Problem diagnosis · Off-Grid · All brands

Off-grid solar not charging

Q: Can cold weather stop an off-grid battery from charging?

Yes — LiFePO4 batteries should not be charged below 0°C. Charging lithium cells at sub-zero temperatures causes lithium plating on the anode, permanently reducing capacity and potentially causing internal short circuits. A properly functioning BMS will block charge current below this threshold. Lead-acid batteries also charge poorly in cold weather — their internal resistance increases significantly below 0°C. If your system is in an unheated outbuilding or shed, cold-weather charging inhibit is a likely cause of reduced or absent charging during winter.

Q: Why does my off-grid system charge fine in summer but stop charging in winter?

Winter charging failure typically has two causes: reduced solar input and low battery temperature. In winter, UK peak sun hours drop from 4–5 hours per day to 1.5–2.5 hours, and the sun angle is low — panels may be partially shaded by horizon obstructions that don't affect them in summer. Simultaneously, unheated battery stores can drop below the charge cutoff temperature. If your winter solar generation is insufficient for your load, the battery may progressively discharge until the BMS enters deep discharge protection. This usually requires either reducing load, adding panels, adding a generator input, or fitting battery heating.

Your panels are producing power but the battery isn't charging — or the MPPT controller is showing zero amps despite bright sunshine. This affects all off-grid brands: Victron SmartSolar, EPsolar, Tracer, Renogy, Outback, SMA, and others.

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13 Trustpilot reviews

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I have a GivEnergy system consisting of two batteries, two inverters and a controlling EMS (Energy Management System) which has not worked since Nov 2025. After six months I discovered Solar Tech Support, reached out to them and Ron phoned me back – how often do you get that service? Could not be more helpful – worked directly with me over the phone, outside what I would call normal working hours. Lucid explanations and we were able to discuss the issues and history using camera and email history. As this was a very rare setup, Ron was able to access an EMS expert in the field to confirm the solution. One sunny day in, I am now only paying for standing charge and a few pence for spikes in grid consumption while battery catches up with house demand.

Ian · May 2026 Trustpilot

When my GivEnergy system had an issue, I was completely left without support and had honestly lost all hope. Thankfully, I searched online and found Ron, which completely turned things around. After sending him a message, he responded incredibly fast and called me to assure me that he would get the problem fixed. I really admire his dedicated, supportive nature and his determination to find a solution. With this kind of outstanding attitude and customer service, he has absolutely secured a future customer in me.

Sree · May 2026 Trustpilot

Ron want out of is way to help, nothing was to much. He was very thorough in what he did Very knowledgeable I would highly recommend Ron and his company He did a fantastic job for me. if you have any problems, he'll do his best to help you out and resolve your problem. I wouldn't hesitate to recommend them

Dennis Brown · May 2026 Trustpilot

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)

Tony Deacon · May 2026 Trustpilot

Contacted Ron with a problem and he sorted it out quickly with no problems at all. Very knowledgeable on anything solar/ batteries. I would recommend him to anyone

Phill · May 2026 Trustpilot

I've spoken to Ron a couple of times with issues with my Givenergy installation. Such a friendly knowledge guy very highly recommended. Thank you very much for resolving my issues

michael fairhurst · May 2026 Trustpilot

Contacted Solar Tech Support in desperation. After explaining the issues I had with my system a diagnosis was made and a solution proposed. Fantastic service, even contacted a manufacturer to arrange replacement parts for me. Great communications, explained all they were doing and what I had to do, clearly and precisly. Followed up to confirm all was ok. Excellent service.

Mr Machin · May 2026 Trustpilot

After GivEnergy went into liquidation, just my luck, my battery started playing up (internal board crashed). Contacted my installer - not interested! Found Solar tech support on a Google search. Sooo glad I found this company! Ron is extremely helpful and has plenty of experience. He soon confirmed what the fault was, and helped me to get my system up and running again. Now moved my GivEnergy account to Solar tech support, and will definitely use again if I have more issues. Unusual to find such a helpful company in these times, no morons reading scripts, just direct contact with the engineer.

