Top 8 Solar Shingles Alternatives of Tesla Solar Roof Tiles 1

Our world has started to pay attention to the fact that we need to use renewable sources of energy if we want to help save the Earth. That is why solar power, which is one of the popular renewable sources, is getting a lot of traction nowadays. More and more people have shown interest in buying solar products like solar panels and solar systems. But there is one solar product that has been introduced quite recently to the world that is also getting a lot of attention. And that solar product is the solar shingle.



Solar Shingles: What Are They? And How Do They Work?

Essentially speaking, solar shingles, sometimes known as photovoltaic shingles, are solar panels that are designed to look like and function as conventional roofing materials while still producing electricity. In other words, solar shingles are considered to be a type of solar energy solution known as building-integrated photovoltaics (BIPV).

From that description alone, it is obvious that solar shingles work like traditional solar panels. They make use of the sun as a source of energy to generate electricity. To be more specific, each cell on solar shingles contains semiconductors that will be the ones to capture the sunlight once it hits the shingles. Once the semiconductors have captured the sunlight, an electron from the particle of light will be naturally knocked off. This freed electron will then travel through an electrical circuit to an area where the other electrons are stored, thus finally generating a current that can be used for electrical power.

Solar shingles are reported to be able to power anything, from a calculator to a skyscraper, and they are also said to be able to produce 100% of a building’s electricity usage. But the latter is still debatable since there are factors that affect the efficiency of solar shingles on buildings: the demand of a building, the amount of sunlight the structure gets at that particular location, the building’s current utility rates, and the availability of sufficient space on the roof that opens to southern skies.

However, that said, solar shingles are still efficient solar products since they can practically work anywhere — even in places that are prone to gray weather. This is because solar shingles can use diffused, scattered sunshine on overcast or even rainy days. And on the opposite side of the spectrum, if the building is on a place that is exposed quite a lot to the sun, then the solar shingles will produce excess energy that will just be sent to the electrical grid. In other words, it doesn’t matter if your geographical location is incredibly sunny or not — solar shingles will still work and help reduce your electricity costs.

Related article: Top 10 Marketplace Websites to Buy Wholesale Solar Panels (in Bulk)


Top Solar Shingle Brands


Tesla Solar Roof

>> Tesla | Reviews, product prices, contact, CEO

Of course, this one is #1 on the list, considering that it is the product that caused the popularity of solar shingles to skyrocket. Elon Musk, the co-founder of Tesla, revealed the news of the company’s new roofing product back in 2016, and in 2018, installations of these new solar shingles began. Production for these solar shingles is still ongoing, and as of right now, Tesla Solar Roof is already on its third version.

Technically speaking, Tesla is not the first company to ever come up with the idea of solar shingles. At the very least, the development of this solar roof concept has been ongoing for a few years now. However, what made Tesla be the company to somehow launch back the popularity of the solar roof concept is its innovation on the product. Unlike other companies before them, Tesla has made sure that its solar system is a roof first. And since the idea of a complete solar roof has not yet been successfully brought to market, it was an incredibly big deal that Tesla managed to achieve that.

The Tesla Solar Roof costs at around $21.85 per square foot. So, if your house needs about 2,000 square feet of roofing, then you would need to pay about $44,000. Additionally, the Tesla solar shingles are made up of quartz, with four available designs: Tuscan glass tile, slate glass tile, textured glass tile, and smooth glass tile. With these four designs and innovations, Tesla is confident that they can make inroads into both the solar industry and roofing industry.


CertainTeed Apollo II Solar Roofing System

CertainTeed is a North American company that focuses on the manufacturing of products for roofing, insulation, wallboard, and more. As of right now, they have two solar products under their Apollo line: Apollo II, which is a shingle that is applied on top of your existing roof, and the Apollo II Tile, which is a replacement tile, very much like the Tesla Solar Roof.

CertainTeed makes use of monocrystalline silicon solar cells for their Apollo products. Additionally, they also don’t use glass louvres or hydrographic printing, and the product doesn’t come in a variety of appearances that mimic conventional high-end roofing products like slate. Because of this, the CertainTeed Apollo II isn’t as physically attractive as the Tesla Solar Roof is.

