Your solar panels are generating — but are they generating as much as they should be?
For many UK commercial operators, the honest answer is no. Soiling, inverter degradation, micro-cracks, and shading losses quietly erode system performance over time, often without triggering a single alert. By the time the drop in output becomes obvious, months of lost generation have already passed.
A well-designed commercial solar PV system will generate clean energy reliably for 25 years or more. But even the best-engineered systems develop faults, and in a commercial setting, every fault that goes undetected translates directly into lost revenue, higher grid bills, and potential safety risk. The good news is that the most damaging solar panel problems are rarely sudden. They develop gradually, leave detectable signals, and when caught early, are straightforward and inexpensive to resolve.
This guide covers the most common faults affecting the three main commercial installation types; rooftop, ground mount, and carport solar, what causes them, how to detect them before they escalate, and what to do when they arise. Whether you manage a single rooftop system or a multi-site portfolio, this is what your facilities team needs to know.
Why Solar Panel Problems Matter?
The most important reason to stay on top of solar panel faults is simple: undetected problems cost money and create risk.
Every kiloWatt-hour your system fails to generate is energy you’re buying back from the grid at a premium. Beyond financial loss, faults like arc faults, ground faults, and overheating panels carry genuine fire risk, particularly on large commercial rooftops where thermal events can escalate quickly.
Here’s what’s at stake for commercial operators:
- Direct financial loss: lost generation = higher energy bills and reduced ROI
- Safety hazards: arc faults and overheating panels are a documented fire risk
- Warranty risk: unresolved faults can void manufacturer warranties
- Carbon reporting inaccuracies: underperforming systems skew ESG and Scope 2 emissions data
- Compliance exposure: UK electrical safety standards, including BS 7671, require systems to be maintained in safe working order
The difference between reactive repairs and a proactive Operations & Maintenance (O&M) strategy is often measured in thousands of pounds per year in avoidable losses.
Universal Solar Panel Problems (All System Types)
The following faults can affect any commercial solar installation, regardless of whether it’s rooftop, ground mount, or carport. These are the most common solar panel problems encountered across the UK commercial sector:
- Potential Induced Degradation (PID)
PID occurs when high voltage differences between the solar cell and its frame cause electrical leakage, gradually degrading panel output. It’s particularly prevalent in larger commercial strings operating at higher DC voltages. PID is invisible to the naked eye and can cause output losses of up to 30% before it’s detected, making monitoring essential.
- Hot Spots
Hot spots are localised areas of overheating caused by cell defects, partial shading, or soiling — and they can permanently damage panels if left untreated. A single bird dropping or patch of debris can cause a bypass diode to activate, forcing current through a small area and generating intense heat. Thermal imaging (infrared) inspections are the only reliable method to detect hot spots before visible damage occurs.
- Micro-Cracks
Micro-cracks are hairline fractures within solar cells; often caused during transit, handling, or installation, that are invisible without electroluminescence (EL) imaging. Over time, thermal cycling (repeated heating and cooling through UK seasons) causes micro-cracks to widen, reducing the effective cell area and output.
- Inverter Faults
The inverter is the most commonly replaced component in a commercial solar PV system. Inverters convert DC power from your panels into usable AC electricity. They operate under constant thermal stress and are sensitive to grid disturbances. Common faults include overheating (especially in poorly ventilated plant rooms), grid isolation failures, and capacitor degradation in older units.
- Soiling and Contamination
Dust, dirt, bird droppings, lichen, and pollen accumulate on panel surfaces and block sunlight from reaching the cells. In the UK, soiling is exacerbated by rainfall followed by dry spells (which leave mineral deposits), proximity to agricultural land, and urban pollution. Soiling losses of 10–25% are well-documented if left unchecked.
- Faulty Wiring and MC4 Connector Degradation
Wiring faults are one of the most serious solar panel problems, not just for performance, but for safety. MC4 connectors (the standard DC connectors used in solar PV systems) are exposed to UV radiation, moisture, and temperature cycling throughout their lifespan. Corroded or poorly seated connectors create resistance, generate heat, and can ultimately cause arc faults, a leading cause of solar-related fires. Rodent damage to cabling is also a persistent issue, particularly on ground mount sites.
- Bypass Diode Failure
Bypass diodes protect panels from the effects of partial shading by routing current around a shaded cell. When a bypass diode fails, the shading impact spreads across the entire string rather than being isolated, multiplying the generation loss significantly.
- Delamination
Delamination occurs when moisture penetrates the panel’s encapsulant layer, causing the protective laminate to separate from the solar cells. It’s more common in older panels or those installed in particularly humid UK microclimates, near rivers, coastal areas, or low-lying sites with persistent fog.
Rooftop Solar Problems
Commercial rooftop solar systems face a unique set of challenges because they share an environment with other building infrastructure, HVAC units, rooflights, plant equipment, and the roof membrane itself. The following issues are most common on UK commercial rooftops:
Mounting System Corrosion
Roof-mounted racking systems are exposed to the elements year-round. On flat roofs where rainwater pools around mounting feet, corrosion can compromise the structural integrity of the entire array. This is particularly relevant on older industrial or warehouse roofs with standing water issues.
Roof Membrane Penetration Failures
On flat commercial roofs, solar panels are often ballasted (weighted down) to avoid penetrating the membrane, but some systems do use mechanical fixings. If fixings are incorrectly installed or the membrane degrades around penetration points, water can enter the building fabric below.
Wind Uplift and Racking Failure
The UK’s Atlantic weather patterns particularly in exposed northern and western regions, which means commercial rooftop systems must be engineered to withstand significant wind loading. Incorrectly specified ballast weights or racking systems can shift under wind load, damaging panels and potentially creating falling debris hazards.
