Solar Panels on Flat Roof: Pros, Cons & Costs
- Can You Install Solar Panels on a Flat Roof?
- How Do Flat Roof Solar Panels Work?
- How Much Does a Flat Roof Solar System Cost?
- How Much Can You Save with Flat Roof Solar Panels?
- Benefits and Drawbacks of Flat Roof Solar Systems
- What to Consider When Installing a Flat Roof Solar System?
- How to Install Flat Roof Solar Panels?
- Conclusion
- FAQs
Installing solar panels on your rooftop is a great way to generate electricity from sunlight. But if you have a flat roof, you might be unsure if it’s even possible, or efficient enough, to install solar panels. So, can you install solar panels on a flat roof in the UK? What are the pros, cons, and costs? This guide will get all your questions answered! You will also learn what to consider for installation and how to install solar panels on flat roof easily. Just read on to learn more.
Can You Install Solar Panels on a Flat Roof?
Many people don’t think flat roofs are suitable for solar panels, primarily due to a misconception that solar panels only work if mounted at an angle on a sloped roof. In fact, solar panels on flat roofs are a common and effective option, especially for commercial buildings and modern homes in the UK.
While flat roofs don’t seem to be ideal for optimal energy generation, they can be adjusted with specialized mounting systems. You can leave sufficient space between rows to prevent panels from shading each other. It’s perfectly possible to install solar panels on a flat roof. It can even be better than a pitched/sloped roof when professionally installed.
How Do Flat Roof Solar Panels Work?
Installing solar panels for flat roofs is not only possible but also one of the most cost-effective options. So how do flat roof solar panels work? Solar panels on a flat roof work almost identically to those on pitched roofs in terms of generating electricity, except for specialized design and mounting.
Technically speaking, the most efficient angle for solar panels on flat roof is 30 to 40 degrees to the horizontal, facing due south. This allows solar panels to gain more exposure to the sunlight throughout the day. Meanwhile, by mounting onto a tub, solar panels on flat roof are supported by ballast (gravel, paving slabs, bricks, rocks, etc.) to withstand strong winds.
How Much Does a Flat Roof Solar System Cost?
Solar panels on flat roofs are great for urban homes and businesses in the UK. Is it expensive to buy solar panels and install them on flat roofs? The cost of flat roof solar panel systems in the UK is subject to the home size, system size, mounting type, panel brand, and whether a battery is included.
Generally, you can expect a flat roof solar panel system (3 kW to 4 kW) to cost £2,800 to £12,100 on average for a 2 to 3-bedroom house with installation included. This system size can supply all of the electricity that they require.
You can also check out the breakdown below to estimate the cost:
System Size | Panels (approx.) | Without Battery | With Battery (5–10 kWh) |
3 kW | 6–8 | £4,500–£6,000 | £8,500–£10,000 |
4 kW | 9–11 | £5,500–£7,000 | £9,500–£11,500 |
5 kW | 11–13 | £7,500–£8,500 | £10,500–£13,000 |
6 kW | 13–16 | £9,500–£10,500 | £11,000–£14,500 |
Note: Standard inverters, installation, and simple ballasted flat-roof mounting systems are all included in these costs.
The cost of solar panels on flat roof is also largely impacted by brands. If you are looking for quality products for residential settings, the EcoFlow STREAM Series Plug & Play Solar Plant is a great choice to consider. The solar system can connect directly to standard AC sockets, delivering solar power without complex wiring.
In addition, you can consider getting the EcoFlow STREAM Roof Kit to enhance the integration and installation of solar panels on rooftops. The accessory can seamlessly integrate solar panels with a microinverter, converting sunlight into usable electricity for your home.
How Much Can You Save with Flat Roof Solar Panels?
Installing flat roof solar panels in the UK can lead to considerable long-term energy bill savings. Here’s what you can expect to save annually.
System Size | Household size | Cost | Annual savings |
3 kW | 1-2 bedrooms | £4,500–£5,500 | £500–£650 |
4 kW | 2-3 bedrooms | £5,000–£6,000 | £700–£900 |
5 kW | 2-3 bedrooms | £7,500–£8,500 | £850–£1,050 |
6 kW | 4-5 bedrooms | £9,500–£10,500 | £1,000–£1,250 |
Benefits and Drawbacks of Flat Roof Solar Systems
While installing solar panels on flat roof can potentially save your energy bills, drawbacks come with it. Just have a look at the pros and cons as follows:
Pros:
You can reduce reliance on the grid and benefit from renewable, green, and clean energy.
