Buildings that generate their own energy add another element to sustainable architecture, and solar windows are an effective way to showcase commitment to cutting-edge technologies and environmental responsibility.
Startups like NEXT Energy Technologies have received funding to bring their solar window products to market, but will this innovation help buildings meet net-zero climate goals?
Technology
Solar panels harness energy from sunlight by converting photovoltaic cells to electricity. To do this, they use absorber materials like crystalline silicon to absorb and convert solar rays into energy; these absorbers can even be integrated into glass windows for seamless results that appear and function just like traditional window products.
Ubiquitous Energy has taken steps toward commercialization with their semi-transparent solar window coating that captures infrared and UV light while still allowing visible light through. Furthermore, this coating reduces glare inside buildings or homes, which is an ideal solution suited for a range of applications.
NEXT Energy Technologies has come up with a clear solar window designed to turn existing windows into energy-generating solar panels, known as Building Integrated Photovoltaics (BIPV). These transparent windows are intended to offset 10–20% of commercial office electricity needs while still offering sleek architectural design elements to add visual interest.
Both NEXT and Ubiquitous have taken advantage of research conducted at Energy Department national labs through Tech-to-Market's Energy I-Corps program to accelerate research translation into market applications. Both firms also received significant financial assistance from the California Energy Commission for their research endeavors.
Potential
Traditional solar panels remain at the forefront of renewable energy technology, but transparent solar power windows could soon provide another viable option to bring us one step closer to a greener future.
Integrating solar windows into buildings offers many advantages, particularly for skyscrapers with large amounts of glazed surface area compared to roof space. Furthermore, this technology could increase energy independence as residents would be able to produce their own electricity instead of depending on grid power for supply, and its tinted glass can match any building aesthetic without disrupting views or creating an unsightly solar panel look.
Several companies are actively developing solar-powered windows. Startup NEXT Energy Technologies gained fame when it supplied see-through solar windows to Patagonia's California headquarters, earning them a $3 Million grant to pilot-scale their production process. Ubiquitous Energy aims to begin manufacturing floor-to-ceiling solar power windows for commercial buildings by 2025 or 2026.
Both startups use thin film to capture invisible ends of the light spectrum for energy harvesting purposes while still permitting visible light through. Depending on its design, a solar power window may be up to 10% more efficient than high-quality rooftop PV panels.
Challenges
Before solar windows can reach your home or office, there are a few hurdles they must cross first. They must increase energy efficiency so they can generate enough electricity to offset some of your building's energy use, something many companies are working toward achieving with silicon solar cells converting at 18–22 percent efficiency rates and typically transparent. Recently, however, researchers have developed perovskite microcells that convert electricity at up to 25% efficiency rates; these cells may offer greater efficiencies for solar window products in comparison with silicon alternatives.
Second, solar power windows must be durable enough to withstand environmental factors that could compromise their performance, such as temperature fluctuations, humidity, and air pollutants that cause organic materials to degrade and lose the ability to conduct electrons. To help promote mass market adoption of these technologies, the US Department of Energy supports research into their stability.
Solar windows must also be cost-competitive with standard glass. Many companies are making strides toward this end, including Physee, who installed the first transparent solar-powered windows at a Dutch bank a year later—called PowerWindows—producing enough energy to charge smartphones multiple times daily.
Limitations
Buildings account for 16% of greenhouse gas emissions worldwide, mostly through energy use for heating and cooling. Solar windows that incorporate photovoltaic cells could play an essential part in mitigating climate change.
Traditional window coatings aim to prevent certain frequency bands of light from entering buildings—such as ultraviolet radiation, which fades colors and damages furniture, and infrared waves, which increase indoor temperatures—from entering; but these wavelengths can also be harnessed as electricity by installing transparent solar coatings onto windows—effectively turning windows into electricity-generating powerhouses without sacrificing design or natural daylight.
Technology remains in its infancy stage, though startups like NEXT Energy Technologies and SolarGaps are developing solutions that seamlessly integrate architectural glass. However, in order to broaden adoption, they must increase efficiency and transparency while decreasing production costs and address surface distortion issues and stability concerns.
While challenges remain, some companies have taken significant strides toward commercialization. Last month, Western chemists Daniel Korus and Matt Bergren installed two 4-by-4-foot windows of their own creation in the entryway to the University Gallery—the largest windows ever created by anyone!
Energy-generating windows in Scarborough feature a layer of plastic filled with microscopic pigments called quantum dots that glow when subject to sunlight, and when this light hits its target sensor in each corner detects it and directs it toward small solar panels that generate electricity.
