A guide to solar panels on a flat roof

Most of us are used to seeing solar panels on pitched roofs but what happens if your roof is flat? It’s a question we’re often asked by homeowners who are keen to harness solar energy but don’t think they can because of how their roof is constructed.  

To answer the question, we’ve put together this guide together so that you can explore your options if you’re looking to add solar panels to a flat roof.  

Can you put solar panels on a flat roof? 

The short answer is yes, you can put solar panels on a flat roof, but you’ll need to consider how they’re mounted. You’ll also need to think about whether your roof can take the additional weight of solar panels, but a survey will be able to determine this for you.  

Can you install solar panels on a flat roof if you have high winds?   

You can, but you’ll need to carefully consider how your solar panels will be secured. Before any work starts, your installer should consider weather conditions where you live and offer you a fixing system that’s suitable for your home.  

How do you install solar panels on a flat roof? 

Unlike a pitched roof, flat roofs don’t provide that natural angle that solar panels need in order to capture the most energy. To solve the problem, your panels will need to be mounted at an angle.  

Some of the most common solar panel mounting methods include frame mounting, concrete ballasts or a combination. Bear in mind that there’s no single ‘best’ solution and what’s right for your home will depend on the size of your roof and how much extra weight it can hold.   

Frame mounting solar panels 

With a frame mount, your solar panels will be attached to the frame and the frame then secured to your flat roof, sometimes by drilling into the roof itself. Your installer will need to make sure that your roof stays watertight when fixings are in place.  

Solar panel mounting with ballasts 

Ballasts essentially secure solar panels using a weight. Usually, a ballast system is made with concrete.  

If you can’t drill into your roof, frame mounts can be secured with a concrete ballast instead. Alternatively, the panels can be clipped securely to a ballast system. 

Why can’t solar panels be laid flat on a flat roof? 

Solar panels should be angled between 30° and 50° for optimum performance. This tilt also means rainwater will naturally wash off debris and leaves, keeping them clean so they can work efficiently.  

Laying solar panels flat can also lead to water and debris pooling which can affect how your panels work. In the long term, water could end up seeping through your roof if there’s nowhere for it to drain.  

How do solar panels work on a flat roof?   

The panels themselves harness solar energy in the same way as they would on a pitched roof. It also means you can use them together with a battery so that you can store the energy generated throughout the day, rather than sending it back to the grid.  

Will I need planning permission to install solar panels on a flat roof? 

As a general rule, you don’t need planning permission to install solar panels. That said, there are certain rules and regulations you’ll need to follow if you live in a conservation area or if your home is listed.  

Solar panel planning permission could also vary depending on the guidelines set out by your local planning authority. To be on the safe side, it’s a good idea to check what permissions might be needed at the government’s Planning Portal.  

Does installing solar panels on a flat roof affect my warranty? 

This will depend on the warranty you have. For the panels, you’ll need to ensure they’re mounted at an angle that will allow water to roll off so they avoid water stagnating around them which could reduce their efficiency or lead to damage.  

If you have a warranty on your roof, check what it says about mounting solar panels. Most warranties will allow for solar panels but may specify that certain mounting systems should be used over others.  

What are the advantages or disadvantages to flat roof solar panels? 

Solar panels are a big investment so here’s a quick summary of the pros and cons that can help you reach a decision: 

• Can be quicker to install and maintain  as access to a flat roof is often easier 
• Enables you to use all available roof space to get the most solar energy 

• Usually hidden from full view so doesn’t affect the overall look of your home 
• Frames or mounts can be adjusted to get the optimum angle for your panels  

• Must be mounted properly to allow water to drain off and avoid debris from collecting which could hinder performance 
• Extra consideration will be needed to ensure solar panels are secure in areas with high winds 

• Could affect any warranty you have on your roof 
• Your flat roof might not be able to take the weight needed to mount them securely

   

   

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

Whether you’re putting solar panels on a pitched or flat roof, cost will vary depending on: 

• The size of the system you need 

• The type of panel you choose 
• The amount of energy you want to generate 
• Whether you also want a battery to store excess energy 

As well as all these factors, installing solar panels on a flat roof will also mean you need to consider the most suitable way to secure them. Depending on your roof this could increase the overall cost, but a survey will be able to help you work out what this might be.     

If you want to find out more about installing solar panels on your flat roof, you can call us on 01953 882 787 or email us at info@spartek.co.uk.