What Is the Best Roof for Solar Panels?
September 14, 2021
If you’re looking to acquire solar panels, your first step is to determine if your roof is suitable for a solar panel system. And if you’re planning on using solar panels on a home you’re building, roof design should also be on your mind.
Either way, many different types of styles and materials are used for roofing, and understanding how these factors influence solar panel installations can be a challenge.
Freedom Solar is here to provide you with insight on which roofs work best for solar panels, ensuring your system remains stable and secure for optimal performance.
What Type of Roof Is Best for Solar Panels?
Many types of roofs work great for solar panels, but here are the top types to choose from.
Mounting Solar Panels on Shingle Roofs
Shingle roofs are the most common type of roofing on homes and are composed of either composite or asphalt shingles. Composite shingles are made from a combination of materials such as laminate, wood, and slate; asphalt shingles are made of either a cellulose mat or fiberglass material with asphalt added to the final product at the end of the manufacturing process.
While both options are flexible, composite shingles are a bit more durable than their asphalt counterpart.
Installing solar panels on shingle roofs is quite simple, requiring standard penetrating mounts that easily attach. For installation, studs need to be drilled into the roof for the solar panels to attach to, and the spaces between the panels and studs are then closed off and sealed with flashings to prevent water from leaking in between the roof and panel, and potentially entering your home.
Many homeowners (or homebuilders) use shingle roofing because it’s inexpensive, durable, and lasts between 12 and 20 years, which makes it great for attaching solar panels that you’d potentially keep on your roof for decades.
Mounting Solar Panels on Metal Roofs
Metal roofs work great for solar panel installations. If your home has a metal roof with standing seams, this allows for easy attachment of solar panels because they don’t require any drilling for attachment. And because the need for drilling is eliminated, contractors or crew labor aren’t needed for hire, in turn saving you labor costs during your solar panel installation process.
Metal roofs are also great to have on your home or business in areas that are sunnier or warmer than others — such as Texas, Colorado, and Florida — because they reflect any light that doesn’t hit your solar panels, ultimately keeping your house cooler.
One of the main reasons that people choose metal roofing for their homes is due to their impressively long life cycle. Metal roofs can last anywhere between 40 and 125+ years.
On the downside, metal roofs are about two to three times more expensive than other roofing materials and can be quite noisy during adverse weather. Luckily, if you have solar panels installed, some of that noise is blocked.
Mounting Solar Panels on Tile Roofs
If you have a tile roof, solar panels can be installed using a standard penetrating mount that slightly raises them above the roof. Since tiles don’t always have identical, uniform shapes, cutting or removing certain tiles is sometimes necessary when making way for the mounts. This can result in extra labor costs.
Tile shingles can be made of slate, concrete, and clay; installing solar on clay tile presents some challenges that are not inherent with standard shingle roofs. For one, how you move across the roof itself is very different. Clay tile is very resilient to the elements, but not so resilient to the footsteps of installation teams. However, Freedom Solar takes careful responsibility in servicing this market; we’re well trained on moving across clay roofs without breaking tiles.
Even though tiled roofs are aesthetically pleasing since they have more range in appearance, they’re typically more expensive (although not as much as metal) and heavier than other roofing materials. But they’re also long-lasting and generally more waterproof than other roof types.
Around 90% of roofs in California and Arizona have tile roofs, but they’re growing in popularity in areas such as Central Texas, where preferences are changing alongside spiking population rates.
Mounting Solar Panels on Tar and Gravel Roofs
While most tar and gravel rooftops are flat (some sloped roofs use tar and gravel), it’s still possible to install solar panels on them. However, you’ll need to ensure that your solar panel system is mounted and angled at 30 degrees with tilt bracks so that your panels receive optimal sunlight for your home’s energy generation.
Even though maneuvering around flat roofs to get work done is easy, you should still consider hiring a labor crew or contractor for the mounting and orientation of your solar panel system if you’re inexperienced with the installation process.
Many homeowners enjoy tar and gravel rooftops because they’re the most budget-friendly and have a lifespan of about 20 to 25 years. They’re also sealed tight to prevent cracks and leaks while also providing a great, flat support surface for your solar panel system.
What Is the Best Roof Angle for Solar Panels?
The best roof angle for solar panels is about 30 degrees to maximize energy output, but that doesn’t mean that solar panels won’t work for roofs with steeper or flatter slopes.
Take into consideration that for optimal solar panel performance, you’ll want to add 15 degrees to your latitude in the winter, then tilt your solar panel system to whatever that number is; and for the summer, subtract 15 degrees from your latitude and angle your solar panel system accordingly.
