Can You Put Solar Panels on a Flat Roof in the UK?

One thing that’s made me think solar panels might actually be a possibility for us is the flat roof at the back of our house. It gets the sun pretty much all day and, to me at least, it seems like it could be an ideal spot for some solar panels. I’ve always associated solar panels with sloping roofs though, so I wasn’t entirely sure whether a flat roof would work in the same way.

It turns out that you absolutely can have solar panels installed on a flat roof, although there are a few extra things to think about before you go ahead.

How do solar panels work on a flat roof?

On a traditional sloping roof, solar panels are usually fitted quite close to the roof itself, following the angle that’s already there. With a flat roof, it’s a little different because the panels generally need to be raised at an angle to get the most benefit from the sunlight.

This is done using special mounting frames, often called tilt frames, which position the panels at an angle that’s suitable for the roof and the amount of sunlight it receives. The exact angle depends on the installation, but it’s often somewhere between 15 and 35 degrees.

Most solar panel installation companies will look at the position of your roof and work out which direction the panels should face to generate the most electricity. South-facing panels are often a good option, but an east-west arrangement can work well too, especially if it means you can fit more panels into the available space.

That’s one of the things I’d be interested to find out about our own roof. It gets plenty of sunshine throughout the day, but I’d want to know how much of that we could actually make use of and whether the space we have would make installing solar panels worthwhile.

Would solar panels damage a flat roof?

This was one of the first things I wondered about because the last thing anyone wants is to install something that’s supposed to save money and then end up with an expensive roof repair bill. 😂

One option for flat roofs is something called a ballasted mounting system, which sounds much more complicated than it actually is. Rather than drilling through the roof to secure the solar panels, the frames are held in place using weights, usually concrete blocks or weighted trays.

The idea is that the panels can be securely fitted without having to make holes in the waterproof covering of the roof, which is definitely something I’d prefer if we ever decided to go ahead.

There is a catch though, because those weights obviously add extra load to the roof. Before anything is installed, a professional would need to check that the roof is strong enough to support the panels, frames and weights safely.

With our house being as old as it is, that’s something I’d definitely want properly checked rather than just assuming everything would be fine.

What about the wind?

Another thing I hadn’t really thought about was how much more exposed solar panels can be when they’re sitting at an angle on a flat roof.

Because they’re raised up rather than fitted close to a sloping roof, the wind can get underneath them and create what’s known as wind uplift. It’s not something you’d necessarily think about when you’re looking at lovely pictures of solar panels on a sunny day, but it’s an important part of getting the installation right.

A good installer will take into account the height of your house, how exposed the roof is and the typical wind conditions in your area. They can then work out how much ballast or additional fixing is needed to keep everything secure.

It’s another reason why getting the right advice before making any decisions is so important, particularly when you’re spending a significant amount of money on something you want to last for years.

Do you need planning permission for solar panels on a flat roof?

Planning permission is another thing worth checking before getting too carried away with the idea of solar panels.

In England, solar panels on houses often fall under permitted development rights, which means you won’t always need to apply for planning permission. Flat roofs have their own rules though, including a limit on how high the panels and their mounting frames can sit above the roof.

Under the current rules, solar panels on a flat roof can generally extend up to 600mm above the highest part of the roof, excluding the chimney, while still qualifying for permitted development, provided the other conditions are met. There can also be additional restrictions for listed buildings, conservation areas and certain other locations.

I’d certainly want to check all of this before making any plans for our house, especially as it’s an older property. It’s always worth checking with your local planning authority and making sure your installer understands any restrictions that might apply.

Are flat-roof solar panels worth it?

For me, this is probably the biggest question of all because although I love the idea of generating some of our own electricity, I’d want to know that the cost of installing the panels was going to be worthwhile.

There are quite a few things that can affect how much money you could save, including the number of panels you can fit, how much electricity they generate and how much of that electricity you actually use yourself.

The initial installation cost is obviously a big consideration too. Flat-roof installations can sometimes be more expensive because of the additional mounting equipment and structural checks, so I’d want to compare the upfront cost with the potential savings over the years.

I’d also be interested in whether battery storage would be worth considering, as that would allow us to store some of the electricity generated during the day to use later on. That’s a whole other thing to research though, and I suspect I’d end up with a spreadsheet before making any decisions. 😂

Could solar panels work for our house?

I’m definitely not at the stage of booking an installation just yet, but it’s something I’d genuinely like to look into properly.

The flat roof at the back of our house seems like such a good opportunity because of how much sunshine it gets, and I love the idea of making use of a space that isn’t really doing anything other than being a roof at the moment.

We have plenty of other jobs on our list as we work our way through renovating the house, so solar panels aren’t necessarily going to be our next big project. But knowing that having a flat roof doesn’t automatically rule them out has made me much more interested in finding out what’s possible.

I think the next step for us would be to get some professional advice about whether our roof is suitable, what sort of system we could install and, most importantly, what the numbers would look like.

After all, I’m all for spending money now if it means saving more money in the future, but only when the figures actually make sense. And if we could make our lovely old house a little more energy-efficient at the same time, that would be a pretty nice bonus!

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