Power shingles

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Transforming an asphalt roof shingle into a solar generator hasn’t been easy. But the nascent field of U.S. solar shingle manufacturers is beginning to expand from its small base in building-integrated PV (BIPV), leveraging their systemic reductions in installation costs, their improved roof and solar integration, and their continuing march-out of newer materials. Dow and CertainTeed lead the U.S. residential solar shingle business thus far, but U.S. challengers like GAF and Corning, along with competitors from China, may help drive down costs further. And new technological twists, including flexible glass, thin film and hybrid solar/thermal solutions may tip the pan to favorably balance the cost of solar shingles over panels.

Balancing roofing with PV

The higher cost of solar shingles relative to solar modules has been the bane of the former until very recently. Putting a new asphalt shingle roof on a standard two-bedroom new house can cost $10,000, and retrofitting a new asphalt shingle roof onto an old house can cost $20,000 if the maximum of three old layers of roofing have already been installed, because of the tear-off process. Meanwhile putting a solar panel system on either a new or old roof can cost $30,000 to $40,000; but if a standard shingle roof fails 10 years into the 20 year life of a solar system, then the added cost of taking down and reinstalling the solar system over a new roof can be as much as half the original solar system cost. So the decision to install solar shingles – which sell for a premium of about a third over solar panels – should be made at the time of initial construction or at tear-off, if economics drive the decision-making.
With the U.S. recession behind us and recovering home prices headed north, new housing is booming. U.S. Commerce Department numbers released in August indicate that in July new housing starts were over 1 million, nearly a 16% rise over the same period last year. Now solar shingle manufacturers are banking that they can finally take a fair share of the residential solar market.

BIPV bodes well

One new market research report suggesting that BIPV shingles may take off within the overall BIPV market is from Boston-based Lux Research. “A suite of niche applications will combine to a global market worth 1.2 GW in 2024, led by BIPV that incorporates PV panels directly in building roofs, skylights or facades,” Edward Cahill, Lux Research analyst and lead author of the report wrote in June. “Roofing products like solar shingles have the most traction in BIPV, accounting for 425 MW, or nearly half its market,” he notes. “The Americas market will grow steadily from 61 MW in 2013 to 340 MW in 2024,” he says.
An earlier research report suggests that the total market for BIPV is expected to grow from $2.4 billion this year to nearly $6 billion by 2017 and then on to $23 billion by 2021. A Dow spokesman was quoted by Reuters back in 2009 indicating that their solar shingle, which was only launched in 2011, would yield sales of $5 billion by 2015 and $10 billion by 2020.
While the economics of solar shingles compared with a traditional solar panel system on an asphalt roof only make sense when a new roof needs to be installed, the functional and aesthetic advantages of solar shingles are also facilitating more adoption by home builders across the nation.
Solar shingles have appeared on the U.S. market in a variety of forms, including photovoltaic roof tiles, photovoltaic roof shingles, solar laminates, modules with integrated solar cells as roof covering elements, transparent laminates or modules on lightweight substrate for flat roofs. Although curved tiles are popular in the Southwest, the vast majority of roofs in the United States are flat asphalt shingles.
The PV technology that has been melded to shingles also is wide, having encompassed amorphous, monocrystalline and polycrystalline silicon, as well as thin film, where the most promise is now held.

Dow: market in expansion mode

Dow’s Powerhouse shingles are helping to build out the U.S. market, after several years of R&D, followed by a market launch in 2011. “The market is in expansion mode now: 18 months ago we were active in five states, and today we are in 19 states and all the Canadian provinces,” says Josh Wimble, the Communications Manager for the Dow’s Energy Materials unit, in Midland, Michigan. Time magazine in 2009 trumpeted the upcoming product suggesting that, “The innovative shingle is expected to cost 10% to 15% less than traditional solar panels, and will be cheaper and quicker to install.” That prediction has yet to transpire, but current cost parity with module systems is a nice achievement to build on.
“The cost has come down over the last few years, and is now at parity with a module-based solar system, after you back out the cost of purchasing and installing a new roof,” says Wimble. As a result, Dow has partnered with new home builders. “We are excited about our new partnerships; for example, Brookfield Residential, of Denver, which builds communities in California and in Colorado, is expanding Powerhouse to another 1,100 homes,” Wimble notes. Dow lists over two dozen partner builders and roofing companies on its website.
The sturdiness of the Powerhouse shingles also helps sell the system. “Builders value the 20 year weatherization and performance warranty. We also got it certified for the Miami-Dade market to withstand 150 mph winds, and to withstand 1.25 inch hail, which solar panels may not warranty against,” says Wimble. The solar shingle has Underwriters Laboratories (UL) and International Code Council Evaluation Service (ICC-ES) certifications.
The Powerhouse shingles are installed over a felt underlayment on a matrix of vertical then horizontal wooden battens. ”We also have been working to integrate installation with ceramic tiles and slates, also even cedar shake,” he says. “There are 10 times fewer roof penetrations than with standard solar panels, because the wiring is internal within the shingles and the whole array has a single point of penetration going into the home,” he explains.
“We’re proud that ours is the most simple and efficient process, allowing roofers and builders to easily adapt this technology. It installs in almost the same time as a regular roof and can be done by the same crew,” says Wimble.
To provide the 12 watt/square foot solar component of the shingle, Dow purchased NuvoSun of Milpitas, California, which makes the copper indium gallium (di)selenide (CIGS) cells that power the unit. NuvoSun has a Chinese subsidiary, NuvoSun Shanghai. The shingle is 10 inches (25 cm) high at reveal, 28 inches (71 cm) wide, and one-half of an inch thick (1.2 cm), like a standard shingle.

