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Jump to: Is my roof suitable? | Ideal roof angles | UK roof types | How to measure your roof angle | Flat roof installations | Can solar panels protect your roof? | Planning permission | The future of rooftop solar panels | FAQ
Could solar panels for roofs be the solution to cutting energy bills? With the energy crisis and cost of living on the rise with no end in sight, many homeowners are looking for ways to cut costs. As of October 1, 2022, the current Energy Price Guarantee, set by the UK government, was capped at £2,500—27% more than last year—and this is due to rise to £3,000 per year from April 1, 2023.
Solar panels are a way of generating renewable energy, which in turn can reduce energy bills and help your home to be less reliant on the National Grid and fossil fuels. The most common place to install your solar panels is on top of your roof. In order for them to function at full capacity, you need them to be in an optimal position to receive the sun’s rays. So it makes sense that this is on top of your roof, free of obstruction and hopefully a place that receives lots of daylight.
The amount of energy that your solar panels can generate will depend on the angle of your roof, which direction it is facing, and the number of daylight hours. It can be tricky to figure out how this will affect your roof solar panels, and that’s why we’ve done the research for you.
Is my roof suitable for solar panels?
Whether your roof is suitable for solar panels depends on a few different factors. The angle at which your roof is facing is probably one of the most important things to consider here. The reason for this is certain roof angles will generate more solar power. The more sunlight your roof receives, the more solar energy your panels will generate.
Your roof might not be suitable for solar panels if:
- Your roof is too old
- It’s not at an optimal angle
- Your roof is made from wood
- Little to no roof space
- Your roof is too shallow or too steep
To install solar panels on your roof, it should be structurally sound and not made from any fire hazardous materials like wood. There should also be ample space to install your solar panels, and this will be checked at the quotation stage.
Ideal roof angles for solar panels
Most roofs can accommodate solar panels and generate a reasonable amount of energy. However, there is an optimal angle for your solar panel system.
It should come as no surprise that solar panels function at their most optimal depending on the time of day and season. With that being said, in order to get the most out of your roof solar panels you’ll ideally want them to receive the most sun throughout the day.
In order to do this, you’ll need to know which way the panels should face and what the optimal tilt angle is.
Optimal roof angles
According to Viridian Solar, your solar panels should be south-facing and tilted to a 35-degree angle from the horizontal. This maximises the energy collected by the solar panel and is the most beneficial angle in order to help you save the most on your energy bills.
| Direction panels face from due north | W | S | E | ||||
|---|---|---|---|---|---|---|---|
|
Tilt |
270° |
240° |
210° |
180° |
150° |
120° |
90° |
|
0° |
84% |
84% |
84% |
84% |
84% |
84% |
84% |
|
10° |
84% |
87% |
90% |
91% |
90% |
87% |
84% |
|
20° |
82% |
89% |
94% |
96% |
94% |
89% |
82% |
|
30° |
81% |
90% |
97% |
100% |
97% |
90% |
81% |
|
30° |
78% |
89% |
97% |
100% |
97% |
89% |
78% |
|
50° |
74% |
87% |
95% |
98% |
97% |
87% |
74% |
|
60° |
69% |
82% |
92% |
95% |
92% |
82% |
69% |
|
70° |
64% |
77% |
86% |
89% |
86% |
77% |
64% |
|
80° |
57% |
69% |
78% |
81% |
78% |
69% |
57% |
|
90° |
50% |
61% |
68% |
71% |
68% |
61% |
50% |
Source: Microgeneration Certification Scheme (MCS) guidance for domestic solar installations
The above table clearly outlines the optimal angles for roof solar panels, with the percentages representing how much of your panels’ total potential output you’re likely to achieve based on the angle of their tilt and the direction they are facing. This is a helpful guide to better understand if your roof is optimally oriented. As you can see from the table, the more west or east facing your roof is, the more output your system will lose.
The further your roof moves away from south facing, the lower your system’s output will be. Even if you have a southeast facing roof as opposed to due south, this will decrease your output by 5%. The amount that your roof slopes is just as important to which way it faces. It’s most optimal for your roof pitch to be between 30 degrees and 40 degrees, which gives you the most output.
What type of roofs do UK homes have?
A typical UK home’s traditional roof pitch measures between 30 degrees and 50 degrees, according to Marley. If your roof’s angle is 30 degrees or less, it is considered a low-pitch roof and anything less than 12.5 degrees is considered a flat roof. Ideally your roof should be between 30 degrees and 40 degrees, as this gives you the maximum output from your solar panels.
