Horizontal Vs Vertical Solar Panel Installation

When it comes to maximising solar energy output, the direction and orientation of your solar panels play a critical role. One of the most debated topics among UK homeowners, landlords, and commercial property owners is: Horizontal vs Vertical Solar Panel Installation. 

Your choice impacts not only your electricity generation but also factors like maintenance, installation costs, and suitability for different roof types.

Let’s break down everything you need to know to make an informed decision that aligns with your energy goals and property layout.

Horizontal Vs Vertical Solar Panel Installation: A Quick Comparison

Before diving into the technical pros and cons of each orientation, let’s look at a quick side-by-side comparison of the key factors involved:

Tip: Want accurate, competitive prices for your property? Use Eco Answers' Quote-Comparison Tool,  our free tool connects you with trusted suppliers offering tailored solar panel quotes based on your location and roof setup.

Horizontal Solar Panel Installation

Horizontal installation involves mounting solar panels with their longer side parallel to the roofline or ground. This is the most common installation type for residential properties in the UK.

Vertical Solar Panel Installation

Vertical installation means panels are mounted with their shorter side aligned with the roof slope or structure. This orientation is less common but can be advantageous for certain roof shapes or urban areas. 

Vertical mounting is often the go-to choice for unconventional setups like balconies, façades or shed roofs, where traditional horizontal layouts aren’t practical.

Horizontal Vs Vertical Solar Panel Installation: Which Is Better for Your Property?

Choosing the right orientation isn’t just about aesthetics, it's about performance, maintenance, and your specific roof setup. Let’s evaluate based on critical performance criteria.

Efficiency and Energy Yield

In the UK, solar panel orientation and tilt angle have a significant impact on how much electricity your solar panel system can generate throughout the year. 

The ideal setup for maximum efficiency is a south-facing array tilted between 30–40 degrees, which aligns with the sun’s path across the sky and captures the most solar irradiance, particularly during the peak months of April to September.

Horizontal solar panel installations, when positioned at this optimal tilt and direction, consistently outperform vertical arrays in energy output. This is because they are better aligned with the midday sun, which delivers the highest irradiance levels in the UK.

According to the Energy Saving Trust, a standard 3kW south-facing horizontal system can produce up to 2,800 kWh per year under typical UK conditions. 

By comparison, the same system installed vertically (e.g., on a wall or vertically aligned on a flat roof) may generate 15–20% less output in most locations due to suboptimal angle and limited sun exposure during winter months.

Vertical Arrays: When Do They Make Sense?

Despite their lower average yield, vertical solar panels can still be advantageous in specific circumstances:

• East- and west-facing façades may outperform horizontal setups in the early morning or late afternoon, especially in densely built urban areas where rooftops are shaded.
• In winter, when the sun sits lower in the sky, vertical panels on south-facing walls can capture more low-angle sunlight, slightly reducing seasonal performance gaps.
• Commercial or multi-storey buildings with limited roof access can make use of unused vertical space for supplemental generation.

Other Performance Considerations

• . Horizontal panels on roofs may heat up more in summer, slightly reducing output through thermal derating, whereas vertical panels benefit from better airflow.
• Soiling losses (dust, debris, or bird droppings) can be higher on horizontal panels, especially on flatter roofs, which may require more frequent cleaning to maintain peak performance.

Realistic Performance Expectations in the UK

The average UK household uses around 2,900–3,100 kWh annually. This means a well-positioned 3kW horizontal system can offset most or all of a home’s electricity usage. 

Vertical panels, on the other hand, may be better suited for supplementing rather than fully replacing grid use.

Winner: Horizontal orientation

Best suited for maximum yield, especially on south-facing pitched roofs with little shading.This setup performs well even in less-than-perfect conditions, which helps answer a common question: Do solar panels need direct sunlight to work? Horizontal arrays at the right tilt can still generate power from both direct and diffuse light.

Installation and Setup Time

When considering solar panel installation, time and complexity are important factors that affect your overall project cost and disruption. The choice between horizontal and vertical installations can influence how quickly your system is up and running.

