Can you put solar panels on a north facing roof?
If your only sunny section of roof is angled toward the north, solar panels still might work for you.
If you live in the Northern hemisphere, solar panels will receive the most sunlight if they face south. (This is reversed in the Southern hemisphere, so if you live in Australia the preferred direction is north).
If you’re a homeowner interested in solar, you might not have this option: maybe the south-facing part of your roof is interrupted by vents, skylights or gables, or is shaded by trees. West is usually the next best option (which generates electricity during the evening peak) followed by east.
Sometimes all of these options are unavailable, leaving a homeowner only with a roof that points north. Depending on the pitch of the roof, north-facing solar panels may never see direct sunlight.
While this isn’t an ideal situation, solar panels mounted on a north-facing roof can still be a good option. Whether it makes sense for you depends on the pitch of your roof and your latitude. We’ll get into those details, but first a little background.
How do north-facing solar panels receive sunlight?
If you have a house on the Moon, you know that there’s no atmosphere there. No atmosphere means no clouds, and the sky is black instead of blue like it is on Earth. In fact, during a lunar day, you’ll still be able to see stars. This means that if you look away from the sun while it’s daytime on the Moon, your eyes will see a dark sky.
Not so on Earth. Here, the sky is blue because of atmospheric scattering: incoming sunlight bounces around when it hits the air, making the sky bright even if you aren’t looking in the direction of the sun. This is why, on a clear day, you might still need to squint if you’re looking up at the northern sky.
This is why it’s still possible for north-facing solar panels to generate a decent amount of electricity. While they won’t produce as much power as if they were pointed toward the Sun, on a clear day they can still produce a decent amount of power - maybe enough to make an investment in solar panels worthwhile.
The pitch of your roof matters a lot
The biggest factor in whether an array of north-facing solar panels will make sense for you is the pitch of your roof. “Roof pitch” refers to the steepness, and is typically described in degrees or fractions.
A typical steep pitch you find might find is 12/12 or 45°. While you can find even steeper pitches than this, they tend to be less common.
On the other hand, a flat roof is never truly flat: they need to be sloped at least a little to shed rainwater. The flattest roof you would find is 1/12, or about 8°.
North-facing solar panels on a steep roof will perform quite poorly, while on a flatter roof they will perform better. On a flat roof, such as one with a 1/12 pitch, a north-facing solar array will work nearly as well as a south-facing one.
Here’s a specific example. The table below shows you how many high efficiency solar panels you would need to generate 12,000 kWh of electricity a year in Buffalo, NY (where I live) for different roof pitches:
|Flat roof (1/12)||Moderate pitch (4/12)||Steep pitch (6/12)|
As you can see, the difference between a north and south-facing roof is pretty dramatic, depending on the pitch of the roof. In the worst case, you would need more than double the number of panels if they faced north instead of south.
But with a flat roof, solar panels pointed to the north perform only a little worse than panels facing south. In this theoretical example, you would need only two more panels to generate the same electricity.
Not so with a steep pitch. On a roof that faces perfectly south, solar panels on a house in Buffalo will generate pretty close to the same amount of electricity over the course of a year whether the roof is flat or steeply pitched. But if you put those panels on a steep north-facing roof, power production drops off dramatically and you would need many more panels to generate the same amount of electricity.
This is because with a steep roof, the panels are shaded by the building. It’s kind of like turning your back to the sun. If your roof is steep and north is your only option, solar panels probably won’t work out for you.
Latitude matters too
Along with roof pitch, your latitude on earth - how far north or south you are - also matters. This is because the position of the sun in the sky (as an average over the year) changes with latitude.
At higher latitudes - like Buffalo, NY - the sun is on average lower in the sky, which means that a steeply pitched north roof will tend to be worse for solar panels than the same roof located at the equator.
Let’s do the same analysis above but for a city that’s very far south in the continental US: Corpus Christi, TX. Buffalo sits at a latitude of 43°N while Corpus Christi is much further south at 27°N.
(Again, this is how many high efficieny panels you would need to generate 12,000 kWh of electricity a month.)
|Flat roof (1/12)||Moderate pitch (4/12)||Steep pitch (6/12)|
As you can, north-facing panels on a steep roof are still bad, but not nearly as bad at a northern latitude like Buffalo.
In the Buffalo example, you need more than double the number of panels on a north-facing roof. In Corpus Christi, you only need 75% more panels on a north-facing steep roof to equal the output of an array facing south.
Reverse tilt frames are one solution
A steeply pitched north-facing roof is normally a poor choice for solar panels, but there’s still one option to make it work. You can use what are called reverse tilt frames or reverse tilt racking to make the angle of your panels a little more favorable. Here’s what they look like:
Even though this metal roof has a moderately steep pitch, the use of a reverse tilt frame gives these panels a basically flat angle and improves their output considerably.
The main downside is that this does look a little unattractive because the racking hardware is much more visible. However, this might not matter to you, especially if that part of your roof is facing away from public areas.
Ground mounts make the problem go away
Putting solar panels on the roof is the most common approach for residential solar installations, but it’s not the only option. If you have space in your yard, you can mount your solar panels on ground-mounted scaffolding.
Ground-mounted systems give you the flexibility of placing your solar panels anywhere you have room, which allows your installer to angle them at the pitch and direction that will maximize your electricity generation.
Ground mounts usually cost more upfront but have several advantages, such as higher power output, easier maintenance, and not having to worry about your roof.
North-facing panels aren’t ideal, but they still can work for you
The best situation if you want solar panels is to have a big south-facing roof without any shade. Not everyone is so lucky and may have to contend with shade and building orientations that leave them with a north-facing roof as the only option.
If that’s the case for you, it doesn’t mean that you’re out of luck. You can do the same analysis I did above for the Buffalo and Corpus Christi examples yourself. Just plug in the details for your house into the Solar Nerd calculator and you’ll be able to get a quick idea of whether a north-facing solar array would be viable for you. If you’re not sure, an analysis by a professional solar installer is always the best option.