Can you fit Solar Panels ON a detached garage?
You can absolutely fit solar panels on a detached garage roof!
Garages usually come under the ‘existing structure’ category when it comes to planning permission, but it’s always best to check before you get started.
Fitting power in your garage can be a great idea for DIY, charging your tools, hot tub, EV charging, bar or just keeping the lights on.
You can even use power generated on the garage roof to power your home too!
Assessing your garage’s solar potential
Installing anything on, around or near your home can be subject to planning permission, even if you don’t think it does. An installer should always check and file the appropriate paperwork, it’s best to do a little research of your own before you get started.
An average garage in the UK is about 5 metres by 3 metres.
Which would give you a roof size of 15 metres square – enough for around 8 or 9 panels.
We worked that out by calculating the size of the roof and then dividing it by the size of a 405w panel with is around 1.7 x 1.3 metres.
Of course, you may have a double garage, in which case you’ll have tons of room.
Fitting the panels – angle and orientation
The best angle for a solar panel to be fitting is somewhere between 30 and 50 degrees, which is perfect for most house roofs in the UK.
Obviously most garages have flat roofs but we’ll come to that later.
When fitting to the roof of your home, it’s best to have a south facing roof so you can take advantage of the sun for the whole day, but east/west splits are also good.
Learn more about solar panel angle and orientation.
As stated before, you generally don’t need any planning for solar panels on a garage roof.
But, that is dependent on the following things:
- The garage must be located within, or no more than 5 metres, from the property’s boundary.
- Any solar panels on that roof must be more than 1 metre from the roof’s edge.
- The panels must only cause a few notable changes to the house or garage’s overall appearance.
- The system is part of one solar system.
Learn more about planning permission.
Like any other solar installation, the way your roof is made is going to affect the way the panels sit.
Installing your panels on a flat roof is no problem and can even be advantageous.
You will need either solar ‘tubs’ or an angled rail system.
The angled rails systems are lightweight and used in most commercial installations, allowing the panels to be set in any direction and at any angle.
This is good if you have any shading over the garage.
Tubs are also very versatile but do need to be ‘ballasted’ so they may be a little heavy for certain roofs.
Can flat roofs take the weight of solar panels?
That’s going to depend on your roof, I was always told off for climbing on the garage roof as a kid!
Solar panels aren’t that heavy, and their weight is distributed easily because of their size.
But, it’s always a good idea to check the condition of your roof yourself or, more sensibly, get a surveyor to have a quick look.
Also, make sure the mounting system is constructed so the panels won’t be affected by wind or other weather extremes.
Angled roofs are not the ‘norm’ on a detached garage here in the UK, and that’s a good thing!
Putting panels on an angled roof means you are constrained by the direction and tilt of that roof.
A south facing roof is the best for capturing the sun all day, so if your garage has been built like that you’re in luck!
Don’t panic if not though, an East/West roof is also great if you split the panels across both sides.
The pitch is important too, as panels need to be between 30 – 50 degrees to reach the best efficiency.
The angle also helps the panels self-clean when it rains.
Shading is always a possibility no matter where you fit your panels on a domestic system.
But your garage is more likely to suffer from shading as it will usually be a shorter structure than your home – so even your home could shade it.
Check if there are any shadows on the roof of your garage before fitting panels, and ask an expert if it will be a problem.
Optimisers fitted to the panels can sometimes mitigate the problems caused by shading but you need to see how much shading occurs and at what time of the day.
Can I install solar on my garage myself?
Strictly speaking, yes you can, but we wouldn’t advise it.
If your garage-based system is to be part of your domestic feed and is attached to the grid, it will need to be installed by a registered electrician.
Almost all energy suppliers would require the system is MCS certified before they would offer you an SEG so you can sell electricity back to the grid.
Even a fairly lenient company like Octopus would require proof of the professional credentials of whoever fitted the system.
To be honest, even if it’s not going to the grid, electricity can be very dangerous and more than a few panels generating at once could give you a really nasty kick.
So, as the saying goes – if it’s water, wheels or watts always ask an expert.
Powering your detached garage
Following on from that, you may want to have a standalone system that only feeds into your garage, which is totally possible.
You will need a fairly robust system though, as most power tools take a fair amount of electricity when they are running.
Chargeable tools would be perfect, as they can utilise the solar while you aren’t there, and you can use the power when it’s convenient for you.
Of course, if you add a battery to the system, you can use the power in the garage whenever you want.
Plus, we would always advise attaching to the grid so you can take advantage of good SEGs to charge your batteries at night and also sell into the grid at peak times.
Check out some of the tariffs available from Octopus here.
Can I use garage based solar for EV charging?
You can absolutely use solar panels to charge your EV, but you are going to run into a few problems if that’s your only source of power.
Solar panels only work during daylight hours which, unfortunately, is usually when you will want to use your car!
If the car is plugged in when the sun is shining, it will fully charge the battery on a normal UK day, but in winter you are going to need to draw from the grid.
One thing to look out for is the very rare problem of over charging a battery.
This can cause thermal runaway and will, on rare occasions, lead to the battery igniting.
This is extremely rare and, in fact, a recently published paper, could only find 5 examples of a commercially available solar/EV battery doing this in the last decade.
Costs to add solar panels to your detached garage?
Using the space on your garage roof to install a few extra solar panels is probably the best way we can think of for utilising spare surfaces in your home.
Prices for individual solar panels range between £150 and £250 for a modern, monocrystalline unit.
You can add as many as will fit on the roof, but you must ensure your inverter can handle the extra load.
Typically, if you can fit 10 panels on your roof, those and associated inverter would start at around £5000 to £7000 depending on the method of mounting the panels.
Learn more about solar panel costs.