One of the biggest hurdles facing large-scale adoption of solar power is the intrusive nature of solar panels.

Wouldn’t it be great if someone invented a solar panel that doesn’t look like a solar panel and actually forms part of the building’s structure?

Well, someone has. A group of MIT researchers have come up with a solar film that can be applied to the windows of a building to collect solar energy while remaining perfectly transparent. Ubiquitous Energy’s ClearView Power technology is set to revolutionise the way we use solar and could see everything from the screens of mobile devices to entire buildings drawing energy from the sun while remaining practically invisible to the eye.

How conventional solar cells create electricity

Conventional photovoltaic solar cells absorb ambient light (photons) and convert it into electricity (electrons). To do this, they have traditionally needed to be opaque in order to capture the light (if they were transparent, all the light would pass straight through and travel to the eye).

Previous attempts to make them transparent by either thinning down the material or segmenting cells across the module have been unsuccessful, largely because the idea of a transparent solar cell is a contradiction in terms – you can either capture the light or let it pass through, but not both.

ClearView Power solar cells

The MIT researchers and founders of Ubiquitous Energy looked at the problem from a completely different angle. Instead of trying to capture some of the ambient light while letting enough pass through to allow for transparency, they decided to work on only capturing the light that was already invisible to the naked eye.

They redesigned the solar cell to transmit ambient light that is visible to the human eye and absorb only the invisible ultraviolet and infrared light to convert into energy. This means the cell continues to be transparent because the visible light still passes through, while the light that we don’t see anyway is busily converting photons into electrons and creating electricity.

This is achieved by using a transparent luminescent solar concentrator (TLSC). This consists of organic salts that absorb ultraviolet and infrared wavelengths and make them luminesce (glow) in another invisible infrared wavelength. This light is then guided to the edge of the cell, where thin strips of conventional photovoltaic solar cells convert it into energy.

And because two thirds of the light available for energy harvesting is in the ultraviolet and infrared spectrums, up to 90% transparency can be maintained while achieving practical efficiencies of more than 10%. Admittedly, Ubiquitous Energy pilot programs are currently only achieving around 1% at present, but this is expected to rise to 5% before the product is released and it has the potential for 10% efficiencies in the not too distant future.

The ClearView Power story

The fully transparent solar concentrator was the brainchild of a group of MIT researchers, who created a prototype back in August 2014 and have been perfecting it ever since. Richard Lunt, Miles Barr, Ian Millard and Vladimir Bulović co-founded their startup company, Ubiquitous Energy, in Silicon Valley and patented their ClearView Power technology. They are currently working with commercial partners to bring this technology to market, including developing prototypes for applications in mobile electronics.

Ubiquitous Energy has currently raised over $8 million towards research and development and has won a number of prestigious business and technology awards including National Science Foundation Small Business Innovation Research, Small Business Technology Transfer grants and the MIT Clean Energy Prize Renewables Category.

The future of ClearView Power technology

The potential applications for ClearView Power are immense and Ubiquitous Energy is looking at three areas of technology in particular:

  • Building-integrated solar technologies – ClearView Power can provide invisible, energy-producing coatings for windows. These will allow for natural light and views, while converting invisible light into electricity to offset the building’s energy consumption. They can also be used to power electronic smart window functions.
  • Mobile technologies – ClearView Power can compensate for the ongoing problem of limited battery life in mobile devices by providing additional energy to extend their run time. Energy can be harvested through a clear film covering the display, without impacting the aesthetics or performance of devices such as smartwatches, tablets, eReaders and smartphones.
  • The Internet of Things (IoT) – ClearView Power can provide a free ongoing energy source to power smart sensors, digital signage and a range of environmental, medical and home automation devices. The electricity generated from indoor or outdoor light could continuously recharge small, low-cost capacitors instead of batteries, providing infinite device life with no aesthetic impact.

With applications from the small to the very large, transparent solar cells would appear to have a big future. Ubiquitous Energy’s main priorities at the moment are to make their technology as non-intrusive, energy-efficient and affordable as possible and if they manage to achieve these goals, we could soon see (or not see) a proliferation of solar harvesting cells on a variety of different surfaces. We look forward to these technologies becoming affordable and mainstream for the Australian public in the future.
For more information, see How Does Solar Power Work?