Walk around a highly industrialized area, and you’ll notice large buildings with lots of surface space. Look around your office and you’ll notice several glass and plastic surfaces. These surfaces certainly serve a purpose, but what if they could provide another service?
Scientists and engineers at SolarWindow Technologies Inc. have developed a transparent coating technology so these surfaces can generate power using natural and artificial light.
SolarWindow’s building integrated photovoltaic (BIPV) technology replaces conventional building materials in parts such as roofs, skylights, and facades.
“Think of the technology not so much as SolarWindow – think of the technology as a transparent electricity coating system that can be used for so many other purposes,” explains John Conklin, president, CEO, and CFO of SolarWindow.
The first proof of concept in early 2009 showed that the company’s unique coating had potential. Shortly after, SolarWindow entered into a sponsored research agreement with the University of South Florida to go beyond proof of concept to a scaleable prototype.
In 2012, the company entered into a cooperative research and development agreement (CRADA) with the U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) in Golden, Colorado, to redefine development objectives by improving performance, increasing size, maintaining coating transparency, and producing meaningful power.
“We were able to scale the technology while maintaining power and performance,” Conklin says. “In doing so, we have set a record of size and power for comparable organic photovoltaic (OPV) devices and architecture, which has been validated by NREL.”
With the CRADA, NREL and SolarWindow also advanced the development of the company’s invisible wire technology that is as thin as a human hair for improved transmission of electricity from the surface of its power-generating glass and flexible plastic. The process developed for these virtually invisible wires is solution processable, faster, and can be applied using high speed roll-to-roll (R2R) or large area sheet-to-sheet (S2S) equipment.
“Product size, power, transparency, and process development objectives were achieved to scale SolarWindow for extremely important pre-commercial partnerships, and those objectives still hold true” Conklin says.
Despite this extremely fine invisible wire microgrid, SolarWindow’s glass coatings serve as a deterrent to bird collisions, an ongoing environmental concern for glass manufacturers and window producers.
SolarWindow can be applied to glass and flexible plastic, so the opportunities for the coating include automotive, aerospace, and marine applications.
“Looking at the automotive industry, we envision our electricity generating coatings being applied to automotive sunroofs and windows to generate electricity for security systems, comfort control, heat, and air conditioning,” Conklin explains. “We can look beyond the window and at other surfaces inside a building to apply our transparent electricity generating coating, such as curtain walls, room dividers, and glass table tops.
“Just look around your office at all the flat surfaces you see. Walls of glass used as dividers can benefit from this because SolarWindow can generate from artificial light. We can coat in a variety of colors and transparencies to generate power.”
The materials used for the SolarWindow are Earth abundant and mostly organic carbon, hydrogen, nitrogen, and oxygen. Conklin says the exact formulation of each of the layers is proprietary, but it is an organic photovoltaic coating (OPV). SolarWindow is constantly refining each of its coating’s layers to enhance power production and manufacturability.
Science shows us that the composition and structure of a compound lies at the core of chemistry and the movement of those molecules in a compound is based on exciting those molecules.
“We are looking at a chemical reaction. The excitement of the molecules in our solar coating is based on light; light is the energy input,” Conklin explains. “The important distinction between us and conventional solar is that we don’t need natural sunlight to make our technology work, and that it’s transparent. You can’t see through traditional PV panels. These PV panels rely on the visible spectrum of sunlight. SolarWindow OPV generates a chemical reaction by absorbing light energy to generate electricity under natural or artificial light.”
Since SolarWindow is applied to the inside surfaces of double- or triple-pane windows, self-cleaning and water-repelling characteristics are not an issue. Users simply clean SolarWindow the same way they clean their existing glass or plastic.
SolarWindow coatings can be integrated into glass and window fabrication processes without disrupting existing manufacturing methods.
“We want to incorporate our process into existing window manufacturing processes seamlessly. We don’t want to be disruptive, we want it to be integrated to what they currently know and do well in their industry,” Conklin says. “From its inception, SolarWindow is a technology developed for windows.”
The SolarWindow technology is also being developed into a process so it can be coated on very large sheets of glass or plastic and then to be assembled onto a window as a veneer. Conklin adds that the technology may evolve into a canned or spray-on coating in the future, but that’s not in the current commercialization plan.
The flexible veneer technology allows SolarWindow to be unrolled out of the box, coated with an adhesive around its edges, and applied to the surface, retrofitting it to power devices.
Time to market
SolarWindow outperforms rooftop solar technologies by 50x due to its ability to cover large surfaces on a tall tower or skyscraper. It also achieves 15x the environmental benefit compared to traditional solar power technologies.
The company is focused on commercializing its transparent electricity generating coating solution in 2017.
“We are looking in the glass, plastic, and chemical industries.” Conklin says. “Our go-to-market strategy is that there are 5 million commercial buildings in the U.S. There’s a worldwide growing energy demand, so we’re not just looking at the U.S., our market strategy is global in reach.”
“Keeping in mind that commercial buildings consume almost 40% of America’s electricity, our goal is to put a solid dent in reducing carbon emissions and offsetting a building carbon footprint while providing customers with clean electricity-generating solutions that make economic sense.”
National Renewable Energy Laboratory
University of North Carolina Charlotte Energy Production and Infrastructure Center
About the author: Arielle Campanalie is an associate editor of TES and can be reached at firstname.lastname@example.org or 216.393.0240.