Impossible Photovoltaics

28 May 2008

Impossible Photovoltaics

Conventional silicon photovoltaics is a non-starter in Antarctica because it is very poor at low angles of incidence of light let alone low levels of illumination or reflected light and it is heavy. Yet in the recent 'E-Base Goes Live' project in Antarctica a team spent more than two weeks relying exclusively on solar power and other forms of renewable energy to meet their energy requirements.

Dye-Sensitised thin film solar cells reel to reel printed using an ink jet - like process by G24 Innovations (G24i) provided a significant portion of the electricity used during the trip because they are very efficient in these conditions and very light weight. In space travel there is strong light but severe space and weight constraint on payloads so InGaAs multilayer thin films beat silicon hands down. Boeing Spectrolab is a leader here, working with NASA.

By contrast, in many terrestrial applications cost per watt over life is far more important than artificial measurements of efficiency in a laboratory. Here printed organic photovoltaics is an exciting possibility. For example, Andy Hannah CEO of Plextronics, one of the most exciting developers and sellers of appropriate organic materials says, "Plextronics technology enables companies to focus on scaled-manufacturing. Essentially, our inks enable improved performance with custom formulated, low-acidity conductive inks. These inks provide companies and researchers the world-leading performance and consistent supply required to focus on product commercialization, which is extremely important for our industry as a whole."

There are many other distinct sectors emerging in the burgeoning photovoltaic marketplace. Cadmium telluride thin film photovoltaics proves to have superior cost per watt over life and it is flexible and already ordered in billions of dollars for architectural use, yet printed copper indium gallium diselenide CIGS promises something better.

The subject is moving forward very rapidly with new principles and morphologies also part of the picture - from nantennas to inorganic nanowires and solar islands. All the above organizations and approaches will be covered in the unique conference Photovoltaics Beyond Conventional Silicon in Denver, Colorado June 17-18. Indeed, the subject will be brought alive by optional visits to the National Renewable Energy Laboratory (NREL), legendary center of research and validation of the superlatives in the subject.

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Polar explorers have successfully used portable solar panels to charge equipment in the Antarctic. Robert Swan - the first person to walk to both Poles - spent more than two weeks relying on solar power and other forms of renewable energy for the E-Base Goes Live project.

In poor weather and limited sunlight, his team used dye-sensitised thin film solar cells to power satellite, digital and video conferencing technology. The solar cells, produced by Cardiff-based firm G24 Innovations (G24i), do not contain silicon, are lightweight, and do not need direct sunlight.

Robert Hertzberg, chairman of G24i, told edie: "It just needs ambient light - that's the unique selling point. We have used it indoors with the light coming in through the window." He added: "I am over the moon about how it worked in Antarctica."

Robert Swan said: "Levels of sunlight in Antarctica are extremely poor so it is a huge endorsement of G24i's technology that we have had a constant supply of energy. It demonstrates how effective solar power can be."

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