Solar Roof Tiles in San Diego: Should You Install?

Solar roof tiles have been in the news on and off for the last four years, and for good reason. Imagine: all the benefits of a solar panel installation, but without roof penetration and with maximum aesthetic appeal. You’d think with those benefits, solar roof tiles would have completely replaced solar panels at this point. Contrary to what you’d think, solar roof tiles have not really caught on, and it’s hard to find someone to install them even if you want them. Since San Diego was recently rated #2 for solar in the US, you would expect that we would be some of the first in the country to see this technology hit, but there’s little to no evidence that has happened. So what has become of solar roof tile technology? Let’s look at the truth behind solar roof tiles, and explore why they have yet to take off in San Diego. Solar Roof Tiles vs. Solar Shingles First, we need to clear up a common misunderstanding when it comes to solar roof tiles. Often, consumers confuse the terms “solar roof tiles” and “solar shingles.” The main difference between the two is that solar roof tiles are rigid, while solar shingles are flexible. Both products are considered "building-integrated solar" which means, as it sounds, that the solar product and the roofing product have been combined into a single system which is integrated into the building (BIPV). The real advantage of this type of product is seen when it is incorporated into new home construction so the home builder can install it when building the house.  This would be especially attractive to help meet state mandates for solar homes, for example, where builders have to make sure all their new homes have solar panels installed. Perhaps it's stating the obvious here but if you can use one product to both 1) cover the roof and 2) produce solar electricity, that will save money during construction. However, once a home is completed and already has a roof, it doesn't make nearly as much sense economically to remove the old roof and put in a new one using building-integrated solar roof materials because you've spent money on TWO ROOFS instead of just one. This History of Building-Integrated Solar Despite the lack of awareness in the mainstream, the first BIPV systems were actually available in 2005 in the form of flexible solar shingles sold under the brand name “Uni-Solar.” Unfortunately, at the time, BIPV solar was much than traditional solar panels, so didn’t really catch on. Unless the homeowner was re-shingling their home, it wasn’t worth the extra cost. They were also plagued by producing much less solar energy per square foot due to their chemical composition (amorphous silicon vs. crystalline silicon). A later version of BIPV solar became commercially available when DOW Chemical, a subsidiary of Dow Inc., the largest chemical manufacturer in the world, came out with a solar shingle system called Powerhouse in October 2011 which utilized solar cells not made from silicon but rather “CIGS” (layers of copper, indium, gallium and selenide). Although they were more efficient than amorphous silicon and consistently coming down in price, a full rooftop of the tiles, or a cluster of 350, were only able to offset 40-60% of the average home’s power demand, but were around the same price as a full solar system that could offset 100% of the home’s needs. A few other companies began manufacturing rigid solar roof tiles in the years following the Powerhouse, including Tesla in 2016. Despite the availability of the tiles, and the hype surrounding them, they have yet to catch on for several reasons. Let’s take a look at the technology as it exists now, to see how they work and why they haven’t caught on. How Solar Roof Tiles Work  Solar roof tiles are essentially just miniature solar panels - they capture sunlight and turn it into electricity. They are typically larger than a normal roof tile, but are able to be easily integrated into a normal roof. They usually have a purplish, blue or black color, and therefore fit the look and style of most asphalt shingle roofs, which is why so many homeowners are excited about the solar roof tiles. As far as the solar technology goes in the roof tiles, techniques have changed over the years. In the early years, some manufacturers were using solar thin-film technology, which differs from monocrystalline or polycrystalline silicon solar cells that typical solar panels use. Now, most mainstream manufacturers have switched to the standard silicon solar cells, including RGS Energy, CertainTeed, and SunTegra.  As far as installation goes, solar roof tiles have to be installed during a re-roof. Different models of solar roof tiles are mounted differently, but some can be installed directly on roof felt. Some models are actually easier to install than traditional solar panels, but in general, the installation is more difficult and expensive than a typical solar installation.The Pitfalls of Solar Roof Tiles So here again, we have to ask, why haven’t solar roof tiles caught on? If they’ve been around for 15 years, and so many companies have been manufacturing them, why haven’t they completely replaced solar panels?  