Two square metres of solar windows will do the same job as a standard solar rooftop panel, Australian researchers say.

Semitransparent solar cells that can be incorporated into windows could transform architecture, urban planning and electricity generation, Australian scientists say in a paper in Nano Energy.

The researchers, led by Professor Jacek Jasieniak from the ARC Centre of Excellence in Exciton Science and Monash University, have succeeded in producing next-gen perovskite solar cells that generate electricity while allowing light to pass through. The team is now investigating how the new technology could be built into commercial products with Viridian Glass, Australia’s largest glass manufacturer.

If successful, the technology will turn windows into active power generators, with the potential to revolutionise building design. The idea of semitransparent solar cells is nothing new, but previous designs have failed because they were too expensive, inefficient or unstable.

Jasieniak and colleagues from Monash’s Materials Science and Engineering Department and the CSIRO used a different approach. They used an organic semiconductor that can be made into a polymer and used it to replace a commonly used solar cell component (known as Spiro-OmeTAD), which shows very low stability because it develops an unhelpful watery coating. The team’s substitute produced astonishing results.

Jasieniak says the semitransparent cells have a conversion efficiency of 17 percent, while still transmitting more than 10 percent of the incoming light. For comparison, rooftop solar has a conversion efficiency of between 15 and 20 percent.

The team is now working on scaling up the manufacturing. “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,” says co-author and CSIRO research scientist Dr Anthony Chesman.

Solar windows have the potential to bring opportunities and challenges to architects, builders, engineers and planners, but are a boon for building owners and residents.

“There is a trade-off,” says Jasieniak. “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 glazed commercials would generate about 140 watts of electricity per square metre.

The first application is expected to be in multistorey buildings, for which large windows are already expensive to manufacture and the additional costs of incorporating semitransparent solar cells would be marginal. “But even with the extra spend, the building then gets its electricity free!” notes Jasieniak.

“Up until now every building has been designed on the assumption that windows are fundamentally passive. Now they will actively produce electricity. Planners and designers may have to even reconsider how they position buildings on sites, to optimise how the walls catch the sun.”

Lead author Dr Jae Choul Yu, also from Exciton Science and Monash, adds that more efficiency gains would flow from further research.

“Our next project is a tandem device,” he says. “We will use perovskite solar cells as the bottom layer and organic solar cells as the top one.”

The team is aiming to get the semitransparent cells to market within 10 years, depending on how successful the scaling turns out to be.

For more on technological disruptions to the A&D industry, check out the highlights from last year’s Business of Architecture and Design Conference.

This article initially appeared in Facility Management.