Is My Roof Pitch A Good Fit For Solar?

What’s the best angle and direction for solar panels in the UK?

So you’re thinking of installing solar panels for your home, your roof is made from suitable materials and you’re ready to invest, but what angle and direction do your solar panels need to be pointed to perform at their optimum?

To generate the most electricity solar panels in the UK should ideally be mounted in a south-facing direction and angled between 30-40 degrees – the exact angle will depend on your latitude. This set-up will give your solar panels exposure to the sun for the longest period of time, resulting in more energy generation for your home.

Whilst a south-facing roof is preferable, good performance can also be found on an east and west facing roof – with eastern rooftops getting the majority of sun exposure in the morning and the west facing in the afternoon and evenings.

What about north facing roofs?

We wouldn’t advise on installing solar on a north facing roof – the returns in terms of energy output would be minimal making solar an unwise investment. However, as an alternative you could choose to install ground mounted solar panels, should you have some good, open and unshaded ground to use.

What about flat roofs?

If you plan to install solar on a flat roof then be aware of potential pitfalls and extra costs, as it’s likely you’ll want the panels mounted on adjustable frames. This will allow you to position the panels at the optimum angle and direction.

You’ll also need to factor in rainfall which can cause ‘pooling’ on the panels, leading to their deterioration, especially around the seal. The extra cleaning maintenance can be a frustration for many flat-roof owners; when compared to panels installed on a sloping roof, that generally maintain themselves. As water runs downwards and off the panels, helping to clean the panels in the process.

How to measure your roof pitch

So now you know what angle the panels should be mounted, how do you go about measuring your roof pitch? Roof pitch is measured as a vertical rise relative to a 12-inch horizontal run. So a roof which rises 7 inches every 12 inches has a 7 in 12 pitch. This is sometimes expressed in ratio form like this 7:12.

There are several ways to measure roof pitch, the most obvious way is to climb onto the roof spirit level and tape measure in hand. However, this is not practical for most people. Fortunately, there is an easier way. Your roof pitch can be measured much more safely from inside.

You’ll need the following items to measure your roof pitch from the attic:

• Tape measure
• Spirit level
• Pencil

To do this, take a spirit level into the attic and position it so that one end is touching the rafters. Now hold it perfectly level and measure the distance 12 inches from the rafter to the underside of the roof. The distance in inches is the amount your roof rises every 12 inches. Let’s say the distance is 7 inches, so your pitch is expressed as 7:12.

Once armed with this information you need to convert the pitch to degrees. However, this is easier said than done, unless you have a degree in mathematics and are fond of trigonometry. Fortunately, we have done the heavy lifting for you and included the most popular roof pitches in the following image.

Conclusion

Installing your solar panels using the correct orientation and angle will ensure they operate at the highest efficiency level. A poorly positioned panel can be as much as 40% less efficient which will severely impact performance and the amount of money you could get back from schemes such as the Smart Export Guarantee.