Can a Roof Be Too Steep for Solar Panels?
Most roofs aren’t extremely steep, but even if yours is, your solar panels will likely still function well enough to produce enough energy for your home. The optimal roof angle is about 30 degrees, but if your roof tilt is at 40 degrees, this will only decrease your energy generation by approximately 1%.
Any roof that’s over 40 degrees is most likely too steep, and solar panels might not be a logical addition to your home if full energy independence is your goal.
Solar Panels on Flat Roofs
Solar panels can just as easily be found on flat rooftops as on sloped roofs.
The solar panel installation process for flat roofs is usually much simpler than on sloped roofs since it’s easier to move around, leading to a quicker finish.
Solar installations on flat roofs don’t require the penetration mounts that sloped roofs need for the panel system to remain secure. Alternatively, weighted mounting systems (also known as ballast systems) are used for flat roofs, which don’t require drilling into your roof. This type of system eliminates the need for holes and uses gravity instead to ensure your solar panel system is stable and secure.
However, since flat roofs clearly don’t have an angle, tilt-up brackets are used to keep your system angled at 30 degrees.
What Is the Best Direction for Solar Panels on Roofs?
The best direction for solar panels is south. However, if your home’s roof doesn’t face that direction, you can face them southeast or southwest.
Depending on which hemisphere you live in, this answer could be the opposite. For those who live in the Northern Hemisphere, the sun travels along the southern portion of the sky as we follow our orbit throughout the year, so your solar panels will need to face south. Similarly, those living in the Southern Hemisphere will need to face their solar panels toward the north (or northeast or northwest).
How Much Roof Space Is Needed for Solar Panels?
Roof space needed for solar panels entirely depends on the type and manufacturer of your solar panels, the size of your home, and how much electricity you typically use on a daily basis.
One square foot of roof space can potentially generate around 15 watts of solar energy with an average sized solar panel. A smaller home might only require 200 square feet of roof space for panels, but larger homes will require more solar panels, and thus more roof space (about 1,000 square feet), to keep the lights on.
If you’re an avid electricity user, you’ll likely need more roof space to accommodate for more solar panels that can meet the needs of your electricity usage.
Average homes usually use between 19 to 23 solar panels, with each panel needing up to 18 square feet of space. Generally speaking, your roof should have 400 to 600 square feet of available space. Take into consideration any skylights, dormers, or chimneys that might subtract from your total usable roof space.
[Related: How Many Solar Panels Do I Need?]
Roof Strength Requirements for Solar Panels
Solar panels and their required mounting equipment, whether that’s penetration or weight mounts, typically weigh in around 3 to 4 pounds per square foot. This weight is usually acceptable for any roof type.
However, solar panels using weighted ballasts on flat roofs typically weigh a bit more since concrete blocks are used to hold the system in place.
As long as your home has a relatively newer roof that’s in decent condition, weighted ballasts are a fine solution — especially if your panels are from SunPower, which offers the lightest solar panels in the industry, weighing in around 33 pounds per panel.
Are Solar Panels Bad for Your Roof?
Solar panels aren’t bad for your roof, but there are some factors to consider, especially during the installation process. Since drilling is required to secure the panels to your roof, this can inherently leave holes that can potentially lead to water leaks over time.
An installation professional can ensure that long-term damage to your roof, and ultimately your home, is avoided. Solar panel systems have a life cycle of 30 to 35 years, so it’s important that your panels are installed correctly the first time around.
And while holes being drilled into your roof never sounds appealing, numerous safety measures help ensure this won’t result in any damage.
Drilled holes are meant for lag bolts, which secure your solar panel system’s mounting rack. In order to avoid water leakage, the hole is filled with a sealant, and the lag bolt is then surrounded by a metal or plastic flashing, which is a sort of shield that fits under whatever type of roof tiles you have. Flashing is then sealed air-tight with either tar or another durable material to ensure your roof is free of damage and potential seepage.
[Related: Uninstalling and Reinstalling Solar Panels]
Solar Panel Design Considerations: How to Get the Best-Looking Solar Panels
If you’re concerned that solar panels might negatively affect your home’s appearance, remember that you do have options.
Black shingles typically look the best with solar panels. Although black absorbs sunlight, which can make your home feel a bit warmer, darker roofs help blend the appearance of solar panels so that they don’t dramatically stand out.
Freedom Solar offers SunPower solar panels in varying aesthetic options, but their signature black features all-black solar cells as well as anti-reflective glass, which has a chic appearance on any roof type.
Also remember that, whatever type of roof or solar panels you have, they’re a good look in that they represent your character and values of sustainable living.