Published North American Clean Energy | November December 2012 | Pg. 20
Residential Solar Installations Made Easy
Mounting panels on tiled roofs
By Shelby Evans
The United States has over 5,700 MW of installed solar electric capacity, according to the Solar Energy Industries Association (www.seia.org). That’s enough to power more than 940,000 average American households. This year, the residential PV market has continued to show steady, incremental growth. There was 98 MW of residential installations in the second quarter of 2012, which is up 42% over Q2 2011 installations.
Thanks to ever-adapting technology, solar panels can now be installed on a variety of different roof types, making solar energy accessible to nearly every household, at least from an application standpoint. Of course, some applications are easier than others, and most installers would probably agree that mounting solar panels on a tiled roof is one of the most challenging undertakings. This is especially true when installing panels on profiled tiles, such as S-Tiles. These types of roofs are popular in states such as California, Arizona, New Mexico, and Florida.
A tiled-roof home presents difficulty from the very beginning of a solar installation project. Tiles are inherently delicate, so one wrong, or less than careful step, and they can break. As most installations for solar panels include eight or more steps on a rooftop to complete the installation, the process of mounting solar panels to a tiled roof can be tedious and time consuming, with a large margin for error.
Fortunately, solar mounting products that can be installed without cutting tiles are now available, and can save time and money—not to mention tiles. Of course, finding the right mounting product is key. Installers will want to look for products that don’t require the additional purchase of flashing hardware, that reduce the amount of parts and labor needed, and, most importantly, that maintain the roof’s warranty.Most solar tile mounts require the tile to be cut for it to properly attach to the rafter under the decking below the roof. Often integrators have little experience cutting tile. Because of its delicate nature, cutting tile takes skill. And even then, breakages can occur. A better solution is to eliminate cutting the tiles altogether.
Here are three keys to successfully installing solar panels on a tiled roof…
Depending on the type of tiled roof, some adjustments of the mount may be necessary. The solar tile mount selected should allow for vertical and horizontal adjustments. The horizontal adjustment offers some “play” or leniency when fastening to a rafter/truss, which is almost always required. The vertical adjustment allows installers to elevate and lower the mount for use with different types of tile installation, such as direct-to-deck, horizontal batten, and elevated battens.
Solar tile mounts should be elevated above the tile so there is a 1/4-inch minimum gap between the roof tile surface and the solar tile mount. This helps prevent tiles from breaking when load is placed on the panels from wind or snow. If the mount is used with an S-Tile roof, the mount should be positioned over the lowest point in the pan of the tile.
- STEP 2: Fastening
Each solar tile mount must be attached directly into the roof framing below the roof deck (i.e. truss, purlin, beam, etc.), with at least two, high-quality fasteners. SDS screws, which don’t require pre-drilling, are preferable. Not drilling saves time and tiles.
Remember to purchase a mount that allows for side-to-side adjustment to locate a structural member. Problems often occur when the pan of the tile and the structural member don’t line up.
- STEP 3: Flashing
There are several options available for flashing the base of the solar tile mount, and installers can:
1. Use a flexible flashing to cover the base, extending the flashing about two inches from the side and top edges of the base. Afterwards, an EPDM roller can be employed to secure the adhesive to the underlayment.
2. Trowel the mastic or butyl so that it’s large enough to cover the entire surface area of the base, and beneath the base before installation.
3. A waterproofed membrane can be applied over the mount base and extended up-slope, lacing it into the roofing felt or underlayment above.
Once the solar tile mount has been fully installed, it’s important to replace the tile from the course above. In order for the tile to sit properly on the course below, the weather-check (bottom lug of the tile) must be removed.
Installing solar panels on tiled roofs is no longer all that challenging with the proper mounting products. After locating the rafter on the roof and loading the materials required for installation, the rest should be simple. Using the steps and options suggested here, mounting solar panels—even to tiled roofs—shouldn’t cause breakage or difficulties. As there are many solar mounting options on the market today, however, spend the time researching and finding the solution that works best for you.
Image 1: S-Tiles shown with and without notch
Image 2: S-Tile mount fastening