Horizontal Installations: Streamlined and Efficient

Horizontal solar panels are typically installed on standard pitched roofs using pre-fabricated mounting racks designed for common roof materials like slate, tile, or metal sheeting. 

These panels suit typical UK homes, including many older or heritage properties, although extra caution is needed when installing solar panels on slate roofs.

Because horizontal orientation is the industry norm in the UK, most solar installers have extensive experience with this setup, leading to:

• Faster installation times, often completed within one to three days for typical residential systems.
• Simplified planning and logistics since mounting hardware and panel layouts are standardised.
• Lower risk of installation delays or unexpected costs due to familiarity and repeatable processes.

This efficiency helps reduce labour costs and minimizes homeowner disruption, which is especially important for busy households or commercial properties where downtime can affect operations.

Vertical Installations: Customised and Complex

Vertical panels, often installed on walls, façades, or narrow roofs, require bespoke mounting solutions. These can include specially designed brackets, stronger structural fixings, and additional weatherproofing measures. Vertical setups often involve:

• Longer planning and design phases to ensure structural integrity, especially for older buildings or those with .
• Increased installation time, sometimes extending beyond three days, depending on site complexity and accessibility.
• Potential need for scaffolding or specialist access equipment, raising costs and logistical challenges, particularly in urban or high-rise settings.

Additionally, vertical arrays may require coordination with other trades (e.g., structural engineers or planners) to ensure compliance with local building regulations and planning permissions.

UK-Specific Considerations

In the UK, variable weather and roof conditions mean installers often plan for weather-related delays, which can impact installation schedules, particularly for complex vertical installations. 

Moreover, vertical systems mounted on external walls may require extra attention to sealing and insulation to avoid damp issues, a common concern in UK properties.

Winner: Horizontal orientation

For most UK homeowners and landlords, horizontal solar panel installations offer a faster, simpler, and more cost-effective setup due to established mounting systems and installer experience. 

Vertical installations, while valuable in specific scenarios, generally require more custom work and longer lead times.

Space Requirements

Space availability and roof geometry are critical factors when deciding between horizontal and vertical solar panel installations, especially in the diverse building stock found across the UK, from Victorian terraces to modern commercial blocks.

Vertical Installations: Maximising Vertical Real Estate

Vertical arrays are uniquely suited to properties with limited horizontal roof space but generous vertical surfaces. For example:

• Narrow terraced houses or flats with minimal roof area but ample façade space can benefit from vertically mounted panels to generate additional energy without structural roof modifications.
• Multi-storey commercial or residential buildings with tall external walls can install vertical panels over several floors, effectively multiplying generation capacity in a constrained footprint.
• In urban areas where rooftops may be shaded by neighbouring buildings, vertical panels on east- or west-facing walls capture morning or evening sun, expanding usable solar space beyond traditional rooftops. In some cases, homeowners supplement this by considering or , especially when roof space is limited or restricted.

Additionally, vertical solar panels can be integrated into building-integrated photovoltaics (BIPV) designs, such as solar glass façades or cladding systems, turning walls into active energy producers without consuming ground or roof area.

Horizontal Installations: Maximising Roof Panel Density

Standard pitched roofs, common in UK residential architecture, offer the ideal canvas for horizontal solar arrays. This orientation allows:

• Optimal panel spacing and tilt to reduce shading between rows, maximising system efficiency and energy yield per square metre.
• Installation of larger arrays due to wider surface area availability, which is crucial for homeowners aiming to offset full household electricity consumption.
• More straightforward racking and wiring layouts, supporting easier scalability and future expansion if needed.

However, roof shape and obstructions such as chimneys, dormers, or skylights can limit effective panel placement horizontally, especially on smaller or irregularly shaped roofs.

Insight: Read our guide on how many solar panels can fit on your roof for a clearer understanding.

Considerations for Flat Roofs and Commercial Properties

Flat roofs, prevalent on many UK commercial buildings present their own spatial challenges and opportunities. 

