solar panels on a flat roof

Solar panels on flat roofs: top 3 things you need to know

Solar is a smart energy decision for homes and businesses with flat roofs, but there are a few considerations you’ll need to keep in mind as you go through the installation process.

What to know about solar on flat roofs

  • Flat roofs are an ideal location for solar panels
  • Flat roof solar doesn’t have to be more expensive than a standard installation on a sloped roof
  • Register on the EnergySage Marketplace to compare customized solar quotes for free

Yes, you can put solar panels on a flat roof with flat solar racking

When you picture a solar installation, you probably see one of two things: a utility-sized ground mounted solar panel system or a rooftop solar panel system. If you have a flat roof, you might not realize that solar works 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 panels.

There are distinct sets of design considerations for solar panels on sloped roofs and ground-mounted solar panels. Flat roof solar panels are no different. For this reason, you may encounter solar installers that tell you they don’t work on flat roofs, particularly if you don’t live in an area where flat roofs are common. Some of the large national solar leasing companies (such as SolarCity) won’t install solar on flat roofs because they work with a limited selection of equipment and standardized system designs in order 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.

Installation costs for flat roof solar panels are competitive with a standard sloped rooftop installation

Labor and installation costs typically make up about ten percent of your total solar panel 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.

As an added benefit, your solar installer won’t need to make holes in your roof to install flat 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 typically use a weighted mounting system instead (known as a “ballast system”). This system uses gravity to sit atop on your roof without the need for any 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.

What is a solar ballast system?

If you’re concerned about drilling holes in your roof, a solar ballast system is a common alternate way to mount panels on a flat roof. A ballast system utilizes gravity to keep panels in place and involves using concrete blocks to weigh down your solar panels. You can also install hybrid systems that use tradional drilled mounts as well as ballasts, depending on your unique roof characteristics.

Solar panels on flat roofs can be installed at the perfect angle to maximize your electricity production 

Solar installers designing PV systems for standard sloped 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, they can be oriented to face south and mounted at the correct angle regardless of which direction your home faces. Both of these specifications ensure that your system can be optimized for maximum electricity production. At the end of the day, that means a better-performing system for your home or business.

How to find a company to install solar panels for your flat roof

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 Solar Marketplace. When you join, simply indicate the location of your property on Google Maps so installers will know that your property has a flat roof (they will 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.

10 thoughts on “Solar panels on flat roofs: top 3 things you need to know

  1. Kathleen Taylor

    Just wondering. We had someone from a solar company come by our house yesterday. This is the 2nd time we were told that they can put solar on a flat roof. We are not understanding why. Any chance you would be able to explain what the reasoning is? Thank you.

  2. Dan Edwards

    I live in San Diego. We are at 33 degrees North latitude. Does someone manufacture racking systems for residential installations on a flat roof that can support angles greater than 15%?

  3. Jim

    Does anyone have info on minimum distances from the edge of the roof on a 2 story residential roof?
    I’ve heard 3ft, 4ft, 6ft and 10 ft?

  4. R Kress

    Does Colorado permit ballasted systems on flat roofs? I have been told that they are outlawed here. They seem to work in NM. What gives?

    1. Kammy Lee

      I know this is old, but for future people reading, it’s about wind. Colorado often has tornado warnings and wind speeds of 60mph or greater since I’ve lived here. Most counties require ALL buildings including sheds to be permanently anchored on a foundation as a result.

  5. Scott

    I didn’t realize that solar panels could be adjusted so that the angle is just right to get the maximum amount of electricity production. I can see why this would be important if your house doesn’t directly face the sun. My aunts and uncles have been talking with my parents about having some installed for their house. I’ll have to mention this to them so that they can be more informed.

  6. Burt Silver

    My wife and I are very interested in putting solar panels on our roof. It is partly because we want to save money on our bills, but also because we want to do our part to help preserve the environment. We have a flat roof, so I was worried it wouldn’t work, but I had no idea that it was simpler to install panels on a flat roof than a regular sloped roof. That means I could have the panels put up for potentially cheaper!


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