In Roof Solar Panels: The Complete Guide for UK Homeowners

In roof solar panels work just like traditional solar panels but are designed to blend seamlessly into a property’s roof rather than being mounted on top of it. These solar panels are a cutting-edge choice for UK homeowners who want both performance and seamless design.

What are In Roof Solar Panels?

Instead of mounting panels on top of your tiles or slates, in-roof solar panels replace a section of your roof covering with panels that protect your home from the weather and generate clean energy. This results in a beautifully streamlined finish that blends seamlessly into your property. Key features:

  • Integrated Aesthetics: In-roof panels fit flush with surrounding tiles, giving a modern, streamlined look.
  • Dual Purpose: In-roof solar panels act as a roof covering and generate energy, saving on materials and integrating with the construction of your home.
  • Custom Fit: They can be used in different patterns and shapes, allowing for creative design solutions in new builds or renovations.

How Do In-Roof Solar Panels Differ from Roof-Mounted Systems?

The biggest difference between these systems is how they look. In-roof panels blend seamlessly with your roof for The biggest difference between these systems is how they look. In-roof systems blend seamlessly with your roof for a sleek, integrated style. Traditional roof-mounted systems stand out more and are often easier to set up, without significant changes to your existing roof structure.

  • Appearance: In-roof panels line up with the rest of the tiles, rather than sitting on top. This approach is especially popular in areas with strict planning regulations. Or with homeowners who want to keep their roofline sleek and contemporary.
  • Weight: In-roof panels are about half as heavy as traditional panels (around 10kg instead of 20kg).
  • Cost: Traditional systems are usually cheaper to install. But for new constructions or roof replacements, in-roof systems can be a smart choice as you may save on roofing materials, with less tile area required.
  • Environment / Pest Control: In-Roof panels eliminate access beneath solar panels, stopping birds from nesting below. Traditional panels may require additional pest control measures such as mesh, spikes or solar skirting.
  • Solar Panel Capacity: In-roof models and wattage can be restricted, whereas traditional panels have a wide product selection, allowing for higher wattage models

If you’re starting a roof from scratch, it often makes sense to install in-roof solar panels. This can save on roofing materials and avoids duplicate work in the future. In-roof solar panels are therefore a great option for a new property or roof replacement.

Comparing In-Roof and On-Roof Solar Panel Systems

When choosing between in-roof and on-roof solar, it’s important to compare them across several key areas:

  • Appearance: In-roof systems offer a superior aesthetic, blending into the roofline for a subtle look. On-roof panels are more noticeable.
  • Installation: In-roof installation is more complex and best suited for new builds or re-roofing. On-roof systems are simpler to retrofit.
  • Efficiency: Efficiency levels are broadly similar, though some argue on-roof panels benefit from better airflow, which can slightly improve performance in hot weather.
  • Lifespan: Both systems are designed to last for 25 years or more, with robust warranties.
  • Maintenance: Both require minimal maintenance, mainly consisting of occasional cleaning to ensure optimal performance.
  • Cost: In-roof solar panels typically have a higher upfront cost due to the more complex installation and materials required
  • Warranty: Most mainstream In-roof mounting tray manufacturers offer between a 10 – 15 year product warranty on components. On-roof solar mounting kits can range between 10 – 25 years for premium brands

If you’re re-roofing or building new, in-roof solar panels can be more cost effective since you’re combining roofing and solar work in one go. They are often preferred in conservation areas or developments with strict visual regulations.

comparison chart of in roof solar panels to on roof solar panels across key areas #inroofsolarpanels

If you’re re-roofing or building new, in-roof solar panels can be more cost effective since you’re combining roofing and solar work in one go. They are often preferred in conservation areas or developments with strict visual regulations.

How Do In Roof Solar Panels Work?

The way in-roof solar panels work is similar to standard panels. The panels contain photovoltaic cells that absorb sunlight and convert it into DC electricity. This power is then sent through an inverter, which turns it into the AC electricity your home runs on.