Keith Ballard · Apr 2026 Trustpilot

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 Trustpilot

Ron is a super star. Two months ago my GivEnergy battery failed a firmware upgrade leaving it a brick. My installer couldn't/wouldn't fix it. GivEnergy couldn't/wouldn't fix it. Then they went into administration and all hope was lost. A flurry of emails later and Ron had diagnosed the fault (failed USB flash drive, something I'd suspected) and talked me through resolving it. Two months of nothing resolved in about 3 hours. It's great to work with someone who pays attention to the details, knows that they're doing (not just following a script) and gets stuff sorted without a fuss or up-charging.

Christopher · Apr 2026 Trustpilot

I can add to the list of customers who had already 'given up' on GivEnergy due to their appalling customer service, and that was before they went into administration (their Trustpilot reviews don't lie!). So you can imagine my desperation when, having changed my ISP and my Inverter, predictably, proving to be the only device that didn't connect automatically to my new network, I found zero prospect of any customer support with GivEnergy having called in the administrators just five days earlier! The salvation came from Solar Tech Support. My IT advisor stumbled across their web site and some very helpful tips for beleaguered GivEnergy customers, as well as an offer to provide direct assistance. Nothing ventured, I decided to drop them an E-Mail, with very low expectations based on my experience of GivEnergy customer support. Within an hour Ron had responded with some pin point advice, and after a few exchanges of E-Mails he had nailed the problem, enabling the combined efforts of my IT advisor and solar installer to resolve it and reconnect my Inverter. Thank you Solar Tech Support, and Ron in particular, for coming to the aid of a deserted and despondent GivEnergy customer. Expert, razor sharp advice and first class customer service, even though I wasn't officially a customer.

customer · Apr 2026 Trustpilot

This company are a rare gem, I had a very unusual problem following a failed firmware upgrade on my GivEnergy kit. I then found out GivEnergy were in administration and had dismissed all their support staff! None of the usual fixes to try and restore my inverter comms would work, and I looked everywhere, forums, GivEnergy youtube support videos - even AI couldn't figure it out. My installer was talking about huge sums for system replacements, and being vague / evasive about if they'd even install replacement GivEnergy inverter. Enter Solar Tech Support, reassuring and knowledgeable from the very start, I've learnt loads about my solar system though the friendly chat while my engineer worked as he diagnosed the problem and figured out a fix procedure that I've not found anywhere else - amazing . If you need solar system repairs - especially if you like me have been left high and dry by GivEnergy, I cannot recommend this company enough. Give them a call.

Andy Thomas · Apr 2026 Trustpilot

I sent a message on their website regarding a problem I have on my Givenergy system. Although not supplied by Ronald, I thought it was worth an email. Within the hour on a Saturday, he phoned and we discussed the problem. He logged in remotely and gave excellent advice. I'm too far away for his on-site help but he did diagnose the problem and was happy also to chat through my thoughts about an upcoming solar/battery install I'm planning. Great bloke.... if only he was nearer!

Philip · Apr 2026 Trustpilot

Ian · May 2026 Trustpilot

Sree · May 2026 Trustpilot

Dennis Brown · May 2026 Trustpilot

Tony Deacon · May 2026 Trustpilot

Contacted Ron with a problem and he sorted it out quickly with no problems at all. Very knowledgeable on anything solar/ batteries. I would recommend him to anyone

Phill · May 2026 Trustpilot

I've spoken to Ron a couple of times with issues with my Givenergy installation. Such a friendly knowledge guy very highly recommended. Thank you very much for resolving my issues

michael fairhurst · May 2026 Trustpilot

Mr Machin · May 2026 Trustpilot

Keith Ballard · Apr 2026 Trustpilot

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 Trustpilot

Christopher · Apr 2026 Trustpilot

customer · Apr 2026 Trustpilot

Andy Thomas · Apr 2026 Trustpilot

Philip · Apr 2026 Trustpilot

⚡ Safety Warning

Do not open your inverter or interfere with DC cabling. Solar panels produce live DC voltage whenever exposed to light. Always use your DC isolator switch and contact a qualified solar engineer for hands-on fault diagnosis.

⚡

Off-grid charging is different from grid-tied charging. Grid-tied hybrid inverters report charging faults through their monitoring portals and usually diagnose themselves. Off-grid MPPT controllers often have minimal displays and communicate faults through LED codes or simple numeric error codes. The diagnosis sequence below covers both simple and advanced controllers.