CertainTeed: flat or curved

The other leading player in the U.S. solar shingle market is CertainTeed Saint-Gobain, based in Blue Bell, Pennsylvania, which markets its Apollo II Solar Roofing System, with a 56 watt per panel output and a total weight of only 12 pounds. A curved version of the Apollo tile was launched at the Intersolar show in San Francisco in July. The company’s initial flat roof solar shingle was unveiled last year, says Christopher Fisher, a PV product development leader for the company.
CertainTeed’s shingles are comprised of an embedding monocrystalline cell on a hard plastic base, with a thin-tempered glass top, rated at 250 pounds per square foot (1,220 kg/m2 ), strong enough for a roofer to stand on. The black panels carry a 30% cost premium over a traditionally metal-racked PV system, not discounting the cost of the original roof, but are more aesthetically pleasing, at just over an inch thick, and designed to be more dependable. The panels carry a 25 year power output warranty – 25% longer than most standard panels, and a 15 year installation workmanship warranty, still unusual in the industry. The shingles will withstand a 100 mile per hour (161 km/h) wind, and are UL 790 Class A approved for fire and UL 1703 approved as a solar device.

Heda Solar tests export markets

Chinese solar shingle and tile manufacturer Zhejiang Heda Solar Technology, based in Fuyang City, in Zhejiang Province, has found the local market receptive enough for its portfolio of products that the company is now marketing in Korea, Japan and Scotland. “Our solar tiles are designed to last on average 40 years longer than standard architectural tiles,” claims a website statement by Joseph Shaw, the company Manager for Strategic Development.
Heda’s 20 watt solar tile measures 30 cm × 75 cm, and weighs about 6.5 kilograms, coming in flat and wave shapes. They are designed to be installed over concrete purlins, a waterproof barrier and wooden battens. With a variety of configurations, the solar cells may be covered by cut-out tiles or inserted into cut-out tiles.
Heda gained TÜV Nord certification for its solar shingles in 2013, covering both five inch and six inch monocrystalline tiles. The tiles also are built to IEC 61215 and IEC 61730 standards.

Atlantis: PV/thermal shingles

One effort to efficiently capture heat from the solar shingle has arisen from Atlantis Energy Systems, based in Sacramento, which markets its BITERS (building integrated thermal electric roofing system), protected under several patents, says Joe Morrissey, the Vice President of Sales for Atlantis.
A Swiss company until 2001, Atlantis offers what it calls a “premier” slate in its Sunslates line of tiles, says Morrissey. “Our product has always been pricier than the standard model, and because our market is more of a premium niche, our customers were not hurt as badly as the rest of us during the recession,” he says. “In the past few months we have been getting more inquiries offshore than we’ve seen for some years, including inquiries from Croatia, Egypt and West Africa,” he adds.
“When thermal is included in the solar harvest, the efficiency will rise to 40% to 50%, and with Sunslates the installation price rises to $10.50 to $11.00 per watt,” Morrissey says. The Sunslate system carries a 20 year warranty for power generation, a 20 year weatherability warranty and a 25 year material integrity warranty, although the company states that it expects a 50 year performance.
Each Sunslates6 generation slate weighs just over 14 pounds, and weighs 715 pounds (324 kg), based on 50 slates per square (100 square feet of roofing). The slates are designed to resist a 125 mile per hour (201 km/h) wind load.
The slates’ electrical component is comprised of six monocrystalline silicon cells in series, with a 23 watt capability. Although the Sunslates are manufactured for a 600 VDC rating, no more than 36 slates yielding 828 watts are recommended in a single 15 amp fuse protected series, more voltage can be achieved through the use of combiner boxes.
Installation requires proprietary hooks and protection shields, along with a connection opener. Once the roof rafters are in position, a standard 30 pound (14 kg) felt is applied for waterproofing (an optional EPDM ice and water shield is recommended), horizontal 1 inch × 4 inch battens are nailed on, above which 2 inch × 2 inch vertical battens are nailed to secure the tile hooks. Where field cables penetrate the roof, expanding firestop foam or silicon seal is prescribed to waterproof the hole.

Thin film shingles

One key to solar shingle cost reduction may be a lower-cost, higher-efficiency thin film. Such a project is being developed by Solexel, of Milpitas California, which in July captured new venture capital. Solexel raised $31 million of equity financing to begin commercial production of its high-performance, low-cost, lightweight, thin crystalline silicon solar modules. Among new investors in the company is GAF, the largest roofing materials manufacturer in North America. Solexel is also working with Owens Corning on a BIPV solar roofing shingle, with support from a $13 million U.S. Department of Energy SunShot “Solar Extreme Balance of System” grant; expectations were said to be high-volume sales in 2014. Gunther Portfolio reported that Solexel has ambitions to add power electronics to the back of its cells. The SunShot project for BIPV carries a goal of a total system cost of $2 per watt, at scale, by 2017.