You can use this electricity straight away. If you have a battery, you can store some for after the sun’s gone down. If you generate more power than you use, you can even sell the surplus energy back to the National Grid. Some modern in-roof setups include smart tech that tracks the sun’s position, so you get the most energy possible throughout the day.

Modern in-roof systems are highly efficient and can include smart technology to optimise ‘solar harvesting’ by tracking sunlight throughout the day.

How In Roof Solar Panels Work:

  • Absorption: PV cells collect sunlight, even on cloudy days.
  • Conversion: They turn sunlight into DC (direct current)
  • Inverter: An inverter, hidden in your loft or garage, converts DC to AC (alternating current) for household use.
  • Usage & Storage: Power your home directly, store excess in batteries for later, or export surplus back to the National Grid for bill credits.
Ariel shot of in-roof solar panels installed on a new homes development in Warrington in 2025 by E-Verve Energy

Are All Roofs Suitable for In-Roof Solar Panels?

A lot of homes in the UK are good candidates for in-roof solar, but it’s not a one-size-fits-all solution. They are a good option if your roof is South-facing, the ideal direction for capturing the most sun. An East or West-facing roof will also work well, especially if you can locate panels on each elevation, capturing daylight in the early morning and late evening.

The pitch of your roof matters, too. Most experts say between 30° and 40° works best, but there’s wiggle room. It’s also important that your roof is in decent condition and structurally sound. Large, open expanses are preferable, as shading from chimneys, trees, or neighbouring buildings can reduce energy capturing.

Even bungalows and homes with dormer windows can usually be fitted with an in-roof system. Installers often offer free surveys, so you can get a professional view before you make any decisions. Here’s what to consider when assessing suitability:

Orientation

  • Best: South-facing roof slopes for maximum daily sunlight.
  • Good: East/West orientations still generate significant energy.

Roof Pitch

  • Optimal: Between 30° and 40° for sunlight capture in the UK.
  • Possible: As low as 15° or as steep as 50°, depending on system manufacturer and location.

Roof Size, Strength

Large, uninterrupted areas work best, but panels can be custom-fitted around features like roof windows. The roof should be sound and able to bear the weight of panels and frames. Avoid frequent shading from trees, buildings or chimneys for peak performance..

How Are In-Roof Solar Panels Installed?

The installation is a bit more involved than traditional mounting, but results in a beautifully integrated finish. The below sequence is for typical solution, a reputable installer will be able to advise on the differences between each product.

  1. The installer surveys your roof and designs a custom layout, using MCS certified products in the UK. Consideration should be given with regards to the final perimeter roof tile size and set out to avoid small tile cuts and maintain integrity of the surrounding roof tile.
  2. Existing tiles or slates will be removed where the solar panels will be located.
  3. Wooden lattice battens will be secured to the exposed rafters which are used to secure in-roof panel trays to the roof. Some systems use the same battens as the tile, whilst others require additional battens to align with the manufacturers fixing points.
  4. Perimeter flashings will be added below the in-roof system to weatherproof the roof structure.
  5. The in-roof solar panel mounting system is then mechanically fixed to the lattice framework using pre determined screw locations.
  6. An additional perimeter weatherproof flashing is installed around the perimeter of the mounting kit. This can be either flexible lead type flashings combined with rigid pressed sheet metal to traywork to aid water run off to tile or gutter below.
  7. Solar panels are secured into the trays using integrated clamps allowing the roof to be re-tiled around the perimeter and sealed.

Installers should be MCS-certified (Microgeneration Certification Scheme). This is essential for accessing incentives like the Smart Export Guarantee (SEG) in the UK.

Types of In Roof Solar Panel systems

There are two main types of in-roof solar panel systems in the UK frame based systems and bespoke or integrated systems.

Frame Based systems

Solar panels from various manufacturers are installed onto a tray based system which is fixed directly to the roof battens. GSE integration and Edilians Easy Fit Evolution manufacturer tray based systems providing flexibility on solar panel selection.

Bespoke / Integrated systems

Solar panels are designed to integrate with unique purpose-built frames, with both panel and frame manufactured by the same company. Viridian, GB-Sol, Solfit and Wienerberger provide bespoke solutions offering an aesthetically pleasing finish.