That said, the Apollo tiles are still more attractive than the typical solar module. This is because the Apollo tiles sit flush on top of your existing roof, unlike the solar panel where there will be several inches of air space between the back of the panel and the roof. Additionally, the Apollo product is approximately 47 inches by 17 inches in size, and it has an STC rating of 63 watts and a PTC rating of 53.5 watts.

The current pricing for the Apollo products aren’t advertised, but it is reported that it is around $178 per tile. So, this would mean that the price per watt is $2.82.


Luma Solar Roof

Just like Tesla, Luma Solar offers a complete roof replacement product that is simply named the Solar Roof. And the company’s solar roof replacement products include both non-solar and solar cell components that give the roof a more uniform appearance than the solar-only shingles offered by other companies such as CertainTeed.

In addition to the solar roof replacement, Luma Solar also offers its PV shingles as a standalone product that can be mixed with conventional roof shingles. Each of their shingles is 54.37 inches by 15.62 inches and is made up of polycrystalline cells to generate 60 watts. Luma Solar prides themselves as customer-focused, and so, for their customers, they offer a 25-year warranty and 5-year warranty for materials and workmanship.

Just like a lot of solar companies, Luma Solar also doesn’t list the pricing of the Solar Roof on their website. A rough guess for the price would probably be $4 per watt. It is actually at the very high end of pricing for premium modules.



The POWERHOUSE line of solar shingles was actually originally a Dow Chemical product based on thin-film solar. Dow stopped producing solar products back in 2016 and sold its POWERHOUSE product line to RGS Energy the year after that. The first change that RGS Energy implemented onto the POWERHOUSE line is to use monocrystalline cells instead of thin-film.

Just like the CertainTeed Apollo II Tile, POWERHOUSE is a roofing shingle that can be used instead of the conventional asphalt shingle. The dimensions of one shingle are 41.6 inches by 31.5 inches, and each of them generates 60 watts. Additionally, RGS reports that the efficiency of each cell is 17.1%.

Unlike the Tesla Solar Roof which comes with various designs, POWERHOUSE only comes in one style — an all-black appearance similar to the Apollo Tile. This design allows the solar cells to be clearly visible when viewed from above but not apparent when viewed from street level.

As for the price, RGS Energy did publish a press release that claims that the installed cost for a 6 kW system is $3.30 per watt, including labour and materials. In addition to that, RGS also offers a 24-year power production warranty and an 11-year product workmanship warranty for their shingles.


SunTegra Tile and Shingle

SunTegra is a New York-based solar products company that provides two solar roof products. The first is their Shingle, which is mounted on top of your existing asphalt shingles, and the second is their Tile, which is the replacement for concrete tile products. Both of these products are offered with PV-option only. In other words, both the SunTegra Shingle and Tile are meant to be integrated alongside conventional roofing shingles or tiles.

The SunTegra Shingle is actually a little different from the other solar shingles considering that it is larger than asphalt shingle. To be specific, the SunTegra Shingle measures at 52 ⅝ inches by 23 ⅛ inches. The reason for these particular dimensions is that the Shingles sit on top of the roof and do not replace your existing shingles.

Additionally, the Shingle is also very low-profile as it only measures ¾ inches high. Because of that, SunTegrs has incorporated an air channel on the backside of the module, thus keeping the panel cooler and improving efficiency.

Both the SunTegra Shingle and Tile use monocrystalline cells and have a peak output of 100 to 110 watts. The pricing for either is not listed on their website, but both products do come with a 25-year power warranty and a 10-year product warranty.


Exasun X-Tile and X-Roof

Exasun is a company based in the Netherlands, and they offer multiple solar products. Two of which are solar-roof-related: the X-Tile which resembles a terracotta tile that can be laid in place of roof tiles, and the X-Roof, which is a complete roof replacement.

To be more specific, the Exasun X-Tile is based on its back-contact-on-glass technology and equipped with a suspension system for quick assembly. It has a high-efficiency rate of 18-18.6% as well as a high-performance ration of 4-7% more kWh/kWp.

On the other hand, the Exasun X-Roof system consists of small X-Glass panels of 60 cm by 82 cm. These roof panels are attached to the roof in seconds with an innovative but simple mounting system. These panels also have great ventilation behind them, optimally cooling them for a high-performance ratio. Additionally, the X-Roof is also perfected against rain, hail, and any other extreme weather conditions.


