continue to operate solar generation on the AC side — you only lose battery charging and discharging
→GivEnergy's 12-year warranty (systems installed from 11 September 2023) and the earlier inverter warranty (5 years, or 10 years if an extended warranty was paid for: your paperwork shows which) are no longer a live route. GivEnergy Ltd entered administration on 9 April 2026 and the administrator has been explicit that no further hardware warranties will be honoured, so a direct claim against GivEnergy Ltd is unlikely to succeed
→Cover may still be open elsewhere: workmanship cover from your installer if they are still trading, an insurance-backed guarantee, Section 75 if you paid by credit card, or MCS Consumer Code redress. Our GivEnergy warranty page walks through each route, and the administration hub sets out the record
→If none of those routes apply, inverter replacement starts from £1,495
Do not repeatedly reset a DC MCB that trips immediately. Each reset attempt forces the failed MOSFET to conduct high fault current through the MCB contacts. This degrades the MCB itself over time and can cause contact welding, which turns a replaceable breaker into a more costly repair. If the MCB trips on the first reset, leave it off and arrange a diagnosis.
Cause 3 — less common
Battery BMS

BMS protection event — battery management system triggers a disconnect

The battery management system (BMS) inside the GivEnergy battery monitors cell voltage, temperature, and current. If it detects a condition outside safe limits, it can trigger a protection disconnect. In some configurations this causes the DC MCB to trip as a secondary protection layer. Where the fault codes point to a failed pack rather than wiring or comms, see refurbished GivEnergy batteries, supplied and installed at fixed prices.

BMS fault codes to look for

STORAGE_WARN_BMS_SHORT_CURRENT_DISCHARGER The BMS has detected a short-circuit condition on the discharge side. Most commonly caused by incorrect cable polarity or a wiring fault — check that the DC cables are connected to the correct positive and negative terminals.
STORAGE_ERROR_BAT_UNDER_VOLTAGE_FAULT The battery has been deeply discharged — often because the DC MCB was tripped for an extended period and the battery drained its own standby power. The BMS prevents reconnection until the cells are recovered.
STORAGE_WARN_BMS_COM_FAIL The inverter is having trouble talking to the battery's BMS, often because of the comms cable or a connector, battery addressing or a firmware mismatch. The inverter cannot read battery state, so the BMS disconnects as a safety precaution. On batteries with a plug connector (Gen 2 and Gen 3) the comms run in the same plug-in cable as the battery power. Gen 1 batteries have their power on cable lugs and a separate data cable on a green pin connector. At the inverter the comms land on a green pin connector on a Gen 1, an RJ45 BMS port on a Gen 2 and a plug on a Gen 3.

What to check

→Check the GivEnergy portal event log for the specific BMS fault code — this tells you whether the issue is electrical (polarity, wiring) or communication-related
→If the battery has been isolated for more than a few days, the cells may have self-discharged below the BMS threshold. A controlled recovery charge may be needed
→If STORAGE_WARN_BMS_COM_FAIL is present, look at the comms connector at both the battery and inverter ends: it should be fully home, with its clip engaged where it has one. If it looks loose, do not push or pull it with the system running. On batteries with a plug connector the same cable carries battery power, so an engineer reseats it with the system isolated
→A battery restart (hold the restart button on the battery for 3–5 seconds) can clear some transient BMS faults. Only do this after checking fault codes first
Reference
Where to find it

DC MCB location by GivEnergy battery

Where the DC MCB sits depends on which GivEnergy battery you have, not which inverter. Batteries and inverters are interchangeable, so a Gen 1 inverter can be running a Gen 3 battery. Knowing where it is helps you check its state and communicate clearly with your engineer.

