Have you ever noticed that, on most properties, solar panel arrays span only one side of the rooftop? Well, this isn’t an aesthetic choice; it’s because the direction solar panels face is critical to optimizing their power draw throughout the day.
Unfortunately, this means that many homes simply aren’t as suitable for solar augmentation as others, which isn’t to say it would be a waste of time and money, but there are certain limitations you should be aware of before forking out for installation.
What Is The Best Direction For Solar Panels?
In the Northern Hemisphere, due to the nature of the Earth’s orbit, the sun always charts a course through the southern zone of the sky, meaning the best possible way to max out solar efficiency is to install south-facing panels.
A south-facing solar panel is exposed to more direct sunlight than its east-, west-, and north-facing counterparts and will provide the greatest energy yield.
This is why you’ll see those homes I mentioned earlier that only have solar panels on one side of the roof. The northern side of a property wouldn’t be anywhere near as bounteous as the south, so many feel the cost of materials and installation of a second array just isn’t worth it.
What About Southwestern- Or Southeastern-Facing Solar Panels?
While a south-facing rooftop is prime for some sensational solar action, it’s not a golden rule that all panels must face directly south if they’re going to pay off in the end.
Southwestern and southeastern facing solar panels are also considered highly efficient, as they still partially face the sun as it makes its journey through the sky each day.
All things considered, the difference between the draw of a south-facing and semi-south-facing solar panel will be fairly negligible.
What About Eastern and Western Rooftops?
It’s when we install solar panels that don’t face the south at all that we start to see some real energy loss — we’re talking roughly 15%.
Granted, it’s not a huge difference, but this deficit builds over time, meaning you may be more reliant on grid power than you’d like, especially throughout the gloomier months.
I wouldn’t say this is a dealbreaker, as you’ll still be pulling in quite a bit of free, green energy and doing your part to ease the environmental burden on our shared home, but it should certainly be a consideration.
The Argument For West-Facing Solar Panels
There’s a fairly cogent argument for west-facing solar installations, but whether they’d be worth your while depends on the rate structure of your power supplier.
Say, for example, that your energy provider charges you Time of Use (TOU) rates, meaning power is more expensive at certain points of the day.
These peak hours are usually late afternoon through to early evening, as it’s in this period that kids return from school, adults return from work, and we consume a lot of grid power.
Over time, this can end up costing a small fortune, but western solar panels may be just the thing you need to reduce your reliance on mainstream energy when the prices are at their highest.
During this timeframe, the sun is heading for the western horizon where it will eventually set, giving west-facing panels a fair few hours to slurp up some lovely sunlight. You can then use this incoming power in real-time to reduce your dependency on expensive grid energy.
Of course, a south-facing solar array connected to a few homes solar batteries, such as this Lifepo4 cell, will achieve the same thing, but I still consider this a feather in the west-facing panel’s cap.
Are North-Facing Solar Panels Useless?
North-facing solar panels are the least efficient of all, but I wouldn’t say they’re completely useless.
They will soak up some energy during a sunny day, but, as I mentioned earlier, they’re perhaps not the best investment in purely financial terms, as they won’t pay for themselves for decades.
It is possible to pitch them up against the angle of the roof and have them soak up some of that southern sun, but this makes them harder to maintain and, also, in my opinion, looks a little silly.
When Are South-Facing Solar Panels A Bad Idea?
If you’re using solar panels on the ground, setting them up southwards is always going to be your best bet, but a south-facing rooftop isn’t always the best idea. If, for instance, the roof is shaded by another building or a row of trees, your panels won’t get the sun they need to power your appliances.
Another reason a south-facing roof may not be suitable for the job is if it’s too steep or shallow. 15 degrees or below is considered an unacceptable angle, as debris and water deposits would build up, limiting panel efficiency.
50 degrees is too far on the other side of the spectrum. At this angle, the panels would be shaded most of the day.
You should also consider the structural integrity of a roof before installation. If your roof is old or in a state of disrepair, it might not be able to support a solar array.
What Angle Should Solar Panels Be Set?
Photovoltaic cells work at their best when struck by sunlight at a perpendicular angle, which means, typically speaking, you should set your solar panels at 30–40°, but that’s by no means a golden rule.
The sun’s path through the sky changes throughout the year, so the angle of solar panels must also change to maintain optimal energy absorption.
Final Thoughts
Nothing beats a south-facing solar panel, so as long as there’s nothing to the south obstructing the passage of sunlight, that’s the direction you should be angling your solar array.
However, if access to the southern sky is blocked, that doesn’t mean you can’t get in on some solar power.
Southwest and southeast facing solar panels are also very effective, and, failing that, you can choose to pitch them against the western sky to catch some golden hour magic and prevent peak hour grid energy from robbing you blind.