One of the toughest engineering quests is to create a transparent solar panel, and a team in the US has taken the biggest step so far.

Fully transparent solar cells could turn world’s windows into its power stations, or simply lead to devices such as mobile phones that charge themselves through their screens.

Now, engineers at Michigan State University sya they have come up with a material that can harvest invisible light while letting the bright stuff through.

“When you look at tall buildings, there is a tremendous amount of surface area. They can act as efficient collectors throughout the day,” says Richard Lunt, MSU assistant professor of chemical engineering.

“In many buildings, we are already installing films to reject infrared light to reduce [heating and cooling] costs. We aim to do something similar while also generating power.”

The clear film in imbued with molecules that absorb energy and “glow” with infrared light.

The infrared glow is pushed to the sides of the material, where it is gathered converted to electricity using edge-mounted solar-voltaic technology.

The prototype converts only about 1 per cent of incoming light to electricty, compared to a typical rate of over 20 per cent for traditional solar panels.

But film has the advantage of being able to spread over large areas such as the side of the building, without inhibiting its function. Researchers say this will provide a great many more options for sites to install the cells, despite them being less efficient.

“Ultimately we want to make solar harvesting surfaces that you do not even know are there,” Lunt says.

The project has spun-off into its own company, Ubiquitous Energy, which is aiming to commercialise the team's work.

Professor Lunt is optimistic that a viable product might exist within five years.