Shading from Roof Plant and Equipment
New HVAC installations, communication masts, or additional roof equipment installed after the solar system can create shading that wasn’t accounted for in the original design. Even partial shading from a new air handling unit can disproportionately affect generation due to the string effect.
Ground Mount Solar Problems
Ground-mounted solar panels offer excellent yield potential and access for maintenance, but their open, exposed environment introduces hazards that rooftop systems simply don’t face.
Vegetation Overgrowth
Vegetation shading is the single most common and avoidable ground mount problem in the UK. Grass and scrub beneath and around ground mount arrays grow rapidly during UK spring and summer. If left unmanaged, vegetation shades the lower rows of panels, creates hot spots, and provides nesting habitat for rodents that damage cabling. A vegetation management plan, typically using ground-cover plants, gravel, or regular cutting is a standard part of EvoEnergy’s O&M recommendations.
Animal and Rodent Damage
Ground mount sites are particularly vulnerable to animal interference. Rabbits gnaw through cable insulation; birds and foxes nest under the array structures; and larger animals can physically displace lower racking sections. Rodent damage to DC cabling is a significant cause of arc faults on ground mount sites.
Soil Subsidence and Racking Misalignment
In the UK, freeze-thaw cycles and waterlogged soils can cause ground movement beneath pile-driven or ground-screwed mounting structures. Over time, this leads to misalignment of the array, affecting both panel angle (reducing yield) and panel-to-panel gaps (increasing wind loading risk).
Waterlogging and Flooding
Low-lying UK sites particularly in flood plain areas or clay-heavy soils are at risk of waterlogging after prolonged rainfall. Submerged cable trenches, flooded junction boxes, and saturated cable runs are all serious hazards. Flood risk assessment should form part of any ground-mount feasibility study.
Cable Theft and Vandalism
Ground mount sites are more physically accessible than rooftop systems and therefore more exposed to cable theft, a persistent and growing problem in rural UK. DC cabling contains copper and is a target for opportunistic theft. Security measures including CCTV, perimeter fencing, and cable routing in steel conduit are standard mitigation.
Solar Carport Problems
Solar carport systems transform underused car parks into productive energy assets and they’re increasingly popular across the UK commercial and public sectors. But the car park environment introduces a specific set of maintenance challenges.
Steel Frame Corrosion
Solar carport structures are built on steel frames that are permanently exposed to the elements. In coastal UK locations or areas with high atmospheric salinity, frame corrosion can accelerate significantly. Regular inspection of structural steelwork, including welds, bolts, and connection points is essential to maintain both safety and structural integrity.
Vehicle Impact and Clearance Damage
Vehicle impact is a unique risk for solar carports that simply doesn’t exist in rooftop or ground mount environments.
Delivery lorries, HGVs, and oversized vehicles that exceed the designed clearance height can physically strike carport structures or panels. This can dislodge panels, damage racking, and in serious cases, compromise the structural integrity of the entire canopy.
Vibration from Traffic
Constant vibration from vehicles passing beneath the canopy causes gradual loosening of panel fixings, MC4 connectors, and racking bolts in ways that would not affect a rooftop or ground-mount system. Annual torque-checking of all fixings is a recommended best practice for carport systems.
Drainage and Gutter Blockages
Carport canopies channel all roof rainwater into gutters and downpipes. Blocked or overwhelmed drainage systems cause water to pool on or around panels, accelerating soiling and potentially allowing water ingress into junction boxes. Gutter clearance should be scheduled at least twice per year in line with leaf fall seasons.
EV Charger Integration Faults
Where solar carports are paired with EV charging infrastructure which is increasingly standard across EvoEnergy carport projects DC coupling, metering, and load management faults can affect both systems simultaneously. Monitoring both the generation and the EV charging data in an integrated platform is essential to catch integration faults early.
EvoEnergy designs solar carports with integrated EV charging infrastructure. Our monitoring systems track both solar generation and EV charging performance from a single dashboard. Learn more about our solar carport solutions.
How to Detect Solar Panel Problems Early?
The earlier a solar panel fault is detected, the cheaper and simpler it is to resolve.
Follow these steps to build an effective early detection routine:
- Monitor your inverter dashboard daily: Most commercial inverters provide real-time string-level data; set automated alerts for output drops.
- Establish performance ratio benchmarks: Compare actual generation against modelled yield using local irradiation data from tools like PVGIS.
- Schedule bi-annual thermographic (infrared) inspections: The only reliable way to detect hot spots, PID, and delamination before visible damage occurs.
- Carry out quarterly visual walkarounds: Use the checklist format from Section 5 above; include roof, frame, and cabling inspection.
- Review string-level data after weather events: High winds, hail, and heavy snow are trigger events for racking and panel damage.
- Act immediately on any string-level underperformance: A single underperforming string left unaddressed will compound losses over time.
Prevention Costs Less Than You Think. Inaction Costs More Than You Expect.
Every solar panel problem in this guide shares one characteristic: it’s significantly cheaper to prevent than to repair. A thermographic survey that catches a hot spot early costs a fraction of the panel replacement, roof damage, or in worst-case scenarios, fire remediation that follows an unchecked fault.
For UK commercial operators with ESG commitments, warranty obligations, and energy budgets to protect, a proactive O&M strategy isn’t a luxury, it’s due diligence.
EvoEnergy was built to support commercial solar owners for the long haul. From the first thermographic survey to a full system re-power a decade down the line, our aftercare and optimisation services are designed to maximise every kilowatt-hour your system generates. Our aftercare team provides the monitoring, expertise, and rapid response that keeps your solar asset safe, compliant, and generating at its full potential year after year.
Ready to take the guesswork out of solar maintenance? Explore EvoEnergy’s Aftercare & O&M Services or get in touch with our team to discuss a maintenance plan tailored to your system.