Hanenergy HanTile


Hanenergy is a solar company based in San Francisco that specializes in thin-film solar. Their HanTile product attempts to replicate the look of a dark terracotta roofing tile, and it also integrates thin-film PV. Not much information is available for this product at the time, except for the company’s planned 25-year warranty for their HanTile product line.



>> Sunflare | Reviews, product prices, contact, CEO

Sunflare is an American company that has been in the business of PV design and manufacturing since 2009. As such, they have offered a variety of PV products for about a decade now — from parking retrofit systems to semi-rigid products for large-scale ground-mount installations. Arguably their most popular product is their flexible solar panels that are designed for rooftop installations. These panels stick to roofs without any need for mounting hardware or roof penetration.

However, despite its wide array of solar products, Sunflare is still planning on branching out. And this time, they’re planning to get into the residential solar shingle market as well. That is why to date, they’re currently working on developing on a new line that will be similar to the other BIPV options. Sunflare plans that these solar shingles will not be adhesive but will be applied using traditional roofing methods.

Not much information is yet available for this product. Nevertheless, Sunflare has announced that they expect to release their solar shingle technology to the market sometime in 2020.



The rise in popularity of the solar industry means that there is now a huge demand for building-integrated photovoltaics (BIPV) products. After all, the available solar products right now sound great and effective. But not everyone will be attracted to buy when they don’t have space for it in their houses. So, the solar industry has to find a way to integrate all these solar technologies into the residential spaces without it being too conspicuous.

Luckily, the industry has come up with the idea of solar shingles. Simply put, the idea behind solar shingles is to combine two primary purposes — to act both as a roof and as solar panels simultaneously — into one solar product. Basically, solar shingles aim to solve a lot of problems that people face when it comes to acquiring residential solar. Hence, making it an innovative BIPV product.

Even though the development of solar shingles has been around for years, its integration into the solar market has been relatively new. That is why there are only a handful of companies out there that actively sell solar shingles. Tesla is arguably the most popular of the companies. But slowly yet surely, other companies have caught up with the trend. Some have started to develop their own version of solar shingles while others are still in the planning stage.

Long story short, solar shingles are relatively new solar products that can be the solution to people’s solar problems. And with these nine companies, the popularity of this product may just skyrocket in the near future. Thus, making it a huge victory for the solar industry.

Related article: Top 20 Solar Panel Manufacturers in the U.S.



Archived news

The Marketing of A Solar Tile

SRS Energy, who have developed a so-called “residential solution” for United Solar (see page 28 of the Investor day presentation), is in full-force marketing offensive. Last week they used a hapless “journalist” to plant a CNET story [cached] containing several false and misleading statements.

The article starts with the picture above and the credit reads “Solé Power Tile system developed for US Tile by SRS Energy integrates seamlessly with its terra-cotta counterparts.” Presumably, the dark-blueish tiles are “solar tiles that offer style” (at least that’s what the title of the article implies). That picture is fake, of course. A total fabrication. No tile on that roof generates any electricity! All the blue tiles are actually red clay tilesin real life (the picture is simply digitally altered in someimage-editing software). The picture on the left shows how the actualroof looks like (from a brochure of US Tile). If that is not convincing enough,


