The excitement surrounding Elon Musk’s announcement of the Tesla Solar Roof is the envy of every company conducting a product launch. The buzz it’s creating is sending shock waves through the renewable energy sector. After all, what’s not to like about solar panels that don’t look like solar panels, but instead take on the appearance and function of an attractive roof with an ‘infinity’ warranty that purportedly costs less than a new roof with traditional solar panels? Pretty compelling stuff, right?
As with all new and shiny things, it is important that we take a step back and put on our analytical glasses.
Realize that solar tiles are not a new thing. They’ve been around for a long time and have been manufactured by the likes of Sharp, Dow Chemical, Kyocera, SunPower, and Suntech – all of whom have stopped manufacturing them for both cost and safety concerns (more on this in a moment). Solar roof tiles fall under the BIPV or Building Integrated Photovoltaics product umbrella. Tesla has been very careful not to call their product BIPV for the simple reason that this class of solar panel has been the subject of controversy and safety recalls for many years.
First, we need to understand why traditional solar panels are installed the way they are. The average solar array sits 3-5 inches above the roof surface. The reason for this is that convective air flow under the solar panels keep them cooler. Cooler solar panels make more electricity. Elevated solar panels are easier to troubleshoot and repair since they are mounted on rails and can be easily removed and replaced. Another benefit is that the shade the panels provide to the roof below increases the life of your roof and actually helps to keep your home cooler (like a large shade tree might).
Wiring is managed within the mounting system and aggregated in conduit for both grounding, safety, and future maintenance. Lastly, most of today’s solar arrays use panel level optimizers to guarantee each individual panel is operating at maximum efficiency and can be isolated for troubleshooting, maintenance, and repair.
Now let’s examine solar roof tiles. While the specifics of the Tesla Solar Roof are vague, we can assume that the product will be installed in a manner similar to all of the BIPV products that came before it.
A standard residential solar panel contains 60 cells. Each Tesla solar roof tile contains two. Thus, 30 Telsa roof tiles would need to be strung together to make the equivalent of one traditional solar panel. All of this wiring would be run in the very tight, very hot space sandwiched between tempered glass and roofing tar paper. Additionally, such an installation would require significantly more wiring that a standard array allowing for the opportunity to have more bad splices and installation errors.
As electric wires heat up, they become less efficient at moving electrons. That resistance causes additional heat to be generated. Since the tempered glass tiles will become very hot in the bright summer sun, additional heat from hot wires turns the installation from inefficient to potentially dangerous as this News @ 10 expose of a BIPV system overheating shows.
As if this wasn’t reason enough to stick with traditional solar panels, consider long term care and maintenance. Since the Tesla solar roof tiles aren’t individually optimized, how will one know if a tile has failed? Are they wired together in series? If so, a failure in a single solar tile could potentially take out dozens of other tiles, and you’d have no way of knowing until you received a big electric bill. Then comes troubleshooting and repair. Imagine a scenario where your entire solar roof is being torn up in order to find the one ‘bad’ tile.
So, while the idea of Tesla solar tiles is sexy, there are a lot of questions and safety concerns (particularly around heat, wiring, and repairs) that need to be addressed before the product is ready for prime time.
If you’re considering solar for your home, let the experts at Flex Advisers help guide you toward the best solar equipment for your home. Contact us today for a complimentary solar analysis.