Two groups of researchers in the United States and in Italy have developed clear solar power windows that create electricity from the sunlight going through them. The new technology increases the potential for “net-zero” energy cities.
The first group at Western Washington University, as reported by the Bellingham Herald, created the “Smart Solar Window” that by using ultraviolet light can create enough electricity to reduce a building’s heating and cooling costs by up to 30 percent. The windows open and close automatically for ventilation and cooling and can be operated by phone, computer, or ventilation system. The EPA gave the group a $75.000 grant to develop the product.
Eight graduate and undergraduate students from the chemistry, engineering, design, and business and economics departments worked on the project, headed by James Kintzele in 2014-15. Kintzele says, “I feel strongly this could be in buildings a year from now, given the proper funding and a motivated team.”
The second group at the Center for Advanced Solar Photophysics of Los Alamos and the Department of Materials Science of the University of Milan-Bicocca in Italy have created a non-toxic coating of quantum dots for windows. Reported in Physics.org, “the coating forms a luminescent solar concentrator that converts any window into a daytime power source” with record efficiency.
A nearly transparent window turns into a generator which can power an air conditioner for cooling or a heater for heating. Nanosized particles, heavy-metal-free colloidal semiconductor quantum dots, absorb a fraction of the sunlight light passing through the window, re-emit it at an invisible to the human eye infrared wavelength, and wave-guide it to a silicon solar cell on the window edge. Through uniform coverage of the solar spectrum, the quantum dots add only a neutral tint to the window so perceived colors are not distorted.
The quantum dots are composed of copper (Cu), indium (In), selenium (Se) and sulfur (S), abbreviated as CISeS. The new CISeS dots are low-hazard since cadmium was eliminated and significantly less expensive to manufacture than previous quantum dots in luminescent solar concentrator (LSC) demonstrations.
The lead Italian team researcher, Sergio Brovelli, says “Quantum dot solar window technology now becomes a reality that can be transferred to the industry in the short to medium term, allowing us to convert not only rooftops, but the whole body of urban buildings, including windows, into solar energy generators. This is especially important in densely populated urban area where the rooftop surfaces are too small for collecting all the energy required for the building operations.”
The team estimates that it would be possible to generate the energy needs for over 350 apartments if skyscraper glazing like at One World Trade Center in New York City, or 72,000 square meters divided into 12,000 windows, would be replaced with the technology they have developed. Combined with the filtering effects of the LSC windows, that reduce sunlight heating indoor air space and therefore air conditioning needs, and high efficiency construction techniques, the technology will at minimum provide more environmentally friendly and self-sustaining buildings.