a partially altered picture can be found on SRS Energy’s web site and in another article [cached] -the vegetation in all these pictures looks exactly the same, whichexcludes the possibility that the building was reroofed with the bluetiles at some point. It is all one and the same picture, only the roofhas been digitally “painted.” If you have the patience, you can spotthe differences and similarities here.
But these are not all the fake pictures SRS Energy can offer. Look at the image on the company’s home page , which can also be found in their “sell sheet,” and in this story [cached]. A fake,of course. The actual roof is done entirely with red ceramic tiles.Here are the actual and “remastered” pictures side by side:
You can find the actual picture on US Tile’s web site, by clicking on “Why US Tile,” and then on “see Faux Mission.”
Thedeception and misinformation do not end with fake pictures. Here aresome of the statements made in the story by SRS Energy’s MarketingDirector, who claims to “work for the greater good.”
  • Cell efficiency for the tiles is between 8 percent and 10 percent.“That, of course, is an outright lie (except maybe for a few hours oflight exposure – Unisolar laminate degrade rapidly in the first hoursand weeks under the sun until they settle to their rated efficiency).The stabilized cell efficiency of the PV laminate material is lower. Asthis spreadsheetshows, Unisolar’s best “stated” cell efficiency is 8.5%, but the tilesystem from SRS Energy won’t use those cells. According to theirdocumentation, the 3-cell tile is 17 Watts,and as each Unisolar cell is 0.239 meter x 0.356 meter, it means theeffective cell efficiency is 6.7%, which corresponds to 7.5% “stated”cell efficiency (the same cell used in Unisolar’s latest laminate, PVL-128). However, to make things worse, the documentationstates that 30 interlocking tiles cover 100 sq ft, and since each panelis 17 W, that means 510 Watts per 100 sq ft. (actually, this and thisstories claim the tiles are only rated 500 watts per sq ft). Using the510 number and dividing by the area in square meters, the calculated”panel”-level efficiency is just 5.5% (30 * 17 W / 9.29030 sq m /1000). Even the PVL-128 laminate (made with 22 cells) has a slightlyhigher, 5.9%, panel-level efficiency.
  • That [cell efficiency] puts it slightly below what others in thin-film photovoltaics have been getting.” Not true. First Solar’s panel-level efficiency is at least 10.4%, thus the solar tile efficiency is not just slightly below, but 47% below that of First Solar’s thin-film modules. This is one of the reasons why First Solar sales are increasing, while Unisolar sales are declining.
  • SRSEnergy system’s overall efficiency makes up for the difference insunlight to electricity conversion figures. ‘If a homeowner bought 4kWof crystalline silicon panels and then 4KW of the Solé US Tiles, theywill get 10 to 15 percent more output in terms of a KWh (kilowatt hour)on their electricity’” The “make-up” statement is a red herring,of course – a 4KW solar tile system will occupy 3.5x the area of a 4KWcrystalline SunPower system. The “10-15% more kWh/kW” statement isfalse as well, including the concocted explanations of panels waking upearlier, or better absorbing the light spectrum, etc. Severaldocumented real-world performance records in various climates in the USand Europe demonstrate that the alleged kWh/kW advantage is a myth (I, II, III, IV, V, VI).The advantage, if any, is 5% and below. Thus, “effective” panel-levelefficiency could potentially rise to only 5.8% (5.5% *1.05). Of course,that 5% advantage will be there only in the first 5-10 years, as thefaster degradation of the Unisolar laminates relative to otherthin-film and crystalline modules will eliminate it over time (averageannual degradation for Unisolar triple-junction laminates has beenshown, see page 9,to be 1.22%, while crystalline’s is typically 0.5-0.7%). But that’s notall. What makes things worse is that the tiles are curved, thus evenfor a roof that is south-oriented and tilted at optimal angle, thelight hits the PV cells at various suboptimal angles. Even a casualsimulation analysis with the PVWattscalculator indicates that, in fact, the curvature could result in lessenergy than a flat panel tilted at zero degrees slope. For example,a flat panel, tilted flat (zero degrees), in San Diego is estimated togenerate 1314 kWh/kW AC electricity a year. A south-oriented30-degrees-tilted flat panel generates 1500 KWh/KW, but east-oriented30-degree-tilted panel generates just 1160 KWH/KW, while awest-oriented 30-degree-tilted one does 1268 KWH/KW (note how the east-and west-oriented tilted panels generate less electricity than azero-tilt panel). Thus, almost certainly the tiles will underperformcrystalline and CdTe panels (which, of course, both have flat surfaces)on the same roof on kWh/kW basis.
