So, How Much Power Could Solar Cells Contribute To The World?
Written by Neal Babcock
Solar cells, also known as photovoltaics, use semiconductor materials to convert sunlight into direct electrical current. As of now, they provide just a small portion of the world’s electricity. Their global generating capacity is about 5000 MW, or only 0.15% of the total generating capacity from all sources. Still, sunlight could provide as much as 4500 times as much energy as the world currently consumes.
You must admit, that’s pretty impressive.
Due to technology improvements, the cost continues to decline. There are many government policies that are favorable to solar power in many states and nations, so the annual production of photovoltaics has increased by more than 25% a year over the past decade. Japan currently has solar cells that produce 833 MW. Germany produces 353 MW and the United States produces 153 MW.
Solar cells can be made from quite a range of materials, from those traditional crystalline silicone wafers that still dominate the market to a very thin-film silicon cell. There are even solar cells composed of plastic or organic semiconductors.
Thin-film photovoltaics are cheaper to produce than crystalline silicon cells but are not quite as efficient at turning solar power into electrical power. In some laboratory tests, crystalline solar cells have achieved efficiencies of 30%; current commercial cells of this type range from 15-20%. Both laboratory and commercial efficiencies for all kinds of solar cells have been rising steadily, indicating that by increasing research efforts, we could further improve the performance of solar cells.
Solar voltaics are easy to use because they can be installed in many places. They can be put on roofs or walls of homes and office buildings, in huge arrays in the desert, or even attached to clothing to power portable devices, such as an iPod.
California has joined Japan and Germany in leading a push for solar installations. A program called the Millions Solar Roof commitment is intended to create 3000 MW of new generating capacity in the state of California by the year 2018. Studies done by the Renewable and Appropriate Energy Laboratory at the University of California, Berkeley, informs us that annual production of solar voltaics in this country could grow to 10,000 MW in just 20 years if these current trends continue.
The biggest challenge will be lowering the price of the photovoltaics, which are now pretty expensive to build. Electricity produced by crystalline cells have a total cost of about $.23 per kilowatt hour, compared with $.04 to $.06 for coal-fired electricity and $.05 to $.07 per power produced by burning natural gas.
The cost of nuclear power is harder to determine, because people tend to disagree on how many expenses should be included as part of the total cost. However, though, the estimated range is between $.02 and $.12 per kilowatt hour.
Surprisingly enough, Kenya is the global leader in the number of solar power systems installed per capita, though not the total number of watts. More than 30,000 small solar panels, with each one producing about 20 watts, are sold in that country annually. For as little as $100, the system can be used to charge a car battery which can then provide enough power to run a small lamp or a small television for a few hours a day. More Kenyans adopt solar power every year than make connections to the country’s electric grid.