Panels are typically mounted on angled racks to optimise tilt, often arranged horizontally for maximum density, but vertical mounting may be an option where space or structural factors demand.

Winner: Tie – depends on roof shape and site specifics.

Choosing between horizontal and vertical depends largely on your building’s architecture, available surface area, and shading patterns. Both orientations can complement each other in hybrid setups, maximising total system capacity on complex properties.

Maintenance and Servicing

Routine maintenance is crucial for ensuring your solar panels perform efficiently over their 25+ year lifespan. While solar PV systems have no moving parts and minimal upkeep, the ease of access, cleaning needs, and servicing costs vary significantly depending on orientation and placement.

Horizontal Panels: Easier Access, Lower Maintenance Costs

Horizontal panels, particularly those mounted on pitched roofs, are easier and safer to access for routine checks and cleaning. This setup benefits from:

• Gravity-assisted cleaning from rain, especially at a 30–40° tilt
• Easier access for technicians using roof ladders or fall-protection systems
• Lower likelihood of debris accumulation when tilted properly

However, horizontal panels on flatter roofs may suffer from more dust, bird droppings, moss, or leaf buildup, particularly in tree-heavy areas or regions with low rainfall, such as parts of southeast England.

Regular cleaning (once every 6–12 months) ensures peak output and prevents "soiling losses", which can reduce efficiency by up to 5% annually if left uncleaned.

Vertical Panels: Challenging Access, Lower Soiling

Vertical panels benefit from their upright positioning, which naturally sheds rainwater, snow, and debris more effectively. This can reduce the frequency of cleaning but access becomes the issue:

• Wall-mounted or façade-based panels on multi-storey buildings may require scaffolding, cherry pickers, or abseil access, which adds significantly to maintenance costs
• Urban pollution or bird droppings may still accumulate, especially on lower-storey panels or near nesting spots
• Inspections are harder to carry out without professional height access equipment

In short, while vertical panels may need cleaning less often, the complexity and cost of doing so can be considerably higher, especially for landlords managing apartment blocks or commercial façades.

UK-Specific Maintenance Considerations

According to the Energy Saving Trust, solar PV systems should be professionally inspected every 5–10 years, while regular cleaning every 6–12 months is advised depending on the environment. 

Failing to clean panels regularly can lead to warranty exclusions from manufacturers or insurers.

Winner: Horizontal orientation

Weather Performance (Wind & Snow)

In the UK, where wind gusts can exceed 70mph in coastal regions and snowfall, though irregular can still accumulate in northern and high-altitude areas, solar panel orientation plays a critical role in determining how well systems hold up in adverse weather conditions.

Vertical Orientation: Better Aerodynamics, Natural Snow Shedding

Vertical panels tend to have less surface area exposed to uplift forces from wind due to their perpendicular positioning. This gives them a more aerodynamic profile, especially when mounted flush against walls or parapets. As a result:

• They are less likely to experience uplift or vibration in high winds.
• Vertical panels also benefit from natural shedding of rain, snow, and sleet, especially during storms, since gravity pulls precipitation downward without obstruction.
• For wall-mounted systems on multi-storey buildings, snow accumulation is virtually nonexistent, a huge advantage in colder regions such as Scotland, Cumbria, and the Pennines.

Additionally, the weight load on brackets is more evenly distributed vertically, reducing structural stress over time.

Horizontal Orientation: More Exposure, More Uplift Risk

Horizontal panels, especially those mounted on low-pitched or flat roofs are more exposed to lateral wind forces. In storm conditions, wind can flow under the leading edge of the panels, creating uplift pressure that must be countered by secure anchoring systems.

• Inadequately secured systems may suffer bracket failure, loosening, or panel displacement, particularly in coastal areas such as Cornwall, Devon, or Northern Ireland, where wind speeds are routinely higher.
• Horizontal arrays on flat roofs require ballasted mounting systems or mechanical fixings that add weight and complexity, especially for large-scale .

