Roof space is not always available. Some homes have limited roof area, large shadows cast by chimneys or dormers, or roofs that are structurally unsuitable for solar panels. In these cases, wall-mounted solar panels can be an alternative. Mounting panels on a south, east, or west-facing wall of your property allows you to generate solar electricity even when roof installation isn’t possible.
However, wall-mounted systems come with important trade-offs. Vertical panels generate less electricity than roof-mounted panels angled at 30 to 40 degrees. Installation is more complex and expensive. Planning permission requirements are stricter for wall-mounted systems than roof installations. In this guide, we’ll explore when wall-mounted solar makes sense, what to expect in terms of generation, costs, and planning, and how to maximise performance if you choose this option.
The key takeaway: wall-mounted solar is a viable solution for homeowners without suitable roof space, but it requires careful assessment to ensure the performance reduction is acceptable relative to the installation costs.
Contents
- 1 Key Takeaways
- 2 How Wall-Mounted Solar Panels Work
- 3 Generation Performance of Wall-Mounted Systems
- 4 When Wall-Mounted Panels Make Sense
- 5 Wall-Mounted vs. Ground-Mounted vs. Pole-Mounted
- 6 Planning Permission for Wall-Mounted Panels
- 7 Cost of Wall-Mounted Installation
- 8 Maximising Wall-Mounted Panel Performance
- 9 Case Study: Wall-Mounted Solar on a Listed Building in Bath
- 10 Expert Insights From Our Solar Panel Installers About Wall-Mounted Systems
- 11 Frequently Asked Questions
- 11.1 How much less electricity do wall-mounted panels generate than roof panels?
- 11.2 Do wall-mounted solar panels need planning permission?
- 11.3 How much more does wall-mounted installation cost?
- 11.4 Is a south, east, or west-facing wall best for solar?
- 11.5 What is the payback period for wall-mounted solar?
- 11.6 Can I use bifacial panels on a wall-mounted system?
- 11.7 What’s better, wall-mounted or ground-mounted panels?
- 11.8 Can I install wall-mounted panels on a listed building?
- 12 Summing Up
Key Takeaways
- Wall-mounted panels generate 20-30% less electricity than roof-mounted panels due to steeper vertical angle and shading
- South-facing walls are ideal; east and west-facing walls generate 15-20% less than south-facing
- Wall-mounted installations cost 15-25% more than roof-mounted due to additional structural work and complexity
- Planning permission is required for wall-mounted panels on listed buildings and in conservation areas
- For homes with limited roof space or unfavourable roof orientation, wall-mounted panels can still provide worthwhile generation
- Pole-mounted or ground-mounted systems are often better alternatives to wall-mounted if space allows
- Commercial buildings and industrial sites benefit most from wall-mounted arrays (large blank walls, less aesthetic concern)
- Bifacial panels on light-coloured walls can recover some generation loss through light reflection
How Wall-Mounted Solar Panels Work
Wall-mounted panels are fixed vertically (or nearly vertically) to the wall surface of your property. They are secured using brackets bolted into the wall structure, with wiring running down the wall to an external or internal inverter. The mounting system must be rated for the weight of the panels and the structural loads from wind pressure.
Unlike roof-mounted arrays where panels are angled 30 to 40 degrees from horizontal (the UK’s optimal angle for solar generation), wall-mounted panels are close to vertical. This angle is less efficient for capturing sunlight, particularly in winter when the sun is low in the sky. However, wall-mounted panels do receive direct sunlight during morning and afternoon hours when the sun is lower on the horizon.
The orientation of the wall determines performance. A south-facing wall receives the most sunlight and generates the most electricity. East-facing walls receive strong sunlight in the morning and generate reasonably well. West-facing walls receive afternoon and early evening sunlight. North-facing walls are generally not suitable for solar panels in the UK due to very poor sunlight exposure.
Generation Performance of Wall-Mounted Systems
A 4kW roof-mounted system angled at 30 to 40 degrees generates approximately 3,100 to 3,300 kWh per year in the UK (depending on location, shading, and weather).
The same 4kW array mounted vertically on a south-facing wall generates approximately 2,200 to 2,400 kWh per year. This is a reduction of 25 to 30% compared to roof-mounted.
The performance loss comes from two sources: the steeper angle is less optimal for UK solar angles (particularly in winter), and wall-mounted installations often have some shading from nearby structures, eaves, or vegetation.
An east-facing wall generates approximately 2,000 to 2,200 kWh per year (35 to 40% less than south-facing roof). A west-facing wall generates approximately 2,000 to 2,200 kWh per year (similar to east-facing). A north-facing wall generates less than 1,000 kWh per year and is not recommended.
In financial terms, a 4kW south-facing wall-mounted system saves approximately £330 to £360 per year in avoided grid electricity (based on 25p/kWh) compared to £465 to £495 for an equivalent roof-mounted system. The additional payback period is 3 to 5 years longer than a roof-mounted system due to lower generation.
When Wall-Mounted Panels Make Sense
Wall-mounted solar is most appropriate for homes where roof installation is genuinely not possible:
Limited or unsuitable roof space: Homes with very small roofs, heavily pitched roofs, or roofs cluttered with chimneys, dormers, and vents may not have space for a roof array.
