Can It Get Too Hot For Solar Panels?

Installing solar panels is one of the most effective ways to lower energy bills and reduce your carbon footprint. 

But as the UK sees increasingly warmer summers, many homeowners and landlords are asking: can it get too hot for solar panels? The short answer is yes, but it’s a bit more nuanced than that.

Solar panels work best under specific conditions, and extreme temperatures can impact their efficiency. 

This guide explains how heat affects solar panel performance, what to expect during a UK summer, and how to maximise your investment.

How Does Heat Affect Solar Panel Efficiency?

High temperatures reduce solar panel efficiency by causing a drop in voltage output, which lowers overall energy production. 

This is because heat increases the electrical resistance within the panel's components. 

So, while clear, sunny days are ideal, scorching hot days can slightly diminish output.

Most solar panels are tested under Standard Test Conditions (STC), which assume a temperature of 25°C, 1,000 watts of sunlight per square metre (irradiance), and no wind. 

But in real-world settings, especially during warm summer months, the surface temperature of a solar panel can rise significantly above ambient air temperature, often reaching 40°C to 60°C, depending on airflow and roof material.

The performance drop caused by temperature is measured by the temperature coefficient, a value expressed as a percentage of efficiency lost per degree Celsius above 25°C.

This means that if your solar panels reach 35°C, you could see efficiency reductions of up to 5%, depending on the technology used. 

While this might sound concerning, the impact is often offset by longer daylight hours and higher solar irradiance during summer, resulting in strong overall output even on hot days.

Real-World Performance in the UK

In the UK, average summer temperatures typically range between 18°C and 25°C, with peaks reaching 30°C or more in southern regions. This keeps most panels operating within or just above their optimal efficiency range. 

According to the Energy Saving Trust, modern solar panels are engineered to remain reliable year-round, even as surface temperatures rise in direct sunlight.

Can Commercial Buildings Be Affected Differently?

Yes, commercial buildings can be affected differently by heat-related performance issues, largely due to the scale of installations, roof structure, and usage patterns. 

While the core technology (solar PV) is the same, commercial setups present unique challenges and opportunities when it comes to managing heat and optimising output.

Why Commercial Systems Are More Susceptible to Heat

Commercial solar arrays are typically:

• Larger in scale — often 30kW to several hundred kW or more
  
  
• Installed on flat or low-slope roofs, such as those found on warehouses, factories, schools, or office blocks
  
  
• Mounted on surfaces with limited natural airflow or heat-retaining materials like bitumen or dark membranes

Flat roofs absorb and trap more heat, especially in urban environments where the Urban Heat Island effect (UHI) can raise rooftop temperatures well above ambient air temperature. 

Without adequate ventilation or reflectivity, solar panels on these surfaces can reach operating temperatures of 60–80°C, pushing the limits of their temperature tolerance and slightly increasing the risk of performance degradation.

What Happens to Solar Panels in a UK Heatwave?

As climate change drives more extreme weather events, UK heatwaves are becoming both more frequent and more intense. 

According to the Met Office, the UK experienced record-breaking temperatures in July 2022, when parts of England exceeded 40°C for the first time on record. This has raised valid concerns among homeowners and landlords investing in solar.

Built to Handle Extreme Conditions

Solar panels are rigorously tested to international standards and are designed to function in much harsher climates than the UK. Most modern panels are built to operate within a wide temperature range, from -40°C to 85°C. 

This means they’re more than capable of withstanding the peak rooftop temperatures experienced during UK summer heatwaves, which can climb to 50°C–70°C on black or tiled roofs in direct sunlight.

This heat does not cause panels to fail or shut down. Instead, the impact is a temporary reduction in efficiency, which is typically well within the tolerances of a properly installed system.

In the UK, even a few days of 35°C+ weather aren’t enough to cause long-term concern. For context:

• A monocrystalline panel with a temperature coefficient of -0.4%/°C would lose around 6% efficiency if its surface reaches 40°C.
  
  
• That still means it’s producing 94% of its rated output and often for longer hours due to extended daylight in summer.

