Can you install solar panels on a tile roof and avoid leaks?

Tile roofs look great, don’t they? Not only do they really suit the architecture of the southwest where they are most popular, but they’re practical too. A well-installed clay or concrete tile roof can last 50 or even 100 years.

But when it comes to installing solar panels, tile roofs represent the biggest challenge for solar installers. Not only can installing on a tile roof be more expensive, but there can be a higher risk of a poor installation causing damage to the waterproof integrity of the roof, leading to expensive repairs down the road.

That doesn’t mean that you should shy away from solar if you’re a homeowner with a tile roof. In this article, we’ll talk about the challenges, equipment that manufacturers have designed to make solar tile installations better, and things to watch out for when hiring a contractor to work around your tile roof.

Why is tile more difficult to work with than shingle roofs?

The most common roofing material in the US is asphalt shingles. With this type of roof, a solar racking system is secured to the roof with footings that sit on top of the shingles. These footings will typically be screwed or bolted through the shingles into the structure below and waterproofed using some combination of flashing, a gasket, or a sealant.

In any case, the job of properly waterproofing the installation isn’t diffult because the shingles remain in place, and the screw or bolt holes are relatively small.

That’s not the case when installing on a tile roof, which requires significantly more effort.

Roofing tiles are brittle

Roof tiles made of clay or concrete are strong when it comes to holding up to wind and rain, but they are brittle. This is a problem for workers who have to climb on your roof to install several hundred pounds of solar equipment.

Simply stepping on a clay tile can fracture it. For a solar installer who normally has to spend a day or more on top of your roof, this means taking extra precautions when working around tile. This means being careful and slowing down - but time is money for contractors, so this can mean a more expensive install.

Also, because it’s so easy to break a tile by stepping on it, the installer will be responsible for replacing any broken materials that result from their solar install. This can also increase the costs of the job.

How your tile roof stays waterproof

Whether your tiles are made of clay or concrete, neither of these materials alone will keep the rain out of your house.

While tiles do shed water, both clay and concrete are porous, which means that rain will eventually soak through. In addition, wind can drive water underneath the front lip of the tiles.

This means that the waterproof membrane underneath the tiles, known as underlayment, is the final barrier that keeps your house dry. It’s these two components working together that make a tile roof so durable. The tiles do most of the work of blocking the sun, wind, and rain, allowing the more delicate underlayment to do its job as a waterproof barrier.

Good installation practices and the use of correct materials are critical for this system to work properly. This is why when you hire a solar installer it is important to ask some key questions. You can start by understanding the types of installation methods.

Solar mounting options with a tile roof

Solar panels are attached to a roof with a racking system that must be anchored to the roof deck in some way. With a tile roof, there are a few common techniques an installer might use.

Comp-out or picture framing

The comp-out technique, also known as picture framing, involves removing all the tiles from the section of roof where the solar panels will go, and then installing a brand new roof with tar paper on the roof deck and asphalt shingles on top. It’s called a comp-out because this type of shingle is also known as a composition shingle.

The solar array is installed onto the new shingle roof, and then finally the original tiles are reinstalled around the perimeter of the solar array. This leaves a “hole” in the tiles where the array is placed, but the tiles on this new section of roof are purely aesthetic: it’s the new shingle roof underneath that provides the waterproof integrity for your home.

From a distance, this maintains the appearance of having a tile roof, but upon closer inspection you’ll be able to see the gap in the tiles. Here’s an example:

This is the preferred method for many installers. Done correctly, it’s completely waterproof because it uses the same methods used to install solar panels on any asphalt shingle roof. A comp-out is also usually less expensive than other methods. This might sound counterintuitive because the method involves installing a brand new roof underneath your existing tiles, but the other installation methods described below can be so much more finicky that their labor costs outweigh the additional material costs of going with a comp-out.

Tile cutting

If your tiles are strong enough that the installers can cut through them without risk of fracturing, there are products that will let you install mounting points through the tile.

This can be a more aesthetically-pleasing alternative to a comp-out because you aren’t left with a visible gap in tiles on your roof.

However, it’s a more complicated installation. First of all, the installation crew will need to work on your roof while breaking as few of your tiles as possible.

The other issue is that there are multiple steps to make sure the installation remains waterproof. For example, Ironridge, a manufacturer of a mounting system for tile roofs, describes multiple steps: removing the tile for the mount, applying sealant to the mount, covering the mount’s flashing with tar paper, covering the flashing with sealant, applying a layer of mesh fabric on top of the flashing, and then applying another layer of sealant on top of that.

Then the installer has to cut a hole through the tile, place it over the mount, and then install a collar with flashing on top of the mount. Finally, more sealant must be applied on the collar. And you might have to repeat this dozens of times for a typical rooftop installation.

Whew! That’s a lot of steps. If you’re interested in the details, you can view the video instructions on the Ironridge website under the “videos” tab of this page.

While the result can look great, it’s a complicated job.

Tile hooks

Instead of cutting through tiles, some companies make hooks that go around the tiles, avoiding the need to cut through them.

This simplifies one part of the installation, but it still requires careful waterproofing where the hook is attached to the roof deck underneath the tiles. Unirac is one company that makes L and S-shaped tile hooks.

Replacement tile mounts

Finally, some manufacturers make roof mounts in the shape of common roof tiles. Made of composite or aluminium, each of these mounts will take the place of a whole tile on your roof. They include all the hardware required to securely bolt into the roof deck and are designed to keep the wind and rain off the delicate membrane underneath.

These tile mounts are a great option, but you may be limited by the available shapes. See below for a few examples.

Manufacturers that make solar mounts for tile roofs

There are several manufacturers that make products for mounting solar on tile roofs, including Everest Solar Systems, Unirac, EcoFasten, Pegasus Solar, and Quick Mount PV.

Here’s some of the products currently on the market. Keep in mind that this isn’t an endorsement of any particular product - just a list of examples.

Quick Mount PV replacement tiles

These Quick Mount PV tiles come in a few common shapes.

Everest Solar Systems S-Hook

The Tile Hook 3S from Everest Solar Systems fits underneath the front end of a tile, eliminating the need for cutting or drilling through tiles.

EcoFasten tile mount

This aluminium tile replacement comes in a variety of shapes and includes aluminium flashing underneath to maintain the waterproof integrity of your roof.

Pegasus Solar Tile Replace Mount

Pegasus Solar is another manufacturer that makes tile replacement mounts. It comes in flat, S, and W-shaped tiles.

Questions to ask your installer

If you’re planning to go solar, be sure to ask your installer these questions if you have a tile roof. Do this at the proposal stage, before you sign any contract.

• Do you do the roofing work yourself, or do you subcontract?
• What method will you use to attach the racking to my roof?
• Is this method non-destructive (ie. drilling through tile or using the comp-out method)?
• How do you waterproof the attachment points?
• Will you replace, for no cost, any tiles that you damage during the installation?
• Does your installer warranty cover roof damage, such as leaks? For how many years?

Bottom line: tile roof and solar panels can go great together

If you have a tile roof, this article isn’t meant to scare you away from putting solar panels on your roof. In fact, tile roofs and solar panels are a great combination, because a properly installed tile roof can last 100 years. This will outlast your solar panels (which usually have 25 year warranties). That means that you shouldn’t have to worry about needing to pay to remove your solar panels to fix a roof issue underneath.

But all of this depends on having a good installer to do the work. Use this guide to help you find a great contractor, and use The Solar Nerd to get multiple quotes from qualifed contractors in your area.