Solar+Energy+Technology

TEM 194 – Andres Vargas
 * Solar Energy **



**Background of Solar Energy ** Whether we know it or not, solar energy has actually been used for millions of years here on Earth. In fact, we aren’t the first to discover or utilize solar energy. Every living thing you see around you has found a way to harness the power of the sun and transform it into some form of usable energy. The best example of this is plants using photosynthesis to fuel themselves.

But of course what we are interested in is how Solar Energy can be converted into usable electricity.

Solar Energy has been studied since the late 1800’s and you might be surprised at how many people studied it in those times. In 1876 a man named William Adams wrote a book called //A Substitute for fuel in Tropical Countries// which talked about the use of solar power to replace energy consumption of engines. Just a few years later he was able to construct a 2.5 horsepower steam engine with the use of mirrors which would create the heat necessary to create steam. This concept was so good that even today some power plants use it to produce the energy for running the plant. Just five years later in 1883, Charles Fritz successfully con verted solar rays into electricity using a solar cell he constructed. His solar cell had a conversion rate of only 1-2%!

1954 marked a milestone year for solar energy when Calvin Fuller, Gerald Pearson and Daryl Chaplin of Bell Laboratories stumbled upon the use of silicon for solar conduction. This led to the production of the first solar panel. This solar panel had a conversion efficiency of only 6%!

**Solar Energy Today **

At this time there are only two ways that we can convert solar energy into usable electricity: **Photovoltaic devices** and **Solar Electric Power Plants.**

Photovoltaic devices are used to capture sunlight and convert it directly into usable electricity. This is the Technology that we see people installing on rooftops of building, houses, schools and in the middle of fields. These panels are made out of a semiconductor material with the most popular one being silicon. When sunlight hits the surface of the panel, electrons are released and funneled into and external chamber where they can be used for electricity. However, because the electricity produced is in Direct Current, or DC, the current must pass through an inverter which turns it into an Alternating Current (AC).

Solar electric power plants concentrate solar energy and heat fluids to produce steam which is then used to power a generator. This is done in a very similar fashion to the way William Adams powered his solar steam engine in 1878. Of course that concept has been optimized to produce the most amount of energy. There are 13 power plants in the United States that are Solar Electric Power Plants most of which are in California.

Although the first solar panel produced only 6% efficiency today there are solar panels which can produce up to 22% efficiency. As with anything though, the better the solar panel the more expensive it becomes. Amazingly though, there are several photovoltaic power plants that can produce a huge amount of energy. One such power plant in China is able to produce up to 200 Megawatts per year and another is being constructed in California with an estimated production of over 500 Megawatts. Many schools have jumped on the solar energy kick with small time players such as local high schools all the way up to the leader in solar energy which is Arizona State University. ASU now has 57 solar photovoltaic projects with the capacity to generate 15.3 megawatts across four campuses. This has allowed them to reduce carbon emissions greatly and help provide energy to power their university in a cost effective and earth friendly way.

**T ****ren ****<span style="font-family: "Verdana","sans-serif"; font-size: 21.33px;">ds ****<span style="font-family: "Verdana","sans-serif"; font-size: 21.33px;">and the ****<span style="font-family: "Verdana","sans-serif"; font-size: 21.33px;"> Future of Solar Energy ** <span style="display: block; font-family: "Verdana","sans-serif"; font-size: 16px; text-align: left;">Current trends in Solar Power show a lot of ground breaking improvements to this exciting and relatively new energy source. Many people have been skeptical of solar energy because of the fact that when it storms or is cloudy, no sunlight can be captured for energy. Additionally there are only around 12 hours in the day in which solar power can be used. But a solar electric power plant in Madrid, Spain has been able to figure out a way to use solar energy 24 hours a day and even on cloudy days. They are able to store the solar energy and dictate how much of it they want to use. Because they can ration off the energy usage, they are able to provide a continuous stream of energy to the plant. Also energy companies offer the option to store excess solar energy in batteries that you can use when the sun is not shining.

<span style="font-family: "Verdana","sans-serif"; font-size: 16px;">The movement actually seems to be leaning back towards the old method of using mirrors for creating energy. Much in the same way that a local Phoenician might use a tanning mirror to maximize their sun exposure, people are using parabolic mirrors <span style="font-family: "Verdana","sans-serif"; font-size: 16px;">to focus sun light which creates huge amounts of heat. This heat is used in a solar electric power plant, mentioned above, in order to create steam to power a generator.

<span style="display: block; font-family: "Verdana","sans-serif"; font-size: 16px; text-align: left;">This is not to say that Photovoltaic cells might one day disappear. Many researchers are still working hard to find ways to decrease the cost of producing more efficient panels. The hope is still to be able to create cheap and efficient solar panels that can be used to help relieve our country of its dependency on fossil fuel energy sources.

<span style="display: block; font-family: "Verdana","sans-serif"; font-size: 16px; text-align: left;">Sources http://www.eia.gov/kids/energy.cfm?page=solar_home-basics

http://www.powermag.com/issues/features/The-Power-of-Light-U-S-Solar-Energy-Trends_2308.html

http://www.azcentral.com/community/tempe/articles/2012/04/13/20120413asu-solar-energy-efforts.html

http://www.facts-about-solar-energy.com/solar-energy-history.html

http://www.azsolarcenter.org/

http://www.forbes.com/sites/tonyseba/2011/06/21/the-worlds-first-baseload-247-solar-power-plant/