Moreover, these temporary dips are often offset by the overall increase in solar irradiance during heatwaves, which can help maintain strong total energy yields for the day.

Insight: Following the July 2022 heatwave, data from several domestic solar monitoring platforms showed that overall solar energy production remained strong, even with temperature-related efficiency dips. 

In many cases, longer daylight hours and minimal cloud cover resulted in daily generation levels that exceeded spring and early summer averages.

This underscores the point: even during a heatwave, solar remains a high-performing renewable energy option in the UK.

Ready to start your solar journey? Use Eco Answers' free Quote-Comparison Tool to connect with trusted UK installers and get tailored solar panel quotes in minutes.

Will Hot Weather Affect Solar Panel Lifespan?

In the case of modern, high-quality solar panels, the risk of heat-related deterioration is minimal when the system is correctly installed and maintained.

Solar panels are made from semiconductors and layered materials that expand and contract with temperature fluctuations. 

Over many years, this process, known as thermal cycling, can contribute to material fatigue and micro-cracks in the silicon cells or lamination layers. 

This is especially true in inferior, non-certified panels or in installations with inadequate ventilation, where trapped heat accelerates wear and tear.

However, most panels installed in the UK, especially those classified as Tier 1 are manufactured under strict quality controls and tested to endure these stresses.

According to Ofgem, the quality of components and professional installation are crucial for ensuring your solar system performs reliably over its full lifespan.

Designed for Longevity — Even in Heat

Leading manufacturers design panels to withstand decades of environmental exposure, including UV radiation, rain, snow, and heat. Panels typically come with two warranties:

• Product warranty: Covers material or manufacturing defects (usually 10–15 years)
  
  
• Performance warranty: Guarantees at least 80–85% efficiency after 25 years

These warranties assume the panel will be operating in a variety of climates, including hotter ones than the UK.

In fact, solar panels installed in Mediterranean or Middle Eastern regions, where ambient temperatures often exceed 40°C, routinely last well over two decades with proper care. 

So, occasional UK heatwaves won’t significantly affect the lifespan of panels from reputable brands.

Installation & System Design Matters

While the panels themselves are built to last, poor installation practices can reduce lifespan more than the weather ever could. Key factors that help mitigate long-term heat impact include:

• Adequate airflow beneath panels: Prevents overheating by allowing heat to dissipate
  
  
• Use of thermal-resistant materials: Higher-grade mounting structures and panel backing materials improve durability
  
  
• Strategic placement: Panels mounted too close to dark, heat-retaining roof surfaces may suffer more from heat buildup

This is why choosing a certified installer matters. Systems installed under the Microgeneration Certification Scheme (MCS) are required to meet strict performance and safety criteria, giving homeowners extra peace of mind that their investment is future-proof.

Ofgem also notes that proper system design and solar panel maintenance is key to securing eligibility for incentive schemes and ensuring consistent long-term savings

Interestingly, the UK’s temperate maritime climate may actually help extend solar panel lifespan. 

Because we don’t experience the extreme and prolonged heat seen in some countries, panels here are subject to less thermal stress overall, reducing the risk of accelerated degradation over time.

What Are The Financial Implications of Heat-Related Efficiency Loss?

A common concern for potential buyers is whether high temperatures will noticeably reduce the return on investment (ROI) of solar panels. 

Fortunately, for homeowners and landlords in the UK, the answer is reassuring: the financial impact of heat is minimal, especially when systems are properly sized and installed.

Small Drops, Big Picture

Solar panels may experience 3–5% efficiency loss on very hot days due to elevated surface temperatures, but this doesn’t translate into significant financial loss. 

Why? Because those same hot days typically come with longer daylight hours and higher solar irradiance, which help compensate for the drop in efficiency.

In the UK, peak summer months (June to August) offer around 16–18 hours of daylight, with the sun remaining strong and consistent even into the evening, particularly in southern regions.

Let’s break this down with a real-world scenario:

Even on the hottest days, your system may only lose about 1 kWh of generation, the equivalent of roughly 30p–40p based on current average electricity rates in the UK (28–30p per kWh as of 2025). 