Roof materials commonly fitted in the UK are:
- Composite
- Tile
- Metal standing seam
- Tar and gravel
- Wood
Some roof materials are more suitable for solar panels than others, according to Roofer UK, and some are not suitable at all for safety reasons. So if you’re wondering if your house is suitable for roof solar panels, the below table should help you decide.
| Roof material | Key facts | Suitable for solar panels |
|---|---|---|
|
Composite |
Inexpensive, hard-wearing and long lasting, best option for solar panels |
Yes |
|
Tile |
Durable and long lasting, relatively low maintenance, solar panels will need to be fitted using brackets |
Yes |
|
Metal standing seam |
Thin film and standard PV can be fitted, long lasting and hard wearing |
Yes |
|
Tar and gravel |
Used for flat roofs, brackets would need to be fitted to tilt at 30 degrees |
Yes |
|
Wood |
Fire risk for solar panels, likely to rot and not last as long as other materials |
No |
How to measure your roof for solar panels
It’s important to know the angle of your roof. How much it slopes, or doesn’t, will affect how much energy your solar panels can generate. It might even influence your decision to install solar panels all together. We’ve put together a guide on how to measure your roof for solar panel installation below.
To measure your roof’s angle you’ll need:
- Tape measure
- Spirit level
- Pencil
One way to measure your roof would be to climb up to it with the above equipment, but there is a safer way to measure your roof’s angle.
The easiest way to measure your roof’s angle is surprisingly from inside your loft. Follow our step-by-step guide to help you do this.
- Take your spirit level into the loft
- Position your spirit level so that one end is touching the rafters (sloped wall of your roof)
- Holding it level, measure the distance 12 inches from the rafter going up the wall
The measurement you have now is the amount your roof rises every 12 inches. So if your measurement was nine, that would now be 9:12, which is how much your roof is expressed by. You’ll now need to convert this into degrees using the formula below.
- Divide your measurement by 12 (e.g. 9/12=0.75)
- Input this number into a scientific calculator, such as the one here, and calculate the arctangent (e.g. the arctangent of .75 is 36.869897645844)
- Round this number and the result is your roof angle. In the above example, the angle would be 37 degrees
Can solar panels be installed on a flat roof?
The short answer to this is yes: There are ways in which to install solar panels on flat roofs, such as by installing special mounting equipment. However, this doesn’t mean they will be highly effective, nor are they likely to have a low power output.
Things to consider:
- Panels need to be self-cleaning
- Thin film solar cells work better than traditional solar panels
- The pitch of the solar panels should be carefully considered
It’s important that solar panels on a flat roof are able to self-clean during rainy weather and avoid damage during adverse weather conditions. If you consider that a typical roof pitch is 35 degrees, rain would naturally run downwards and not cause dirt to build up.
Thin film solar cells, although not as effective as crystalline solar panels, are incredibly flexible and work well on flat roofs. You may also opt for moving panels over stationary ones. This type of panel moves with the sun throughout the day, ensuring your panels capture as much daylight as possible.
Solar panels should be pitched between 20 degrees and 50 degrees on a flat roof in order to catch maximum sunlight and generate a feasible amount of solar energy. This will also help them to be self-cleaning and free of debris.
Can solar panels protect your roof from damage?
There’s a myth surrounding this topic claiming that rooftop solar panels can damage your roof. It’s actually quite the opposite, providing your roof is in good condition and the solar panels are installed correctly.
As well as a lot of attractive renewable energy benefits, solar panels can protect your roof from damage from factors such as:
- Bad weather
- High temperatures
- No holes from installation
Solar panels provide a small layer of protection for your roof from bad weather. Extreme weather such as snow, hail, heavy rain, and wind can cause damage to your roof over the years. When solar panels are attached to the roof they can block some of the adverse weather, and in theory your roof could last longer.
Roof solar panels also have a cooling effect. By absorbing the sunlight that would otherwise penetrate your roof without solar panels, they keep temperatures down. There’s also a small gap between your solar panels and the roof, which allows airflow and creates a shaded layer of protection from the sun’s rays.
It’s a common misconception that rooftop solar panels can leave you with unwanted and unsightly holes in your roof. According to the Federation of Master Builders (FMB), solar panels are installed using anchors. A few tiles are briefly removed for the anchors to be inserted into the roof and are put back without any damage if installed properly.
Do you need planning permission to install solar panels?
There’s no straight answer to this question, as it will depend on the size of your solar panel system and where you live. As mentioned by FMB, most solar panel installations do not require planning permission. Although, you should let your home insurance company know since solar panels are a structural element added to your roof.
There are some instances where planning permission may be necessary. If your home is Grade II-listed or you live in a conservation area then you may need planning permission.
You can check your local authority’s planning rules here.
The future of rooftop solar panels
Solar energy is becoming increasingly popular as the UK moves towards ensuring cleaner power is more readily available. Like with any new technology, the amount it costs usually decreases over time. One of the main stumbling blocks for solar power at present is cost. A typical 4 kW solar panel installation is around £6,500, and for most that is a costly sum.
With that being said, the future of solar is promising and in the years to come the investment may become less costly.
Could your roof be covered entirely with solar panels?
It’s possible to have solar panels spanning the entirety of your roof. This maximises the amount of solar power that you will generate and in turn should save you more on your energy bills. With that being said, your roof would need to be thoroughly assessed to make sure it is structurally sound just like when you’re installing only a few solar panels.
