To get the best performance out of your PV system, they need to face the right direction. Solar panels produce more energy when minimizing the angle of attack between the sun and the panel’s surface. The optimal angle is 180 degrees, or when your panels are perpendicular to the sun. This is an ideal situation and isn’t always logistically possible. Latitude, seasonality, the slope of your roof, and the simple progression of the day all come into play when trying to maximize performance. Even the energy policy of your local utility company can affect how you orient your panels. So, what direction should your solar panels face in order for their cells to work at optimum efficiency?
Ideally, your solar panels should face south if you want to maximize your performance throughout the day. This is because the sun travels over the equator as the Earth rotates, and for those in the Northern Hemisphere, the equator lies to the south. This is reversed in the Southern Hemisphere, where orienting your solar array to the north will give you the best performance.
Solar Panel Orientation
For the entirety of the year, the sun travels over the equator as the Earth rotates and orbits the sun. So if you live in the Northern Hemisphere, where the US, Canada, and Europe are located, the sun will travel through the southern portion of the sky. The angle of the sun changes depending on the season. During the summer, the sun comes closer to the zenith, or the highest point in the sky, and takes a lower angle during the winter. Though in either case, the sun will still be towards the south. So despite the changing of the seasons, you should always have your solar panels facing south.
This is reversed in the Southern Hemisphere, in countries like Australia, New Zealand, or Argentina. Since the equator is toward the north, the sun will travel through the northern portion of the sky, so your solar panels should face towards the north. Like in the Northern Hemisphere, seasonality will affect the sun’s angle of attack.
Tilt, Latitude, & Seasonality
Whether you’re in the North or South, the angle of attack will differ depending on your latitude, or distance from the equator. Higher latitudes are closer to the poles, while lower latitudes are closer to the tropics. Depending on your latitude, you need to know the optimal tilt for your solar panels to maximize your power output. Granted, this applies to systems that allow for pitch changes. If you have a roof-mounted system, you probably won’t be able to adjust the pitch. The tilt of your solar panels will depend on the slope of your roof.
Solar panels do best when set perpendicular to the sun. You can have your panels at a smaller, more horizontal, angle at lower latitudes, where the sun is higher in the sky. At higher latitudes, the sun is lower in the sky. That means your panels should have a tilt with a higher angle or be more vertically oriented.
The sun’s angle changes with the seasons, so you should adjust your solar panels to maximize your overall yearly performance. Generally, you should increase the tilt in the winter and decrease it over the summer.
What Direction Should my Solar Panels Face for Net Metering?
Even if you want to optimize your solar array system for net metering, your panels should still face south. Some believe that west-facing panels will give the best rates because energy demand is higher during the evening. But if you have a 1:1 net metering ratio, then it doesn’t matter what time of day that you produce electricity; what matters is that you produce it efficiently. Ideally, you want to optimize the amount of overall power you produce to get the maximum benefit from your utility company. As a matter of fact, your solar panels generate the most power during midday, which is when the demand for electricity is lower. That means you’re less likely to use the power you generate during your peak production hours, giving you more surplus electricity and maximizing your return.
TOU Billing Rates
On the other hand, if your utility company uses a Time-of-Use (TOU) system, then having your panels oriented towards the west can have its benefits. A TOU system means that rates fluctuate with demand. So the electricity you generate will sell for a higher price in the evening when more people are home and consuming electricity. Since the sun sets in the west, having your panels point to the southwest will earn you more credits, as the price of electricity will be higher.
Optimizing for TOU rates has the side-effect of lowering overall electricity production throughout the day. So when deciding how far west your panels should face, you should note the difference between off-peak and peak rates. If the difference is small, your panels should face further south to maximize production throughout the day. If there’s a large difference, then you should orient your panels further west to get higher production during peak hours. Either way, you shouldn’t orient your panels completely to the west, but rather a medium between south and west depending on your local TOU rates.