When it comes to snowfall, horizontal panels installed at the optimal 30–40° pitch will shed snow relatively well in the south of England and Midlands, where snow events are brief and light. 

However, in northern areas with longer cold spells, snow may accumulate and block sunlight, reducing energy generation unless actively removed.

Insight: According to guidance from Met Office UK, orientation and slope significantly influence snow retention and shedding.

Moisture Drainage and Weatherproofing

Orientation also affects drainage patterns and moisture retention:

• Vertical panels shed rainwater quickly and are less likely to trap moisture, helping reduce long-term risks like frame corrosion or electrical faults.
• Horizontal panels may accumulate pools of water or condensation if drainage is poor, which could affect wiring or degrade panel seals over time.

Winner: Vertical orientation

Particularly in storm-prone or snowy regions, vertical panels offer better weather durability and less maintenance concern related to precipitation.

Cost Comparison

When planning your solar investment, the upfront installation cost is one of the most important factors to consider. 

The cost of solar panels vary depending on orientation, system size, property type, and installation complexity.

Horizontal systems tend to be more cost-effective due to standardised racking and simpler mounting techniques, while vertical installations often require custom brackets and additional labour.

Below is a breakdown of average installation costs for different system sizes in the UK:

Prices include VAT and standard labour. Based on average installer rates across the UK from the Energy Saving Trust.

Winner: Horizontal orientation (lower upfront costs)

Lifespan

Solar panels are built to last and with proper care, most systems in the UK can operate efficiently for 25 to 30 years or more. 

However, the orientation and installation method can influence how well your panels withstand long-term environmental stress, especially in relation to mounting structures, exposure, and maintenance.

Panel Lifespan: No Major Difference by Orientation

In terms of the solar PV modules themselves, there's no significant difference in expected lifespan between horizontal and vertical installations provided that:

• The panels are MCS-certified
• Installation follows manufacturer guidelines
• They’re installed by a reputable, accredited installer

The silicon cells, glass coating, and anti-reflective layers are designed to handle decades of exposure to UV radiation, wind, and temperature variation regardless of how they are mounted.

According to the Energy Saving Trust, the output of solar panels typically degrades by around 0.5% per year, meaning after 25 years, you can still expect roughly 87–90% of the original performance, a critical consideration for long-term energy savings.

Mounting System Durability: A Key Differentiator

While the panels themselves are durable, the supporting structures, especially with vertical systems can have shorter lifespans or require more frequent inspection:

• Horizontal installations use tried-and-tested roof racking systems with a lifespan of 20–25 years when installed on standard pitched roofs.
• Vertical installations, particularly those mounted to walls or façades, often rely on custom brackets, bolts, and fixings exposed to higher wind forces or direct rainfall. These may require replacement or tightening within 10–15 years, especially if corrosion is an issue in coastal areas.

Degradation Risks

Several factors can accelerate system wear:

• Moisture ingress if seals or flashings degrade
• Frame corrosion, especially in coastal or highly polluted urban environments
• Thermal cycling stress, particularly in flat-roofed or vertically mounted systems with more exposed fixings

Routine inspections and maintenance help mitigate these risks, ensuring your system performs reliably over its expected lifespan.

Winner: Horizontal orientation

Due to longer-lasting mounting systems, lower exposure-related wear, and fewer corrosion points, horizontal installations offer greater long-term durability with lower maintenance demands.

Overheating Risk in Summer

While the UK enjoys a relatively temperate climate, solar panels can still experience performance drops due to overheating, especially during heatwaves and prolonged summer sunshine. 

This phenomenon, known as thermal derating, occurs when high panel temperatures reduce the efficiency of photovoltaic (PV) cells.

How Temperature Affects Solar Panel Output

Solar panels are tested under Standard Test Conditions (STC) of 25°C. However, in full sun, panel surface temperatures can rise to 40–60°C, even in the UK. 

For every 1°C above 25°C, panel efficiency typically drops by 0.3% to 0.5%, depending on the panel’s thermal coefficient.

