Across the UK, it is becoming increasingly popular to install solar panels (photo-voltaics or PV) on houses to reduce energy costs over the long term. Many homeowners require an understanding of the benefits, and what the process is for having solar panels installed on their roof.

One of the most common questions asked by homeowners is whether it is possible to install solar panels on flat or low pitch roofs. This is driven by higher levels of construction of flat and low pitch roofs in modern British buildings, a change from traditional buildings that would have a steep pitched roof.

The answer is “yes”. Solar panels can be installed on flat or low pitch roofs.

A Flat or low pitch roof has a pitch of between 0 and 10 Degrees. Unlike pitched roofs, which have a noticeable slope to facilitate water runoff, flat and low-pitched roofs have a much smaller pitch to allow for drainage but still appear predominantly level.

In this article we are covering all there is to know about installing solar panels on flat or low pitch roofs and if it is a justifiable investment. Taking into consideration the equipment needed, the total implemented cost and benefits and disadvantages. Read on to find out everything you need to know.

Crystalline solar panel on a pitched frame

How do flat or low pitch roof solar panels work?

Flat or low pitch roof solar panels operate on the same principles as their pitched roof counterparts, converting sunlight into electricity through photovoltaic cells. Many solar panel manufacturers stipulate a minimum roof pitch of 3-5 degrees. You can learn how to calculate roof pitch in our dedicated article.

The panels and connectors are rated as IP68 and IP67 respectively.  An IP rating is a certification proving a product meets a certain standard of water and dustproofing/resistance. An IP68 for the solar panels and IP67 for the connectors mean they cannot be submersed in water.

There are 3 main photovoltaic(PV) technologies available:-

  • Standard crystalline photovoltaic systems mounted on brackets and a frame which can be used with most roofing materials. 
  • Bonded laminate photovoltaic systems which are particularly suited to metal roofing.
  • Crystalline panels integrated into the roof. These typically are integrated into the roof structure sitting on composite trays to maintain the integrity of the roof. In-roof systems are unsuitable for pitches less than 15 degrees and many stipulate a minimum pitch of 20 degrees, in line with requirements of many roof light systems.

More information about the different photovoltaic technologies can be found in Vertix EasySeam® Roof System Technical Guide.

Approximate costs for flat or low pitch roof solar panel installations vary depending on factors such as system type, size, equipment quality, and installation complexity, typically ranging from £5,000 to £15,000 for residential installations.

Advantages of flat roof solar panels

  • Easy Access for Installation and Maintenance: Flat and low pitch roofs provide convenient access for solar panel installation and subsequent maintenance, minimising labour costs and logistical challenges. Unlike pitched roofs, which may require scaffolding or specialised equipment for access, flat or low pitch roofs offer a level surface for installers to work on, simplifying the installation process and reducing associated costs. Additionally, routine maintenance tasks such as panel cleaning and inspection can be performed effortlessly on flat or low pitch roofs, further lowering long-term maintenance expenses.
  • Minimal Visibility: Solar panels on flat or low pitch roofs are often less visible from ground level, preserving the aesthetic appeal of the property. Unlike pitched roofs where solar panels may be prominently visible from ground level, flat or low pitch roof installations are typically hidden from view, maintaining the architectural integrity of the building and enhancing curb appeal. This discreet placement of solar panels allows homeowners to enjoy the benefits of renewable energy without compromising the visual appeal of their property.
  • Energy Cost Savings: By harnessing solar energy, homeowners can significantly reduce their electricity bills, leading to long-term cost savings. Flat or low pitch roof solar panels generate clean, renewable energy from sunlight, offsetting electricity consumption from the grid and reducing dependency on fossil fuels. With rising energy costs and volatile utility rates, investing in solar panels offers homeowners a reliable and sustainable alternative for powering their homes, resulting in substantial savings over the system’s lifetime.
  • Environmental Benefits: Solar panels contribute to reducing carbon emissions and reliance on fossil fuels, supporting a greener and more sustainable future. By generating electricity from sunlight, solar panels help mitigate climate change and air pollution, reducing the carbon footprint associated with traditional energy sources. Switching to solar power promotes environmental stewardship and conservation efforts, aligning with global initiatives to combat climate change and preserve natural resources for future generations.
  • Low Maintenance: Flat or low pitch roof solar panels require minimal maintenance, with occasional cleaning to ensure optimal energy production. Unlike other home improvement projects that require regular upkeep and repairs, solar panels have few moving parts and are designed to withstand harsh environmental conditions. With correct installation and routine maintenance, flat or low pitch roof solar panels can operate efficiently for decades, providing reliable and consistent energy production with minimal intervention.
  • Affordable Labour Costs: Labour costs for installing solar panels on flat or low pitch roofs may be more affordable compared to pitched roofs due to easier access and installation logistics. With flat or low pitch roofs providing a level surface for mounting solar panels, installers can complete the installation process more efficiently, reducing labour hours and associated expenses. Additionally, the straightforward installation process of flat roof solar panels minimizes the need for specialised equipment or complex structural modifications, further lowering overall installation costs for homeowners.
Integrated in roof crystalline solar panel system