Roof tile manufacturers have also developed systems to align with their own roof tile profiles with Marley and BMI Redland both offering bespoke in-roof solar systems

In rood solar panels systems chart of pros and cons and best for products #inroofsolarpanels

When installing an in-roof solar panel system you need to determine which product suits your particular roof pitch, tile type, roof size and shape and budget. 

Solar panel capacities which align with the products should also be considered to achieve an aesthetically pleasing result, which also maximises solar generation outputs.

As for manufacturers, GSE Integration and Viridian Solar (with their Clearline Fusion system) are leaders for integrated panels, while Marley is well-known for solar tiles. Many new developments in the UK use Viridian’s system for its quick installation and upmarket appearance.

In-Roof Solar Panel Manufacturers

GSE In-Roof System

Known for its versatility, this system is compatible with a wide range of solar panels and roof tile types.

GSE in-roof systems are lightweight, watertight and budget-friendly. They are designed to fit around 90% of solar PV panels in the UK. They can be installed on roofs with pitches from 12° to 50°, and their MCS certification means your solar setup will qualify for export payments. 

Built to last, these systems are engineered to handle strong winds and heavy snow with ease.

GSE In Roof System Datasheet

GSE In Roof Solar Panels mounted on roof #inroofsolarpanels #gse
GBSOL Infinity In Roof Solar Panels fitted on sloped roof #inroofsolarpanels #gbsol #gbsolinfinity

GB-Sol Infinity

SolFit provides integrated PV systems that use high-efficiency Bisol laminates manufactured in the EU.

These systems allow for free-flow of air under the panels, resulting in better performance. SolFit systems come with guarantees for PV manufacture workmanship, weather tightness, and linear performance.

The GB-Sol infinity range is ideal for new build and bespoke property designs which are looking a seamless edge to edge Solar roof design.

GB-Sol Infinity Datasheet

Viridian Solar Clearline Fusion

A top choice for its sleek aesthetics, high performance and excellent weatherproofing.

Viridian Solar’s Clearline Fusion system is a cost-effective option that works seamlessly with Viridians own fusion monocrystalline solar panel brand with capacities ranging from 335W – 445W.

Sleek and stylish hidden roof fixing points Clearline Fusion makes high-quality roof integration easily accessible for retrofit projects.

Viridian Solar Clearline Fusion Datasheet

Viridian Solar In Roof Solar Panels installed on sloped roof with 3 velux windows #viridiansolar #inroofsolarpanels

Overall, each brand of in-roof solar mounting equipment has its own strengths and advantages. Whether you prioritise affordability, aesthetics, performance or durability, there is a brand that caters to your specific needs. It is important to carefully consider the features and benefits of each brand before making a decision on which in-roof system to install.

The Pros and Cons of In-Roof Solar Panels

There’s a lot to love about in-roof solar panels. They’re stylish, practically invisible while still powering your house with green energy. They make fantastic use of space and could even bump up your home’s appeal if you ever decide to move. Because they’re part of the roof, these systems offer solid weatherproofing and durability.

There are some downsides. The initial investment is higher, mostly because there’s more installation work involved. If you’re renovating or starting a new build, though, it often balances out. Efficiency can take a minor hit in very warm weather, since the panels are flush to the roof, but in the UK’s generally mild climate, this isn’t much of a problem.

Repairs can be more involved than traditional systems, since you may need to lift the panels to get underneath. Still, with strong warranties and reliable manufacturers, problems down the line are uncommon.

Pros:

  • Superior aesthetics with a seamless, modern look.
  • Acts as part of the roof covering, improving weather resistance.
  • Can increase the value of your property.
  • Ideal for new builds, conservation areas or listed buildings (subject to planning).

Cons:

  • Higher initial installation cost compared to on-roof systems.
  • More complex installation process.
  • Retrofitting can be disruptive and expensive.
  • Slightly lower airflow may minimally impact efficiency in very hot conditions.