North or east-facing roofs: If your home’s main roof faces north or east and adding extra south-facing roof space is not feasible, a wall-mounted south-facing array might be an alternative.
Structural concerns: Some older properties with weakened roof structures cannot support the weight of panels. A wall-mounted system distributes loads differently and may be more suitable (though structural assessment is always needed).
Listed buildings: Historic buildings often have restrictions on roof modifications. Wall-mounted panels on a side or rear elevation may be permitted when roof installation is not.
Aesthetic preference: Some homeowners prefer the appearance of wall-mounted panels over roof-mounted. This is subjective, but if you’re willing to accept 25-30% lower generation for visual reasons, wall-mounted is an option.
Where wall-mounted panels do NOT make sense:
If you have a south-facing roof with adequate space and no obstructions, roof-mounted is always better. The 25-30% generation loss and higher installation cost of wall-mounted are not justified.
If you have any alternative space (ground-mounted, pole-mounted), those options typically deliver better performance than wall-mounted.
Wall-Mounted vs. Ground-Mounted vs. Pole-Mounted
When roof space is limited, you have three main alternatives:
Wall-Mounted
Pros: Uses otherwise unused wall space. Takes no ground area. Can be integrated into building aesthetics on commercial properties.
Cons: Generates 25-30% less than roof-mounted. Higher installation cost. Shading from eaves or vegetation common. Maintenance access can be difficult on upper-story walls.
Ground-Mounted
Pros: Generates 5-10% more than roof-mounted (due to optimal angle and tracking). Easier to maintain and clean. Flexible positioning to avoid shading. Can add more panels later.
Cons: Takes up garden space (typically 20-30 square metres for a 4kW system). Requires clear space away from trees and buildings. May need planning permission.
Pole-Mounted
Pros: Single pole structure uses minimal ground footprint. Can be positioned on a pole or mast with optimal south-facing angle. Seasonal tracking is possible (adjustable angle for summer vs. winter).
Cons: Structural engineering required for the pole. Wind loads on exposed mounting can be significant. Higher cost than roof-mounted.
In most cases where roof space is unavailable, ground-mounted or pole-mounted systems outperform wall-mounted. Consider wall-mounted only if ground space is also unavailable or inappropriate (small urban gardens, conservation areas where raised structures are restricted).
Planning Permission for Wall-Mounted Panels
Planning permission requirements for wall-mounted panels are stricter than for roof-mounted systems.
In England, roof-mounted panels are generally permitted development and do not require planning permission. However, wall-mounted panels on an external wall are more likely to require planning permission, particularly on listed buildings, in conservation areas, or on properties where the panels would be highly visible from the street.
In practice, wall-mounted panels on a rear or side wall of a typical suburban property often fall within permitted development (especially if the wall is not prominent). However, panels on a front-facing wall or on a listed property almost certainly require planning approval.
Check with your local planning authority before proceeding. A screening opinion (also called a prior notification consultation) can confirm whether your specific installation needs permission. This process typically costs £50 to £150 and takes 3 to 4 weeks.
In conservation areas, listed buildings, and areas of outstanding natural beauty (AONB), wall-mounted installations are more likely to be refused or heavily restricted. Historic environment specialists often view visible solar panels on heritage buildings as harmful to character.
Cost of Wall-Mounted Installation
A 4kW wall-mounted solar system costs approximately £8,500 to £10,500 installed (at 0% VAT, until March 2027). This is 15-25% higher than an equivalent roof-mounted system (£7,000 to £8,500).
The additional cost comes from:
Structural assessment and design: Walls must be structurally assessed to ensure they can support the weight and wind loads of the panels. This requires engineer calculations and may reveal the need for wall reinforcement.
Wall preparation: Existing coatings, rendering, or insulation may need to be addressed before mounting brackets are installed. This can add £500 to £1,500.
Wiring and aesthetics: Wall-mounted systems require wiring to run down the wall to an inverter. This wiring is more visible than roof wiring and may require external trunking or conduit to improve appearance.
Access and labour: Installing panels on a wall (especially upper stories) requires scaffolding or elevated work platforms. This adds to labour costs.
Because wall-mounted systems generate 25-30% less electricity than roof-mounted but cost 15-25% more, the payback period is significantly longer. For a south-facing wall system, payback might be 14 to 16 years (compared to 11 to 13 years for roof-mounted). The longer payback period must be weighed against your personal circumstances and whether you plan to remain in the property for 15+ years.
Maximising Wall-Mounted Panel Performance
If you proceed with wall-mounted panels, several strategies can maximise performance:
South-facing orientation: Prioritise south-facing walls. East or west-facing walls will generate 15-20% less.
Minimise shading: Check for shadows cast by eaves, gutters, chimneys, nearby buildings, or trees. Even small shadows can significantly reduce output. Use shading analysis tools (such as PVGIS, the solar map available via the EU’s PV-GIS tool) to model shading and verify performance predictions.
