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Cut-price solar panels follow the Sun
08 December 2006
NewScientist.com news service
Duncan Graham-Rowe

Enlarge The same power from less material

A solar panel designed to cut the cost of harnessing the sun's energy will go on the market next year. Its trick is to focus sunlight that strikes the entire panel onto far smaller slabs of the pricey material that turns light into electrical energy.

Called Heliotubes, the panels are designed to improve on today's solar concentrators, which use sun-tracking dishes to collect sunlight. These dishes need space in which to move, so they occupy twice the area of flat panels that gather the same amount of light. This rules them out for sites like rooftops where space is limited. They also need an external power source to keep them pointed at the sun.

Each Heliotube panel is made up of 10 troughs, each 1 metre long and 12 centimetres wide, which use motorised lenses to focus light onto a strip of photovoltaic material only 12 millimetres wide. The unit is self-sufficient, because even when the troughs are pointing away from the sun, they generate enough power to drive the motor that swivels them back into position.

By concentrating sunlight onto the photovoltaic strip, a 1.8-square-metre panel of Heliotubes can produce up to 175 watts - about the same as a conventional solar panel of the same area. But as they require only about one-eighth as much expensive and hard-to-source photovoltaic material, they cost about a third less, says Brad Hines of Practical Instruments in Pasadena, California, which developed the technology.

The company is working on an advanced panel with troughs that can swivel on two axes, to track the sun's changing height in the sky as well as its direction. Hines claims that the new panels, whose collectors resemble egg cartons, should produce more than twice the power of conventional panels.

From issue 2581 of New Scientist magazine, 08 December 2006, page 32

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