DC MCB / isolator by battery
Gen 1 battery External DC MCB on the 2.6, 5.2 and 8.2kWh Gen 1 batteries: a separate DIN-rail mounted MCB in an enclosure, installed inline between the inverter and the battery. GivEnergy's Gen 1 manual calls for a 100A DC breaker, and only one is needed even with several Gen 1 batteries. The battery power runs on ring terminal lugs on 16mm² tri-rated cable, with a separate data cable for the comms. The MCB handle is typically green or red.
Gen 2 battery Built-in DC MCB on the 9.5kWh Gen 2 battery. The breaker is part of the battery, behind its flap, and doubles as the battery isolator. Handle UP = on, handle DOWN = tripped or isolated. The battery connects with a plug connector that carries both power and comms.
Gen 3 battery Built-in DC MCB, rated 125A, on the 5.12kWh and 9.5kWh Gen 3 batteries. It sits under a waterproof cover on the battery: close the cover again after checking it. The same kind of plug connector as Gen 2 carries both power and comms.
All-in-One Built-in DC MCB: the AIO has the battery and inverter in one unit, and its DC MCB sits behind the DC cover.
Mixed stack Extra DC isolator: where a Gen 3 battery is the master and older Gen 1 or Gen 2 batteries are slaves, GivEnergy's Gen 3 manuals call for a DC isolator to protect the slave batteries. Where a Gen 1 battery is installed after a Gen 2, the inverter manuals call for a DC MCB between them too. So a mixed stack can have one more isolation point as well as the battery breakers.
Related GivEnergy pages
Inverter not turning on

AC-side power issues — tripped consumer unit MCBs, DC isolator positions, and no-display faults.

See inverter not turning on →
Red status light

Battery and inverter alarm states — fault codes, BMS alerts, and protection events.

See red status light →
Battery not charging

If the MCB was tripped for days, the battery may have self-discharged and need recovery.

See battery not charging →
Click of death

Relay cycling faults — similar clicking symptoms but from the AC relay rather than the DC circuit.

See click of death →

This is a brand-specific guide. For other GivEnergy issues, see the GivEnergy problems hub. For general battery troubleshooting across all brands, see solar battery not charging.

FAQ

DC MCB tripping questions

We see four causes. Poor cable termination: the battery DC cables were not properly ferrule-crimped, or the terminal screws have loosened over time, causing intermittent arcing that trips the MCB. Buck-boost failure: a MOSFET inside the inverter's DC-DC converter has failed short-circuit, drawing excessive current the moment the MCB is closed. A BMS protection event: the battery management system detects an abnormal condition and the MCB trips as a secondary protection measure. And, more and more often, the breaker itself: when it keeps tripping and no other fault is found, the breaker is failing early and needs replacing, which is an engineer job.
Yes, you can reset it yourself the first time. Take one look before you do: scorch marks, discoloured plastic, a burning smell or a breaker that feels warm mean leave it off and call an engineer, because a cooking termination behind the breaker is a fire risk rather than a nuisance. Otherwise flip the handle back up once. If it holds and the battery reconnects normally, the trip may have been a transient event. If it trips straight back, or within minutes, leave it off and stop there. Repeated resetting under a short-circuit condition damages the MCB contacts and worsens the underlying fault. Resetting it every morning is not a workaround, it is the pattern that most often turns out to be a fire risk, and it needs an engineer.
This fault message indicates the inverter has detected a short-circuit condition on its DC battery input. In most documented cases this is caused by failure of the buck-boost converter MOSFETs inside the inverter — the power transistors that regulate voltage between the battery and inverter have failed in a short-circuit state. The battery itself is usually fine, which is why the battery LEDs stay green when the DC MCB is switched off. The inverter typically needs repair or replacement. GivEnergy Ltd entered administration on 9 April 2026 and the administrator has been explicit that no further hardware warranties will be honoured, so a direct claim on the manufacturer's warranty is unlikely to succeed. Our GivEnergy warranty page sets out the routes that may still be open.
A free remote diagnostic reviews fault codes and event logs — pay only if we fix. If the cause is poor cable termination, an on-site visit to re-terminate and re-torque the DC cables costs from £295, depending on the number of connections and accessibility. If the inverter's buck-boost circuit has failed, there is no longer a manufacturer route: GivEnergy Ltd entered administration on 9 April 2026 and the administrator has been explicit that no further hardware warranties will be honoured. Cover may still exist through your installer's workmanship guarantee, an insurance-backed guarantee, Section 75, or the MCS Consumer Code, and our GivEnergy warranty page walks through each. Inverter replacement starts from £1,495.
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