Solar System Problems —
Diagnose & Fix Your Solar Fault
Use the sections below to find your fault type. Each page gives you a full diagnostic path — what to check, what the evidence means, and when to call an engineer.
A remote diagnostic identifies the root cause of most solar and battery faults — often within 30 minutes. All major brands supported. You get a written report with the fault, the fix, and a cost estimate.
Book Remote Diagnostic — £75 → How diagnostics workSolar PV and battery storage systems are reliable, but they are also complex installations with hundreds of components and control points. Faults can develop over time for a variety of reasons — some are simple configuration errors that can be fixed remotely in minutes, others require physical inspection or component replacement on site. The good news is that most faults have a specific, identifiable cause. With the right diagnostic approach, you can understand what's wrong and decide on the best path forward.
At STS Solar Tech Support, we specialise in diagnosing solar and battery faults across all major brands. Whether your system uses GivEnergy, SolarEdge, Growatt, Sunsynk, Solis, Enphase, Huawei, Fox ESS, Fronius, Tesla Powerwall, or any of the many other inverter and battery brands available in the UK, we have the knowledge and tools to identify the root cause. We maintain detailed fault databases built from hundreds of real repair jobs, covering everything from firmware quirks to configuration best practices for every brand we support.
If you're not sure where to start, our remote solar diagnostic service is designed exactly for this — we analyse your system data, inverter logs, and setup to provide a full diagnosis without a site visit, usually starting from just £75.
System-level problems
Your system has stopped generating, is producing less than expected, or has lost backup capability.
Panels and inverter installed but generating zero — or a figure that makes no sense.
Generating, but not as much as it should be. Output has dropped or never met expectations.
Battery didn't switch to EPS or backup mode when the grid went down.
Inverter problems
Fault lights, display errors, or an inverter that won't start.
Battery problems
Battery not charging, not discharging, or showing communication errors.
Monitoring & connectivity
Portal offline, WiFi not connecting, or data not updating.
Configuration problems
Installation or setup errors causing incorrect behaviour.
Financial & billing problems
Export payment issues, tariff registration, and missing income.
No export payments arriving — SEG registration, metering, or supplier billing issue.
Smart Export Guarantee application stuck, rejected, or taking too long.
Feed-in Tariff payments missing, late, or stopped after supplier change.
Installation quality
Post-installation issues, snagging, and workmanship concerns.
Off-grid problems
Faults specific to off-grid and island-mode systems — battery protection trips, charge failures, and generator interaction problems.
How to identify your solar problem
The problem sections above cover the main categories of faults. If you're not sure which one applies to your situation, use these starting points to narrow things down. If your system is producing nothing at all — no generation, no power, completely offline — start there. This covers total system failures, dead inverters, and zero-output scenarios.
If your system is generating but the output is consistently lower than you'd expect — especially if it has dropped over time or never reached the performance figures your installer quoted — check the system underperforming page. This covers partial faults, soiling, shading, and efficiency losses that don't stop generation entirely.
For battery-specific issues, if your battery isn't storing energy or the system won't charge it, go to battery not charging. If the battery is full but won't discharge or the system won't use the stored energy when you need it, check battery not discharging. Battery faults often stem from configuration settings rather than hardware failure, so these pages focus on the most common causes.
If you're seeing fault codes on your inverter display or in your monitoring app, the fault code itself is usually the fastest way to diagnose the issue. Check your brand's specific page — we have detailed fault code guides for GivEnergy, SolarEdge, Growatt, Sunsynk, Solis, and all other major brands. You can also browse the fault codes section to look up error codes across multiple brands.
If the fault is related to export payments — your system is generating and the grid is importing, but you're not receiving payment from your export tariff scheme — see our dedicated guide on not being paid for solar export. This usually comes down to export metering, tariff registration, or communication settings. A remote diagnostic can quickly determine whether the issue is technical or administrative.
Still not sure where to start? The best first step is a remote diagnostic. Tell us what you're seeing, share your monitoring data, and we'll pinpoint the problem in most cases without needing to visit your site.
When to call a professional
Some solar faults are safe to investigate yourself with guidance — checking settings, restarting the system, or looking at logs. Others require professional intervention. Safety is our priority, so please call an engineer immediately if you see any of these signs:
Beyond safety-critical issues, consider calling a professional if DIY troubleshooting hasn't resolved the problem. If you've checked the obvious things — restart the inverter, check the WiFi, review the settings — and the fault persists, a remote diagnostic can identify the cause. If the system has been offline or non-functional for more than a week, don't let it linger — the sooner you diagnose, the sooner you can get back to generating. If error codes keep reappearing after a reset, that's a signal that the underlying cause needs professional attention, not repeated resets. We're here to help: contact us for urgent situations or book a diagnostic to get started.
Not sure which problem you have?
The Solar Not Working page walks you through the full triage process — inverter, battery, monitoring, and grid — in one place. Most people find their fault within two or three steps.
Fault behaviour varies by brand
The problem pages above are brand-agnostic starting points. For brand-specific fault codes, portal steps, and known firmware issues, go to your inverter or battery brand directly.
Common questions
The most common sudden failures are an inverter fault (often shown by a red light), loss of grid supply, a tripped AC isolator, or a WiFi issue that makes the system appear offline when it is still generating. Start with the inverter display — any fault code or unusual light state will point you in the right direction. Use the full triage guide button above if you are unsure where to start.
Check your system mode settings first. Many batteries default to Eco Mode after a firmware update, which prevents scheduled or grid charging. Also check your CT clamp direction — a reversed CT clamp is one of the single most common causes of a battery appearing not to charge. See Battery not charging and CT clamp installed wrong.
It depends on the fault. If the inverter has shut itself down with a fault code, leave it in that state — the protection trip is intentional. Do not attempt to reset repeatedly. If you smell burning, see physical damage, or notice arcing, isolate the system at the consumer unit and do not restart it. Call a qualified engineer.
Yes — the majority of solar faults can be fully diagnosed remotely. With access to your monitoring portal data, inverter event logs, and a short walkthrough of your setup, an experienced engineer can identify the cause of most faults without a site visit. Remote diagnostics start from £75.
Many faults can be fixed remotely — these include configuration settings, software issues, firmware updates, and connectivity problems. We can guide you through resets, parameter adjustments, and other non-invasive fixes without a site visit. However, physical faults (damaged panels, broken cables, faulty hardware components) require an on-site inspection and repair. During a remote diagnostic, we'll identify whether your specific fault can be fixed remotely or if a site visit is needed.
A remote diagnostic starts from £75 and provides a full diagnosis with recommended actions. Many configuration and software issues can then be resolved during the same session at no extra cost. If an on-site visit is needed, repairs typically start from £245 depending on the fault and parts required. In many cases, fixing a fault is much cheaper than replacing the entire system — and it almost always returns your investment through years of restored generation and export revenue.
Some basic troubleshooting is safe — we'll guide you through system resets, checking settings, and reviewing logs. However, never open the inverter or battery enclosures yourself; the high-voltage components inside can be dangerous. Always isolate the system at the consumer unit before touching any electrical connections. If you're uncertain about any step, stop and ask — it's much safer and often faster to get professional guidance. We're here to help you understand the problem and guide you toward the right solution, whether that's a simple reset or a professional repair.
Not sure which fault you have?
Describe what the system is doing — fault lights, generation figures, what the app shows — and we’ll identify the root cause. Most faults are diagnosed remotely in 30 minutes.