Solar power is growing at an alarming rate, becoming common for households worldwide. What that normally means is mounting solar panels on an already existing roof. But what if your roof was not just a platform for solar panels but the solar panels themselves? What if the very tiles had the ability to power your home?
The dual-purpose is the appeal of Tesla’s Solar Roof, a product that appeared with a lot of hype in 2016 and has been honed in for its eventual third-generation roll out in 2019. As the Tesla roof is being installed in homes, the question is, how durable is the roof? Read on to learn everything you need to know about the durability of the Solar Roof.
The Parameters to Consider
The first thing to define is what to look at for durability. Tesla is selling a product that has two functions, serving as:
- A roof
- A solar power system
When a product accomplishes or tries to accomplish two things at once, it runs the risk of doing neither well and mixing two things that really should not go together. The product could end up ineffective.
So, when looking at durability, it is important to ask whether Tesla has created a product that will last doing the two things that the company says it can. Will the Tesla Solar Roof serve as a good roof and good solar power system at the same time?
The durability of the Solar Roof has to be thought of in terms of both its ability to shed and resist inclement weather, including weather events like high winds and hail, and its ability to create energy for the foreseeable future.
Durability of the Roof: What Does That Mean?
If you are going to have a Solar Roof, it has to do its most primary function well, or the whole thing is pointless: it has to be a good roof.
The third generation of the Solar Roof consists of individual tiles made of tempered glass that encloses and protects the solar components. The tiles interlock together when installed so that they look comparable to slate tiles.
Tiles and other roofing materials, like shingles, are laid with one end of the tile resting on the opposite end of the one beneath it. Laying them like that allows water to run down the end of the upper row of tiles and onto the lower tiles without leaking into the roofing paper and plywood underneath.
Tesla tiles are laid much the same way, so they must function the same as normal roofing materials. What this means is that they have to be as durable as normal roofing materials with a normal life span.
Wind, Fire, and Hail
The Tesla Solar Roof has been independently rated for wind, fire, and hail according to the standards by which all roofing materials are rated. The tiles have achieved the highest ratings in all three categories. Bolstered by this great benefit, Tesla offers a warranty of twenty-five years for the tiles.
- The tiles have a Class F rating for wind resistance as rated by ASTM’s D3161 standard, which means the tiles can withstand winds of at least 110 miles per hour.
- They have a Class A fire rating by the UL 790 standard, which means that the tiles are resistant to severe fire exposure in tests.
- They have a Class 3 rating for hail as rated by the ANSI FM 4473 standard. This means the tiles will not break when hit with hail up 1 and ¾ inches in size.
Clearly, at least where wind, fire, and hail are concerned, the Tesla Solar Roof is durable and prepared to go the distance.
The Wind Test
For the wind test done according to the ASTM D3161 standard, the tiles are subjected to a two-hour duration of high winds brought about by fans. They are tested at three different speeds, which include:
- The highest speed tested is 110 miles per hour
- They are also tested at 90 miles per hour
- The lowest speed tested is 60 miles per hour
During the test, qualified inspectors check the tiles for damage. They also check if the tiles have lifted off the testing platform to which they were secured.
There are some limitations to this test that you should keep in mind. Obviously, the test does not employ actual wind with the accompanying drops and gusts. Furthermore, the test does not claim to address issues such as building height or exposure.
Nevertheless, with the tiles theoretically being able to withstand a major wind event, such as might happen in the winter, Tesla’s Solar Roof is off to a good start.
The Fire Test
The fire test done according to the UL 790 standard is meant to reveal a roofing material’s resistance to light, moderate, or severe exposures to a fire that starts from outside the home. The roofing materials are given a rating of C, B, or A respective to the exposures listed above.
To be sure the materials are being tested fairly, they are set up in a test environment that accurately reflects the installation specifications and requirements of the manufacturer.
There are three different kinds of tests used to rate the material.
- The first tests the material with an application of intermittent flames and wind.