Having an energy storage system means that your goal is to maximize the overall production of your PV system. So if you want to optimize your solar array for energy storage, you should still point your panels towards the south. That way, you can generate and store as much power as possible. You’ll be able to power you’re home throughout the day, generating plenty of surplus and charging your battery during midday when you’re less likely to consume electricity. During the peak hours of the late afternoon and evening, you’ll still be able to rely on your panels for power. You can then begin tapping into your stored energy as the night falls.
What if I Don’t Have a South Facing Roof?
It might be the case that you don’t have a south-facing roof. But that doesn’t mean your luck’s run out, you can still get some decent power from your panels even if they aren’t facing south. But be warned, they won’t be as efficient. Orienting your panels towards the true south will get you the maximum power output, and the more you deviate, the lower your output will be.
If your roof faces southwest or southeast, then you won’t be losing too much power. Expect around a 6% to 8% drop in performance. But if your roof faces directly east or west, expect a 13% to 15% drop in performance. Remember that you’ll generate more power in the first half of the day if your roof faces east, and more power in the latter half of the day if your roof faces west.
Now, if you have a north-facing roof, you’re looking at a loss of efficiency that could easily exceed 30%. While it’s not a complete loss, it does mean that your production will be severely impacted, and the payback time for your PV system will be higher. You can use more efficient solar panels, or outright install a larger solar array, to help you make up for the loss in performance.
There are ways to mitigate the effects of having a north-facing roof. Installing your panels with a reverse tilt is a possibility. This is when your solar panels are mounted at an angle opposite to the tilt of your roof. A ground-mounted PV system is an option if you have a large plot of land, and if you have the money, you can even install a tracker system.
Reverse Tilt Mounts
Installing your PV system with a reverse tilt is a way to orient your panels in the right direction, even when your roof is tilted to the north. A reverse-tilt kit will raise the angle on your solar panels against the negative slope of your roof, allowing you to face your panels to the south. If you’re shopping around for solar installers and have a north-facing roof, make sure to ask if they offer reverse-tilt installations, as not every solar company will be willing to take on such a difficult job.
If you have the space, a ground-mounted array will be the ideal solution. You can orient the panels in the right direction and adjust the tilt according to your latitude and the time of year. You are also able to ensure that your panels are free of any possible obstructions, like trees, powerlines, or other buildings. With roof-mounted arrays, you may have to put up with nearby obstructions as you may not have many options as to where you place your solar panels. Ground-mounted arrays can also support solar trackers, which boost efficiency.
Solar Tracker System
A solar tracking system follows the sun as it moves across the sky, helping to maintain that perfect perpendicular angle with the sun. If you have a flat roof or ground-mounted array, then installing trackers will give you a nice boost in performance. But solar trackers are expensive, so they’re usually reserved for utility-scale PV and large solar farms. A PV system with solar trackers could be double the cost of a similarly sized solar array.
The orientation of your solar panels has a huge effect on your performance. After all, what’s the point of having solar panels if they aren’t even pointed at the sun? Since the sun travels over the equator, your solar panels should face south to maximize your efficiency. This is reversed in the Southern Hemisphere, where your solar panels should face towards the north. But if you don’t have a south-facing roof, you aren’t completely out of luck. Panels facing east or west will still give you a decent amount of power, but it’ll come with the cost of a reduced power output. If you have a north-facing roof, solar panels are still a possibility, but performance will be severely limited. The energy policy of your local utility company can affect how you orient your panels as well, as TOU rates mean that tilting your panels toward the southwest can bring you some extra profit if you want to capitalize on peak demand.
Frequently Asked Questions
Your solar panels should face towards the south to maximize efficiency. This is because the sun travels over the equator, which for most of us, is toward the south. This is reversed in the Southern Hemisphere, where your solar panels should face toward the north.
The passing of the seasons doesn’t change what direction your solar panels are facing, just the tilt. Ideally, your panels should be flatter during the summer when the sun is higher in the sky and more vertical during the winter when the sun is lower in the sky.
You can do just fine with an east or west-facing roof, as your efficiency will only be slightly impacted. It’s even possible to generate electricity with a north-facing roof, though you’ll produce much less power. You can always install your panels with a reverse-tilt, or even have a ground-mounted system if you have the space.
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