Wednesday, October 12, 2011

Shedding Some Light on Solar Power

American Thinker - The government tells us that we need to subsidize renewable energy providers with taxpayer money.  Global warming advocates tell us to turn to eco-friendly renewable energy sources like solar power.  They insist that viable alternatives to fossil fuels (like solar) are being ignored because the energy industry is resisting conversion to clean power to protect profits — at the expense of the planet.  But before we padlock our coal- and natural gas-fueled power plants, let’s take a look at the facts and figures regarding solar power.

First, let’s take a look at the sources of our electricity.  Solar power currently provides less than 0.07% of the United State’s electricity.  So if we increased our solar power capacity by a hundred times,  it would still provide us with only 7% of our energy needs.  Study the data in the graph and chart below form the U.S. Energy Information Administration. Solar power is included in “other renewables” — it is so small that it does not rate a call-out.

There are two methods to harness the power of sunlight.  One method works by focusing the rays of the sun to the point where enough heat is generated to boil water (solar thermal power). The resulting steam is used to power a turbine, which turns an electric generator and thereby produces electricity.  The second type of solar power (photovoltaic) converts the energy of the sun directly into electricity.  This second method is the focus of this article.

Photovoltaic solar cells are made of material very similar to the material used to make computer chips.  When exposed to sunlight, the molecules in the solar cell interact with energy from the sun to produce a flow of electrical current.

Solar cells are rated at optimal conditions, which for a solar cell are a cloudless, cool day at noon at a place on the planet where the sun is directly overhead.  If the sun is directly above the cell, the maximum amount of energy is produced.  As the angle the cell makes with the sun deviates from straight-down, the cell’s power output drops off.  Cloudy and stormy days and places where the sun is low in the sky produce only a fraction of the rated power.

Prime time for solar power is from a few hours before noon to a few hours after.  So even in the best of circumstances, the cell’s output will be low in the mornings and evenings.          More