Let the Sunshine In

Aug 29, 2007 4:44 PM
By Lou Pechi, President, STRATA-Strategic Advisors, San Diego, Calif.

In the past, power-supply designers concentrated mainly on designing devices that convert high ac voltages to stable, low dc voltages. Today, such devices perform these tasks at ever-increasing efficiencies and increased capabilities of intelligent communication with each other, to provide higher reliability power conversion.

In one of my past articles, “The Electric Grid – Now and in the Future”, I indicated that based on the recent developments and direction of the energy grid, future designs will provide new design challenges. Converting low dc voltages to the high ac voltages required by the grid, and the complexity of controlling and managing the multitude of such, remote generating locations will challenge the next generation of engineers.

The established hydroelectric, and the polluting nuclear, oil, coal and steam power-generation methods, which presently provide the bulk of the power, are gradually being augmented by clean wind and solar generators. Sun energy and wind energy – while clean and free – provide new challenges of power harvesting, power conversion and power transmission.

Power generating solar and wind locations are mainly a function of regional geography. Solar panels dominate the always-sunny southern regions of the world, as shown on the map. Meanwhile, wind turbines are ubiquitous throughout the world wherever the winds prevail.

To paraphrase Nate Lewis of the California Institute of Technology: "There is plenty of energy hitting the surface of the earth to meet the world’s entire energy needs that could totally solve humanity's energy problem."

Conversion of sunlight to high-voltage ac a is not a simple matter, as I learned during my visit this summer to Valdarno, a small hamlet south of Florence, Italy. Nestled in a small valley, the modern 180,000 ft2 Power-One facility, previously owned by Magnetek, is surrounded by hills topped with stone hamlets.

Figure. Optimum world solar generation regions. The color code indicates kilowatt hours per meters squared per day. (The diagram is courtesy of Nate Lewis of the California Institute of Technology and Siemens Solar Industries.)

My charming host, Avelardo Farri, in his slight Italian accent, enthusiastically talked about the company’s new 97% efficient dc-ac power converter. While this article is not intended to be a travelogue or product promotion, I feel that we can all learn from some of the challenges involved in converting solar- and wind-power energy. In this column, I’ll cover what I learned about solar conversion.

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© 2007 Penton Media, Inc.