A dream of clean energy advocates is turning every window into a solar panel. Just imagine how much solar electricity could be generated around the world if all the windows in factories and office towers helped to power the buildings they were installed in. Researchers in Australia are hot on the trail of a new technology that could make solar windows a reality.
Their work with semi-transparent perovskite solar cells has resulted in new technology that permits a conversion factor — the ratio of how much sunlight is transformed into electricity — of 17%. Before you dismiss that as too low to be of interest, keep in mind that many solar panels available today have a conversion factor of between 15 and 20% and aren’t transparent. ClearVue, a solar window technology company listed on the Australian Stock Exchange, boasts a conversion factor of just 3.3%.
The research is a collaboration between the Australian Research Council and Monash University in Melbourne. In a paper published in the current issue of Nano Energy, team leader Jacek Jasieniak explains that the team used an organic semiconductor made into a polymer to replace Spiro-OMeTAD, a material commonly used in perovskite solar cells which suffers from low stability and develops an unhelpful watery coating. “It’s long been a dream to have windows that generate electricity and now that looks possible,” he tells PV Magazine.
The new technology results in solar cells that allow 10% of the sunlight that strikes them to pass through to the interior of the building. “There is a trade-off,” he says. “The solar cells can be made more, or less transparent. The more transparent they are, the less electricity they generate so that becomes something for architects to consider.” Solar windows tinted to the same degree as current commercial fittings would generate around 140 watts of electricity per square meter. That means roughly 2 square meters of solar window would perform the same job as a standard rooftop solar panel.
The researchers are working with CSIRO — Australia’s highly respected Commonwealth Scientific and Industrial Research Organization — to figure out how to commercialize the technology. Australia’a largest glass manufacturer, Viridian Glass, is also part of the development process. The quest is backed by the Australian Renewable Energy Agency.
Anthony Chesman, co-author of the study and a CSIRO researcher, says “We’ll be looking to develop a large scale glass manufacturing process that can be easily transferred to industry so manufacturers can readily uptake the technology.” The technology will likely be used first in multi-story commercial buildings which typically use very large — and expensive — windows. Adding the transparent solar cells will increase the total cost by a small percentage.
“Even with the extra spend, the building then gets its electricity free!” says Jasieniak. “These solar cells mean a big change to the way we think about buildings and the way they function. Planners and designers might have to even reconsider how they position buildings on sites, to optimize how the walls catch the sun.”
Asked when the solar windows might be available, he said, “That will depend on how successful scaling of the technology will be but we are aiming to get there within 10 years.” If you think that seems like a long time, stop and think where the solar power industry was 10 years ago. Patience, grasshopper.
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