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Does roof orientation affect my solar panel's efficiency?

Posted by Clare Whitehall on Apr 26, 2024

Choosing to install solar panels to your home is a big investment, and it often requires a lot of thought about the ‘payback period’ - the time it will take to recoup your initial investment from the savings in energy bills. 

One of the biggest things that influences the payback period is the efficiency of your solar panel installation. 

There are a variety of factors that can impact your system’s efficiency, including whether you have monocrystalline or polycrystalline panels, if you have a string inverter or micro-inverters, and also whether you’ve opted to store excess energy in a battery. 

However, another important consideration that impacts the efficiency of your solar panel installation is the orientation of your roof.

In this article, we will provide an overview of the best orientation for solar panel efficiency and the considerations you might take into account if your roof orientation isn’t optimally efficient.  


Why is orientation important? 

To explain why orientation matters for your solar panels, it’s important to have a quick recap on how solar panels work and how our location on Earth impacts the sunlight we receive.

PV solar panel systems generate energy by converting sunlight into usable power for your home. The more sunlight they receive, the greater the amount of electricity they are able to generate.

For countries based on the equator, like Brazil, Columbia, Kenya, and the Maldives - the sun is directly overhead for most of the day. It’s why they are often so hot! The orientation wouldn't matter if you were installing solar panels in any of these locations. Any north, south, east, or west-facing solar panel would likely receive a similar amount of sunlight. 

The reality is that the UK is located in the northern hemisphere - the half of the earth that is north of the equator. London is 51.5° N, for example, Manchester is 53.5° N, and Edinburgh is 55.9° N. And in the northern hemisphere, the sun travels across the southern part of our sky. 

So, to capture the most sunlight throughout the day, solar panels ideally need to face south. And as a general rule, the further north you go, the greater the impact of roof orientation on solar panel efficiency. 


What are the most efficient roof orientations?


The important thing to bear in mind is that all solar panel installations, regardless of orientation, will be capable of generating electricity -  helping to reduce monthly energy bills and carbon footprint.

The orientation of your roof just tends to govern how efficient your solar panels are. 

To help put this in context, it’s estimated that a north-facing panel is likely to generate 40% less electricity than a south facing panel.

How that might impact your solar installation's commercial viability and payback period is something to talk through with your solar panel installer. 

Let’s take a look at the best roof orientations for solar panel installations in the UK in a little more detail. 


A south-facing roof: the ideal orientation

In the UK, south-facing roofs are the best for solar panel installations, receiving the most direct sunlight throughout the day for maximum energy production.

East and west-facing roofs: a viable alternative

Both east and west-facing roofs are viable alternatives for installing solar panels, with estimates that they can generate around 80% of the electricity of south-facing panels. 

East-facing roofs often catch the morning sun, which can potentially match your peak power usage if you use a lot of electricity in the mornings.

West-facing roofs are better at capturing the afternoon sun, which can help offset energy costs when you get home and use more appliances in the early evening.

North-facing roofs: the least efficient

North-facing roofs receive the least direct sunlight and are likely to produce only 60% of the electricity that a south-facing panel would.

While modern panels can still generate clean energy for your home, the reduced output means it’s worth an open conversation with your solar panel installer to help determine if a north-facing installation makes commercial sense for you.




How does the angle of solar panels impact their efficiency?

This is a really interesting question and one that we get asked by customers quite often.

Technically speaking, studies suggest that south, east, and west-facing solar panels perform at their optimal efficiency when they’re tilted between 15 and 40 degrees. 

This aligns with the angles of most modern roofs in the UK, which is positive as the angle of a solar panel installation is often dictated by the pitch of your roof. 

For north-facing roofs, solar panels often need to be angled much more steeply,  at around 60 degrees. This can make it challenging to install, as the required angle is steeper than the natural angle of most roofs.

Can I still install solar panels on a north-facing roof?

The short answer to this is ‘yes’; it’s still possible to generate sustainable energy from solar panels if your only available installation location faces north. 

But when we work through the numbers, occasionally it can leave homeowners feeling uncomfortable over the likely return on investment of their solar panel installation. 

However, it’s also worth bearing in mind that there are a wide range of factors that can influence the efficiency and return on investment of a solar panel installation, such as the type of panel that is used, the type of inverter you choose, whether or not part of your roof is in the shade, and if you choose to opt for battery storage. 

It really does depend on your own unique circumstances and the overall specifications of your solar panel system. 

This is why it’s important to choose a solar panel installation partner you can trust, who can provide a professional assessment for your home’s best solar panel system, advise on your potential energy yield, and design a solution that maximises your investment.

At Projects4Roofing, we’ve been delivering professional roofing projects for more than a decade. We’re MCS certified and are proud to be a Which? Trusted Trader. 

So, whatever the orientation of your roof, if you want to understand how solar energy can work for you - get in touch with our team for a no obligation assessment.


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Topics: Building regulations, Solar energy, Solar panels, Solar panel installation

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