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US PV firm develops world’s largest ultra-thin solar cell

Solexel’s flexible silicon cell has proven efficiency of over 19%

The silicon cell is a new development for solar cell technology

A US PV firm has developed what it claims are the world’s largest ultra-thin solar cells. The full-square 156 by 156mm back-contact cells, which California firm Solexel has developed, are the largest ultra-thin crystalline silicon solar cells, according to the company. Solexel said the cells have a proven efficiency of 19.4 per cent in its pilot factory, a world record for thin film silicon.

The cells are made from an ingot and wafering process. Inexpensive trichlorosilane gas is deposited on a reusable mono-crystalline silicon template, through a process called epitaxy.

A proprietary tool releases the ultra-thin cell from its reusable template, which can be reused more than 50 times, without any degradation in cell performance.

Solexel cells can also bend and flex, making them unaffected by wind or snow load. This means they can be made without a frame, which lowers production costs.

Solexel said: “Our cells are made of an ultrathin layer of mono-crystalline silicon (35 micron, compared to 150-160 micron for a normal silicon PV cell), attached to a specially designed backplane material (approx. 100 micron). Thanks to their thinness, our cells can be bent, without causing damage to the cell.

“The benefits of flexible cells are applicable to a range of market segments. For instance, weight-restricted roofs (flat commercial roofs) benefit from lighter modules, and reduced cost of course benefits all segments.”