So, a 40°C panel could lose 4.5% to 7.5% in efficiency which may affect your summer yield.

Insight: Read our article on solar panel efficiency to get a better understanding.

Horizontal Orientation: Higher Overheating Potential

Horizontal panels, especially those on flat or low-pitch roofs, are more prone to heat build-up due to:

• Reduced airflow underneath the panel arrays
• Greater surface exposure to midday sun
• Heat being trapped between roof and panel backsheet in close-mount installations

Dark roofing materials can exacerbate this by radiating additional heat, raising ambient temperatures around the system and increasing thermal strain on electrical components like inverters and connectors.

Vertical Orientation: Better Natural Ventilation

Vertical panels benefit from better air circulation due to their upright positioning:

• More airflow behind panels, especially on walls and façades
• Panels are less exposed to the midday sun’s direct angle
• Heat dissipates more effectively, reducing internal temperature stress

As a result, vertical systems typically experience less thermal derating, which may improve relative performance during summer months, especially in urban locations with low wind movement where heat retention is common on rooftops.

Impact on System Longevity

Persistent overheating doesn’t just reduce output, it can accelerate material degradation:

• Panel frames and backsheets may warp or crack over time
• Solder joints in PV cells can weaken, increasing the risk of microcracks
• Inverters operating in high-heat environments tend to fail earlier than those in well-ventilated setups

Proper ventilation, mounting angle, and shading analysis should all be factored into your system design and orientation plays a key role.

Winner: Vertical orientation

Vertical installations benefit from better passive cooling, reducing overheating risk and prolonging system component lifespan, a significant advantage during hotter summers or on thermally insulated buildings.

Bird Nesting Risk

Bird nesting beneath solar panels is an increasingly common issue in the UK, particularly among urban and suburban homeowners. 

Nesting can lead to damage, fire risks, reduced efficiency, and frequent maintenance, making it a serious consideration when choosing between horizontal and vertical installations.

Why Birds Nest Under Solar Panels

Solar panels create a warm, sheltered space between the module and roof surface, an ideal environment for birds such as pigeons, starlings, and sparrows, which are prevalent across much of the UK.

Common issues include:

• Debris build-up from nesting material
• Blocked drainage and ventilation gaps
• Damage to cabling or insulation caused by pecking or movement
• Guano accumulation, which corrodes components and reduces panel output

Nesting can occur rapidly in spring and summer, and once established, removal often requires a licensed pest control specialist due to legal protections around active nests. 

Horizontal Orientation: Higher Risk for Nesting

Horizontal installations on pitched roofs are the most common target for nesting, particularly when:

• Panels are raised just enough to allow entry underneath. For those looking to reduce exposure and maximise hidden integration, could offer a bird-resistant alternative by eliminating gaps entirely.
• There’s no protective mesh or bird-proofing installed.
• Neighbouring properties already have established bird activity.

The gap between the panel backsheet and roof tiles becomes a secure and attractive space for birds to shelter and breed.

Vertical Orientation: Lower Nesting Likelihood

Wall-mounted vertical systems pose a significantly lower nesting risk:

• The lack of horizontal cavities or gaps deters most species
• Panels installed flush with a wall or façade provide no sheltered access
• Wind exposure and upright positioning make vertical surfaces less inviting for nesting birds

As a result, vertical installations typically avoid the bird-proofing challenges often faced by rooftop arrays.

Winner: Vertical orientation

Vertical installations offer superior protection against bird nesting, making them more appealing for those seeking low-maintenance, wildlife-resistant systems especially in urban environments or bird-heavy areas.

Government Grants & Incentives

One of the most attractive aspects of installing solar panels in the UK regardless of whether they’re horizontal or vertical is the . 

These incentives are designed to encourage renewable energy adoption and reduce household or commercial energy bills.

1. Smart Export Guarantee (SEG)

The Smart Export Guarantee (SEG) allows homeowners and businesses to earn money by exporting unused electricity back to the National Grid.

