Is that a Power Plant in My Window?

Electronics New Product Development

Development of an entirely new solar glass product that integrates thin film organic photovoltaics could make it possible for buildings to function as visually attractive solar collectors.

An entirely new product category--transparent and aesthetic building-integrated photovoltaics (BIPV) that are not only energy-efficient, but also energy-producing--may become a reality if an advanced product development agreement between Konarka Technologies, Inc., and Arch Aluminum & Glass Co., Inc., yields the results that the companies are hoping for. The two companies agreed in May to collaborate on integrating Konarka's patent-protected thin film solar material into glass for commercial BIPV applications. Their goal is to develop attractive, semi-transparent, glass BIPV products, known as Active Solar Glass® (ASG), for building applications such as windows, skylights, and curtain walls.

It's hoped that by integrating Konarka's semi-transparent Power Plastic®, ASG will make it possible for every glass surface in a building to become, in effect, a solar power plant. Active Solar Glass will also incorporate passive solar technologies, such as Low-E coatings, to make ASG energy-efficient as well as energy producing.

"Until today, aesthetic and performance concerns limited the ability of architects to use BIPV technology in their designs," commented Arch Aluminum & Glass CEO Leon Silverstein, in a statement announcing the development agreement. "This product development investigation is about the creation of a new product category, one that had been unavailable until today. It is energy-efficient and transparent, with superior vertical performance and a subtle red, blue or green aesthetic. With these features, BIPV will no longer need to be confined to spandrel or overhead applications. An entire building can be put to use, producing its own power, and looking good doing so. We're excited about our efforts with Konarka to bring this technology to the building community."

Arch Aluminum & Glass (, based in Tamarac, Fla., is a manufacturer of specialty architectural aluminum and glass products. The company offers in-house laminating, heat-treating, and fabrication. Konarka Technologies, Inc. ( develops and manufactures solar plastic films that convert light to energy. The company is the developer of Power Plastic®, designed using a proprietary polymer-based, organic photovoltaic (OPV) technology that provides a source of renewable power in a variety of form factors.

"Konarka is making great strides with our aggressive plans to expand into various markets, including building and construction," commented Rick Hess, president and CEO of Konarka, headquartered in Lowell, Massachusetts. "Because our solar material is flexible, lightweight, and semi-transparent, it integrates easier and is more aesthetically appealing than other solar products, making it ideally suited for BIPV applications. We expect that our collaborative work with Arch Aluminum & Glass will advance the delivery of Konarka Power Plastic on a large scale basis into this market segment."

According to Arch Aluminum & Glass, the Active Solar Glass that's currently in development will provide building products with an unprecedented combination of performance and aesthetics. Instead of being limited by the drab, cloudy aesthetic of current BIPV technology, designers will have "the ability to make every building envelope a visually attractive solar collector, with the choice of subtle red, blue, and green colors." Also, the ability to collect energy at up to 70 percent off-axis will reportedly allow ASG to be used on vertical surfaces, as well as horizontal. Other distinguishing features are reported to include "the highest transparency of any BIPV glazing product on the market," and the ability to harness energy from both indoor and outdoor light.

Design-2-Part Magazine recently spoke with Arch Aluminum's Leon Silverstein and, separately, with Konarka Vice President of Product Development, Dan Williams, about the unique features and potential impact of the developing BIPV product. Edited excerpts of their conversations with us follow.

D2P: What is unique and cutting-edge about the type of Building Integrated PV products you will be making with Konarka?

Leon Silverstein (Arch Aluminum): This is the first time in solar technology that a solar panel that's integrated as part of the building won't look like a Darth Vader type of solar installation, or one that you can't see through. Most solar panels in use today are opaque and you can't see through them. This is really an application that we can use in vision applications.

If you go to the airport and look up at the skylights, you'll see this dot matrix pattern that's used to diffuse the sun. But instead of visualizing the glass in that same application, with a similar look, whether it's a skylight or a window, that's now a solar panel generating power. Before when you talked about windows, you talked about more energy efficient products, improved U values, improved shading coefficients. The reality with our product is you can get everything in the same product.

You'll be able to see through our panel, and you'll have visible light transmittance, which makes the building brighter. And we'll still be able to rate that same insulated glass, which gives you energy efficiencies that people are desiring. You always hear about people that want their buildings to be LEED certified, or have certain performance levels. We will not only get performance levels from the makeup of the glass, but the glass will be visually acceptable and acting as a solar panel. This is because of the thin film technology applied to our glass fixtures.