- The second, called the Burning-Brand Test, is literally the way it sounds. A technician places a burning substance directly onto the roof material for an hour and a half.
- Finally, there is the Spread of Flame test, which evaluates the material’s resistance to direct flame and wind. Once again, this occurs over an extended period of time.
The length of time is one factor that determines whether or not the tiles achieve the class rating they were manufactured for.
The Hail Test
The hail test is conducted according to the American National Standard for Impact Resistance standard FM 4473, which is a long name to describe what is a simple test. In it, frozen balls of water are used as a stand-in for hailstones and are projected at the material at high velocity.
A video by SolarWorld shows them conducting a similar kind of test on their own solar panels, appearing to hit their panels with cubes of ice at speeds between 50 and 262 miles per hour.
The Tesla Hail Test Video
Tesla put its own hail test video on YouTube, which shows the tile’s durability compared with tile and slate shingles. Unfortunately, the video contains a pretty clear discrepancy in how the tiles are mounted. Tesla’s tile is mounted horizontally with supports offset from the edges of the tile and more toward its center.
Meanwhile, the other tiles are mounted vertically with the supports placed on the vertical edges of the tiles, giving the impression of an intentional setup to show the weaknesses of the slate and tile roofing materials rather than a truly comparable test.
Clearly, Tesla aims for a broad roofing market and does this to appear as good as possible. However, this little oddity means little, especially when the Tesla tiles received the highest hail rating by the independent testing standard ANSI.
More than What You See
There is more to a roofing material’s ability to shed water than simply the tiles or the shingles. A lot depends on the roofing paper or underlayment that is laid underneath the tiles.
Roofing paper adds another critical layer of protection for the plywood that forms the roof deck of your home. Sometimes water can be driven underneath tiles or shingles by wind-driven rain, or sometimes shingles can be broken loose and expose the paper underneath. In cold regions, ice can melt through roof cracks to the paper.
In all these cases, the appropriate roofing paper or roofing underlayment can help protect the home and avoid a leak. In cases where leaking through a shingle goes unnoticed, roofing paper can help prevent mold or rot damage. Roofing paper can even affect the fire rating of some shingles.
Tesla’s Underlayment Mistake
Recently a Version 3 install for a homeowner in Florida was significantly delayed by Tesla’s use of the wrong underlayment material. Tesla was part of the way through the installation when the homeowner was plagued by leaks that caused water damage in the home.
Further investigation revealed that Tesla had switched to a different underlayment without testing it with their tiles. This mishap resulted in Tesla having to restart the project from the decking up with new underlayment.
More to Roofing than Meets the Eye
This episode underscores something about Tesla that you should definitely consider if you are looking at a Solar Roof. Tesla is not a roofing company.
Tesla’s ambition to create clean energy homes is certainly admirable. Still, they have created a new space between two existing industries, and it requires a workforce that does not quite exist yet because they have to have both roofing and technical knowledge.
Installing a Solar Roof is a bigger task than installing solar panels. But it is also more technical than installing just a roof. So, while the Solar Roof would appear to be a mash of two industries, it differs from either one in crucial ways.
True to form, Tesla initially sought to conquer the roof installing world on their own. But as early as October 2019, Musk was signaling that Tesla would look into partnering with existing roofing contractors and creating a preferred vendor list.
More than Just a Roof
Of course, being able to complete the normal functions of a roof admirably is just one aspect of Tesla’s Solar Roof. It also needs to generate solar energy.
Tesla offers both solar generating tiles and non-solar generating tiles, which means that you can scale the amount of solar production that works for your home, much like you can with solar panels.
With solar panels, you would have to consider how many arrays to install and where to put them. With a Solar Roof, it becomes a question of how many tiles you want to have functioning solar cells and how many do you want to be non-functioning.
The tiles are a little less solar receptive because the sensors are enclosed in the black glass (as opposed to the clear glass of solar panels, but, again, you can always add more functioning tiles to compensate. However, the solar function of the roof is where durability becomes a little more interesting.