• Available to both horizontal and vertical installations
• Panels must be installed by an MCS-certified installer
• Export payments vary by supplier typically ranging from 1p to 15p per kWh

Tip: SEG eligibility depends on system performance, not orientation. However, horizontal systems may earn more due to higher energy yield.

2. ECO4 Scheme (Energy Company Obligation)

The ECO4 Scheme helps low-income and vulnerable households improve energy efficiency, including solar panel installation in some cases.

• Covers both roof-mounted (horizontal) and wall-mounted (vertical) systems if they contribute to energy efficiency
• Priority is based on property condition, EPC rating, and household eligibility
• Administered via obligated energy suppliers and local councils

3. VAT Relief for Energy-Saving Materials

As of April 2022, VAT on energy-saving materials (including solar panels) was reduced to for qualifying residential installations.

• Applies equally to horizontal and vertical systems
• Valid for both homeowners and landlords installing on domestic properties

4. Local Authority & Regional Grants

Some local councils offer incentives, grants, or financing for solar installations as part of regional decarbonisation plans. 

While these vary by region, most are orientation-agnostic as long as the installation meets efficiency and safety standards.

Check with your local authority’s housing or energy department for up-to-date schemes in your area.

Horizontal Vs Vertical Solar Panel Installation: Which Should You Choose?

Choosing between horizontal and vertical solar panel installation ultimately comes down to how well each option aligns with your property’s physical characteristics, location, and long-term energy goals.

Ask yourself the following:

• Is your roof south-facing and unshaded? A horizontal system will maximise energy yield and return on investment.
• Are you working with limited horizontal space or a tall, narrow structure? Vertical panels may offer a practical workaround.
• Do you live in an area with frequent bird activity or planning constraints? Vertical systems might minimise maintenance and visual impact.
• Is aesthetics or architectural integration a top priority? Horizontal arrays often blend more seamlessly with traditional pitched roofs.

You don’t have to choose one or the other exclusively, hybrid systems combining both orientations can sometimes unlock the full potential of complex rooftops or multi-facade buildings.

Key takeaway: There’s no one-size-fits-all. The right orientation depends on your site conditions, structural layout, shading, and how you value efficiency, aesthetics, ease of maintenance and the number of solar panels you will need.

Before making your final decision, speak with an MCS-certified installer to carry out a solar site assessment. They’ll evaluate your roof’s pitch, orientation, obstructions, and energy goals and recommend the optimal setup tailored to your property.

FAQs

1. Can I mix horizontal and vertical panels on the same property? Yes, hybrid installations are possible and can maximise roof usage, especially on complex or multi-slope roofs. However, separate inverters or optimisers may be needed.

2. Is vertical installation suitable for commercial buildings? Absolutely. Vertical panels are often mounted on façades or parapets of commercial properties where horizontal space is limited.

3. Does vertical orientation affect solar panel lifespan? No significant difference has been found in panel longevity due to orientation, provided the installation is done correctly with quality materials.

4. Are there planning permission differences between horizontal and vertical panels in the UK? Generally, both fall under permitted development for domestic use, but vertical wall-mounted systems may need planning approval depending on visual impact. Check with your local council or refer to .

5. Will vertical panels still qualify for SEG payments? Yes, as long as the panels meet the Smart Export Guarantee (SEG) criteria and are installed by an MCS-certified installer, orientation doesn't affect eligibility. Learn more via Ofgem’s SEG guidance.

Conclusion

Choosing between horizontal and vertical solar panel installation in the UK depends largely on your property's layout, local shading, aesthetic preferences, and energy goals. While horizontal panels typically provide better efficiency and cost-effectiveness, vertical arrays have unique benefits for narrow or shaded urban properties and commercial walls.

For a tailored recommendation and competitive quotes, try Eco Answers’ Quote-Comparison Tool. It’s free, easy to use, and connects you with trusted solar installers across the UK — helping you find the best solution for your property.

Whether you’re a homeowner, landlord or commercial property owner, your solar journey starts with the right orientation and the right quote.