Scientists from Michigan State University have produced a new type of solar concentrator which can be installed on pre-existing windows to convert them into renewable energy devices without compromising their appearance.

The “transparent luminescent solar concentrator” can be attached to clear surfaces of any size – from the screens of cell phones to full-scale building windows, to transform them into solar power generators without significantly compromising their transparency or colour.

The solar harvesting system developed by Richard Lunt from MSU’s College of Engineering makes use of small organic molecules to harvest specific non visible wavelengths of sunlight.

According to Lunt, these small organic molecules can be used to “fine tune” the material to only pick out ultraviolet and near infrared wavelengths, which are then channeled to its edge to conversion into electricity using narrow strips of photovoltaic solar cells.

The ability of the material to only absorb ultraviolet and near infrared wavelengths without affecting light waves in the visible spectrum is the key to its remarkable appearance,  which it completely transparent to the naked eye and devoid of colour.

While other scientists have previously attempted to develop solar cells using transparent plastic-like materials, their efforts invariably resulted in products which were either highly inefficient or heavily tinted, compromising their ability to generate adequate amounts of power or their aptness for usage in certain environments.

“No one wants to sit behind coloured glass,” said Lunt. “We take an approach where we actually make the luminescent active itself transparent…we want to make solar harvesting surfaces that you do not even know are there.”

Lunt said the non-intrusive nature of the material should pave the way for the large-scale deployment of solar energy in residential or commercial environments, or even on personal electronic devices. It can be attached to the windows of shops or offices without producing a gaudy tinted light for occupants, or attached to smart phones and iPads without impeding image quality.

Lunt and his team are now working on raising the efficiency of the material, which possesses a solar conversion rate of about one per cent. They aim to lift efficiencies to over five per cent when fully optimised – a level which compares favourably to the best coloured materials, whose efficiencies hover around the seven per cent level.