  • SRSEnergy’s statistics say the average homeowner with Solé Power Tiles canget 860 kilowatt hours per square foot annually living in an area with’5.8 peak sun hours’ per day.” SRS Energy has no suchstatistics, as they would contradict the real world experience ofinstallations with Unisolar laminates. Actually, the laws of physics make it impossiblefor a PV solar system to generate 860 kilowatt hours per square footannually in an area with “5.8 peak sun hours” per day. SRS Energy’s literaturemakes a more believable claim of 860 kilowatt hours per square (asquare is 100 sq ft). But even that claim is deceptive. For the “860kWh per square” claim to be true, the tiles must be generating 1686kWh/KW AC electricty on an annual basis (as a square has 0.510 kW worthof solar tiles). Luckily, there are few Unisolar installation in SanDiego, an area with “5.8 peak sun hours,” according to PVWatts(solar radiation hitting south-oriented 30-degree tilted panels), sothe claim can be verified. SIT has installed Unisolar-based roofs at 28schools in the area (installations and performance have been summarizedin a spreadsheet).The median/average performance was below 1470 kWh/kW, or 13% less thanwhat SRS Energy claims. A Unisolar system installed by Sullivan Solar,an installer in the area (see the same spreadsheet) has done a bitbetter, 1550 kWH/kW (accidentally, just 1% better than the average andmedian of three crystalline installations nearby). True, these Unisolarinstallations are on flat roofs, but as explained above, zero-degreetilt “panels” would likely outperform the curved solar tiles.
TheCNET story ends with a picture of the SRS Energy’ CEO’s ice-creamparlor (sporting mostly red tiles and a row of the blueish solartiles), which according to the story is “the first commercial buildings to implement the Solé Power Tile system.” But his store’s home page shows grey shingles and so does Google maps’ satellite image.So, SRS Energy’s CEO had to waste money and labor to tear down andreplace a perfectly nice roof, so that he could install 1KW or so worthof solar? Is that SRS’ idea of “eco-nomics?”. Is that “the sustainable upgrade [made] a simple one for the homeowner, which means it is also more accessible?” (see here [cached]).
The CEO stated [cached] that “choosingto upgrade to a sustainable roof from SRS Energy puts energy savings inhomeowners’ pockets immediately and delivers compelling long-termreturns.” That wasn’t the case with his “sustainable” roof, buthe is clearly hoping that the showcase will transfer the homeowners’savings into his pockets, and, hopefully, deliver some return on the millions [cached] put in his venture by “angel” investors.
Beforeanalyzing the prospects of a success for this product, let’s exploresome more “marketing messages” scattered across product documentationand planted articles:
  • SRS Energy materials are UL recognized as trusted and safe solar roofing components.” (source: here). Possibly, but why is the “UL Recognized” logo missing from the “sell” sheet? The solar tile is obviously not UL certified,and using UL recognized materials means little for an electricaldevice. Here is an example: copper wire is UL certified, but solderingit to short the solar tile electric connector will lead to overheatingand even fire under the sun. Will these tiles ever pass any UL or IECcertification? Note that Unisolar laminates’ IEC 61730 certification may still be “pending,” and the original Unisolar “residential product”, the SHR-17solar shingles (now taken off the market), no longer carry the ULcertification and were shown to degrade in likely violation of theirwarranty (and then Unisolar simply stopped disclosing degradation data).
  • Solé Power Tile … bringing the first building-integrated photovoltaic (BIPV) roofing product to curved roofing systems.” (sources: here [cached] and here [cached]) . This is patently false, of course, as SRS Energy’s patent application, as well as the CAD drawing indicate that the tiles have to be nailed to straight, not curved, underlayment given their interlocking design.
  • Chart titled “They wake up earlier and stay up later” and footnoted “Amorphoussilicon thin-film technology incorporated within the Solé Power Tileallows the system to produce an estimated 8-20% more energy thanincumbent crystalline silicon panels” (source: here).

