August 31, 2007

Mirrors help solar energy option

Some people have known the properties of mirrors for a long time. Magicians, for example, have often used them to create illusions of reality. So have politicians.

Now engineers have come up with a way to use them that could mean generation of solar electrical power at half the cost of existing solar systems.

One of the problems of most alternative energy technologies has long been cost. Wind power was pricey, although it has improved a lot. Solar power, tidal power, hydrogen fuel cells — all of them work, but at a price.

Internet Resources

Korky Koroluk

A large part of the cost of solar power is the price of the photovoltaic material needed to collect the sun’s rays and convert them to electricity. But a new mechanism has been developed for focusing light on small areas of the material so that much less of it is needed. The result could be solar power for both residential and commercial applications that will be cheaper than electricity from the grid in most parts of North America. It’s likely to happen in just a few years.

In fact, one company, Soliant Energy, plans to begin shipping such a system before the year is out.

The idea of using mirrors to concentrate the sun’s rays is scarcely new. Archimedes, the great Greek mathematician, used parabolic mirrors, or “burning glasses” to destroy an invading Roman fleet in 214 BCE. The story is probably myth, but we know from the writings of some of his contemporaries that Archimedes understood the principle.

Parabolic mirrors are in fairly common use today in large arrays of cells built on the ground because of their size. There are occasional roof-mounted systems, too, but they are pole-mounted so they can pivot easily to follow the sun as the day progresses. This makes them vulnerable to storm damage, and they haven’t become popular.

Soliant has come up with a concentrating system in which elongated solar cells are mounted in tilting reflective troughs. The tracking system is built into the panel.

The system uses 88 per cent less photovoltaic material than traditional panels, which brings the cost down. Because they are built into flat, rectangular frames, installation is simple and cheap.

The company’s first offering will be for commercial roofs, although it plans to launch a product for residential use next year. It claims that installation of those will be so simple any handyman will be able to do it.

The system has caught the attention of both the Massachusetts Institute of Technology and the U.S. department of energy.

Scientists at both places are enthusiastic, although they point to a few drawbacks.

Because the troughs are close together they shade each other during parts of the day, and that decreases the total amount of electricity they produce. And since they only track from side to side, it’s not possible for them to follow exactly the arc of the sun across the sky.

But Soliant is already at work on a second-generation system in which each trough will be divided into sections. Each of them will be able to pivot from side to side and also up and down for more precise tracking.

Also in the works is more efficient photovoltaic material that will produce three times as much power per unit of area, and be cheaper as well. And, company officials say, it will remain as simple to install as the first-generation device.

Sustainability has become an important concept for the architecture-engineering-construction industry, so a cheaper, more efficient way of generating electricity should attract immediate attention.

For if all this turns out as planned, commercial buildings with these flat, concentrating photovoltaic panels on the roof will be able to achieve electrical self-sufficiency. And, given a somewhat larger roof, it may be possible for a system to produce surplus energy that can be sold to the local grid.

More information is available at www.soliant-energy.com.

Korky Koroluk is an Ottawa-based freelance writer. Send comments to editor@dailycommercialnews.com

Print | Email | Comment