Diagnostics

5-step off-grid charging diagnosis

Work through these in order. Each step rules out a cause and narrows down what to check next. You don't need specialist equipment — a multimeter helps for step 3 but is not essential.

Check the MPPT controller display for fault codes and PV input readings

The controller tells you what it can see. Check for active fault codes and note the PV voltage reading:

What the PV voltage reading tells you

PV voltage = 0V: No power reaching the controller — blown fuse, open circuit, or damaged panel/cable.

PV voltage = battery voltage: MPPT output connected but no panel input — check PV fuse and combiner box.

PV voltage normal, charge A = 0: Controller has power but isn't charging — fault code, BMS inhibit, or parameter issue (steps 2–4).

PV voltage normal, charge A normal: System is charging — check whether the battery voltage is actually rising.

Common fault codes: Victron Error 38 (PV over-voltage) — see our Victron MPPT error codes guide. EPsolar Tracer: E01 (battery over-voltage), E02 (battery under-voltage). Renogy: P01 (battery connection fault).

Verify the battery charge parameters — absorption and float voltages

Wrong voltage settings are the most common cause of apparent charging failure. Verify these against your battery spec:

Correct charge voltages by battery type

12V LiFePO4: Absorption 14.2–14.6V · Float 13.5–13.8V · No equalization

24V LiFePO4: Absorption 28.4–29.2V · Float 27.0–27.6V

48V LiFePO4: Absorption 56.8–58.4V · Float 53.6–54.4V

12V AGM/GEL: Absorption 14.4–14.8V · Float 13.6–13.8V

12V Flooded LA: Absorption 14.7–15.0V · Float 13.2–13.8V · Equalization 15.5–16.0V

If the battery type selector is set to the wrong chemistry, the controller may complete the charge cycle prematurely (too-low absorption voltage) or overcharge (too-high float). Select a custom or lithium profile and enter the manufacturer's values manually.

Check for shading, panel damage, or a blown DC fuse on the PV string

Physically walk the site and inspect the panels and wiring:

• Shading: Even a single shaded cell on a series string reduces total output significantly. Check for new obstructions — tree growth, satellite dishes, aerial cables, bird nests.

• Panel damage: Cracked glass, delamination bubbles, or burnt cell marks (hotspots) reduce output. Check visually from the ground with bright light.

• PV fuse or breaker: Series fuses in combiner boxes can fail silently. Check each fuse with a multimeter on continuity mode. A tripped DC circuit breaker may have reset visually but can still have failed internally — replace if in doubt.

• Open-circuit voltage test: With multimeter on DC voltage, disconnect the PV string at the controller and measure across the positive and negative PV terminals. A 4-panel 12V string should read 75–90V OC in full sun. Below that points to shading, a damaged panel, or a wiring fault.

Check for charge inhibit — BMS lockout, low temperature, or deep discharge protection

Lithium batteries actively block charging under certain conditions. This is protective — not a fault:

• Low temperature cutoff: LiFePO4 batteries stop accepting charge below 0°C. The BMS sends a charge inhibit signal to the MPPT controller. Check the battery temperature display or probe. If the battery is in an unheated space during winter, this is the cause — see our cold weather battery guide.

• Deep discharge protection: If battery SoC drops below around 10–15%, the BMS may enter protection mode and lock the battery. Some BMS units require a specific reset — often holding the power button for 5 seconds, or applying a brief external charge. Check the battery manufacturer's manual.

• Cell imbalance: If one cell in the battery is significantly below others, the BMS may prevent charging to protect that cell. This requires battery monitoring or a cell-level voltage check.

• CAN/RS485 inhibit: If the battery communicates via CAN bus or RS485 to the MPPT controller, a communication fault can cause the controller to default to charge inhibit. Check the communication cable and verify the controller shows the battery as communicating.

Check firmware compatibility and perform a controlled reset of the MPPT controller

If steps 1–4 have not identified the cause, firmware or a corrupted controller configuration is likely:

• Firmware update history: Check whether the charging problem started after a firmware update to the controller or the battery BMS. A firmware update can change charge algorithm defaults or protocol handling.

