by Emma Foehringer Merchant
November 17, 2020

This story is the fifth installment in a GTM Squared series considering what the solar industry will look like in 2030. 


Building-integrated solar has been on the cusp of adoption for over a decade. Boosters envision every roof being built with solar glass, houses studded with solar-producing windows and skyscrapers wrapped in material that turns sunlight into electricity.

The road to commercialization, however, is already littered with failed companies, such as Scheuten Solar, Soltecture and MiaSolé.

Now that solar is relatively cheap, a slate of new companies is trying to will the building-integrated photovoltaic sector to rise again. There are still numerous barriers, however, such as bridging the gulf between the building and solar industries and improving aesthetics enough to encourage BIPV’s mainstream success.

Over the next decade, the companies taking a gamble will be challenged to prove that BIPV is a legitimate technology, rather than a futuristic novelty. The industry remains split on whether the technology will pan out and how soon that might happen. 

BIPV past and present

Building-integrated PV is a broad category, encompassing some rooftop installations as well as transparent solar glass that can be installed vertically.

The most high-profile example of BIPV is Tesla’s solar roof. That product has been viewed with skepticism for years, but it’s also generated significant buzz.

“Elon Musk got this right with his focus on aesthetics,” said Martin DeBono, president at GAF Energy, which sells a solar tile product called DecoTech, introduced the same year as Tesla's solar roof. GAF Energy is a sister company to large-scale roofer GAF.

Since last year, in part to prepare for California requirements that most new-build homes install solar, other leading roofers including Citadel and PetersenDean have partnered with solar companies such as Sunnova, Sunrun and SunPower. Those partnerships may foreshadow the next generation of building-integrated PV to rise from the ashes of earlier failures. Though most contractors still rely on traditional solar installations, DeBono believes roofing and solar will become increasingly intertwined.

“There will be convergence between roofing and solar,” DeBono told Greentech Media.

The heavily siloed nature of both the building and solar industries are one reason why BIPV has had a difficult time taking off, according to Lance Wheeler, a researcher at the National Renewable Energy Laboratory.

NREL historically has been focused on drawing down solar costs enough to encourage widespread adoption. Now that the technology is there — the industry met SunShot’s $1-per-watt goal in 2017 — Wheeler says the national lab is starting to look more closely at where PV can feasibly be installed, including the possibility of vertical surfaces.  

The financial muscle offered by large companies like Standard Industries, the parent of both GAF and GAF Energy, will also help BIPV hop over commercialization and marketing hurdles, according to DeBono.

Most previous BIPV failures, such as Konarka and Xunlight, were startups. But oil major BP and industrial giant Dow Chemical also tried their hands at solar shingles, although both ultimately choose to discontinue production. Dow dropped its project just a few months before Musk introduced the solar roof.  

Tesla’s brand appeal often allows it to defy trends in the larger solar industry. But the company’s ability to market its product as something customers seek out suggests to Wheeler that BIPV can be successful. Tesla's devoted customer base may provide the kind of groundswell of interest needed to kick-start BIPV growth.

“You really have to have a base of new adopters that will jump into a new technology, that are excited about it, will take the risk. That will then bring the cost down,” said Wheeler. “A lot of [BIPV] failures in the past, it’s been rationalizing cost and durability, and there weren’t really early adopters.”

The adoption hurdles

The leading barrier to widespread adoption of BIPV, according to experts, is the look of the product. While solar companies strive for maximum efficiency, builders want products to be functional and aesthetically appealing.

“Aesthetics in the solar industry are probably talked about one-tenth as much as they’re talked about in the roofing industry,” said DeBono.

Tesla has tried to make the solar roof look as nondescript as possible. GAF Energy has also worked to lower the profile of its product on a roof. BIPV only makes sense if it’s “aesthetically pleasing,” said Veeral Hardev, director of business development at Ubiquitous Energy, a BIPV startup that produces transparent solar windows.

Hardev cites appearance as the biggest reason why BIPV historically has struggled.

“Everything you’ve seen so far isn’t quite there…in terms of how it looks,” he told GTM. “Then when you add on a huge cost premium, it really killed the whole story.”

Solar costs are a persistent concern as well. According to Wheeler, BIPV products such as solar windows don’t even have to be that efficient to be practical, as long as they’re cheap.

Ubiquitous Energy's windows cost 20 to 30 percent more than traditional models, with efficiencies currently topping out at 9.8 percent, according to the company. Though it’s still in pilot production, Ubiquitous says its modeled payback periods for most buildings as being between five and seven years — a range Hardev said is essential to get the interest of developers and homebuilders.

Some are still skeptical.

“My take is that BIPV isn’t going to make it on pure economics alone,” said Ravi Manghani, Wood Mackenzie’s head of solar research. “So, it will need the right kind of applications where traditional solar modules don’t work," such as urban environments or areas with land-use restrictions. "None of these limits are going to be significant [enough] for BIPV commercialization, not in the next decade.”

Charlie Ćurčija, a scientist at Lawrence Berkeley National Laboratory who works on building technologies, estimated that BIPV will take closer to 20 to 30 years to become mainstream, though he does foresee widespread adoption occurring eventually.

Builders, like solar installers, are cost-sensitive. Many residential construction companies initially opposed California’s requirement for solar on most new-build homes because of the added expense, although solar pays for itself over time in energy savings. To assuage those concerns, the state ended up approving community solar as an alternative route to compliance.

That conflict underscores another significant barrier to BIPV success: integrating products onto buildings while the technology is still in the process of gaining mainstream acceptance.

In the same way that builders are conservative about costs, they’re cautious about new materials. Homes have to stand up to weather and wear and tear much longer than the 20- or 25-year warranties that are now standard for many solar panels. For many BIPV technologies, there’s just not enough data out there on how long the products will last and be able to function effectively. 

“We’ve had silicon out in the field for decades now,” said Wheeler. “New technologies like organic photovoltaics or perovskite…[are] unproven.”

Builder skepticism indicates why solar companies are working to ingratiate themselves with roofers. The best time to add solar is when a new roof goes up. Right now, the number of annual solar installations represent only a fraction of roof builds in the same period. Within the next 10 years, DeBono expects roofing and building materials providers will have swallowed standalone solar companies.

Before then, he sees the need for more universal training and permitting. Installing solar products also means wires on traditionally analog materials, requiring some changes to the process.

“There’s a limit to how much a conservative [building] industry is willing to invest to adopt new techniques, adopt new tools and retrain its labor force,” said DeBono.

Wheeler, too, says solar companies and builders need to work together more closely, although perhaps not to the extent described by DeBono. Besides existing options like solar tiles, Wheeler already sees an opportunity for solar to be deployed where builders currently install opaque spandrel glass, which is used on glass buildings to cover the exterior areas between floors.

BIPV applications that are entirely integrated into a building’s design will likely take more than a decade to achieve full industry buy-in, according to Wheeler. But he sees shorter-term opportunities for PV windows and vertical facade applications.

“I think a lot of the problems we have right now with deployment can be solved in the next 10 years.”