To cut to the chase, solar panels work best when they’re installed at an angle facing the sun. However, that doesn’t mean installing solar panels on a flat roof isn’t possible, because it absolutely is.
So, today, I’m going to clear up a lot of things for you so you can also save money on your power bills. Below is a list of the topics and questions I’m covering in this post. I recommend reading from the top, but feel free to tap on any of the bullets to jump straight to their sections.
- Is it possible to install solar panels on a flat roof?
- How should solar panels be installed on flat roofs? What orientation?
- Does the installation cost more?
- Other things you should know about.
Can you install solar panels on flat roofs?
As I said, yes, you can install solar panels on a flat roof. In fact, flat roofs offer more versatile solar installations than sloped roofs.
With the right mounting system, your installer can orient your system in angles and orientations that are more optimal to your needs and power output. You also have the option to just have the solar panels installed flat (though I don’t recommend it).
That being said, each installation type also has its own set of pros and cons. Let’s talk about each of them so you know your options.
Related: Installing Solar Panels: Flat vs. Angled?
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The best solar panel orientations for flat roofs
Before anything, note that all of the orientations I’m about to highlight need racking systems, so mention this to your installer when you’re in conversation.
Also, we have an article dedicated to the directions solar panels should face in Australia if you want to learn more about that, too. So, without further ado…
Purely east, west, or north-facing solar panels
Like Australian homes with roofs facing north, flat roofs with solar panels tilted north will enjoy a large amount of solar power. That’s because our land down below is in the southern hemisphere, so the sun moves towards the north.
On the other hand, solar panels tilted to the east enjoy more power during the early morning, while west-tilted panels have more energy in the afternoon.
North is the safest option, but east or west can be better for you, depending on the hours you use the most electricity.
That being said, these single orientations also have their drawbacks. You can’t install them too close because they can cast shadows on each other, which limits their efficiency. This, in turn, limits the number of solar panels you can install on your roof.
Mixed (east-west) orientations
Out of all the possible ways to install panels on flat roofs, I like this the best.
Here, you have one row of solar panels facing east, and right behind it is another row facing west. Repeat as many times as your roof and budget allow.
Shading isn’t so much of an issue here, allowing you to install the most solar panels because rows can be installed right next to each other. And when you have more solar panels, you’re also able to generate more renewable energy.
The caveat is that it’s more expensive, and not many solar installers or solar companies accept this kind of project. Lucky for you, we can get you quotes from 3 of our pre-vetted installers—for FREE!
Also, for your reference, the table below shows the power outputs of solar systems installed in different directions, assuming north as generating 100% power.
| Panel Orientation | Power Output (% of Optimal) |
|---|---|
| North | 100% (Optimal) |
| Northwest/Northeast | 90-95% |
| West/East | 85-90% |
| Southwest/Southeast | 75-80% |
| South | 70-75% |
Disclaimer: These values are general estimates for Australia and may vary depending on specific location, roof pitch, local climate conditions, and other factors. For the most accurate data, please consult with a local solar installer.
For further reading: Multi-directional solar panels: Are they worth it?
What about solar panels that are installed flat or tilted south? Why not them?
I don’t recommend south-facing panels to Aussies because they face away from the sun. Meaning they generate the least amount of solar power in total.
On the other hand, yes, you can install panels flat on your roof. This way, you get cheap solar installation costs and a decent amount of solar power.
The problem with flat solar panels, however, is that they’re not self-cleaning and are therefore impractical for many.
Rainwater can pool above the panels, so dust and other debris don’t get washed away. Over time, this can decrease the efficiency and prematurely age your solar system.
I can only recommend this in good conscience if you’re willing to regularly clean, dry, and maintain your solar panels.
Is it cheaper and easier to install panels for flat roofs?
Installing solar panels on a flat roof and a sloped roof tends to be around the same price, which is about 1000 AUD per kW. Although this price still depends on your installer and the rack he/she will use.
That being said, flat-roof solar panels are typically easier to mount because there’s more space to work around. It’s also safer.
Also, installing solar panels on flat roofs generally won’t require your installer to drill holes either because most of today’s racking systems have enough weight to keep the array stable.
On that note, do tell your installer to use a rack that can withstand heavy winds so your solar panels don’t get blown away.
Other things you should know about before getting solar panels for a flat roof:
- Make sure to check with the manufacturer and installer if their warranty covers solar panels on a flat roof.
- Make sure your roof is strong enough to carry the weight of your solar panel system. These weighted racks (i.e. ballast system) make this a necessity.
- Your flat roof solar panels likely won’t be visible from the ground, so they won’t take anything away from the beauty of your home.
- While solar installations might sometimes be more costly, you will still save more money over time because you won’t be as reliant on the grid.
Get 3 Solar Quotes From Quality Local Installers.
Key takeaways: Pros and cons of solar panels on flat roofs
Pros:
- Flat roof systems offer more versatility when it comes to orientations (directions and angles).
- Flat-roof solar panels are cheaper to install; angled solar panels are more efficient and self-cleaning.
- Flat roofs are easier and safer for your installer.
- Weighted racking systems mean no holes will be drilled on your roof.
Cons:
- Installers who accept jobs on flat roofs are harder to find.
- Flat-roof solar panels will require more cleaning.
- Flat-roof solar panels will have water pooling on top of them, possibly leading to damage.
- Wind damage is a possibility with panels that are installed on unfitting racks.
Conclusion
To recap, yes, you can install panels on your flat roof, but it will be a slightly different process. A professional solar installer is the key.
For one, you will have to figure out which orientation best fits your lifestyle and which maximizes your roof space and budget. Your roof also has to be strong enough to handle the weight of the racking system as well as the entire array.
I hope this helped! And, remember, if you’re having trouble finding an installer for your flat roof, we have a network of installers that we trust. You can trust them, too.