Disadvantages of Flat Roof Solar Panels

While flat or low pitch roof solar panels offer numerous advantages, there are several disadvantages to consider before proceeding with installation. These include:

  • Increased Dirt Accumulation: Flat or low pitch roof solar panels are prone to accumulating dirt, dust, pollen, and debris over time, which can hinder their performance and efficiency. Unlike pitched roofs where rainwater helps wash away debris, flat or low pitch roofs require regular manual cleaning to remove build-up and maintain optimal energy production. Failure to clean solar panels regularly can result in reduced sunlight absorption and energy generation, leading to diminished overall performance and output. Bonded laminate solar panels are often available with a textured outer surface that helps to improve the self-cleaning ability of the panels in low pitch applications.  The outer layer of the photo voltaic laminate also helps to focus the sunlight to improve efficiency of the solar panel in low sun angles.
  • Reduced Exposure Without Mounting Equipment: Crystalline photovoltaic systems installed without additional mounting equipment, such as tilt frames or tracking systems, may result in the flat or low pitch roof solar panels not receiving optimal sun exposure, potentially reducing energy generation efficiency. Unlike pitched roofs where panels can be angled towards the sun for maximum exposure, flat or low pitch roofs have a fixed orientation that may not align optimally with the sun’s path throughout the day. As a result, some solar panels on flat or low pitch roofs may experience reduced sunlight absorption and energy production, particularly during morning and afternoon hours when sunlight angles are lower. One way to address this is to use the frame to pitch the crystalline panels to an angle of about 40 degrees, similar to the support systems that you see in the farmers’ fields. This will add to the weight on the roof so will require consideration by a structural engineer.
  • Impact on Warranties: Installing certain types of solar panel on flat or low pitch roofs may impact existing roof warranties, as penetration points and added weight from mounting hardware could void certain warranties. Many roofing manufacturers stipulate specific installation guidelines and requirements to maintain warranty coverage, including limitations on roof penetrations and structural alterations. By installing solar panels on a flat or low pitch roof, homeowners risk voiding their roof warranty and may be held liable for any resulting damage or issues that arise. It is essential to consult with a qualified roofing contractor and review warranty terms carefully before proceeding with solar panel installation.
  • Wind Effects: Flat or low pitch roofs are more susceptible to wind uplift compared to pitched roofs, posing a challenge for solar panel stability and potentially requiring additional reinforcement measures. High winds can exert significant force on solar panels, especially in exposed or coastal areas prone to strong gusts. Without adequate anchoring or support, solar panels on flat or low pitch roofs may become dislodged or damaged during severe weather events, leading to costly repairs or replacements. To mitigate the risk of wind damage, installers may need to implement reinforcement measures, such as ballast systems or mechanical fasteners, to secure solar panels firmly to the roof substrate and prevent displacement. Additionally, periodic inspections and maintenance checks are essential to ensure the integrity and stability of solar panel installations on flat roofs, particularly in regions prone to extreme weather conditions.

What Roof Material Is Best Suited for Solar Panels?

When considering solar panel installations, the choice of roof material plays a crucial role in determining the overall success and efficiency of the system. While solar panels can be installed on various roof types, certain materials offer distinct advantages and considerations:

Metal Roof

Metal roofs are popular choices for solar panel installations due to their durability, longevity, and compatibility with mounting hardware and their ability to act as a suitable carrier for bonded laminate photovoltaic systems. The robust nature of metal roofing materials provides a stable foundation for solar panels, ensuring secure attachment and optimal performance. In the case of standard crystalline systems, proper mounting and flashing techniques are essential to prevent water infiltration and maintain the integrity of the roof structure.