Lookat the Y-axis label on the left. It is in kWh. What this chart claims,then, is that by 1 pm, “conventional” glass modules have generated 400Wh while the tiles have generated only 350 Wh worth of electricalenergy. In the afternoon, all this generated electrical energy isconsumed, bringing net PV generation for the day to zero (for both theconventional panels and the tiles). Of course, the label is wrong. Itshould be “kW” not “kWh.” One is a measure for power, the other, forenergy. But these are probably minor details for SRS Energy and their clay tile partner.Unfortunately, even if the axis were labeled “kW,” that pricture wouldcontradict SRS Energy’s message that the Unisolar’s panels somehow donot “degrade in performance as they get hotter[cached].Around 1pm, a time not known for the lowest temperature during the day,conventional panels, according to this chart, outperform the solartiles!

  • The rest of the Performance and Savings sheet is all wrong, as well. A 4KW tile system in a “5.5 hour day” area (San Franciscoor Santa Cruz) will not generate 6,022 KWh on an annual basis. Even anoptimally (30 degrees) tilted and well-ventilated Unisolar laminategenerates only 1500-1650 kWh/kW in Santa Cruz. A zero-degree-tilted flat laminate makes 1275 kWh/kW, on average. As discussed already, even optimally tilted curvedtiles will likely generate much less than optimally tilted flat panels.Thus, the most SRS Energy can hope for is 1500 kWh/kW for their tiles.That comes to 6,000 kWh for a 4KW system, which is well below the 6,800kWh in their “illustration.” The crystalline number of 6,022 kWh in the”example” is more plausible, by the way. Finally, the term “Efficiency”(see the third term in the calculation illustration) conventionallyapplies to conversion efficiency, not performance ratio.
  • TheSolé Power Tile™ energy advantage allows the system to deliver moresavings in the form of a reduced or eliminated electricity bill andcreates value with increased homeowner equity” (source: the Performance and Savings sheet). To illustrate that bold statement, SRS Energy attaches an electrical bill that indicates 376 kWh electrical energy usage. In fact, the bill shows that electricty consumption increased from 176 kWh in the period 2/14/2009-2/28/2009 to 200 kWhin the periof 3/1/2009-3/17/2009. This surely does not look like ahouse with a solar system installed. It is even more weird that SRSEnergy has decided to “magnify” that 376 kWh energy usage and label it 379 kWh.A Freudian slip, no doubt. The energy bill did not get reduced. Itincreased! The hapless homeowner will actually experience a destructionof value – more on that below.
So, setting aside the marketing propaganda, does this new product make any sense? The answer appears to be no:
  1. Just two SunPower SP-315panels (61 inch x 41 inch each, covering a combined area of 17.6 sq ft)deliver 24% more power under STC than 30 solar tiles (covering 100 sqft). Two SunPower panels can be installed in minutes, laying 30 tilesand carefully connecting them to the underlayment circuitry may takehours. No wonder SunPower has 20%+ share in the California rooftop PVmarket (the first intended market [cached] for the tiles), while Unisolar’s share there is 0.1%, according to the CSI.
  2. Cost will be prohibitive, even after ITC. The tiles need to sell for $6 or more per Watt for SRS Energy to break even (initial plans were for $8 per Watt [cached]). Unfortunately, thin-film solar panels can be found for less than $2 per Watton the market these days, and all the tiles will save in terms ofequipment or materials is a rack (which is only anywhere between 60c to10c per Watt, depending on the installation size).
  3. The solar tiles will not be viewed as a roofing material. Clay tiles can be purchased for $200 per square [cached].At $6 per Watt, the solar tiles will cost $3,000+ per square ($6 x510W), or 15x as much. Their color is attrocious, and they are made ofplastic (polypropylene).There are reasons why people generally don’t put plastic tiles on theirroofs that are supposed to last at least 20 years (cost, discoloration,delamination, degradation from UV radiation over time, and fire hazards [cached]come to mind). The weird rare color makes things worse – a thoughtfulhomeowner would wonder who will provide the dark blueish tiles in 5-6years if breakage or loss occurs, if the sole manufacture ofthe Solé tiles has (god forbid) discontinued the product (the owners ofthe Unisolar’s SHR-17 shingles are currently in that pickle).
  4. GoingPV with solar tiles rather than regular solar panels will be viewed asa risky proposition by the customer, given that 99.9% of the PV marketin California is flat glass panels, even ignoring the lack of certifications or ineligibility for state incentives. Jumping on the tile bandwagon won’t be an “incremental rather than monumental” decision SRS Energy wants us to believe [cached]. Quite the opposite. Of course, SRS Energy could easily “absorb the headaches and paperwork surrounding solar incentive programs” – there simply won’t be any state incentives in California for this product.
  5. Plastic is not a truly “sustainable” material (as it is made from hydrocarbons) and it is not a clean way for homeowners to go “green“, despite SRS Energy’s claims [cached] to the contrary. The solar tiles may not be a truly LEED product either, despite SRS Energy’s claims – unlike ceramic tiles which absorb moisture at night, and thus cool the roof during the day, plastic does not absorb water.
CertainTeed, arguably the country’s third-largest roofing company, acquired [cached] an equity stake in SRS Energy in 2008. What were they thinking?



