Does my roof have to face south for solar to be worthwhile?
Published on August 29, 2018 by Andrew Sendy
Last updated on November 11, 2019
8 minutes read
Categories: Solar 101
If you're looking to install a solar system for your home, you'll want to position your panels so that they receive maximum exposure from the sun.
But which direction will provide that? And what if your roof doesn't face that direction? Will you still be able to accumulate enough energy savings to make solar energy worthwhile?
Learn more about solar panel installations as we explore panel positioning and how it affects your energy output.
Which is the best direction for solar panels to face?
The sun rises in the east and sets in the west, so you may think that one of those directions would be ideal for solar panel positioning. But in fact, because of the way the sun moves across the sky, it actually favors the south.
As such, in the Northern Hemisphere, south-facing panels will provide you with the most direct sunlight.
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How do south-facing solar panels compare to other directions?
In mid-afternoon, when the sun is at its peak, it is shining towards the south. Therefore, you'll maximize your energy production when your panels face that direction.
Experiments have been conducted in select large cities in the Northern Hemisphere, under a variety of weather conditions, on panels facing in all four primary directions. And the verdict is: south-facing panels produce more energy than any other direction.
But what if your roof faces east/west instead of north/south? How much energy will you lose if your panels don't receive direct sunlight at peak hours?
Do west-facing panels produce less than south-facing panels?
If your solar panels face west, they'll receive their direct sunlight as the sun is setting - in the late afternoon and early evening - rather than when the sun is at its peak.
This lack of exposure to direct sun at peak times means you'll lose about 20% of your energy output as compared to a south-facing system. However, this loss can be somewhat offset simply by installing a bigger system.
Despite the loss in overall energy production from west-facing panels, some homeowners are now considering positioning their panels facing west to maximize energy production in the late afternoon - the time when peak energy prices are in effect.
This consideration is especially important to consumers in California, who now have to use time-of-use electricity plans, a system in which power is more expensive in the late afternoon and early evening.
Do east-facing panels produce less than south-facing panels?
Panels facing east receive direct sunlight in the morning, when the sun is rising. They also produce about 20% less energy as compared to south-facing panels.
However, for both east and west-facing systems, if you change the tilt of your panels from 30 degrees to 15 degrees, the energy loss, compared to ideal conditions, is only approximately 15%.
Is it better to face your panels west for time-of-use rates?
There is an exception to the “south-facing is best” rule; whether or not your utility adjusts its rates based on time-of-use (meaning they charge more during peak demand hours). In most areas, time-of-use rates are highest between 3pm to 8pm.
South-facing panels receive maximum exposure at noon when the sun is at its highest point in the sky. However, west-facing solar panels get more exposure in the late afternoon and early evening, while the sun is setting. Therefore, they will produce more energy during those “peak hours” when it costs more to get energy from the grid.
How can you optimize your solar system's efficiency?
Until now, we’ve inferred that mounting fixed solar panels in either a south or west direction can help you achieve a greater return on your solar investment.
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However, fixed solar array systems that face south or west can only produce energy for a limited number of hours each day.
In fact, you can track the sun all day long and achieve optimal solar power output — no matter the season, location, or time of day — by using solar panel trackers.
Utilizing solar panel trackers to maximize your solar system's performance
Solar panel tracking systems can improve a system’s output by ensuring constant, direct exposure to the sun, both during the day and across seasons. Axis trackers generate more electricity by using about the same amount of space as fixed systems.
The image below shows that dual-axis trackers can achieve a noticeable boost in solar panel output, especially during the fall and winter months.
Solar energy production in Los Angeles, California, during different seasons. Image source: EIA
Seems ideal, right? You might even be wondering, “Why doesn't everybody get a tracking system?” Well, the reason is quite simple: solar trackers are proportionately much more expensive than the value of the extra power they produce.
For instance, for a standard 4 kW system, the typical price for a fixed, ground-mounted array is about $14,000. A single-axis tracking system serving the same sized home costs about $22,000. This is a premium of 57% over the cost of a stationary array — for a solution that will only increase production by around 25-30%, at best.
To learn more about the value proposition of solar trackers, read this article: Are solar axis trackers worth the additional investment?
What if your roof doesn't face south?
Ideally, your rooftop solar power system should be facing south for maximum efficiency. Of course, this isn’t always possible: many homeowners don’t have roofs that face in that direction!
The good news is that this is not a dealbreaker. There are plenty of homeowners in America without south-facing roofs, who have solar panels installed and are enjoying huge savings on their electric bills.
Here are some workarounds for homeowners who don’t have south-facing roofs:
Install solar panels on your roof anyway
You can install solar panels facing west or southwest; in some cases, this works out to be as or even more profitable because of time-of-use billing.
If that is not an option either, then you can simply install more solar panels, which will help compensate for the decreased level of sunlight.
Install your panels on a wall
If your roof doesn't face due south, you could install solar modules on a south-facing wall instead.
This will only work if the wall receives lots of direct sunlight, i.e. it is relatively shade-free. Trees, bushes, or other buildings that cast shadows on the wall will make the solar panels less efficient.
You should also be aware that installing solar panels vertically tends to be more expensive.
Install a solar array on the ground
You can also install a ground-mounted solar system in your yard. This is less expensive than creating racks on your roof or hanging them on a wall, but it does require a lot of yard space.
One of the best aspects of ground-mounted solar panels is easy maintenance. You can brush leaves or snow off of them without having to climb onto your roof.
How much power will your solar panels produce?
Other technological advancements for solar panel direction
Researchers are working on ways for solar panels to achieve maximum energy output without difficult and/or costly manual adjustments. Here are some of the more promising developments:
- Watch this interesting video on how robots pivot solar panels to face the sun
- Read this article that shows how researchers are now developing a glass coating that can help underlying solar cells harvest sunlight from multiple directions
- Explore the Smartflower™ solar automation system, which is inspired by the sight of a sunflower turning to follow the sun
Despite these advancements, no technology currently offers more cost-effective electricity production than traditional fixed-mount solar panels — and it’s impossible to say if and when that will ever change.
In the meantime, we recommend that you use our solar roof estimate calculator to learn everything you need to know about installing solar panels on your roof.
South-facing solar panels provide you with maximum energy savings for your home. But no matter what direction your roof faces, you will still see a significant impact from solar power.
Solar panels will save you money and energy year-round - in any weather, rain or shine.