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Have a flat roof? Why it could be the perfect setup for solar

Solar is a smart energy decision for homes and businesses with many different types of roofs, including those that are flat. However, with a flat roof, you’ll need to keep a few considerations in mind as you go through the installation process. We’ll walk you through what you need to know about solar for flat roofs before you install and how your flat roof solar system could end up being even more efficient than a traditional solar system.

Key takeaways about solar on flat roofs

  1. Solar can be installed on flat roofs but you may need to add additional solar mounting to ensure your system is optimally installed.

  2. You can orient solar panels on flat roofs to face south and be at the optimal angle for energy production, maximizing renewable energy production for homeowners and commercial buildings.

  3. Whether you have a flat roof or not, you can compare quotes from local solar installers on the EnergySage Marketplace.

What’s in this article?

  1. Can you install solar on a flat roof?

  2. Challenges of installing solar on a flat roof

  3. Does it cost more to put solar on a flat roof?

  4. Are solar panels still efficient on a flat roof?

  5. Frequently asked questions about solar for flat roofs

Can you install solar on a flat roof?

When you picture a solar installation, you probably see one of two things: a utility-sized ground mounted solar photovoltaic system or a rooftop solar panel system. If you have a flat roof, you might not realize that solar can work well for your property type, too. Flat roof solar panel systems can actually be more flexible in their design than sloped rooftop installations, making it easier to get the most out of your solar panels.

There are distinct design considerations when you install solar panels on sloped roofs or ground-mount them – flat roof setups are no different. As you’re searching for a solar company, you may encounter installers that don’t work on flat roofs, especially if you don’t live in an area where they’re common. Some of the large national solar leasing companies won’t install solar on flat roofs because they work with a limited selection of equipment and standardize system designs to minimize their costs.

However, this issue is easily remedied by shopping around for a second (and third) opinion. If you get solar quotes from multiple installers, you should easily be able to find one that has experience designing and installing solar panel systems for flat roofs.

Challenges of installing solar on a flat roof

Whether you have a common asphalt roof, a metal roof, or a flat roof, running into some challenges when installing a solar panel system is common, but typically fairly easily remedied (depending on your setup). However, when you install solar panels on a flat roof, there are some unique and common issues that may arise, including:

  1. If you install solar panels flat against your flat roof, they get much dirtier over time because they aren’t installed at an angle; dirt reduces production, so you’ll need to be much more on top of cleaning your panels than you might otherwise be.

  2. In the U.S. (and in the entire northern hemisphere), the sun moves from east to west throughout the day across the southern part of the sky. Southern-facing solar panels will have the best energy production – you’ll miss out on significant output if you lay them flat against a flat roof.

  3. Many manufacturers include clauses that void the warranty if the panels are installed flat against a flat roof; there’s an increased risk of water damage because water can pool up on top of the panel and sit there. However, this is easily remedied by mounting solar panels on a flat roof at an angle, allowing rain (or anything else) to run off them.

  4. Some installers don’t work on flat roofs in order to keep costs low – make sure to indicate that your roof is flat when shopping around for quotes to connect with installers who will work on roofs like yours.

Luckily, as long as you mount your solar panels at an angle on your flat roof and shop around for solar installation companies, you should be able to avoid these challenges.

Does it cost more to install solar on a flat roof?

Labor and installation costs typically make up about 10 percent of your total solar PV system costs. This is partially due to the logistics of climbing around on a steep roof to affix solar panels and their mounts. The process of installing a solar panel system on a flat roof is simpler by comparison – workers can move freely on the roof without special equipment, and most of the roof materials used on flat roofs can easily handle the wear that occurs during the installation process. Generally, installation costs for flat roof solar panels are competitive with a standard sloped rooftop installation.

As an added benefit, your solar installer won’t need to make roof penetrations to install flat roof solar panels. Solar installations on sloped rooftops typically use a “penetration mount”, which fixes the racking that holds the solar panels to your rooftop by drilling multiple holes. Flat roof systems often use a weighted mounting system (known as a “ballast system”), which uses gravity to sit atop on your roof without the need for drilling holes.

