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Transparent solar tech turns tinted tower blocks into power blocks

Tinted windows could turn office blocks into power stations thanks to a transparent solar films that can fit between panes of double-glazed glass.

German solar power technology firm Heliatek is hoping its photovoltaic film will be adopted by the building industry into standard double-glazing units.

Heliatek's transparent solar cells

The thin film can be deposited onto glass without distorting the light, and the company predicts that in two years it will be able to turn seven per cent of solar energy into electricity with a film that blocks half the light coming through.

It also doubles its efficiency at low light levels, and doesn’t lose any performance when it gets hot, unlike traditional solar power cells.

Dr. Martin Pfeiffer, co-founder and CTO of Heliatek, adds: “Our thin and lightweight solar films can be integrated directly into various kinds of building materials, so there is no need for separate mounting structures.

“As the film maintains its efficiency at high temperatures, unlike traditional PV technologies, no cooling is required.

“Similarly, its low light capabilities mean that the orientation and angle of the film is not critical and it maintains its efficiency even when cloudy, north-facing, or in the morning and evening.”

The company’s current production film cuts out three-quarters of incoming light for the same power, but they have an experimental version which blocks just 60 per cent of the light coming through.

The key to Heliatek’s transparent solar cells is are organic molecules called oligomers, which it produces at its own lab in Ulm, Germany.

The technology is very similar to the well-established OLED technology (organic LEDs) used in mobile phone displays and cutting edge TVs, except that it operates in reverse, taking in light to create electricity.

Heliatek has already developed a technology to turn concrete building facades into solar power units, and is working with the building industry to turn its transparent solar cells into commercial products.

Thibaud Le Séguillon, CEO of Heliatek, said: “Our solar films offer unique and compelling key benefits for all kinds of building integration applications.

“Thus, our business model is to be the leading supplier of customised solar films to the building and construction material industry. They will integrate our solar films as energy harvesting components into their products.”