In-roof systems tend to be more versatile when it comes to roof shapes and sizes. They can often cover a larger percentage of your roof area than on-roof systems, potentially allowing for a higher capacity solar array. 

From a technical perspective, in-roof systems can offer better performance in certain conditions. The flush mounting means there’s less air circulation behind the panels, which can help them retain heat in colder weather. This can lead to improved efficiency and energy generation during the UK’s chilly winter months, which could mean more savings on your electricity bills in the long run.

Installing solar panels on any new build property provides a great way to meet the energy efficiency requirements of building regulations. Whilst also reducing the price of electricity for the occupant.

What Affects the Cost of In-Roof Solar Panels?

The number of panels you need, the type of system you choose and the complexity of your roof all play a role. It’s usually cheaper to install in-roof solar panels in a new build or whilst re-roofing because you save on roofing materials and extra scaffolding.

For new builds, extensions or complete roof replacements, in-roof systems can bring surprising cost savings. While the upfront installation might cost more, you’ll save on the roof tiles the panels replace. On a large roof, those savings can really add up, often meaning 400 – 500 fewer tiles to buy for a typical home.

Choosing an in-roof system from the start is often simpler than retrofitting solar later, allowing your roof to be designed and built with solar in mind right from the beginning.

High-end solar tiles or panels with smart features will cost more but may offer longer warranties or extra energy output.

Adding battery storage, system monitoring or linking your solar panels up to charge an electric vehicle will bump up costs, but also increase your home’s efficiency and value in the long run. Check for local grants or incentives, too. Sometimes they can make a surprising difference to your final bill.

Final Thoughts

If you’re building a new home or planning a major renovation, in-roof solar panels are a great way to unite aesthetics with excellent performance.

By choosing an experienced installer and a quality manufacturer, you can trust that your in-roof solar panels will be a smart, long-lasting investment that cuts your energy costs and shrinks your carbon footprint for years to come.

How E-Verve Energy Can Help

At E-Verve Energy, we specialise in designing and fitting in roof solar panels for all types of UK homes. We’ll assess your property, explain your options, and handle everything from installation through ongoing support. Whether you’re building from scratch or planning a renovation, we’ve got the experience to help you get the most from your roof.

Ready to get started? Reach out to The Most Trusted Renewable Energy Installers 2024 for a free, friendly chat or use our online quote tool below to design your solar panel array directly onto your own roof!

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That’s okay, we’ve answered some of the more commonly asked questions here but if you still have questions, just get in touch and we’ll be happy to provide any support you need.

Installing in roof solar panels, also known as building-integrated photovoltaics (BIPV), replace a section of your roof tiles. They integrate directly into the roof’s structure, creating a seamless and modern look.

But will this sleek technology work for your specific home?

Whether in-roof solar panels are a viable option depends heavily on your roof’s type, age, and condition. A professional survey is always necessary, but here are the key considerations for various common roof scenarios.

Standard Pitched Roofs

Pitched roofs are the ideal canvas for in-roof solar panels. The natural slope provides a good angle for sunlight exposure. Because the panels replace the existing tiles, the system sits flush with the roofline, offering a major aesthetic advantage over bulky on-roof panels. If you have a standard tile or slate pitched roof, an in-roof system is often a straightforward and visually appealing choice.

New Builds and Roof Replacements

In-roof solar truly shines when integrated into new construction projects or complete roof replacements. Installing the panels at the same time as the roof is highly efficient, reducing both labor costs and material waste. For new builds, architects can design the roof structure from the start to accommodate the BIPV system, ensuring a perfect fit and optimal performance. This makes it a cost-effective and forward-thinking choice for anyone building a home or undertaking a major renovation.

Older and Listed Properties

For older properties, especially those in Conservation Areas or with listed status, in-roof solar can be a game-changer. Local planning authorities often prefer them because they preserve the building’s original character. The panels blend into the roofline, making them far less visually intrusive than on-roof arrays. However, a structural engineer must first confirm that the roof’s framework can support the system. The timbers in older homes may need reinforcement before installation can proceed.