Regular cleaning: Wall-mounted panels accumulate dust and debris more readily than roof panels because they’re vertical and receive wind-blown particles. Clean them annually with a soft brush and deionised water.
Bifacial panels: Some wall installations benefit from bifacial panels if a light-coloured surface (white gravel, light rendering, or reflective paint) sits below. Reflected light can recover 5-10% of lost generation.
Ensure the wall surface is clean and light-coloured: A light-coloured wall reflects more light back to panels than a dark surface.
Case Study: Wall-Mounted Solar on a Listed Building in Bath
Background
A homeowner in Bath owned a Georgian listed property with a small roof and strict conservation area planning restrictions. Roof-mounted panels were not permitted due to visual impact on the listed building. The property had a large, rear-facing wall facing south-west that was not visible from the street.
Project Overview
The homeowner applied for planning permission to install 4kW of wall-mounted panels on the rear wall, with wiring hidden behind external conduit. The local planning authority approved the application because the panels were not visible from public viewpoints and the rear wall was appropriate for contemporary additions.
Implementation
A structural engineer assessed the wall and confirmed it could support the weight and wind loads with standard mounting brackets. The system was installed on the rear elevation, generating an estimated 2,400 kWh per year (south-west facing reduced performance by approximately 10% compared to south-facing). The total installation cost was £9,200 (15% higher than a roof-mounted system would have cost).
Results
The system generates approximately 2,400 kWh per year, saving the homeowner £300-400 in annual electricity. With SEG payments for exported surplus (approximately £50-100 per year), total annual benefit is approximately £350-500. Payback is estimated at 16-18 years. The homeowner accepted the longer payback as a trade-off for being able to install solar on a heritage property in a conservation area.
Expert Insights From Our Solar Panel Installers About Wall-Mounted Systems
One of our senior solar panel installers with over 18 years of experience says: “Wall-mounted systems are interesting solutions for specific properties, but they’re not a first choice. The generation loss is real: 25-30% less than a roof system, and that compounds over decades. I only recommend wall-mounted to customers with genuine constraints: small roof, poor roof orientation, or listed building restrictions. Even then, I first explore ground-mounted or pole-mounted options. For typical properties with suitable south-facing roofs, roof-mounted is always better. Wall-mounted is a backup option, not a preference.”
Frequently Asked Questions
How much less electricity do wall-mounted panels generate than roof panels?
Wall-mounted panels on a south-facing wall generate 25-30% less electricity than roof-mounted panels due to steeper angle and potential shading. East and west-facing walls generate 35-40% less. A 4kW roof system generating 3,100 kWh would generate approximately 2,200 kWh on a south wall.
Do wall-mounted solar panels need planning permission?
It depends on location. Wall-mounted panels on non-prominent rear or side walls often fall within permitted development. However, panels on front-facing walls, listed buildings, or in conservation areas usually require planning permission. Check with your local planning authority or request a screening opinion.
How much more does wall-mounted installation cost?
Wall-mounted systems cost 15-25% more than roof-mounted due to structural assessment, wall preparation, wiring concealment, and labour. A 4kW system costs approximately £8,500-10,500 installed versus £7,000-8,500 for roof-mounted.
Is a south, east, or west-facing wall best for solar?
South-facing is optimal, generating the most electricity. East and west-facing walls generate 15-20% less than south-facing (equivalent to 35-40% less than roof-mounted due to angle loss). North-facing walls are unsuitable for the UK and are not recommended.
What is the payback period for wall-mounted solar?
Payback is typically 14-18 years for wall-mounted systems, compared to 11-13 years for roof-mounted. The longer period reflects lower generation and higher installation cost. This must be weighed against your long-term plans for the property.
Can I use bifacial panels on a wall-mounted system?
Yes. Bifacial panels can recover 5-10% additional generation through light reflection if mounted on a light-coloured wall or above a reflective surface. This is particularly useful for wall-mounted systems where generation is already reduced.
What’s better, wall-mounted or ground-mounted panels?
Ground-mounted systems are usually better. They generate 5-10% more than roof-mounted (due to optimal angle) and are easier to maintain. Wall-mounted is a compromise option only when ground space is unavailable. Consider ground-mounted first if space allows.
Can I install wall-mounted panels on a listed building?
Yes, but planning permission is almost always required. Panels on rear or side walls not visible from public viewpoints have better chances of approval than front-facing panels. Work with your local planning authority early to understand what’s permitted on your specific property.
Summing Up
Wall-mounted solar panels are a viable alternative when roof space is genuinely unavailable, but they come with trade-offs: 25-30% lower generation, 15-25% higher costs, and longer payback periods. South-facing walls offer the best performance; east and west-facing walls perform significantly less well. Planning permission is more likely to be required for wall-mounted systems than roof-mounted. Before choosing wall-mounted, explore ground-mounted or pole-mounted options, which typically deliver better performance. Wall-mounted makes most sense for listed buildings, conservation areas, or homes with unsuitable roofs. To assess whether wall-mounted solar is right for your property and to explore alternatives, contact us for a free quote. Our installers can evaluate your specific situation and recommend the best option for your home.
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