Durability of Production
Having a roof where the tiles are given a twenty-five-year warranty sounds like a pretty good deal. But cast your eyes down to the warranty of the inverter, which is twelve and a half years. Just like with Tesla’s solar panels, that is half the time of the roof warranty.
What this means is that while you still have a great warranty left on your roof, your inverter, which includes the strings that attach to the tiles, could go bad. You would have a durable roof that does not produce solar. That defeats the purpose of getting a Solar Roof in the first place.
More than that, the tiles seem to have a lifespan for energy production. The tiles will decline in energy production by a small percentage every year until they cannot produce anymore. This means that a few years after the warranty goes up on your roof, you are looking at replacing it anyway because it has stopped creating energy.
Even solar panels have a limit to how long they can run. Everything does. But the point is that while replacing solar panels is an expense, replacing a Solar Roof is a much greater one.
How Are Solar Roof Customers Responding?
One of the problems of discussing the durability of the Tesla roof is that the product is so new, there is not a good time span to see how normal wear and tear is affecting the roof, if at all.
There is also not a good indication of how roof repairs may go with the Solar Roof. What if you have a leak and roofers need to replace shingles? How will that process go? Will roofers be able to tarp the roof to protect the home until repairs can be done? It is hard to say.
These and other unknowns, like how easily the roof can be repaired after partial fire damage, will have to be answered as the years go by. But there is at least one thing we learn about now.
A Unique Aspect of Durability
For many solar panels cleaning the clear glass covering is optional. Rain is most likely going to wash away the dust and dirt that naturally accumulates. The same would seem to be true for the Solar Roof.
However, since the roof tiles are already working with a slight deficiency compared with solar panels, dirt can make an additional difference. One owner of a Solar Roof estimated a ten percent kWh difference between when the roof was dirty (after a long period without rain) and when the roof was clean after it rained.
Add it up over time, and a deficit in energy production can have an impact on what you might otherwise be able to get out of your roof. So, it would seem that an occasional hosing off would be appropriate for your system’s maximum efficiency.
It also makes sense to hose off your roof if you look at it from another point of view. Aesthetics is a big part of why people want to go with the Solar Roof and why the Solar Roof was created in the first place.
It seems only fair to mention that black glass tiles really show the dirt. If you think about it, shingles and concrete tiles have a multi-faceted color pallet of grays, browns, and blacks, so the accumulation of dust and dirt is not really noticeable. But it is on a Solar Roof.
If you do decide to hose off your roof, do it from the ground. Walking on a shingle roof is a caution-inducing prospect, walking on a tile roof even more so. But walking on a roof made of tempered glass is just a bad idea.
The Improvements of Version Three
In the four years since the unveiling of Tesla’s Solar Roof idea, Version 3, which was released in 2019, is the first generation of the product that is scalable.
The second version of the tiles worked (there are even positive reviews of them). It was also promised that they would come with more appearance options available to match the existing aesthetic of your home. However, they were problematic, particularly in installation.
The early tiles were fragile and hard to work with. Some of the tiles had to be cut at the job site to fit gutters and valleys. The tiles were not necessarily designed to endure that, so a lot of material was wasted at the job site.
Because the Version 2 tiles were so much smaller, about 14×9 inches, they had to have more internal components to put them together. That, plus the added headache of their breakability, slowed down installation dramatically.
Also, since the tiles were smaller, it took more of them to cover a roof. However, Version 3 tiles are roughly 45×15 inches, which means they cover more of the roof per tile and require less time and additional components to install. Their larger size also makes them beefier and able to withstand the demands of a construction site installation.
A Troubled History of Development
Getting Tesla’s Solar Roof tiles to this point has been a long and difficult four years. Elon Musk has even admitted as much.
The history has its share of Tesla-style hype and showmanship, often covering a flawed (and, at the beginning, a non-existent) product. So, it is worth taking a look back to see how the durability of the product has evolved.
