How To Troubleshoot Your Solar Panels

Solar panels are designed to deliver reliable performance for decades, but occasional drops in output can still happen. When they do, it’s not always clear whether you’re dealing with a simple issue or something more serious.

This article walks you through a step-by-step process to diagnose solar panel issues, helping you understand what’s normal, what’s not, and when to take action to restore performance.

Power your home with Upvolt’s smart solar solutions.

Key Takeaways

• Not every drop in solar output indicates a fault; weather and seasonal changes often play a role.
• Your inverter and monitoring system are the fastest way to identify potential issues.
• Simple checks like isolators, breakers, and shading can resolve common problems.
• Persistent faults or electrical issues should always be handled by a qualified professional.

Before You Troubleshoot: What To Check First

A drop in solar performance doesn’t always indicate a fault. In many cases, it reflects normal environmental changes rather than a system failure. Understanding this distinction early helps you avoid unnecessary concern and focus on the checks that actually matter.

Is The Issue A Fault Or Just Low Output?

Solar generation naturally fluctuates throughout the year. Weather conditions, seasonal daylight changes, and shading all influence how much energy your system produces.

Start by comparing current performance with previous trends. If output aligns with recent weather or similar systems nearby, it’s likely a normal variation rather than a fault. However, if generation remains unusually low during clear daylight conditions, further investigation is warranted.

What Your Monitoring App Or Inverter Display Can Tell You

Your inverter and monitoring platform provide the most immediate insight into system health. These tools track performance in real time and flag potential issues through alerts or error codes.

Check for:

• Normal operating status (typically green indicators)
• Consistent generation during daylight hours
• Any warnings, faults, or loss of connection

Recording any error codes or unusual behaviour will help speed up diagnosis if professional support is required.

When To Stop And Call An Installer Instead

Basic checks are useful, but there is a clear point where professional support becomes necessary. Solar systems operate at high voltages, and attempting to diagnose internal faults can pose serious safety risks.

If you notice persistent faults, repeated shutdowns, exposed wiring, or signs of damage, stop troubleshooting and contact a qualified installer. Acting early not only protects your safety, but also prevents further damage to your system.

Step 1: Check Your Isolator Switches

Isolator switches are one of the most common causes of system shutdowns, and one of the simplest issues to identify. A quick check can often restore your system without further intervention.

Where To Find Your AC And DC Isolators

Your system includes two main isolators:

• DC isolator – typically located near the inverter or on the roof
• AC isolator – usually positioned near your consumer unit or beside the inverter

Your installer’s handover documentation will confirm their exact locations. Familiarity with these components makes basic troubleshooting far more efficient.

What A Tripped Isolator Looks Like

An isolator may trip as a protective response to an electrical issue. When this happens, the switch will move to an “OFF” or “TRIPPED” position, sometimes with a visible indicator.

While this can explain a sudden loss of generation, it should not be ignored. A tripped switch often signals an underlying issue rather than a one-off event.

How To Reset Safely And What To Do If It Trips Again

If a switch has tripped, you can attempt a single reset by returning it to the “ON” position. If the system resumes normal operation, it may have been triggered by a temporary fluctuation.

If the switch trips again, do not attempt further resets. Repeated tripping indicates a deeper electrical fault that requires professional diagnosis.

Step 2: Check Your Inverter

The inverter is the central component of your solar system, converting the electricity your solar panels generate into usable power for your home. When performance drops or stops entirely, it is often the first place to check.

How To Read Your Inverter’s Status Display

Most modern inverters use LED indicators or display screens to show system status. A normal operating system will display a steady green light or clear generation data.

Warning signs include:

• Red or amber lights
• A blank or unresponsive display
• No recorded generation during daylight hours

Consult your manufacturer’s guide to interpret specific indicators accurately.

What Common Error Codes Mean

Error codes provide direct insight into the cause of a problem. Some of the most common include:

• Grid voltage high/low – local network conditions outside safe limits
• Isolation fault – potential wiring issue or moisture ingress
• Communication error – loss of connection between system components

While some issues are temporary, persistent errors usually indicate a deeper issue that requires attention, such as a faulty inverter.

How To Perform A Safe Inverter Reset

A reset can resolve minor or temporary faults. To do this safely:

1. Switch off the AC isolator
2. Switch off the DC isolator
3. Wait at least five minutes
4. Turn the DC isolator back on
5. Turn the AC isolator back on

If the system restarts and operates normally, the issue may have been transient. If the error returns, further troubleshooting should stop, and a qualified installer should be contacted.

