Southern California based Boeing subsidiary Spectrolab Inc., announced yesterday that a solar cell it manufactured has set a new world record for terrestrial concentrator solar cell efficiency--what on earth does that mean?. The cell can convert 41.6 percent of concentrated sunlight into electricity. The local team takes the record away from the Fraunhofer Institute in Germany, whose previous world record cell was able to convert 41.1%. The world record was validated by the U.S. Department of Energy National Renewable Energy Laboratory in Golden, Colo., which independently tested the efficiency of the Spectrolab cell.

So what is a "terrestrial concentrator solar cell"? You will not be putting these on your roof, unless your house is the size of a Wal-Mart. Although according to the company, "Spectrolab cells power 60 percent of all satellites orbiting the Earth, as well as the International Space Station", these new record setting cells are designed for use on earth, hence, they're called terrestrial. David Lillington, president of Spectrolab, indicated the light spectrum in space is different than on earth, so the design of the cells is different.

These cells use sunlight which has been concentrated by mirrors and/or lenses, thus, they are called "concentrator" cells. Using the same process by which a magnifying glass can direct sunlight to burn a piece of paper, these cells use sunlight which has been concentrated by a factor of between 500 and 1,000. Lillington said "These can be equivalent to 500 suns intensity or even a thousand suns intensity, so it's very, very bright light."

Also, this type of cell requires direct sunlight, which means that the system must employ mirrors to achieve concentration, plus a moving mechanism of lenses to keep the cells pointed directly at the sun as it moves across the sky during the day.

According to Lillington, the solar cells which you might put on your roof, do not need to be pointed directly at the sun and they do not use concentrated sunlight. This means that it requires many more cells on your roof to produce the same amount of electricity. He indicated the typical efficiency of residential cells is between 10 and 18% of unconcentrated sunlight. Thus, the Spectrolab cells are more efficient by the concentration factor.

There is a cost, however, of the systems of mirrors and lenses needed to use these high efficiency cells. But, they use much less semiconductor material. Lillington said "If you are using concentrated sunlight, you need about 500 times less semiconductor material and if it's twice as efficient, 1,000 times less semiconductor material, but you do need lenses and some sort of tractor system to track the sun."

Thus, the minimum cost effective size is much larger than needed for a single home. Lillington said the typical smaller application might be greater than 50 kilowatts, where a typical home might need about 5 kilowatts. Spectrolab is targeting systems for larger solar power producers, such as solar farms which provide power to the grid.

Lillington said Spectrolab currently manufactures about 100 megawatts worth of solar cells with an average efficiency of about 38%. They employ about 450 people and expect that number to increase by about 50 associates next year as they ramp up production. Lillington said they expect to be producing about 300 megawatts of 40% average efficiency cells by the end of next year. Even though the new cell achieved a 41.6% efficiency, Lillington said production efficiency is usually a little less than the maximum.

The cost effective production of high efficiency solar cells is part of reducing the need for fossil fuels to produce electricity. Lillington said the cost of electricity produced by solar farms "needs to be comparable with what we pay on our electricity bills every month. Where we are making the breakthrough is that we are able to make solar cells with 40% efficiency now, and ultimately 50% in the future, that brings the solar technology one step closer to being able to generate affordable electricity."

Spectrolab Inc. is part of Boeing Space & Intelligence Systems in El Segundo.