That being said, solar panels installed on flat roofs sometimes require specialized equipment to maximize their electricity production. Instead of laying flat solar panels on a sloped roof, your solar installer will likely use angled mounts that tilt your solar panels up so that they’re exposed to the sun for as much of the day as possible. This can sometimes result in a slightly higher price tag for your flat roof solar panel system.

Are solar panels still efficient on a flat roof?

Solar installers designing PV systems for standard pitched roofs have to incorporate roof angle and roof orientation into their system designs. Ideally, solar panels will be installed facing south at an angle equal to the latitude where they are located. If you have a roof that faces east or west, or can only install solar panels on the north side of your roof, your system will produce less electricity on a day-to-day basis. Additionally, some sloped roofs are steeper than others, which can result in less-than-ideal electricity production. While this doesn’t mean solar isn’t worth it, these considerations can decrease your total 20-year electricity production.

Flat roofs offer more flexibility in terms of your solar panel system design. If you install solar panels on your flat roof, you can orient them to face south and mount them at the optimal angle to maximize your solar energy generation. At the end of the day, solar panel systems on flat roofs can often result in better performance compared to those on sloped roofs.

Is it safe to install solar on a flat roof?

When it comes to the actual installation process, installing solar on a flat roof is much safer for the people doing the installation themselves. (However, you still should have your solar system installed by professionals as opposed to attempting a DIY installation.)

If you elect to install your solar panels flat against your flat roof, you’ll run the risk of dirt accumulation and water pooling. While dirt accumulation is more of a nuisance than anything else (requiring more cleaning than tilted panels), pooling can pose a real risk to the integrity of your roof. When it rains, water may pool up on top of and around flat solar panels and remain there, risking damage to both the panels and the roof. However, as long as you mount your panels at an angle on your flat roof, you should avoid this issue.

Frequently asked questions about solar for flat roofs

Can I still get the solar tax credit if I put solar on my flat roof?

Yes, solar incentives and rebates should still be available to you whether you’re installing solar on a flat roof or a sloped roof.

Do I need a specific type of solar racking system to install solar panels on my flat roof?

Yes, you’ll most likely need additional racking to install solar panels on your flat roof to make sure they’re producing as much electricity as possible.

Is a solar panel installation more difficult on a flat roof?

Not necessarily! When installing a solar power system on your flat roof, there may be a few more considerations to take into account – just make sure to indicate that your roof is flat when you’re speaking with installers about your home solar system.

Can I combine battery storage with my flat roof solar system?

Yes, you can install battery storage with a flat roof solar system. You’ll be able to talk to your installer about your energy storage needs to see what type of solar-plus-storage system is right for your home.

Can I get solar shingles for my flat roof?

You may be able to install solar shingles on your flat roof, but they likely won’t be very efficient unless you’re able to mount them at an angle. When it comes to maximum energy production, you’ll want to go with traditional mounted solar panels.

Will my flat roof solar system produce less energy than a regular solar system?

No, the energy production of your flat roof solar system should be just as good as a solar system on a roof with a more traditional tilt angle. In fact, flat roofs can often offer more flexibility when it comes to system design and allow you to install your panels at an optimum angle for peak solar production, potentially making them more efficient.

Find a solar company that installs panels on flat roofs

If you live in an area where many homes have flat roofs, it’s likely that your local installers will have experience working with these kinds of systems. However, you should always get multiple quotes from installers to ensure that you’re working with a company that has the right expertise and background for your needs. The best way to find multiple local solar installers is to register your property on the EnergySage Marketplace. When you sign up, you’ll input your property address so installers will know that your property has a flat roof (they’ll see an overhead satellite image). To ensure that you get quotes from companies who will work on your property, you can also indicate that you’re looking for a flat roof installation when you set up your preferences after joining.

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