Over a month, that’s a potential reduction of around £9–£12, assuming consistently high temperatures, which, in the UK, is extremely rare.

Minimal Impact on Long-Term ROI

Let’s say your solar PV system saves you £600–£700 per year on electricity bills. A few isolated hot days might reduce that savings by £10–£20 annually, at most, less than 3% of your total savings.

Meanwhile, solar panel systems continue to pay for themselves within 7–10 years, especially with energy prices on the rise and smart export tariffs allowing you to sell excess electricity back to the grid.

According to the Energy Saving Trust, a typical 4–6kW solar PV system in the UK can save a household £450–£750 per year, depending on usage patterns and export tariffs.

What About Commercial or Landlord Properties?

For commercial buildings or multi-tenant properties, where solar arrays are often larger, small efficiency losses can seem more significant. But in reality:

• Larger arrays generate substantially more energy overall, mitigating percentage-based losses.
  
  
• Many commercial properties benefit from time-of-day usage (e.g. daytime air conditioning, server loads), which aligns with solar production hours, even during hotter days.
  
  
• Capital allowances and smart export tariffs further improve ROI despite occasional dips.

In short, the financial impact of heat-related efficiency losses is statistically insignificant compared to the long-term gains of reduced energy bills, lower grid reliance, and increasing property value from solar panel installation.

Are There Ways to Reduce the Impact of Heat on Solar Panels?

Yes, there are several proven strategies to minimise the impact of heat on your solar panel system. .

Here’s how:

1. Elevated Mounting Systems

Allowing airflow beneath the panels is one of the simplest yet most effective ways to prevent overheating. Most modern UK installations are designed with mounting frames that lift panels a few inches above the roof surface, allowing for passive ventilation. 

This air gap helps dissipate excess heat and keep panel temperatures closer to ambient air levels.

Solar panel systems installed flat against the roof, or integrated into roof tiles without sufficient airflow, can experience higher surface temperatures, leading to steeper efficiency drops during heatwaves.

Tip: Ask your installer if your mounting system promotes adequate cooling and complies with MCS design standards

2. Reflective Roofing or Coatings

Your roof colour and material can significantly influence panel temperature. Dark-coloured roofing materials, such as black asphalt or slate tend to absorb more heat, which can transfer to the underside of the panels and increase surface temperatures.

Solutions include:

• Applying reflective or cool-roof coatings to reduce heat absorption
  
  
• Installing panels slightly raised off dark roofs to minimise direct contact
  
  
• Opting for roof-integrated panels only if they are ventilated and include thermal-resistant layers

While retrofitting an entire roof might not be practical, these adjustments can make a measurable difference in maintaining solar efficiency in hotter conditions.

3. High-Quality Inverters & Real-Time Monitoring

Inverters play a critical role in overall system performance, especially during temperature fluctuations. Premium inverters can better tolerate voltage drops caused by high temperatures and maintain stable output levels.

Additionally, real-time performance monitoring systems allow homeowners to:

• Track daily energy production
  
  
• Identify anomalies related to heat, shading, or malfunction
  
  
• Get automated alerts when output deviates from expected baselines

Active monitoring systems help extend the life of your solar PV system by enabling early detection of performance issues.

4. Selecting Panels With Low Temperature Coefficients

When selecting panels, don’t just look at wattage, look at the temperature coefficient. This figure tells you how much performance drops per degree above 25°C. A lower temperature coefficient means the panel is more resilient to heat.

While thin-film panels are the most tolerant to heat, they tend to have lower efficiency per square metre, meaning they may not be ideal for smaller UK rooftops. 

In contrast, premium monocrystalline panels offer excellent efficiency and good thermal performance, making them a popular and reliable choice for most UK property types.

Advancements in solar technology are now focusing on thermal stability and long-term resilience, particularly in residential applications where rooftop temperatures can vary significantly.

5. Strategic Placement and Panel Orientation

South-facing panels get the most sun exposure, but in high-temperature scenarios, you might consider slightly adjusting tilt angles to:

• Maximise morning and late-afternoon sun (when it’s cooler)
  
• Avoid direct overhead exposure during peak heat

This can help smooth out thermal load across the day while maintaining strong energy generation. Additionally, avoid installing panels too close to surfaces that trap or radiate heat, such as chimneys or dark-coloured walls.