Step 3: Check For Shading Or Physical Issues

A noticeable drop in performance is often linked to external factors rather than a system fault. Environmental changes, even minor ones, can significantly affect how much energy your panels generate. A simple visual inspection from ground level can quickly highlight common issues.

New Sources Of Shading On Your Panels

Shading is one of the most common causes of reduced solar panel output. Even a single shaded solar cell could lead to a 30% reduction in output power.

Check for:

• Tree growth or overhanging branches
• New buildings, extensions, or scaffolding
• Seasonal changes in sunlight angles

Observing your roof at different times of day can reveal patterns that aren’t immediately obvious. If new shading is present, trimming vegetation or reassessing panel placement may be required.

Visible Damage, Dirt, Or Debris

Surface-level issues can also reduce efficiency by blocking sunlight from reaching the cells. While rain helps keep panels clean, it’s not always sufficient, particularly in areas with heavy dust or bird activity.

Look out for:

• Dirt, dust, or bird droppings
• Leaves or debris accumulating on panels
• Cracks, discolouration, or visible damage
• Loose or exposed cabling

If panels appear heavily soiled or damaged, professional cleaning or inspection is recommended to restore performance safely.

How To Identify Which Panels Are Affected

Monitoring systems are one of the most effective ways to pinpoint performance issues. Drops in output at specific times of day often indicate shading, while consistent underperformance may point to a panel or connection fault.

Advanced platforms, such as Upvolt’s Skygate®, go further by providing detailed, real-time insights at system level. This makes it easier to identify exactly when and where performance drops occur, helping both homeowners and installers diagnose issues faster and more accurately.

If a fault is suspected, avoid accessing the roof yourself. Solar systems operate at high voltage, and any physical inspection beyond ground level should always be carried out by a qualified professional.

Step 4: Review Your Generation Data

Your solar system continuously generates performance data, and this is one of the most effective tools for diagnosing issues. Analysing trends over time helps distinguish between normal variation and genuine faults.

How To Compare Current Output Against Historical Data

Access your monitoring platform and review daily, monthly, and yearly generation figures. Comparing current output with the same period in previous years provides a reliable benchmark.

Seasonal changes in the UK can significantly affect performance, so always compare like-for-like periods to avoid misleading conclusions.

Identifying When The Drop Started

Pinpointing when performance began to decline is key to identifying the root cause.

Check whether the drop coincides with:

• Weather changes
• Installation of nearby structures
• Maintenance work or electrical events

A clearly defined starting point makes diagnosis faster and more accurate.

What Sudden Vs Gradual Changes Suggest

The pattern of downtime often indicates the type of issue:

• Sudden drop – typically linked to electrical faults, tripped switches, or inverter shutdowns
• Gradual decline – often caused by dirt build-up, shading, or natural degradation
• Fluctuating output – may indicate wiring issues or grid instability

Understanding these patterns allows you to act early and avoid more significant performance losses.

Step 5: Check Your Consumer Unit

Your consumer unit (fuse board) plays an important role in protecting both your home and your solar system. If your system stops generating unexpectedly, this is one of the final checkpoints to review.

Locating The Solar Circuit In Your Fuse Board

Most systems have a dedicated circuit within the consumer unit, often labelled “Solar PV” or “Inverter.” This controls the connection between your system and your home’s electrical supply.

If labels are unclear, refer to your installation documentation or proceed with caution to identify the correct breaker.

What A Tripped Breaker Means For Your System

A tripped breaker is a protective response to an electrical fault or surge. When triggered, it cuts power to prevent damage to your inverter and wiring.

This will typically result in:

• No solar generation
• A blank or inactive inverter display
• Possible fault messages such as “Grid Fault”

When Resetting The Breaker Is And Isn’t Safe

You can attempt a single reset by switching the breaker back to the “On” position. If it remains on and the system resumes normal operation, the issue may have been temporary.

If the breaker trips again immediately, do not attempt further resets. This indicates a deeper electrical fault that requires professional diagnosis.

What You Should Never Try To Fix Yourself

While basic checks are safe and often helpful, certain areas involve high-voltage components and specialist equipment. Attempting to fix these yourself can lead to serious safety risks, system damage, or voided warranties.

Wiring, Cabling, And Electrical Components

Solar systems operate at high DC voltage, even when the system appears to be switched off. Interfering with wiring or electrical components without the correct training can result in electric shock, fire risk, or long-term system faults.

If you notice exposed cables, burning smells, or signs of overheating, stop immediately and contact a qualified installer. These are not issues that can be safely resolved without professional expertise.