Flat Roofs

In-roof solar systems generally do not suit flat roofs, as the technology integrates into a sloped, tiled surface. Flat roofs require specialised mounting frames that tilt the panels to an optimal angle (usually 10-30 degrees) to capture sunlight effectively and allow for water runoff. For a flat roof, a traditional ballasted or penetrative on-roof system is the appropriate and effective solution.

In-Roof vs. On-Roof: A Detailed Comparison

Choosing between in-roof and on-roof solar panels involves balancing aesthetics, cost, performance, and installation requirements. Let’s break down the advantages and disadvantages of each.

The Pros of In-Roof Solar Panels

  • Superior Aesthetics: This is the primary advantage. In-roof panels offer a sleek, unobtrusive look that integrates seamlessly with your home’s design. They appear as part of the roof itself rather than an addition.
  • Ideal for New Builds: When planning a new roof, you save on the cost of tiles or slates that the solar panels will replace. This can offset some of the higher initial cost of the BIPV system.
  • Preferred for Planning Permission: In sensitive locations like Conservation Areas, the discreet appearance of in-roof systems often makes it easier to gain planning approval from local councils.
  • Potential for Higher Resale Value: The premium look and integrated nature of in-roof solar can be a strong selling point, potentially adding more value to your home than a standard on-roof system.

The Cons of In-Roof Solar Panels

  • Higher Initial Cost: In-roof systems are typically more expensive than their on-roof counterparts. The technology is more specialised, and the installation is more involved, especially for retrofits.
  • Lower Airflow and Efficiency: Installers mount on-roof panels with a gap underneath, allowing air to circulate and cool them. In-roof panels sit flush and can get hotter, which may slightly reduce their energy-generating efficiency, particularly on very warm days.
  • Complex Installation and Repairs: Installing an in-roof system is more complex than simply mounting brackets. Repairing or replacing a panel can be more difficult and costly because it requires interacting with the roof structure itself.
  • Less Flexibility: Once installed, an in-roof system is a permanent part of your roof. You cannot easily move or upgrade individual panels without significant roofing work.

Summary: Are In-Roof Solar Panels Right for You?

Deciding between in-roof and on-roof solar panels ultimately comes down to your priorities, budget, and specific property.

You should strongly consider in-roof solar panels if:

  • Aesthetics are your top priority. You want a sleek, modern look that doesn’t compromise your home’s curb appeal.
  • You are building a new home or replacing your entire roof. This is the most cost-effective scenario, as you save on roofing materials and labor.
  • Your property is in a Conservation Area or is a listed building. Planners are more likely to approve a discreet in-roof system.
  • You are prepared for a higher upfront investment for a premium, integrated look.

An on-roof system is likely a better choice if:

  • Your primary focus is budget and a faster return on investment. On-roof systems are less expensive and quicker to install.
  • Your existing roof is in good condition and doesn’t need replacing anytime soon.
  • You have a flat roof. On-roof mounting is the only viable method for flat surfaces.
  • You want to maximize energy efficiency. The better airflow around on-roof panels can lead to slightly better performance.

Ultimately, both systems provide a fantastic way to generate clean energy, lower your electricity bills, and reduce your carbon footprint. By evaluating your roof type, budget, and aesthetic preferences, we can help you choose the solar solution that best fits your home and goals!

When investing in solar technology for your home, one of the most important questions is about longevity. You want to know that your investment will deliver clean energy for decades to come. In-roof solar panels, which integrate seamlessly into your roofline, offer a sleek and modern alternative to traditional on-roof systems. But how do they stack up in terms of lifespan?

The Lifespan of In-Roof vs. On-Roof Solar Panels

Manufacturers build both in-roof and on-roof solar panels to be durable, reliable, and long-lasting, designing them to withstand the elements and consistently generate power for many years. Generally, you can expect a high-quality solar panel system, whether in-roof or on-roof, to have a productive lifespan of 25 to 30 years.

Most leading manufacturers back this up with performance warranties that guarantee their panels will produce a certain percentage of their original output after 25 years—often 80-90%. This means that while the energy production will slowly decline over time, the panels will continue to function effectively long after the initial warranty period ends.

