Thin Solar Cells (Germany/US)

Friday, 17 July 2009 00:00

A new kind of technology used for harnessing solar power, the ‘Thin-Film Solar Cell’, is gaining ground on the traditional solar cells which are becoming an increasingly familiar sight in places such as rooftops.

UN youth magazine Tunza reports that some extra- ordinary developments based on thin-film technology are underway, such as plastics, windows and even paint that all generate solar electricity.

One development is semi-transparent thin-film cells which can be applied directly to windows as glazing. These cells will then function as window tinting while generating electricity. Such developments mean that, soon, entire buildings are likely to be providing power from the sun, not just the panels we see on rooftops.

Tunza writes that thin-film solar cells are expected to account for a fifth of the market by next year, and call this an imminent “rooftop revolution”, perhaps even one that will eventually render traditional solar cells obsolete (even though their use currently doubles every year).

TIME Magazine has also given the new technology its seal of approval, naming thin-film solar cells one of the ‘Best Inventions of 2008’.

Recent installations of thin-film cells include an ongoing project in southern California to install 250 MW of thin-film rooftop panels, a 10 MW plant in the Nevada desert, a large pitched roof system in Moers, Germany, delivering a total of 837 kW, as well as several other projects in the United States and Germany.

Thin-film cells are made by depositing one or more thin layers (thin film) of photovoltaic material on a substrate (e.g., silicon), but unlike regular silicon panels, which need to be baked in large batches, thin-panels are able to roll off the assembly line in thin strips, as if coming through a printing press. For this reason, thin-film cells are much more inexpensive to produce.

The disadvantage, at present, is their lower energy conversion efficiency, but solutions to overcome this problem are already being developed. The advantage of thin-film cells, however, is their size and weight: The thickness of these cells can be as little as a few millionths of a millimeter, thus requiring  much less space than that of wafer, or ‘bulky’, silicon, which make up the familiar circles in traditional solar cells.

Photo: Solar Energy Industries Association