Color-Changing Roof Tiles At MIT


Energy Secretary Steven Chu says painting all the nation’s black roofs a heat-reflecting white could cut global warming. But white isn’t that popular a color for rooftops. And what aboutwintertime, when black roofs help cut home heating bills by absorbingthe sun’s heat?

A team of graduate students at the Massachusetts Institute of Technology think they might have an answer – the Thermeleon roof tile, which turns white when it’s hot and black when it’s cold.

Named to rhyme with chameleon, the color-changing roof tiles wonfirst place in MIT’s Making and Designing Materials Engineering Conteston Wednesday, MIT’s news office reports.

Now the team behind the tiles is seeking to test their durabilityand find opportunities to bring the technology to market, Nick Orf, MITpost-doctoral student and Thermeleon team member, said Friday.

The tiles use commercial polymers and solvents encapsulated betweena clear plastic top layer and a black backing layer, Orf said. Whencold, the polymer remains dissolved in the solvent, letting the blackbacking show through. When it gets hot, the polymer condenses into awhite, heat-reflecting surface.

“When light hits this rough surface, it causes a lot of scattering,and that’s what you see – white light reflected back,” Orf explained.That white surface can reflect 80 percent of the sunlight falling onthem, which could cut cooling costs by 20 percent compared to a darkroof.

The Thermeleon tiles are made with “pretty cheap polymers,” commonly used in commercial products like hairspray, Orf added.

“The cost of our materials came out to be less than what common roof asphalt shingles sell for,” he said.

Now, “we have to start looking into the lifetime of the materialsunder different environmental conditions,” he said. Durability issueswill play a big role in whether the Thermeleon technology can beconsidered for commercial-scale production.

“Cool roofing” materials have been available since the 1990s, thoughthey don’t change color. The Environmental Protection Agency, whichcertifies roofing materials under its Energy Star program, reports thatcool roofing materials made up about a quarter of the commercialroofing market and one-tenth of the residential market in 2006 (see Building a Cool World, With New Roofs).

Those cool roof materials tend to be 5 percent to 20 percent more expensive than conventional roofing products, the EPA’s cool roofs Web site notes. But they can cut building air conditioning needs by up to 15 percent, according to the Cool Roofing Rating Council industry group.

Orf said that he’s seen other research projects looking intocolor-changing roofing materials, but that those have concentrated onmore expensive color-changing dyes.

The Thermeleon website notes that the team is welcoming interestfrom potential investors or licensing partners, but “We’re just rightnow taking a step back and seeing if there’s any interest, andcontinuing this work on our own,” Orf said. “It’s too soon to predictwhat will happen next.”

One of the new projects the team is planning to work on is amicroencapsulated version of its polymer-solvent mixture that can bepainted or sprayed onto existing roofs, he said.

California is one state that has cool roofing regulationsin place. Beyond savings on air conditioning bills, there areenvironmental benefits to take into account, according to a December study by Lawrence Berkeley National Laboratory researchers.

The study found that heat-reflecting roofs, combined with lighter-colored road surfaces, could reduce the “heat island“effect that sees heavily developed urban areas heat up by as much as anadditional 8 degrees Fahrenheit as their dark roofs and roadways absorbheat by day and release it into the atmosphere at night.

The wide-scale adoption of heat-reflecting roofs and roadways couldlead to a global warming reduction equivalent to cutting 44 billionmetric tons of greenhouse gas emissions, the study found.

But given that leading climate scientists are warning that a wholehost of immense “geoengineering” projects might be necessary to combatglobal warming, perhaps a massive project to make roofs and roads moreheat-reflective could gain traction (see Geoengineering May Be Mandatory, Royal Society Says).

On a smaller scale, a 1,000-square-foot roof that reflected 60percent of the sun’s heat (compared to conventional roof’s 10 percentto 20 percent reflection) would be equivalent to cutting 10 metric tonsof emissions, the study found.

Photo via MIT News Office.


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1 Comment

  1. Awesome article! Very informative and very up to date. How I wish we could have a solar panel roof to help save the earth.

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