Tile Roof

Tile roofs present unique challenges for solar panel installations due to the fragile nature of tiles and the need for specialised mounting hardware. They are also not suitable for bonded laminate photovoltaic options.

Whilst tile roofs can support selected solar panel systems, installation may be more complex and labour-intensive compared to other roofing materials.

Careful consideration is required to ensure proper attachment and alignment of solar panels without damaging the underlying tiles or compromising the roof’s integrity.

Tar & Gravel Roof

Tar and gravel roofs pose challenges for solar panel installations due to their uneven surface and potential for water pooling. The presence of gravel and other debris on the roof surface can impede proper mounting and may require professional assessment and preparation before installation.

The risk of water infiltration and damage to the roof membrane must be addressed to prevent long-term issues and ensure the effectiveness of the solar panel system. They are also not suitable for bonded laminate photovoltaic options.

Standing Seam Metal Roof

Standing seam metal roofs are considered the best option for solar panel installations due to their durability, compatibility, and ease of installation. The raised seams of standing seam metal roofs provide secure attachment points for standard crystalline solar panels, eliminating the need for roof penetrations and reducing the risk of water leakage.

The smooth, uniform surface of standing seam metal roofs facilitates straightforward mounting and ensures optimal sun exposure for maximum energy generation. They are also the ideal carrier for bonded laminate photovoltaic options, which can be placed between the seams, with cabling concealed under the ridge cap. You can learn more about “What is a standing seam roof” in our dedicated post.

More information about the different photovoltaic technologies that standing seam systems are compatible with can be found in Vertix EasySeam® Roof System Technical Guide.

Whilst solar panels can be installed on various roof types, standing seam metal roofs stand out as the preferred choice for their durability, compatibility, and ease of installation. 

Vertix EasySeam® Roof System is a standing seam made from pre-finished steel and is a suitable carrier for photovoltaic solar panels. For further advice and guidance please visit the EasySeam® Roof System page or contact our technical team on 01600 734 000.

Homeowners considering solar panel installations should consult with roofing professionals to assess the suitability of their roof material and ensure proper preparation and mounting techniques for optimal performance and longevity of the solar panel system.

Stick on laminate solar panel

What’s the optimum angle for flat or low pitch roof solar panels?

The optimum angle for flat or low pitch roof solar panels depends on factors such as geographic location, roof orientation, and energy production goals. In general, a tilt angle of around 10-15 degrees from horizontal is recommended to maximise solar energy absorption throughout the year.

The frame used with crystalline solar panels can be used to pitch the panels to an angle of circa 40 degrees, similar to the support systems seen across the agricultural landscape. The anchors that connect the frame to the roof structure to prevent the panels from detaching would require consideration by a structural engineer. Weight considerations would need to be taken into consideration for this type of solar panel.

Do you need planning permission for flat or low pitch roof solar panels?

In most cases, installing solar panels on any type of flat roof does not require planning permission, however the installation must deliver the correct criteria, such as not protruding above the roofline and complying with building regulations. However, it’s advisable to check with your local planning  authority or consult a professional to ensure compliance with regulations.

Things to consider before installing flat or low pitch roof solar panels

Before proceeding with solar panel installation on your property, it’s important to consider the following factors:

  • Weather Conditions: Assess the local climate and weather patterns to determine solar energy potential and system performance.
  • Cost Considerations: Calculate the upfront costs of solar panel installation, including equipment, labour, and potential financing options.
  • Energy Savings: Estimate potential energy savings and return on investment over the system’s lifespan to evaluate long-term benefits.
  • Potential Challenges: Identify potential obstacles on the roof, such as drains, vents, and rooftop units, that may affect solar panel installation and operation.

How much does it cost to install solar panels on a flat or low pitch roof?

The cost of installing solar panels on a flat or low pitch roof varies depending on factors such as system size, equipment quality, installation complexity, and location. On average, residential solar panel installations on flat roofs range from £5,000 to £15,000, including materials and labour.

The potential savings from solar panel installations depend on factors such as energy consumption, system size, local electricity rates, and available incentives. 

On average, homeowners can achieve significant cost reductions annually on electricity bills by harnessing solar energy.

Challenges of Installing Solar Panels on a Flat or low pitch Roof

While installing solar panels on a flat or low pitch roof offers numerous benefits, including easy access and optimal sun exposure, it also presents certain challenges that need to be addressed for a successful installation. 