That’s because the technology doesn’t work too well. Based on their construction, they consistently have issues with efficiency, durability, and installation that makes creating a viable business installing them difficult. Let’s take a look at these factors, and why they have held back solar roof tiles. Efficiency A solar panels’ efficiency is defined by its ability to convert sunlight into usable electricity. Historically, as they have been tried for many years, solar roof tiles have delivered worse efficiency than conventional solar panels.  The lower efficiency of the solar roof tiles is due to heat buildup. When solar panels are mounted several inches above the roof, this allows for ventilation as air moves under the solar panels and keeps them cooler. When that's removed and the solar material is installed flush onto the roof, heat tends to build up which in turn causes the resistance of the wiring in the solar panels to increase, reducing the amount of power that can flow through them, sometimes by as much as 20 percent. Clearly this changes the economics of the installation as it would then take 20% more solar material to produce the same amount of electricity on a sunny day. As a result of this lack of efficiency, solar roof tiles require the homeowner to pay more for a less efficient product. Additionally, with the solar roof tiles you have to pay for a re roof as well, which makes the entire installation more expensive. Durability One of the main reasons solar roof tiles have yet to really catch on is that the companies that manufacture them have had issues with their durability and therefore, warranty. One of the reasons the solar roof tiles don’t hold up as well as traditional solar panels is that they are more likely to be damaged from heat than solar panels. That’s because, since they lay against the roof and there is not space under them for ventilation, they get much hotter under the Sun. This heat wears away at their efficiency much quicker than a traditional solar panel. Installation The installation of solar roof tiles has perhaps been the biggest setback in their ability to be mainstreamed. The installations are highly labor intensive, and can only be done with a reroof. So for homeowners who don’t need a reroof, the immense cost that is incurred to fully re roof can be a setback.  The length of installation is also an issue. Electrek previously reported that the average solar roof tile installation was taking up to two weeks, although that was over a year ago. Due to the fact that every installation of solar roof tiles requires a full reroof, this keeps the installation longer than a typical solar installation. Supposedly, companies like Tesla that are serious about making solar roof tile installation a viable business have dedicated a lot of their energy to making installation of solar roof tiles easier and take less time. So we should see installation times, and therefore costs, decrease over time. Cost For the reasons we have already mentioned, solar roof tile installation is typically more expensive than solar panel installation. By the sheer fact that a reroof is required to install solar roof tiles, the cost is at minimum the cost of a reroof + the installation of the roof tiles themselves.  The national average cost for a reroof is between $5,250 and $10,000 to start. So add the cost of the tiles and labor on top of that, and you can see that the costs can seriously add up. Tesla recently stated that the cost of installing solar roof tiles will be around  $34,000 after incentives for an average home. So that price tag alone is enough to keep homeowners from taking the solar roof tile leap. Solar Roof Tiles in San Diego If you’re looking to get solar roof tiles installed in San Diego, you may have trouble finding a way to actually find someone to do it. If you do some Googling it’s hard to find a solar contractor that will actually install a solar roof. There’s a lot of results for getting a new roof + solar at the same time, but nothing explicitly for a solar roof. You can, of course, place your order with Tesla, but it’s somewhat unclear as to when it will be installed. Why You Should Install Solar Panels Now Instead of waiting for solar roof tile technology, installation and costs to improve, if you’re a homeowner in San Diego, you should strongly consider installing solar panels instead, and soon. That’s because, due to the 26% Federal Tax Credit being around until the rest of the year, there’s never been a cheaper time to install solar. Plus, the longer you wait for solar roof tiles to improve, the longer you will be paying SDG&E for power, when you could be putting that money towards owning your solar system.  So, if you haven’t already gathered, the conclusion here is that, while solar roof tile technology is improving and may one day be a viable alternative to solar panels, right now as it stands, it’s best for most homeowners to install solar panels instead. If you are an aesthetics obsessed homeowner who needs a new roof, and are also looking into solar, you may want to make the leap for solar roof tiles. But for the average homeowner in San Diego, just going with a classic solar panel installation is the better call at this point.  

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