The Tesla Solar Roof first saw the light of day as a concept in October of 2016. During this time, Elon Musk was also on the verge of acquiring SolarCity, the country’s leading solar energy company.
The idea for the Solar Roof seems to have sprung from an idea originally conceived by a Solar City R and D wing called for a metal roof that could be installed over the existing roof and generate solar electricity as an entire roof system. But after a private demo in the late summer of 2016, the concept was scratched.
That is when the idea that is now what we call the Solar Roof was conceived and developed as a model. Although the tiles Tesla used were non-functioning, Musk unveiled them in October 2016 at an event held on the set of Desperate Housewives as if they were generating solar power at that moment.
It’s worth pointing this out to understand that from the time of the tile’s unveiling, Tesla was under the gun to actually make them work. This goes a long way toward explaining why the roofs have only just begun to roll out even though the company started taking down payments in May of 2017.
The Trouble with the Originals
Given all this, it is probably not surprising (though at the time it seemed strange) that Versions 1 and 2 of the roof tiles did not pan out so well. The company was still trying to figure out the ins and outs and refine the concept.
While Version 2 did see some limited installation and did get some positive feedback, the small size of the tiles, the large number of additional components needed for installation, and the relative fragility, especially in the installation process, meant that the tiles were not practical for scalable manufacture.
Version 3 is the first version to be scaled for manufacture at Tesla’s Gigafactory 2 in Buffalo, New York. They began scaling up in October of 2019.
Trouble with Safety
In the meantime, Tesla was experiencing difficulties on a variety of fronts. The company’s regular solar installations declined since its purchase of SolarCity and would reach an all-time low in the 2nd quarter of 2019.
The company experienced further trouble when Walmart filed a lawsuit against them in August of 2019, claiming that Tesla’s solar panels were responsible for several fires on store roofs. Walmart claimed that Tesla was negligent in their installation of maintenance of the systems.
Walmart claimed to have received reports from Tesla identifying the problems that needed to be repaired or replaced. While one would not immediately think of solar panels as a fire risk, panels conduct electricity and contain such components and wiring that could cause a fire if faulty.
Walmart dropped the suit when the two companies reached a settlement in the New York Supreme Court that was undisclosed. Nevertheless, it was an issue that called Tesla’s product safety and its durability into question.
Trouble with Durability
A question mark on the safety and reliability of Tesla’s solar products was not what the company needed. In 2018 they experienced similar issues with regards to their Model 3 electric car.
Off the line, car owners complained of chipped paint, loose panels, and other defects in the car. Consumer reports eventually dropped its recommendation for the car because of its lack of reliability and durability as experienced by CR’s members.
Problems with the Model 3 required Tesla to double down on the car with both a labor and engineering focus to correct the problems they were having. They also had to reroute the production of battery cells to the car.
All this meant a delay in the development and production of 3 of the Solar Roof tiles. This aggravated a wait time that, in 2018, was already two years old.
Trouble with Shareholders
A lawsuit from Walmart was not the only legal swamp the company found itself mired in. Some shareholders filed suit against the company claiming that it overpaid for its acquisition of SolarCity.
The acquisition of the country’s largest solar company was problematic, not the least of which was because Musk was the biggest shareholder in the company. And the two owners were both his cousins.
All this over the last four years has caused headaches for the car turned space turned solar company. The controversies often overshadow the products and cast them in doubt. At times it seems that the scope of Tesla’s ambition goes well beyond the grasp of what the company actually produces.
But that same thing makes up the mystique to which many people are attracted. It is also the case, with the Solar Roof in particular, that Tesla is at the forefront of trying to change significant industries in modern society.
Also, in the case of the Solar Roof, and based on the information that is available, Tesla Solar Roof tiles actually seem pretty darn durable. They meet all the highest roofing material standards for wind, fire, and hail, although we have yet to see how the roofs deal with wear and tear over a period of years.
We also have yet to see how well the roofs produce energy in the long run, but after several years of difficulty and delays, the Solar Roof seems finally to be moving forward.