One of the primary challenges involves navigating structural blockages that may impede the installation process and affect the efficiency of the solar panel system.

Flat or low pitch roofs often feature various structural elements, such as drains, vents, exhaust fans, rooftop units, curbs, and parapets, which can pose obstacles during the solar panel installation process. These structural blockages can interfere with the placement and positioning of solar panels, potentially compromising their performance and efficiency.

  1. Drains: Drainage systems are essential components of flat or low pitch roofs, designed to channel rainwater away from the building. When installing solar panels, the location of drains must be carefully considered to avoid obstructing their function. Mounting solar panels too close to drains can impede water flow and lead to drainage issues, such as ponding or water infiltration.
  2. Vents and Exhaust Fans: Flat or low pitch roofs often feature vents and exhaust fans for ventilation purposes, particularly in commercial and industrial buildings. These protruding structures can create challenges when positioning solar panels, as they may cast shadows or obstruct sunlight, reducing the overall energy output of the system. Strategic planning is required to ensure that solar panels are installed in areas that receive maximum sunlight exposure while minimising shading from vents and exhaust fans.
  3. Rooftop Units: HVAC (heating, ventilation, and air conditioning) units and other rooftop equipment are common fixtures on flat or low pitch roofs, serving vital functions for building climate control. When installing solar panels, the presence of rooftop units must be taken into account to prevent shading and interference with equipment access and maintenance. Coordination with HVAC professionals may be necessary to determine the optimal placement of solar panels relative to rooftop units.
  4. Curbs and Parapets: Curbs and parapet walls are raised structures that outline the perimeter of flat or low pitch roofs, providing a protective barrier against wind uplift and preventing water runoff. However, these architectural features can pose challenges during solar panel installation, particularly in terms of mounting and positioning. Careful consideration is required to ensure that solar panels are securely anchored to curbs and parapets without compromising their structural integrity or waterproofing.

Are Solar Panels a Justifiable Investment?

Yes, solar panels can offer long-term cost savings, energy independence, and environmental benefits, making them a worthwhile investment for many homeowners. While the initial upfront costs of solar panel installation may seem significant, the long-term financial and environmental benefits far outweigh the initial investment.

By generating clean, renewable energy from sunlight, solar panels reduce dependence on fossil fuels, lower electricity bills, and provide a hedge against rising energy costs. It’s also possible for solar panels to increase your property value, improve energy efficiency, and contribute to a greener and more sustainable future.

With government incentives, tax credits, and financing options available, solar panels offer an attractive return on investment for homeowners seeking to reduce their carbon footprint and lower energy costs.

Do I Need Planning Permission to Install Solar Panels?

In most cases, planning permission is not required for solar panel installations on residential properties, but it’s advisable to check local planning regulations. Permitted development rights in the UK allow homeowners to install solar panels on their properties without planning permission, subject to certain limitations and conditions.

Generally, solar panels must not protrude beyond the plane of the roof slope, should not exceed certain height restrictions, and must not significantly alter the appearance of the building. However, homeowners should consult with local planning authorities or a qualified solar installer to ensure compliance with relevant regulations and obtain any necessary approvals before proceeding with solar panel installation.

Will Solar Panels Increase My Property Value?

Yes, solar panels may increase property value by enhancing energy efficiency, reducing utility costs, and appealing to eco-conscious buyers. Studies have shown that homes equipped with solar panels command higher resale values and can accelerate the sale process when compared to properties without solar installations.

Solar panels offer numerous benefits to homeowners, including reduced energy bills, increased energy independence, and potential income from feed-in tariffs or excess energy sold back to the grid. Also, solar panels enhance the green credentials of a property, attracting environmentally conscious buyers and adding to its overall appeal and marketability.

What Are the Average Savings I Can Expect to Make by Installing Solar Panels?

Average savings from solar panel installations vary depending on factors such as energy consumption, system size, local electricity rates, and available incentives, but homeowners can typically achieve annual cost benefits, by generating clean, renewable energy from sunlight, solar panels offset electricity costs and provide long-term financial benefits.

The exact savings will depend on the size and efficiency of the solar panel system, energy consumption patterns, geographic location, and any applicable government incentives or feed-in tariffs. Homeowners can consult with solar installers to estimate potential savings and evaluate the financial viability of solar panel installation for their specific circumstances.

More information about the different photovoltaic technologies can be found in Vertix EasySeam® Roof System Technical Guide.