Dutch bank trials power-generating windows in renewable energy breakthrough

The world’s first fully-transparent solar power-generating windows will be installed on a new Dutch bank in June, in a move the inventor claims could revolutionise renewable power generation in cities worldwide.

The Rabobank headquarters building in Eindhoven, owned by developer OVG Real Estate, will function as a live test bed for 30 sq m of PowerWindow, an aesthetically unobtrusive window that can capture light reflected from the surface and convert it into electricity.

Developed by tech start-up Physee, a spin-off from Holland’s Technical University of Delft, the windows are covered with a transparent luminescent coating that converts the 30% of light normally reflected from the surface into invisible light. The light travels through the glass into the window frame where solar cells convert it into electricity.

One square metre of glazing is able to produce about 20 to 45 watts of electricity, says Physee, about seven times less power than a regular solar panel. However, the windows are roughly 10 times cheaper than solar PV to produce, making them more cost efficient overall.

The product is mainly targeted at the renovation and construction of commercial buildings which are responsible for 40% of global electricity consumption, says company co-founder Willem Kesteloo.

“Most office buildings are limited to installing solar panels and we see PowerWindows as a complementary solution to help create energy-neutral buildings without compromising the surroundings in terms of functionality or design,” said Kesteloo. “Costs are expected to reduce further in line with the cost of solar panels because our windows use the same solar cell strips, which are the main cost driver.”

The bank pilot will aim to validate power performance and overall cost-effectiveness and if successful, OVG plans to roll the technology out to more of its buildings, says Kestoo.

Looking ahead, the company plans to optimise the prototype panels, then examine routes to market with a view to mass scale production. Alternative market segments are being explored, such as panoramic roofs in electric cars, and windows in planes and trains.

Kesteloo started the company with Ferdinand Grapperhaus in 2014 while studying at Delft Technical University, where the pair developed the transparent luminescent coating. The coating works based on the principle of total internal reflection, used in optic fibres, by only allowing reflected light to scatter in one direction, to the sides of window.