How Commercial Installations Are Engineered to Cope

Fortunately, commercial solar systems are often custom-engineered to mitigate the effects of heat more effectively than residential ones. Common heat-reduction strategies in commercial solar include:

Active Cooling Systems

Some large-scale systems integrate mechanical or passive cooling technologies, such as forced-air ventilation, water misters, or heat-dissipating conduits. 

While not typically cost-effective for residential installs, these methods can be worthwhile in high-yield commercial systems where every percent of efficiency counts.

Reflective Roof Membranes

Many modern commercial roofs are fitted with white or reflective membranes (cool roofs) that deflect sunlight and reduce thermal buildup. These can reduce roof surface temperatures by 10–15°C, helping maintain panel performance during warm spells.

Higher-Grade Industrial PV Materials

Commercial-grade panels and inverters are often built with enhanced thermal tolerance, more robust backing materials, and improved cell spacing to help regulate temperature and maintain consistent voltage output.

According to Solar Energy UK, commercial solar adoption is growing in the UK, particularly among logistics and retail operators, many of whom integrate energy management systems that monitor both output and thermal conditions.

Performance Monitoring

Because commercial solar arrays represent a significant financial asset, it’s critical that facility managers or energy officers implement continuous performance monitoring systems. These systems provide:

• Real-time tracking of energy production and temperature data
  
  
• Alerts for heat-related anomalies (e.g. inverter tripping, voltage drops)
  
  
• Long-term insights into seasonal performance trends

By analysing this data, building managers can proactively adjust load schedules, schedule maintenance, or identify areas where panel cleaning or system upgrades may be warranted.

Tailored Installation Is Key

Just like residential systems, panel choice, layout, and mounting design are essential to long-term performance. 

However, for commercial buildings, the stakes are higher, both in terms of upfront investment and potential energy cost savings. That’s why it's critical to work with MCS-accredited commercial solar installers who understand:

• Heat management strategies
  
  
• Regulatory compliance (e.g. Part L, BREEAM, or SBEM standards)
  
  
• System scaling and zoning to avoid overheating hotspots

Will Solar Panel Warranties Cover Heat Damage?

Most UK solar panel manufacturers provide warranties of 20 to 25 years, covering performance degradation. Panels are built to endure high and low temperatures and are tested under thermal stress conditions before being sold.

Ofgem outlines that systems must comply with Microgeneration Certification Scheme (MCS) standards to qualify for government schemes.

So, as long as your system is installed by an MCS-accredited provider, you’re covered.

FAQs

1. Do solar batteries overheat during hot weather?

Modern solar batteries come with built-in temperature regulation. As long as they are installed in shaded, ventilated areas, overheating is extremely rare.

2. Should I avoid installing solar panels in summer?

Not at all. Summer is actually one of the best times to install solar panels due to longer daylight hours. Installers can also assess heat-specific needs during warmer months.

3. Can shading from trees help with solar panel heat?

While some shade may reduce heat, it also blocks sunlight and lowers output. Proper airflow and quality installation are better solutions.

4. Does temperature affect solar panel cleaning needs?

Yes. Hot weather combined with dust or pollen can cause grime to bake onto panels. Consider seasonal cleaning for optimal performance.

5. Are there grants or incentives in the UK to upgrade to heat-resistant solar panels?

While there are no grants specifically for heat-resistant panels, UK homeowners can benefit from the Zero VAT on solar installations scheme. 

Final Thoughts

To sum up, while it can get too hot for solar panels to operate at peak efficiency, UK temperatures rarely reach levels that cause concern. Heat may cause a slight drop in performance, but modern panels are engineered to handle it. 

With smart system design, proper installation, and informed choices, solar panels remain a solid investment, even during heatwaves.

If you're considering solar, now is the perfect time to explore your options. Use Eco Answers’ Quote-Comparison Tool to find the best deal for your home or commercial property. The tool is free, fast, and connects you with trusted local suppliers across the UK.