May 5, 2006 4:34 AM PDT

Old solar tech back in limelight

A handful of solar companies are focusing on a venerable technique to harvest more sunlight.

The high price of silicon--the most common material used in solar panels--is prompting engineers to design solar concentrators, devices that squeeze more electricity out of a slice of silicon or other photovoltaic cells.

Concentrators are one of many solar technologies being tested with the hope of bringing down the cost of solar power, which is seeing a surge in demand. Relatively young companies are coming to market with concentrator products of various forms. The products, aimed mainly at the commercial space, are expected to hit the market this year and next, according to company executives.

The idea of tracking the movement of the sun and intensifying sunlight with mirrors has been around for many years. But the rising cost of electricity, coupled with technical advances in making more efficient solar cells, are fueling new approaches to the concept, say experts.

"That area (of concentrators) is enjoying a resurgence, which went into disfavor in favor of flat panels," said Emmanuel M. Sachs, professor of mechanical engineering at the Massachusetts Institute of Technology. "Because there are 35-percent-efficient cells, as opposed to 20-percent-efficient cells, it makes sense to look at concentrators again."

Much of the use of solar concentrators has been with high-efficiency germanium solar cells in space or at large-scale installations, where arrays of panels are lined up in desert areas, for example, said Sachs, who developed technology at MIT now being commercialized by Evergreen Solar.

But now several companies are developing scaled-down concentrators, which can be placed on roofs and serve one building as a supplement to a grid-tied electricity source.

Although technical hurdles remain--notably excessive heat--and new machines are not yet fully proven in the marketplace, analysts said that growing demand for alternative electricity supplies is prompting entrepreneurs to experiment with new twists on the technique.

Price performance
One company, called Practical Instruments, has designed a prototype concentrator solar panel that borrows an idea out of the PC market: standard components.

The Pasadena, Calif.-based firm intends to build concentrators that fit into standard-size, flat solar panels. Its first-generation product, which the company intends to make in volume next year, will use silicon-based solar cells with concentrators placed in tubes that rotate during the day to follow the sun.

Company CEO Brad Hines said the design is meant to fit into the existing solar panel industry's delivery network for commercial buildings and potentially for residential homes.

Click for photos

"Since we install as the same solar panel, we can sell to the existing channel of installers; we don't have to build our own network," Hines said.

The first product from the company will deliver about the same amount of power for a "lot less money," Hines said, declining to offer specific pricing plans. Practical Instruments is seeking to raise a round of venture capital, Hines said.

Prism Solar Technologies, a small company based in Stone Ridge, N.Y., is also designing solar concentrators for on-roof solar panels, but is using completely different techniques.

The company's panels have special optics that use holograms, what CEO Rick Lewandowski calls a "high-tech Jell-O" sandwiched between pieces of glass. The holograms direct light onto a line of silicon cells, keeping the rays from reflecting off the panel's outer glass, to generate more electricity from a single panel.

CONTINUED: Can't stand the heat?…
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You Missed One - Green and Gold Energy in Australia
Fresnel lens concentrator. Currently in production (as far as I can
tell from their web site).
<a class="jive-link-external" href="" target="_newWindow"></a>
Posted by (10 comments )
Reply Link Flag
Interesting invention
Neat product, but for the people who did not follow the "New Inventors" show the website is a little lacking.

They have a pretty large following and I am sure someone would be willing build a more usable website for cheap or free.

After some digging I found more info on the "New Inevntors" website here: <a class="jive-link-external" href="" target="_newWindow"></a>

The "Watch broadband video" link explains how it works.
Posted by Dachi (797 comments )
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You missed
<a class="jive-link-external" href="" target="_newWindow"></a>

Company based out of El Paso, Tx


Mike Labay
Posted by Michael Labay (9 comments )
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a technology that overcomes limitations of PV
HI - two things -
1 - check out Stirling Energy Systems in Phoenix, AZ - utilizing the Stirling engine, limitations of photo V cells appears to have been overcome, effectively and efficiently...SoCal Edison has bought in big time!
2 - I want to work in a job that serves the solar energy field, potentially from the publishing perspective (editorial discussing the various competing technologies for the engineering and applications personnel serving solar ingenuity) and I'm curious if you can turn me onto some of the more reliable, reputable publications &#38;/or publishers serving the field. Also, a research firm may be providing insights to companies either investing in or evaluating applying solar/renewable resource solutions.

thanks - John
Posted by johncmoon (1 comment )
Reply Link Flag
Missed another one- Sopogy
I found another one. Sopogy, out of Honolulu, HI. They use concentrators to create power. This focus on alternative technologies is great and with the climate issues its wonderful to see the venture capitalist investing in these solutions.
Posted by hydrid (1 comment )
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