subject: Photovoltaic Systems [print this page] All photovoltaic solar cells work by converting sunlight directly into electrical energy through a fairly complex process. However photovoltaic systems differ from one another, with varying characteristics depending on their applications. Furthermore, a photovoltaic system may be of the concentrated solar thermal type (CST) or a concentrated photo voltaic (CPV) array.
Ancient Technology
Of the two types of solar technology, CST is the older by several hundred years, in fact. About 2,000 years ago experiments with mirrors and the magnification of sunlight using glass were taking place in Han China as well as Classical Greece. Using concentrated sunlight to boil water to run machinery has been done since the late 1800s. But it wasn't until almost 1970 that parabolic mirrors and focusing lenses were assembled into arrays that would enable the use of solar heat for boiling the large amounts of water needed for running turbines.
Unfortunately, these CST plants aren't particularly efficient because some heat energy is invariably lost in the process. The next generation of solar cell technology, photovoltaic solar cells, are another matter, however.
Going Direct
A photovoltaic cell is a device that directly converts sunlight into electrical energy using semiconductors (generally this is silicon mixed with other elements, but other configurations are being studied). Although a CST array allows for greater control over temperature, a CPV array is more efficient at generating electricity.
The Problems And Solutions
Currently, it is not practical to build an entire power plant that runs off of photovoltaic solar cells; the cost would be prohibitive (around $1 billion dollars). In addition, the best locations for such facilities are far removed from the grid and would require massive construction projects. The bottom line for consumers is that electricity would cost as much as .18c a kilowatt hour well over twice the national average.
The technology behind the photovoltaic solar cell is constantly advancing, however, and they are steadily becoming lighter and more portable. In addition, the cost to build CPV arrays is falling, as is the case with most technology, meaning that they are affordable for individuals and small organizations.
This means that in the future, a photovoltaic system is likely to be a small setup that powers an individual home or building something that is going to be practical and cost-effective within a few years.
