My Solar System Isn’t Working —
Full Troubleshooting Guide
If your solar system has stopped producing, your battery isn’t charging, your monitoring has gone dark, or your inverter is showing a fault — this page covers every common cause and what to do next. No jargon. No guesswork.
Most solar faults are diagnosed remotely in a single session. Tell us what you’re seeing and we’ll work it out.
Book a Remote Diagnostic — from £89 → See the Solar Health PlanSafety: do not open inverter or battery enclosures. If you smell burning or see arcing, isolate at the consumer unit and call 999.
5 things to check before anything else
These five checks take under five minutes and rule out the most common causes. Do these before digging deeper.
Look for the solar circuit — often labelled ‘PV’, ‘Solar’, or ‘Inverter’. If a breaker is tripped (handle down or in the middle position), reset it. If it trips again immediately, stop and book a diagnostic — do not force it.
There are typically two isolators: an AC isolator near the inverter and a DC isolator between the panels and inverter. Both must be ON. Visual check only — do not open any covers or touch internal components.
Write down the exact text, number, or letter code shown. Different brands use completely different coding systems — a photo of the display is ideal. This single piece of information can identify the fault precisely.
These are two different problems. If your inverter display shows a current power output figure (e.g. “2.4 kW”) but your app shows offline, you have a monitoring/comms fault, not a generation fault. The system is working — only the data link is broken.
A firmware update, a power cut, a router replacement, a stormy night, or a recently changed electricity tariff are all common triggers. The timing of a fault is often the fastest route to its cause.
Safety: Never open the inverter or battery enclosure. Never touch the DC cables from the solar panels — these carry live voltage even at night. If you smell burning, see arcing, or notice scorch marks anywhere in the system, isolate using the main consumer unit switch and call a qualified engineer immediately.
Inverter showing a fault or not turning on?
Inverter faults are the most common reason a solar system appears to have stopped working. Most show a code — the code is the starting point for diagnosis, not a cause for alarm.
Red status light typically indicates a protection fault, grid issue, or hardware alarm. Each brand uses different flash patterns — the meaning varies significantly.
Diagnose this fault →No display, no lights, no response. Could be a tripped breaker, a failed internal fuse, or a hardware fault. Requires systematic elimination before assuming hardware failure.
Diagnose this fault →Inverter looks fine but output reads zero. Often a configuration issue — export limits, grid impedance, or CT clamp errors — rather than a hardware failure.
Diagnose this fault →Output lower than the MCS design estimate. Could be shading, a failed string, optimiser issue, or a misconfigured export limit capping generation.
Diagnose this fault →Inverters display alphanumeric codes that identify specific fault conditions. Look up your brand’s fault code index for the exact meaning and recommended action.
Browse fault codes →Understanding how your inverter converts DC from panels to AC grid power — and what can interrupt that process — makes every fault diagnosis faster.
Read guide →Brand-specific inverter fault pages
Our remote diagnostic reviews your monitoring data and fault history to identify the exact issue. From £89.
Battery not charging, not discharging, or showing an alarm?
Battery faults are the fastest-growing category of solar support calls in the UK. Many trace back to configuration errors made at installation — not hardware failure. The most common single cause is a CT clamp installed backwards.
Battery stays empty despite solar being available or cheap-rate tariff being active. Charge window settings, CT clamp orientation, BMS fault, or firmware mismatch are the typical culprits.
Diagnose this fault →Battery is full but not supplying the house. Discharge schedule, grid settings, minimum SoC threshold, or a CT clamp reading the wrong circuit are typical causes.
Diagnose this fault →Inverter has lost communication with the battery — shows as a comms error code. Common after firmware updates, power interruptions, or on new systems with mismatched firmware versions.
Diagnose this fault →You have a battery but the house went dark during a grid outage. EPS must be explicitly enabled — it’s off by default on most inverters. Also requires a dedicated EPS output circuit.
Diagnose this fault →A backwards CT clamp causes the inverter to misread the grid — resulting in battery charging when it should discharge, importing when exporting, or readings with the wrong sign. One of the most frequently missed installation errors.
Diagnose this fault →Understanding BMS logic, SoC thresholds, charge rate limits, and dispatch scheduling makes it much easier to spot when something is wrong versus how the system is designed to behave.
Read guide →Brand-specific battery fault pages
We review charge/discharge logs, CT clamp readings, and schedule settings to find the exact cause. Most battery faults are fixed remotely.
Monitoring app offline or not updating?
