Photovoltaic cells are seen as one of the leading alternatives to “traditional” energy. It is a renewable source that will never go out. No matter how much of its energy we transfer.
The theories of what we call “alternative” energy are actually the first energy sources known to man, that we know of. Windmills and wind generators are all over the world and have been used by farmers for as long as anyone can remember. There have been generators that used river current and ocean current as a source of power by natives all over the world, long preceding modern energy plants.
The only use, of some of the Egyptian batteries that have been uncovered, seems to be photo voltaic. Using nature's sources for power in one form or another has been shown by American Indians, South American Indians, Aborigines, Swedes, Germans, Celts, Chinese, Japanese, Vikings, Romans, Greeks, Egyptians, Persians, and just about any other group of people that you can think of. However these natural resources didn't start being looked at for modern electricity until the mid twentieth century when governments started doing research on how to power space stations.
Modern photo voltaic cells have been around since, at least, the nineteenth century. They weren't really studied or made efficient until the 1960's when we were trying to figure out how to power stations in space. Now energy companies are using photo voltaic cells as an alternative power source. The effectiveness is going up and the cost is coming down, to the point that, potentially it will be cheaper for each house to have its own energy source than it will be to pay an electric bill. There are many people that are using photo voltaic cells to power their electric fences, back up generators and some are even using it as the sole source of power for their home.
Ideally, we will all be able to cost effectively, power our own homes using our roofs, windows, siding, or any number of other aspects that are already there. Best of all, we don't need to worry about reducing the stockpile of petroleum or coal based fuels for our energy sources.