Roof-Level Panel Work

Accessing your roof introduces both electrical and physical risks. Solar panels are heavy, mounted at height, and connected to live systems, making inspection or cleaning far more complex than it appears.

Even minor tasks, such as removing debris or checking for damage, should only be carried out by trained professionals with the correct safety equipment. Attempting this yourself can put both you and your system at risk.

Inverter Internal Components

The inverter is one of the most critical and sensitive parts of your system. Opening it or attempting internal repairs is unsafe, as components can retain charge even after shutdown.

Any internal fault should be handled by a qualified technician. DIY intervention not only creates safety hazards but can also invalidate warranties and lead to more expensive repairs.

How Upvolt Supports Homeowners With Solar Faults

When your system underperforms or stops generating, fast and accurate diagnosis is essential. Upvolt combines advanced monitoring technology with hands-on expertise to identify faults quickly and restore performance with minimal disruption.

Remote Diagnosis Using Monitoring Data

Every investigation starts with your system data. Using advanced monitoring tools, including Upvolt’s Skygate®, our team analyses real-time and historical performance to identify where and why output has dropped.

This approach allows us to:

• Detect faults without unnecessary delays
• Distinguish between environmental issues and technical failures
• Identify problems before a site visit is required

In many cases, issues can be diagnosed remotely, saving time and accelerating resolution.

On-Site Fault Finding And Repair

Where a physical inspection is required, Upvolt engineers carry out a full system diagnostic, not just a surface-level check. Every component is tested to ensure safety, performance, and compliance.

This includes:

• Inverter diagnostics and performance checks
• Panel output and string testing
• Wiring, connections, and system integrity

Repairs are completed efficiently, whether that involves replacing components, resolving electrical faults, or optimising system performance.

Let’s Recap

Troubleshooting your solar panels starts with understanding the difference between normal performance changes and genuine faults. Many issues, such as shading, dirt, or tripped switches, can be identified quickly without specialist tools.

However, your system’s inverter, wiring, and internal components require a more cautious approach. Attempting to fix these yourself can create safety risks and lead to further damage.

The most effective approach is to carry out basic checks, use your monitoring data to guide decisions, and involve a professional when issues persist. This ensures your system continues to operate safely, efficiently, and reliably over the long term.

About Upvolt

When solar panels stop performing as expected, speed and accuracy matter. Upvolt combines advanced monitoring technology with expert diagnostics to identify issues quickly and restore your system with minimal disruption.

From initial diagnosis through to final testing, the entire process is managed with a focus on safety, performance, and long-term reliability.

If your system isn’t performing as it should, fill in our quick online form to get expert support and a clear path to getting it back to full output.

FAQ

Why are my solar panels not working as efficiently as they used to?

A drop in performance is often caused by dirt, debris, or new shading from trees or nearby structures. These factors can reduce how much energy your panels produce, especially if buildup blocks sunlight. Weather conditions, particularly prolonged cloud cover, can also lower output temporarily. If performance remains consistently low during clear conditions, it may indicate a system issue or panel degradation and should be assessed professionally.

How can I tell if there is a fault with my solar inverter?

Your inverter will usually indicate faults through warning lights, error codes, or a loss of display. A blank screen or persistent error message is a strong sign of inverter problems. Monitoring apps may also highlight communication or generation issues. If these indicators continue, a qualified installer should investigate.

Is it safe for me to troubleshoot common issues myself?

Basic checks, such as reviewing your monitoring app, inspecting panels from the ground, or checking for tripped breakers, are safe to carry out. You can also perform a simple inverter reset if instructed by the manufacturer. However, you should avoid anything involving wiring, internal components, or signs of physical damage. For more complex inverter problems or safety concerns, always contact a professional.

What should I do if my solar PV system is not generating any power at all?

Start by checking your consumer unit, AC/DC isolators, and inverter status for any obvious issues or error messages. A tripped breaker or switched-off isolator is a common cause of complete shutdown. If everything appears normal but the system remains inactive, the issue may be electrical or grid-related. Regular maintenance and a professional inspection will help identify and resolve the fault safely.

When should I call a professional solar technician like Upvolt?

You should contact a professional if faults persist after basic checks or if you notice electrical issues, warning codes, or repeated shutdowns. Any work involving high-voltage components or roof-level access should always be handled by a trained technician. Professional support ensures solar panel problems are diagnosed accurately and resolved safely. It also protects your system performance, warranty, and long-term reliability.

Alex Lomax

CEO & Co-Founder

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