Key Differences in Longevity

While the core photovoltaic (PV) cells in both systems have a similar lifespan, the installation method introduces some differences that can affect their long-term durability.

  • On-Roof Panels: These are mounted on top of your existing roof with a gap underneath. This gap allows for air to circulate, which helps cool the panels. Lower operating temperatures can reduce stress on the electronic components, potentially contributing to a slightly slower rate of degradation. However, exposure to the elements may require inspecting or maintaining the mounting hardware over the system’s life.
  • In-Roof Panels: Also known as building-integrated photovoltaics (BIPV), these panels act as a part of the roof itself, replacing tiles or slates. This integrated design means there is less airflow underneath, which can cause them to run at higher temperatures. While this can lead to a minor reduction in efficiency on very hot days, modern in-roof systems are engineered to manage heat effectively. A key advantage is that the panels and their integrated flashing systems protect the underlying roof structure, potentially reducing the wear and tear on your roof deck.

Ultimately, the functional lifespan of both systems is very similar. The choice between them often comes down to factors other than longevity, such as aesthetics, installation complexity, and initial cost.

Factors That Affect In-Roof Solar Panel Lifespan

Several key factors can influence how long your in-roof solar panel system lasts and how well it performs over its lifetime. Understanding these can help you maximise your return on investment.

1. Quality of Installation

This is arguably the most critical factor. An in-roof solar system becomes an integral part of your home’s roofing structure. A poor installation can lead to significant problems, including water leaks, poor panel performance, and damage to the roof deck.

A professional, certified installer ensures proper panel seating, perfectly seals the flashing and waterproofing, and secures all electrical connections. Correct installation not only guarantees the system’s performance but also protects the structural integrity of your roof, preventing issues that could shorten the lifespan of both the panels and your home.

2. Material Durability and Manufacturing Quality

The quality of the materials—from the PV cells themselves to the glass, backing, and frame—plays a huge role in their durability. Reputable manufacturers invest heavily in research and development to produce panels that can resist physical impacts from hail, withstand heavy snow loads, and endure decades of UV radiation exposure.

When choosing an in-roof system, look for brands with a proven track record, robust warranties, and certifications from recognised industry bodies. High-quality materials resist degradation and ensure your panels continue to produce power efficiently for years to come.

3. Regular Maintenance and Cleaning

In-roof solar panels are low-maintenance, but not zero-maintenance. Because they sit flush with the roof, they may not benefit from rain washing away debris as effectively as angled, on-roof panels. Dirt, dust, leaves, and bird droppings can accumulate over time, blocking sunlight and reducing output.

Periodic cleaning—usually once or twice a year—with water and a soft brush will keep your panels operating at peak efficiency. It is also wise to have the system professionally inspected every few years to check for any potential issues with the wiring, seals, or surrounding roofing materials. Proactive maintenance helps catch small problems before they become major ones.

4. Environmental Conditions

Where you live can impact your solar panel’s lifespan. Factors like extreme temperature fluctuations, high humidity, heavy snowfall, and salt spray in coastal areas can put additional stress on the system.

Modern in-roof solar systems are designed and tested to withstand these harsh conditions. The integrated nature of in-roof panels can offer better protection against extreme wind uplift compared to some on-roof systems. However, prolonged exposure to severe weather can accelerate wear. Choosing a system specifically rated for your local climate is essential for ensuring its longevity.

Conclusion

In-roof solar panels are a durable and reliable technology, designed to provide clean energy for 25 to 30 years or more. Their lifespan is comparable to traditional on-roof systems, with the primary difference being their seamless integration into your roof’s structure.

To ensure your in-roof system lasts as long as possible, you should:

  • Prioritise a professional installation from a certified and experienced team to protect your roof and guarantee performance.
  • Invest in high-quality panels from reputable manufacturers that offer strong performance warranties.
  • Commit to regular cleaning and periodic inspections to maintain efficiency and catch any issues early.
  • Choose a system that is properly rated to withstand your local environmental conditions.

