How Do I Know If My Solar Panels Are Working? 7 Signs to Look For

Spotting the signs your solar panels are not working is crucial for UK property owners, as even minor faults can contribute to annual degradation rates of 0.5-1%, per research from the University of Manchester on silicon solar cell degradation mechanisms.

By identifying the issues early on, you can prevent costly downtime and ensure your photovoltaic system continues delivering optimal energy output. 

In this guide, we'll dive into practical checks tailored for residential and commercial properties, helping you maintain peak performance amid the UK's variable weather.

What Are the 7 Signs Your Solar Panels Are Not Working?

Here's a breakdown of seven key signs why your solar panels are not working:

1. Unusually low electricity generation readings

If your generation meter shows consistently lower kilowatt-hours than expected, under 3,200-4,000 kWh per year for a standard 4kWp south-facing system in southern England, your panels might be underperforming. 

A typical UK system generates around 850-950 kWh per kWp annually, so cross-check against your inverter display or app during peak sunlight hours (10am-2pm).

2. Inverter displaying error lights or no lights at all 

The inverter, your system's 'brain', often flashes red or remains dark if faulty. Industry reports indicate that inverter failures account for about 43% of solar system breakdowns in the UK, with replacements needed every 10-12 years. Listen for unusual humming or buzzing too, these signal overloads.

3. Higher-than-expected energy bills despite sunny weather

If your bills spike even on clear days, your solar export or self-consumption isn't kicking in. Research indicates that effective solar setups can cut household bills by 20-50% for average UK usage of 2,700-3,600 kWh yearly, so a sudden rise points to wiring issues or panel shading.

4. Visible dirt, debris, or bird droppings on panels

In the UK's damp climate, grime buildup reduces panel efficiency by 5-20%. Ground-mounted arrays or those near trees are prone, inspect quarterly and rinse gently with water if needed.

5. Hot spots or discoloured sections on panels

Thermal imaging reveals hotspots from cracked cells or poor connections, causing up to 25% output loss. The University of Surrey's studies on perovskite solar durability emphasise that such defects accelerate in humid conditions, common in northern England.

6. No alerts from monitoring apps or systems

Modern inverters send email notifications for faults, but silence during daylight hours means a glitch. Industry data shows that monitored systems can catch a significant portion of issues early, preventing £50-150 in annual losses per household.

7. Physical damage like cracks or loose mounting

Hail or high winds, prevalent in coastal areas can warp frames. Renewable energy reports indicate that a small percentage of UK installations face weather-related faults within five years, so a biannual roof check is essential for landlords.

How to Safely Check Your Solar Panels at Home?

To safely check if your solar panels are working without risking injury, start with non-invasive methods suited to UK rooftops.

1. Review your inverter's LED indicators

Begin by reviewing your inverter's LED indicators and generation meter daily during summer months when output peaks at 14.43 billion kWh nationally in 2025.

2. Use a smartphone app

Use a smartphone app linked to your inverter. Most systems like those from SolarEdge or Enphase provide real-time data on voltage, current, and efficiency. For deeper diagnostics, employ a clamp meter on DC cables to measure amperage; normal readings should hit 5-10 amps per string under full sun.

If you're a commercial property manager overseeing multiple sites, integrate IoT sensors for remote oversight.

Tip: Remember, for elevated inspections, hire a certified MCS installer, avoid DIY climbs, especially on pitched roofs common in Victorian-era rentals.

What Role Does Weather Play in Solar Panel Performance?

Weather significantly influences how effectively your solar panels convert sunlight into usable power, with the UK's cloudy skies reducing irradiance to just 900-1100 kWh/m² annually in most regions. 

Overcast days can drop output by 70%, but resilient monocrystalline panels maintain 80-90% efficiency even in diffuse light.

An accumulation of snow or frost can block panels entirely, preventing sunlight from reaching the photovoltaic cells and effectively stopping energy generation until the obstruction is removed. This effect has been documented in research found on ScienceDirect.

Extreme events like Storm Eunice in 2022 caused widespread power outages and localised damage to energy installations, including solar panels dislodged by high winds, underscoring the need for wind-rated mounts. 

While proper installation has always been crucial for solar PV systems, severe weather highlights the importance of using certified mounting products that meet rigorous standards for structural integrity.

To protect homeowners and ensure solar installations are robust enough to withstand the UK's often harsh weather conditions, a certification standard was created for solar mounting systems. 

This standard, officially published by the Microgeneration Certification Scheme (MCS), requires mounting kits to be tested for resistance to wind uplift before they can be sold and installed by MCS-certified professionals.

The technical document, "The Solar Mounting Standard" (MCS 012), outlines the rigorous testing procedures that a product must pass to prove its structural soundness and weather-tightness. 

By choosing products and installers that adhere to this standard, you can have greater confidence that your solar PV system is securely anchored to the roof and built to last in challenging weather.

Why Is Regular Maintenance Key for Long-Term Solar Efficiency?

Regular maintenance ensures your solar panels sustain 85-95% efficiency over 25 years, aligning with warranties from leading UK manufacturers. 

Neglected systems can lose an additional 0.5% efficiency yearly from dust and micro-cracks, equating to £100-300 extra bills for a typical 3kWp setup.

Schedule annual professional cleanings for dusty urban sites, and trim overhanging foliage biannually to avoid shading losses. 

Batteries, if paired, need firmware updates quarterly to optimise storage, boosting self-use by 20-30% amid rising wholesale prices.

Insight: Unsure if your solar battery is still working properly? Read our guide to learn the signs of a failing battery. 

When Should You Call a Professional for Solar Repairs?

Call a professional immediately if you spot any of the seven signs above, as delays can void warranties and amplify faults. Thresholds include zero output for over 48 hours or inverter errors persisting beyond a reset.

Seek MCS-accredited technicians via Solar Energy UK's directory; expect diagnostics at £100-200, with repairs ranging £300-1,500 for common inverter swaps. 

For commercial managers, prioritise during off-peak seasons to minimise disruption. Post-2025, with installations up 22% in the first half per government data, wait times may lengthen, book ahead.

FAQs

Can shading from nearby buildings affect my solar panel output year-round?

Yes, partial shading from buildings can reduce output by 50% or more across unshaded panels due to bypass diode activation, but strategic pruning or micro-inverters mitigate this.

How does panel orientation impact detection of working issues?

South-facing panels at 30-40° tilt maximise UK sunlight capture, making deviations easier to spot via lower-than-expected yields; east-west orientations suit shaded sites but require adjusted benchmarks for troubleshooting.

Are smart home integrations helpful for ongoing solar monitoring?

Absolutely, integrations with platforms like Google Home or Alexa alert you to anomalies in real-time, flagging 95% of efficiency drops before they hit bills.

What if my solar panels work fine but battery storage isn't charging?

This often indicates a charge controller fault; test by monitoring voltage levels, under 13.5V DC signals issues. Upgrading to lithium-ion batteries, now standard in 60% of new UK installs, enhances reliability.

How do seasonal changes influence interpreting solar performance data?

Summer boosts output by 2-3x over winter due to longer days, so baseline comparisons should factor daylight hours; apps auto-adjust for latitude, helping pinpoint true malfunctions versus natural dips.

Our Verdict

Empowering UK homeowners and landlords with these insights equips you to safeguard your solar investment, from swift sign detection to proactive upkeep amid growing adoption. By staying vigilant, you'll maximise returns on a technology poised to power 5 million homes by year's end, fostering sustainable properties that endure.