Electrical Apparatus magazine, August 2004 Electricity From the Sun--Where do we Stand?"

Unlimited electrical energy throughout the world--that's the promise of using arrays of silicon solar cells to directly convert sunlight into electricity, a technology known as photovoltaics. Such a cell produces a low d-c voltage. Connecting multiple cells in series-parallel groups, then connecting their output to an inverter producing alternating current, allows a photovoltaic system either to serve as an isolated generator or to be directly connected into the utility grid.

Such systems are being used in developing nations, where utility grid power is unavailable, to operate pumps, light school buildings, support agriculture, and otherwise improve living conditions.

Much larger installations (with outputs in the megawatt range) have been installed in industrialized countries, most often as heavily-subsidized experimental projects. Such efforts have supported development of new types of cells such as those using "thin film" crystalline silicon.

Solar cells alone represent only part of the system cost. The inverter, controls, and backup battery or generator (for operation at night or in overcast weather) add significant expense.

Consequently, the cost of photovoltaic energy remains prohibitive in most areas where alternatives exist. In the United States, the Department of Energy continues to support photovoltaic research with $75 million to $100 million annually. The goals are an equipment cost approaching $1 per peak watt of output, and an energy cost of $0.08 to $0.10 per generated kilowatt hour. Both goals have proven difficult to achieve.

One obstacle continues to be the low value of energy conversion efficiency--the percentage of solar energy that the cell can turn into electrical output. Instead of the 30% to 40% efficiency needed, figures have ranged between 5% and 20% for many years.

Nevertheless, the market for photovoltaic equipment continues to grow at from 15% to 35% per year. Worldwide, the total solar power generating capacity now exceeds 2000 megawatts.

Industry news...

Featured Technical Article
August 2004

On this page is a summary of the Electrical Apparatus August 2004 featured technical article, by Richard L. Nailen, P.E. , "Electricity From the Sun--Where do we Stand?"" Elektrizität aus Sonnenenergie - Wo stehen wir? ... Électricité solaire - Oú en sommes-nous? ... Electricidad solar - ¿donde quedamos?..

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