Most flat roof solar panels are free-standing, which makes them easy to upgrade to more efficient solar panels in the future.
Solar panels on flat roof can be hidden from plain view, making them look more aesthetically discreet.
Easy to adjust the flat roof mounting systems and alter the angle of the system seasonally for optimal energy generation.
Cons:
Specialized mounting techniques for flat roof solar panels can increase installation expenses.
The ballasts and mounting system can add additional weight to your roof.
Require frequent cleaning as there are more areas to accumulate debris, dust, and other environmental hazards.
Solar panels on flat roof require spacing to avoid overshadowing each other, taking up more space than installing solar systems on a sloped roof.
What to Consider When Installing a Flat Roof Solar System?
Although solar panels on flat roof present some unique challenges compared to pitched roofs, they offer excellent efficiency and aesthetic benefits. Before installation, there are a few things to consider:
Roof Structure & Load-Bearing: Flat roofs often require ballasted mounts. Make sure your roof can handle the additional weight of panels, racking, and ballast.
Mounting & Tilt Angle: Panels must be tilted to maximize sun exposure. Use ballasted or penetrative mounting systems to secure solar panels in place.
Orientation & Spacing: Use a south-facing orientation for best output in the UK. Ensure spacing between rows to avoid solar panels on flat roofs shading each other.
Drainage & Water Runoff: Solar panels should be elevated for water flow to flow freely. Make sure solar panels do not block the roof drainage systems.
Wind Load & Weatherproofing: In high-wind areas, panels must be weighted with ballast or properly anchored to resist uplift and tested against local wind and rain conditions. Pairing your flat-roof array with the EcoFlow STREAM Series Plug & Play Solar Plant can drive home solar to 100%, reduce bills to 0, and leverage an AI-powered solar network to optimise energy use and ensure reliable performance in all weather.
Ecoflow Stream Series Plug & Play Solar Plant
For homeowners seeking a simple, budget-friendly setup without energy storage, the EcoFlow STREAM Plug & Play Solar System is perfect for first-time solar adopters. It bundles just solar panels and a microinverter—no batteries—so it’s inexpensive and easy to install on flat roofs.
EcoFlow STREAM Plug & Play Solar System
How to Install Flat Roof Solar Panels?
Compared to pitched roofs, installing solar panels on a flat roof requires a slightly different strategy. Here’s a quick walkthrough.
Site Assessment: Measure and identify usable roof area. Evaluate the roof’s condition and structural integrity.
Decide on the Systems: Determine panel layout and tilt angle. Calculate the number of panels required, row spacing, and system types.
Choose Components: The options include string inverters, microinverters, power optimisers, and the right mounting system.
Install Racking System: Place racking on the designated layout and add ballast blocks or fasten anchors based on system types.
Mount and Wire Solar Panels: Install solar panels and wire them as per your design. Run wiring through conduit to the inverter.
Inverter and Electrical Setup: Install inverter(s) and connect to the electrical system.
Testing and Commissioning: Make sure the system is correctly installed. Conduct a thorough inspection to ensure all connections are secure.
Conclusion
Thinking about installing solar panels on flat roof spaces? It’s definitely doable and can be a great way to save money while using clean, renewable energy. We’ve covered the main pros, potential costs, and what to keep in mind before getting started. With the right setup, even a flat roof can deliver excellent results. And if you're after a reliable, easy-to-use system, EcoFlow has some solid options that make going solar feel a lot simpler.
FAQs
Is planning permission required for solar panels on a flat roof?
No. You don’t need planning permission when it comes to installing solar panels on flat roof. However, if you want to install solar panels in a conservation area or a listed building, you are recommended to contact the local planning authority beforehand.
Do solar panels need to be tilted on a flat roof?
Yes. Solar panels should be tilted on a flat roof because tilt allows them to capture sunlight more efficiently throughout the day and year. Meanwhile, tilted solar panels on flat roof allow rain to wash away dirt, dust, and debris.
How many solar panels can I fit on a flat roof?
You can roughly estimate the number of solar panels by dividing the usable roof area by the area of each panel. For instance, for a 50 square meter roof, you might have 40 square meters usable. Dividing by 1.7 square meters (per panel) means you can use 23 panels roughly.