Residential solar panel installations are usually mounted on rooftops, though they can be stand-alone fixtures if you have a big enough yard or happen to own an adjacent field. The key thing is to install your solar array in a place where it will get the most sun exposure.
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If you’re considering installing solar and a new roof, though, you might be wondering what types of roof are best for solar.
The short answer is that most roofs are just fine for installing solar arrays. That said, some types of roof provide a more stable foundation and are better suited to solar panels. And last, keep in mind that installing solar is a big investment that you will want to leave in place for 15 years or more. For this reason, the best roof for home solar is one you won’t be replacing anytime soon.
Asphalt shingles are the most common type of shingle for residential rooftops and are also, conveniently, the best roof type for solar panels. Asphalt shingles typically comprise a cellulose or fiberglass mat that is both durable and flexible.
These qualities of asphalt shingles make them very suitable for installing solar panels as you can drill studs into the roof to attach mounting racks. To keep your roof watertight, flashings help seal the space between the panel and the stud.
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Light-colored, metal roofs are a great choice for keeping homes cool in hot climates. They’re also great for installing solar panels, assuming the roof has standing seams. These seams can be used to attach solar panels, eliminating the need to drill into shingles. Not only does this help keep your roof watertight, it also cuts down on labor, which helps keep the cost of solar installation low.
Tile roofs can make for a more complicated and expensive solar installation, but it is still possible. Tiles, whether, clay, slate, or concrete, are also a great roofing choice overall as they tend to be more watertight and long-lasting than both asphalt and metal.
If you have a tile roof, your solar installer will almost certainly want to remove at least some tiles before installing your home solar array. This is both to prevent damage to the tiles and to allow the installer to fasten the solar panels directly to the roof for stability.
Some solar installers now offer solar panel mounts that are integrated into Spanish tile or clay roof tiles. This makes for a more seamless installation and can save both time and money while preserving the visual appearance of your roof.
Tar and gravel rooftops
Tar and gravel rooftops tend to be flat, which might not seem ideal for a home solar installation. However, there are ways around this constraint and the layers of asphalt in tar and gravel rooftops offer excellent support for panels and protection against leaks and cracks.
If you’re considering installing solar panels on a flat tar and gravel rooftop, look into mounting hardware that tilts the panels to a 30-degree angle. This will help maximize efficiency. You might even want to invest in a mounting system that tracks the sun throughout the day, to further maximize electricity production.
EPDM rubber, TPO, and PVC roofs
While more common on commercial buildings, some homes have flat roofs made of ethylene propylene dienterpolymer (EPDM) rubber, thermoplastic polyolefin (TPO) and polyvinyl chloride (PVC). It’s best not to cut into these types of roofing material, so solar installers typically use a ballast system (a weighted mounting system) for solar arrays.
Because solar arrays on EPDM rubber or TPO and PVC roofs don’t involve drilling into the roof itself (usually), this makes for a quick and inexpensive installation.
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Again, if you’re installing a home solar array on a flat roof, you’ll want to look into hardware that tilts the panels to around 30 degrees. Anything less than 15 degrees and your panels won’t wash off with rain, which can seriously hamper performance.
Aesthetic considerations when installing solar panels
There are two main aesthetic considerations when installing solar panels: size and color.
Solar panels are typically black or dark blue. High-efficiency monocrystalline panels tend to be darker, while polycrystalline panels are usually a speckled blue, with crystal fragments reflecting more sunlight than their black counterparts.
Bluer solar panels coordinate nicely with most roofs. Black solar panels often contrast nicely with lighter-colored roofs, however, and can add a modern touch to a home’s appearance.
Solar panels tend to be about 65 by 40 inches; or about 5.5 feet by 3.25 feet. Some panels, such as those by REC are a bit bigger. Installing a few bigger panels tends to disrupt the appearance of a home less than installing lots of smaller panels.
Depending on which way your home faces, and the tilt of your roof, you may want to install solar panels just on the back side of the roof. This way, there is no change in the appearance of your home from the front. Bear in mind, though, that homes with solar arrays tend to sell for more than homes without, so a rooftop array can actually add to your home’s curb appeal!
Where to position your solar panels
Location, location, location. It’s important for real estate and for solar setups. The ideal rooftop for solar is one where panels sit directly under the noonday sun. It’s also best to position your array somewhere with no or few nearby buildings, trees, or other objects, such as chimneys, that will shade the panels at any point during the day.
If you can, try to position your solar panels to allow easy access for cleaning and snow removal (if necessary). And if you live somewhere really windy, with a history of branches falling on your roof, consider positioning panels to avoid possible impacts and debris.
In the northern hemisphere, you’ll get the best results from solar panels on a south-facing roof (unless this roof is heavily shaded by other buildings or trees). A broad roof with no dormers, chimneys, skylights, or other awkward angles is the easiest and most effective for solar installations. As a general rule, you’ll need about 100 square feet of roof space for every kilowatt of system size. So, a fairly standard 5 kW solar array will need 500 square feet, such as a square roof measuring 20 by 25 feet.
To figure out which way your roof faces, check Google Maps. True south is different to magnetic south, so standing outside your home and using a compass won’t always be your best guide. Where a south-facing roof installation isn’t possible, consider a southeast or southwest installation. Basically, avoid north-facing installations as you’ll get very little sun exposure for much of the year.
If your south-facing roof space is limited, think about whether a shed or garage might be a better spot for a solar array. Or, if you have the space, a ground solar array or even a pole-mounted solar array might work best.
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Final thoughts on what types of roof are best for solar
The worst roofs for solar installation are slate tile roofs and wood roofs. This is because these materials are liable to shatter or break. While still possible, installing a solar array on these sorts of roofs will require some ingenuity and additional hardware. As you’d expect, this can substantially increase the cost of a home solar array.
Finally, because solar panels are heavy, you’ll want to make sure your roof is in good enough shape to hold the mounting racks and panels safely. This is also important because solar panels often last 25-30 years. As such, the best roof for home solar is one you won’t be replacing anytime soon.