Also with ordinary solar panels, it's usually one size fits all. So if you're going to build an integrated solar installation into a building, you do it based on the standard size panel that that manufacturer makes. Our vision, with our product development, is that we're not changing the size of the building. We'll be able to make a solar panel whatever size the architect designs, with the aesthetics that he or she wants. Since we make custom laminated and insulated glass products, we can make the panel any size it needs to be to fit into the building space, whether it's a small window or a large window, or a skylight. I think this is the first time anyone has ever made a visionary type of panel. This should be a cutting edge type of product, using our skill set working with glass, and Konarka's thin film technology.

D2P: How many different types of conventional building materials will your products replace?

Leon Silverstein: Whether it's a house, a hospital, a school, or an office building, in theory, it can fit all of those applications. So the building envelope can act as a solar solution. Maybe 50% of a given building can't have a solar solution, but 50% can. You're now taking the whole surface area of glass, and instead of just trying to make it more energy-efficient for cooling and heating, you're now designing in all of those products, where not only are they going to be energy-efficient, but they are going to produce energy. We're talking about windows, curtain walls, skylights, any application that uses glass.

D2P: Your press release states that your new BIPV product creates a new product category that wasn't available until now. What is this new product category?

Leon Silverstein: There are categories for energy-efficient glass, but not for energy-generating glass. So our product is a new category. If you go and work with the architects while they're designing a building that will have energy-efficient glass, they use building codes that are written that way, and modeling that is written that way. We're not concerned about how efficient one portion of a curtain wall might be. We want to measure the whole curtain wall, and hopefully, instead of being just energy-efficient, it will generate power and maybe even sell it back to the grid. An all-glass high rise, or other building, is called a curtain wall, or they're called building envelopes, or window walls. This product is ideal for a curtain wall building.

D2P: How will aesthetic and performance concerns change for Building Integrated Photovoltaics now that your companies are working together?

Dan Williams (Konarka): There are limitations in what's currently available for PV materials that are used in BIPV; we will be able to offer architects and developers more choices. Usually PV panels are of a silicon nature, or they're thin film on glass with limited light transmittance. When we're working with Arch, we'll be taking advantage of our thin film material, which has a transmission capability of up to 70%. It can be tuned to be lower or higher, as a factor of how we deposit the material on our film. And once it's laminated with the glass, we'll be able to provide people with not only a PV solution, but one that behaves like a transparent window.

The other factor is being able to offer color to a PV product. We have a reddish polymer color that is a standard material, and we've developed a green polymer and a blue polymer, and so we hope that when the Arch product is introduced, all three colors will be available. We feel that it's very cutting edge to come out with these colors for the product. We've talked with a number of architects and builders. The frustrations for many years are the limitations. More and more builders are integrating renewable technologies into their product plans, but you still have to accept the look of the solar material that's available. There's a lot of work going on in the industry in general, we're seeing a lot more introduction of products that emulate the actual building components. Where you see PV roofing tiles, they look more like real roofing tiles.

D2P: What is this new product category that has been created?

Dan Williams: It's the use of transparent photovoltaic material for window and building fenestration. (Fenestration comes from the root word fenestra, meaning window. It's usually a product that fills an opening in a building envelope, like windows, doors, skylights, and curtain walls. It is designed to permit the passage of light or air, or people). A lot of what's been developed in BIPV has been limited to spandrel walls or curtain wall applications, where the properties of windows were not required. In this category, we're actually enabling the building of vertical surfaces to remain a window, but also to provide the envelope with a power collection capability.

One of the advantages of organic photovoltaic material is that it has sensitivity to low light, as well as to off-angle light. If you are to put the Konarka material on a vertical surface, it still has very good light absorption qualities. Because if you think of a tall building, maybe 80% to 90% of the surface is vertical, and only a small percentage is rooftop surface. So architects and builders will be able to take advantage of most of the envelope with our vertical products, in addition to regular panels on the rooftop.  Our products will be applied mostly in window and skylight applications with Arch. There is also a possibility for using the material in greenhouses, anywhere light comes into a building where the light can be harvested. So it really opens up PV possibilities for anywhere that there is glass in a building.  

Our material could even be applied to canopies and awnings. A lot of using thin film is about weight issues, since a lot of buildings can't support the full weight of a traditional solar panel array. I hear a lot from the building community that the more integrated or the less visually impactful the PV can be on the building, the more interest there is to use these technologies, especially on older, historical types of buildings.

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