By focusing on quality from the start, you can be confident that your in-roof solar panels will be a sound, long-term investment that lowers your energy bills and reduces your carbon footprint for decades.

In-roof panels are undoubtedly better looking. They sit flush with your roof tiles, creating a seamless, modern aesthetic. But does this good look come at a cost? A common question homeowners ask is whether in-roof solar panels are less efficient than their on-roof counterparts.

The short answer is: potentially, yes, but the difference is often smaller than you might think.

The Core Difference: Heat and Airflow

To understand the efficiency difference, you first need to understand how solar panels react to heat. It might seem counterintuitive, but solar panels actually work less efficiently as they get hotter. They love sunlight, but they dislike high temperatures.

On-Roof Efficiency

Traditional on-roof panels are mounted on rails that sit a few inches above your existing roof tiles. This gap is crucial. It allows air to circulate freely underneath the panels. This “chimney effect” draws cool air in and pushes warm air out, keeping the panels at a manageable operating temperature even on sunny days.

In-Roof Efficiency

In-roof panels, by design, replace the roof tiles. They sit flush with the roof surface, meaning there is little to no gap underneath for air to flow. Without that cooling ventilation, in-roof panels tend to run hotter than on-roof systems.

According to industry data, for every degree the temperature of a solar panel rises above 25°C (77°F), its efficiency drops by roughly 0.3% to 0.5%. In-roof panels can get hotter, which might slightly lower their total annual energy output—typically by an estimated 3% to 5% compared to an equivalent on-roof system.

Factors That Affect In-Roof Efficiency

While heat is the main culprit, several other factors influence exactly how efficient your in-roof system will be.

1. Ventilation Technologies

Not all in-roof systems are created equal. Early BIPV models suffered significantly from heat buildup. However, manufacturers have recognised this issue and innovated. Many modern in-roof mounting systems now include engineered ventilation channels behind the panels. These allow for some airflow, mitigating the heat issue and narrowing the efficiency gap significantly.

2. Roof Angle and Orientation

The angle of your roof plays a massive role in solar capture. On-roof systems provide slightly more flexibility, as installers can sometimes adjust the mounting rails to optimise the tilt. In contrast, in-roof panels remain strictly bound to your roof’s pitch.

If your roof has a shallow pitch (less than 15-20 degrees), in-roof panels might not catch the optimal amount of sunlight compared to a tilted on-roof frame. However, for standard pitched roofs (30-40 degrees), the angle is usually perfect for solar generation regardless of the installation method.

3. Shading Issues

Shading is the enemy of solar production. Because in-roof panels sit lower—flush with the tiles—they are sometimes more susceptible to shading from nearby obstacles like chimneys, vent pipes, or dormer windows. An on-roof panel, sitting a few inches higher, might just clear a shadow that would otherwise partially obscure an in-roof panel.

However, modern systems use micro-inverters or power optimisers. These devices ensure that if one panel is shaded, it doesn’t drag down the performance of the entire array. If you choose an in-roof system, using optimisers is a smart move to maintain high efficiency.

4. Dust and Self-Cleaning

Solar panels generally rely on rain to wash away dust and debris. On-roof panels are distinct units with clear edges, and rain runs off them easily. In-roof systems are integrated into the roof surface. Depending on the specific design and how flush they sit, debris might accumulate around the edges or frames differently than on a mounted panel.

While this is rarely a dealbreaker, it emphasises the need for occasional maintenance. Keeping the panels clean ensures that dirt doesn’t block sunlight and reduce efficiency.

Aesthetics vs. Output

So, are they “less efficient”? Technically, yes. But let’s put that into perspective.

If a 4kW on-roof system generates 3,400 kWh of electricity a year, a similar in-roof system might generate around 3,250 kWh. That is a loss of about 150 kWh. At current energy prices, that might equate to a small monetary difference annually.

For many homeowners, this small drop in output is a price worth paying for the superior aesthetics.

  • On-roof panels can look bulky and industrial, potentially disrupting the visual appeal of a home, especially on older properties or in conservation areas.
  • In-roof panels look intentional and premium. They can increase the curb appeal and potentially the value of your home, which can financially outweigh the small loss in energy generation over time.

