Photovoltaics: Safe, Clean Electricity from the Sun

July 31, 2006
Photovoltaics have a number of unique advantages over any other electrical-energy source

By J. Peter Lynch

Photovoltaics (PV) or solar cells, as its name implies, is a technology that converts sunlight directly into electricity (photo = light and voltaic = electricity).

Photovoltaics are starting to show up everywhere you look: as the power source for emergency phones on highways (PV is the little module on the top of the roadside pole), wristwatches, desk calculators, yard lights, and, increasingly, on the rooftops of commercial buildings.

Photovoltaics have a number of unique advantages over any other electrical-energy source (minimal maintenance, high dependability, durability, long life [30-plus years], silent operation, maximum output coincident with peak utility power loads, no emissions, easy installation, available everywhere there is sunlight, and an ability to integrate into existing and new buildings).

How Do Photovoltaics Work?
Photovoltaic cells are currently made of semiconductor material such as silicon, which is the most commonly used material. When light (photons) strikes the solar cell, a certain portion of it is absorbed within the cell material. This flow of electrons creates an electrical current; by placing metal contacts on the top and bottom of the PV cell, this current can be drawn off to use externally to charge a battery or power a device, a home, or a small town.

If more power is needed, a number of cells are put together to form a module. If even more power is needed, the modules are grouped together to form arrays. These arrays can range from a small number of modules to power a home to thousands of modules to power a town or city.

The Current Market
The photovoltaic industry is already one of the fastest-growing industries in the world. It is growing at an annual rate of greater than 30 percent in total, and it is growing at close to 60 percent per year in the utility-grid-connected market segment.

Most analysts assumed that PV would only be deployed in remote locations where power lines were not available. However, because of tax incentives and beneficial legislation, the majority of new installations are not in remote locations, but are on commercial buildings and homes, and in states and counties that offer the best incentives. (A listing of federal and state incentives can be found at [].)

Currently, the photovoltaic industry is facing a silicon feedstock shortage, resulting in product demand dramatically outstripping supply with a resultant slowdown in growth that will be reflected over the next few years.

The Future Market
This silicon shortage will result in a number of key developments: First, the production of silicon feedstock will expand dramatically to try to keep up with demand; second, the development of next-generation technologies will accelerate. The real answer to the supply problem may lie in the next generation of PV technologies that will allow production at a much lower cost and at a far greater scale. These technologies utilize various thin films, such as amorphous silicon or CIGS, which use far less material and allow far higher production speeds.

The bottom line: The future of photovoltaics is clean, safe, and, most importantly, renewable.

J. Peter Lynch is a renewable-energy expert. Lynch currently serves as a financial and technology consultant in the renewable-energy field. He can be reached at ([email protected]).

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