Solar roof tiles
If you’re concerned with the aesthetic appearance of solar panels, then solar roof tiles could be another option to consider. Solar roof tiles are small modular tiles that can be attached to your roof. The appearance is somewhat more attractive than traditional solar panels. Solar tiles blend in with your existing roof tiles.
The main difference between traditional solar panels and solar tiles is their efficiency. Solar tiles generate less power, and the cost is higher than that of solar panels. Solar roof tiles cost up to three times as much as solar panels, which could mean paying £10,000 to £12,000 for a 3 kW solar tile system, according to The Switch. A solar panel system of the same size is around £5,000.
Advantages
- Solar tiles are eligible for the same government grants as traditional solar panels
- More aesthetically pleasing
- Can increase the value of your property due to the rising demand for renewable energy
Disadvantages
- Cannot be installed on existing roof tiles so it is more suitable for new buildings
- You would need to replace existing tiles with solar tiles
- More costly than traditional solar panels
Solar roof tiles are still relatively new to the market, and for this reason won’t be a viable option for most cost wise. This is more of a good option if you’re looking to generate solar energy but are hesitant to have unsightly solar panels on your roof.
Solar panels for car roofs
As you most likely already know, the UK is pushing ahead with its plan to ban the sale of new petrol and diesel cars and vans by 2030, with the aim of only selling zero-emission vehicles from 2035. Electric cars still need to be charged, either at home or via a charging point. Now, if you were to charge your car at home, you would most likely see an increase in your electricity bill.
This is where solar panels for cars could be the future. In fact, many automobile companies are working towards making solar-powered vehicles, according to Interesting Engineering. Solar-powered vehicles are electric and use photovoltaic cells on the body of the vehicle to convert energy from sunlight. The vehicles can store a small amount of energy, allowing them to run at night time or on cloudy days.
However, don’t get your hopes up just yet. Buyacar sheds some light on why the idea far surpasses the current technology. Roof solar panels on cars unfortunately don’t generate that much electricity. Currently, the solar panels on cars are mostly used for powering the air conditioning, radio, steering, and sat-nav, and don’t provide enough energy to charge the car’s main battery. Still, this is a great way to generate free electricity and boost your car’s battery should you have an electric car.
Rooftop solar panels FAQ
What roof angle is best for solar panels?
The best roof angle for solar panels is between 30 degrees and 40 degrees. In order to generate the maximum amount of solar energy, your roof would ideally be south-facing at 35 degrees.
Do solar panels work in the winter?
Solar panels work through all four seasons. However, they do tend to generate more solar energy during the spring and summer months thanks to the longer daylight hours.
Is my roof suitable for solar panels?
This depends on various factors. Your roof should be structurally sound and not made of a fire-hazardous material such as wood. If you have a flat roof, low angled roof, or a roof that’s not south-facing you can still install solar panels. But, you should know that your panels are likely to generate less solar energy than if they were at the optimal 35-degree angle.
How much do solar panels for roofs cost?
The cost of rooftop solar panels depends on a number of factors, so it can vary from installation to installation. However, as a guide price, you can expect to pay around £6,800 to £8,000 for a typical 4 kW system, which is usually big enough for a household of three to four people. For a full analysis on solar panel costs, read our guide here.
How long do rooftop solar panels last?
If solar panels are kept clear of dirt, dust, and debris regularly, they can typically last upwards of 30 years. While solar panels can still function beyond this point, their efficiency will start to degrade every year, though most manufacturers on the UK market say their panels will still have 85% to 90% efficiency after 25 to 30 years.
Are solar panels bad for your roof?
Many homeowners who are researching solar panels may wonder whether adding a system can actually damage their roof. While the installation process does require drilling into the roof to install the mounting rails, when done by a professional this will not cause any damage. If you do experience any leaks or other problems after your solar panels are installed, you should contact your installer immediately to rectify any damage. In fact, as mentioned earlier in this article, solar panels might even go some way to protecting your roof from damage, as they can act as a barrier to harsh weather conditions.
Are solar panels too heavy for roofs?
Provided your roof is in a good state of repair and your house is structurally sound, solar panels should not be too heavy for most roofs. As solar PV technology has advanced, panels have become lighter over time—but remember that the typical system needed in the UK consists of 12 to 16 panels. However, this question highlights why it’s so important to seek a reputable installer for your solar panels, as they will often carry out a survey of your home during the quotation process to ensure the structure can safely handle the weight of a solar panel system. Proper installation of the mounting rails is also key, as this will prevent any damage to your roof and ensure the panels can withstand high winds.
What are my options if my roof is not suitable for solar panels?
Solar panels don’t always have to be installed on roofs, although it is the preferred option because it optimises the amount of sunlight that hits them and saves space. If you’re keen to switch to solar power but have been told your roof is not suitable for solar panels, you can opt for ground-mounted systems. However, due to the amount of panels needed to power the typical household, you would need a lot of ground space to accommodate the system. For this reason, you will likely need to seek planning permission from your local authority, particularly if the resulting structure is larger than 9 square metres or more than 4 metres high.