So you’re wondering if solar panels will work if you mount them facing North.
Perhaps you’re expanding a preexisting system or the only roof space you have available slopes away from the sun.
Well, you might be surprised to know that installing North facing solar panels is on the rise.
But does that mean it is actually worth the investment or would it be a big waste of money?
Well, let’s take a look at the power and energy impact of solar panels facing North.
P.S. This information is based on the Northern Hemisphere, like the USA and UK, where the equator is South of these locations.
Can You Put Solar Panels on a North Facing Roof?
Yes, you can put solar panels on a North facing roof. From a theoretical point of view, there’s nothing to stop you mounting the equipment on this orientation of roof.
The question really applies to whether it is efficient to mount solar arrays North facing. Well, most experts will tell you that you should avoid doing this at all costs. This is because you are likely to run into a number of problems including shading and a lack of direct sunlight. This particularly becomes an issue outside of peak summer months.
Despite these obstacles, you will still see solar panels mounted on a North Facing roof from time to time. This is because in certain circumstances you can still create an efficient system that generates a decent level of energy for your investment.
Next, let’s look at how much energy you would typically lose with a Northern orientation.
How Much Power Loss From North Facing Solar Panels
On average a North facing solar panel can reduce its performance by 30% – 40%, and sometimes even more.
Over the course of a year, studies suggest that the energy generation will be 60% to 80% compared to that of a South facing solar panel. Many are surprised by this number, as it still delivers an acceptable output in spite of traditional thinking.
As a visual representation use this diagram below which compares the various orientations of solar arrays:
As you can see South is by far the best way to face solar panels, followed by East or West. While North leaves you with a poor efficiency in comparison.
But this average efficiency loss is not equal at all times of year as you can see below.
You can see that the angle of the sun changes throughout the year. During winter the sun is lower in the sky meaning it sits nearer to the Southern horizon. The result of this is that direct sunlight rarely hits the North side of a roof and the shading is increased.
Compare that to summer months where the sun sits high in the middle of the sky. At this time of year, it will still be able to deliver direct sunlight to both South and North facing areas of the roof.
This means that a North facing solar panel is likely to be much more efficient in the summer as it can get direct sunlight, compared to the winter where it is constantly shaded.
Diffuse Sunlight Remains the Same
Solar panels will also generate electricity from diffuse sunlight. This is all the other light from the sun which is not direct sunlight. For example, the sky’s blue glow. These are still particles of light traveling to Earth with useful energy. The benefit here is that orientation does not affect energy production from diffuse light. And around 30% of a solar panel’s electricity generation is derived from diffuse light.
This is why the performance of North facing solar panels is surprisingly good and the performance drop is not always as aggressive as you might believe.
Put simply, quite often North facing solar panels beat expectations!
3 Factors to Consider for Roof Mounted Solar Panels
Now that you understand the relationship between orientation and direct sunlight hitting a rooftop, we can look at the 3 key considerations to selecting a roof for solar panels. These are orientation, tilt angle (roof pitch), and shading. Let’s look at each in-depth.
Orientation
As we’ve already discussed, orientation is the first thing a solar installer will take into account. You want to try to face the solar panels in the direction that gets the highest amount of direct sunlight. Usually, that means South facing. But you can still get away with a North facing solar panel as long as it still receives direct sunlight.
It’s even more important to be precise with a solar panel not facing South as the other factors like roof pitch and sharing become more pronounced.
Tilt Angle
For best performance, a solar panel should be tilted at an angle between 30 degrees and 45 degrees towards the sun. This helps the cells to receive an increased amount of direct sunlight.
As you can see in the table below the combination of tilt and orientation seriously affects overall performance. For example, South facing at 40 degrees is far better than any other setup.
You won’t find a North orientation on charts like this as it is generally avoided by the solar industry.
On a building rooftop, the slope angle is dictated by the pitch. This is because the panels are mounted parallel to the roof. If you want to mount solar panels on a North facing rooftop then you should consider the pitch of your roof. A steep pitch will deliver a very poor performance in this scenario as very little sunlight will ever reach your solar cells. Contrastingly, with a shallow pitch you can still generate decent performance in the summer as sunlight can still travel over the ridge to your solar cells.
Shading
The final consideration is shading. Once again, this is all about direct sunlight hitting your solar cells. Anything that blocks sunlight and creates a shadow over your array will cause shading. This case dramatically affects performance, often 70% or more!
Most often shading on a roof occurs from the ridge at the peak of a pitched roof. You can almost think of it as the North side of a mountain compared to the Southside. The North gets minimal sunlight as the peak of the mountain blocks the light. And this shading effect becomes greater at steeper pitches with sharper ridges. So if you’re looking at a North aspect, consider the shading that will occur. Is it constant or will there be a chance for the sun to come over the top, particularly in the summer.
Will North Facing Solar Panels Be Worth It?
In the right circumstances, a North facing solar panel can be worth it. In fact, many people are surprised by the amount of electricity you can still generate. Diffuse light still delivers the same efficiency as any other orientation.
In terms of direct sunlight, you must be very careful and should only consider this orientation if you can still receive direct sun to the solar cells. During the depth of winter, the performance will suffer more dramatically than in the summer. In addition, you should consider the pitch and shading on your roof. For example, a shallow pitch roof is going to receive better sunlight than a steep angle with a pronounced ridge.
To be honest, you’ll always be better off with solar panels facing the equator. But if that’s not an option then consult an installer before making any decisions. They will be able to help you understand the impacts in your local area, calculate requirements, and suggest a bespoke solution.