A monitoring failure is not a generation failure. The two are completely separate systems. Every year, thousands of homeowners think their solar has stopped working — when it’s only the data link that’s broken. Check the inverter display directly before assuming the system has failed.
App shows no data or ‘last updated X days ago’. Could be a local WiFi issue, a data logger hardware fault, a cloud-side outage, or a firmware update that broke the cloud connection.
Diagnose this fault →Most inverter loggers only support 2.4GHz networks. Changing your router, updating the WiFi password, or switching to a band-steering mesh system are the most common triggers.
Diagnose this fault →Understanding the data logger → cloud → app chain makes it easy to pinpoint exactly where a monitoring failure has occurred and whether the system is still generating behind a broken data link.
Read guide →Brand-specific monitoring & connectivity pages
Grid overvoltage, export limit problems, or system tripping on sunny days?
Grid-related faults are often the most frustrating because they’re caused by infrastructure outside your property — not your solar system. But they still need to be diagnosed, documented, and escalated correctly to the DNO.
Inverter cuts output on sunny days because grid voltage exceeds 253V AC. This is required by law — the inverter is protecting the grid. Requires a DNO evidence pack to get fixed at the infrastructure level.
Diagnose this fault →A misconfigured export limit caps generation at the wrong level, sometimes at zero. Can be set wrong at installation, reset by a firmware update, or misapplied when switching between G98 and G99 connections.
Diagnose this fault →SEG payments not arriving, FiT payments stopped, or export meter not registering generation. These are separate problems with separate fixes depending on which scheme applies to your installation.
Diagnose this fault →G98, G99, DNO agreements, and what a correctly configured export limit looks like.
Read →Grid connection standards, thresholds, notification requirements and compliance.
Read →We build timestamped voltage logs and formal DNO complaint packs that get the issue escalated properly. Without this, DNO responses typically go nowhere.
If none of the above describes your problem exactly — a remote diagnostic is the right next step.
Not every fault fits neatly into a category. Some systems have multiple concurrent issues. Some faults only appear under specific load or weather conditions. A structured remote diagnostic reviews your monitoring data, settings, error history, and fault patterns to identify what’s actually happening — not what it looks like from the outside.
We respond to all enquiries same day. Remote-first — on-site only confirmed necessary before booking.
Know your brand? Go direct to the right page.
Every major UK solar brand has a dedicated hub page covering its specific fault patterns, fault codes, configuration tasks, and diagnostic guides. Brand-specific advice is always more accurate than generic troubleshooting.
Don’t know your brand? This guide explains how to identify your inverter make and model →
Don’t know what you have, who installed it, or what’s wrong with it? We identify the system, establish monitoring access, check MCS documentation, and get you in control. A completely different journey from a repair customer.
Start the new owner journey →Monitoring access locked, no warranty support, orphaned system with no documentation — we handle the full recovery: access transfer, documentation rebuild, warranty claims, and getting you back in control.
Get installer-gone-bust recovery →Common questions about solar faults
The most common causes of a sudden stop are a tripped breaker on the solar circuit, an inverter fault triggered by a grid voltage spike, a power cut that left the inverter in a fault state, or a firmware update that introduced a bug. Check the consumer unit first, then the inverter display for fault codes. See inverter not turning on →
It means your system is generating fine but the data logger — the small device that sends readings to the cloud — has lost its internet connection. This is a monitoring fault, not a generation fault. Check your router is online and that the logger has power. Most logger reconnections are triggered by a simple power cycle of the logger unit. Full monitoring offline guide →
If it worked and then stopped, the most common triggers are: a firmware update that reset the charge schedule to defaults, a tariff change (e.g. switching to Octopus Intelligent) that requires different schedule settings, or a CT clamp that was marginal and finally failed. If your energy tariff or app changed recently, check the charge window settings first. Battery not charging guide →
Most solar faults are not immediately dangerous — they just stop the system working. However, certain situations require immediate action: if you smell burning near the inverter or battery, see scorch marks, notice a sparking sound, or observe arcing anywhere in the system, isolate from the consumer unit and call a qualified engineer. Do not investigate these yourself. For all other faults, a systematic remote diagnostic is the safe starting point.
A remote diagnostic is £89 and covers the fault identification, written action plan, and settings validation where possible. Most configuration faults — CT clamp errors, charge schedule issues, export limit misconfiguration — are resolved during the diagnostic session. On-site repairs start from £249. We always confirm the cost before starting any physical work. See full pricing →
Still not working? Let’s diagnose it properly.
Tell us what you’re seeing — fault codes, display behaviour, app status, when it started. We’ll review your details and come back with a clear diagnosis path, usually same day.