Is the Efficiency Drop a Dealbreaker?

In-roof solar panels are marginally less efficient than on-roof panels, primarily due to higher operating temperatures caused by reduced ventilation. However, the gap is narrowing thanks to better technology and ventilation design.

In-roof panels are a good choice if:

  • Aesthetics are a priority: You want a sleek, non-intrusive look.
  • You are building new or re-roofing: You save money on tiles, which offsets the cost.
  • Planning permission is strict: They are often preferred in sensitive areas.

On-roof panels are a better choice if:

  • Maximum yield is your only goal: You want every possible watt of power.
  • You have a flat roof: In-roof systems aren’t suitable for flat roofs.
  • Budget is tight: They are generally cheaper to install on existing roofs.

Ultimately, the “efficiency loss” is minor in the grand scheme of things. Both systems will significantly lower your bills and power your home with green energy. The best choice depends on whether you value peak performance or peak style.

Investing in solar panels is a major financial decision. Therefore understanding the warranties that protect your investment is crucial. This is especially true for in-roof solar systems, which become an integral part of your home’s structure.

So, what kind of warranty can you expect with in roof solar panels, and how does it compare to the warranty for traditional on-roof systems?

Understanding the Three Core Solar Warranties

Solar panel warranties are not a single, all-encompassing guarantee. They are typically broken down into three distinct parts: the product warranty, the performance warranty, and the workmanship warranty. This structure is the same for both in-roof and on-roof systems, but the details can differ.

Generally, you can expect the core product and performance warranties for high-quality in-roof and on-roof panels to be very similar. Reputable manufacturers stand by their technology regardless of how it is mounted.

1. The Product Warranty (or Materials Warranty)

The product warranty protects you against defects in the solar panel’s materials and manufacturing. This covers issues like frame failures, faulty junction boxes, delamination of the panel layers, or moisture getting inside. It ensures the physical panel itself will hold up as intended.

  • In-Roof Panels: For premium in-roof solar panels, the product warranty typically lasts for 25 to 30 years. Because these systems also function as a roofing material, manufacturers often provide extensive coverage that includes the integrated flashing and mounting components that ensure the system is watertight.
  • On-Roof Panels: The industry standard for high-quality on-roof panels is also 25 to 30 years. This covers the panel itself, but not the separate mounting rails or hardware, which may have their own, often shorter, warranty from a different manufacturer.

The key takeaway is that top-tier brands offer comparable product warranties for both system types. A long product warranty is a sign of a manufacturer’s confidence in its build quality.

2. The Performance Warranty (or Power Output Warranty)

The performance warranty is arguably the most important guarantee for your energy production. It promises that the solar panels will not lose their ability to generate power too quickly. All solar panels experience a slow, gradual decline in efficiency over time—a process known as degradation. This warranty puts a floor on that degradation.

A typical performance warranty guarantees that the panels will still produce a certain percentage of their original rated power after a set number of years.

  • In-Roof & On-Roof Panels: The standard for both is very similar. Most leading manufacturers guarantee that their panels will operate at 85-92% of their nominal power output after 25 or 30 years.

For example, a panel might be warrantied to lose no more than 2% of its output in the first year and no more than 0.25% each year after that. A strong performance warranty ensures your system will continue to deliver significant energy savings for decades. There is no significant difference between in-roof and on-roof systems in this regard when comparing products from the same quality tier.

3. The Workmanship Warranty (or Installation Warranty)

This warranty is provided by your installer, not the panel manufacturer. The workmanship warranty covers any defects related to the installation itself. This includes issues like improper wiring and loose connections.

Conclusion

To ensure your investment is fully protected, follow these guidelines:

  • Choose a reputable manufacturer: Select brands known for their quality and strong, long-term product and performance warranties.
  • Prioritise a certified installer: Look for a company with proven experience, especially with in-roof systems if you choose that path.

A solar panel system is built to last for decades. By understanding and securing strong warranties, you can enjoy peace of mind knowing your investment in clean energy is safe and secure.