• Victron SmartSolar: Open VictronConnect, check firmware version under the device info page. Update via Bluetooth if available. If recently updated, the update history is shown — compare timestamps against when the fault appeared.

• Factory reset: Most MPPT controllers support a factory reset via a settings menu or button combination. This clears any corrupted or conflicting settings. After resetting, re-enter all battery parameters manually from the manufacturer's specification sheet — do not rely on auto-detect for lithium batteries.

• Victron-specific: For Victron systems with a BMS-managed battery, also check the battery BMS disconnect guide and verify DVCC is configured correctly on the Cerbo GX.

Why off-grid charging faults are harder to diagnose than grid-tied faults

Grid-tied hybrid inverters from brands like GivEnergy, Sunsynk, or Lux report detailed fault codes through cloud monitoring portals, making diagnosis straightforward. Off-grid systems are often built from components — an MPPT controller, a separate battery BMS, and loads — that don't share a common monitoring platform. The MPPT controller may only show a two-digit error code. The battery BMS may only communicate via a proprietary app. There is no shared event log.

The good news is that off-grid charging faults are almost always caused by one of the five issues above. In our experience, wrong battery charge parameters and low-temperature charge inhibit account for the majority of cases where an off-grid system appears healthy but won't charge. Actual hardware failure — failed MPPT controller, failed battery cell — is relatively rare and usually accompanied by obvious symptoms like a hot enclosure, burning smell, or visually damaged components.

Related off-grid guides

Low voltage disconnect — loads cutting off →

Cold weather battery performance →

Off-grid system sizing →

Generator integration guide →

Brand-specific MPPT guides

Victron MPPT error codes 33 & 38 →

Victron battery BMS disconnect →

Battery communication fault — all brands →

Victron Energy hub →

FAQ

Off-grid not charging — common questions

Why is my off-grid system not charging even though the sun is shining?

The most common reasons are: incorrect battery charge parameters (wrong voltage thresholds for your battery chemistry), a BMS charge inhibit signal from a low-temperature or cell fault, a blown PV fuse or tripped breaker, partial shading on a panel string, or a fault code on the MPPT controller. The controller display or monitoring app will usually identify which applies — check there first before investigating the panels or wiring.

What does it mean when my MPPT controller shows zero amps charging in full sun?

Zero charge current in full sun usually means one of four things: the battery is already at the float voltage and the controller has reduced charging to maintenance level, the BMS has sent a charge inhibit signal, the PV voltage is not reaching the controller (blown fuse, damaged cable, or panel issue), or the controller has a fault condition active. Check the PV input voltage reading on the controller — if it is zero or below battery voltage, the PV side is the problem. If PV voltage is normal but charge current is zero, the issue is on the battery or BMS side.

How do I know if my battery voltage settings are wrong for a LiFePO4 battery?

Compare your controller's absorption voltage setting against your battery specification. For a 12V LiFePO4 battery, absorption should be 14.2–14.6V and float should be 13.5–13.8V. For 24V, double these values. For 48V, quadruple them. If your controller is set to a sealed lead-acid (SLA) profile, the voltage may be too high for lithium cells. Always select a custom or lithium profile and enter the battery manufacturer's exact voltage specifications.

Can cold weather stop an off-grid battery from charging?

Yes — LiFePO4 batteries should not be charged below 0°C. A properly functioning BMS will block charge current below this threshold. Charging lithium cells at sub-zero temperatures causes lithium plating on the anode, permanently reducing capacity. Lead-acid batteries also charge poorly in cold — their internal resistance increases significantly. If your battery is in an unheated outbuilding, cold-weather charge inhibit is a likely cause of missing or reduced charging during winter.

Why does my off-grid system charge fine in summer but stop charging in winter?

Winter charging failure typically combines two causes: reduced solar input and low battery temperature. UK peak sun hours drop from 4–5 hours to 1.5–2.5 hours per day in winter, and a low sun angle means horizon obstructions that don't shade panels in summer will shade them in winter. If your battery store is unheated, it may drop below the LiFePO4 charge cutoff temperature. The result is a battery that progressively discharges until the BMS enters deep discharge protection.

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