YOMAG - Environment - Solar Energy

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Solar Energy

Tesero 20. 01. 2008

The history of solar energy is as old as humankind, but only in the last two centuries we started using Sun’s energy to make electricity.

The first scientist who studied the phenomenon of solar energy was Alexandre Edmond Becquerel, who in 1839 discovered that some materials exposed to sunlight produced a small quantity of electricity.
Later on also William Grylls Adams, and his student Richard Evans Day, discovered that selenium, a solid material, produced some electricity when exposed to light. Selenium’s photovoltaics cells were able to convert light to electricity at 1 to 2 percent efficiency.
The word that we use to describe converting sunlight into electricity is Photovoltaic (PV): photo means pertaining to light, and voltaic means, to produce voltage. But at the beginning the concept of electricity from sunlight was only an experiment, because few people believed in the possibility. It therefore took more than 100 years to accept that it was not an experiment but an important achievement that could be exploited.
Several years later many people tried to find new ways to reach a better efficiency with solar energy and photovoltaic cells, and then finally in 1993 in the U.S. people began to build the first grid-supported photovoltaic system. We also know that in the year 2006, solar cell production reached 1,868 megawatts, and that’s a very good result.

But how can we use solar energy?
The heat of the sun and its light produce a big source of energy, that can be used in many ways. In fact there are a lot of technologies developed for the exploitation of solar energy, like for example solar power systems, photovoltaic systems, solar hot water and solar processes for space heating and cooling.
Solar power can be used in many sectors, starting from factories to offices, they save money because they don’t have to pay electricity bills. House owners use solar power systems for heating and cooling and for water heating, and there is still some energy left that can be used to produce electricity for computerized equipment, televisions, radios or electric household appliances.
There are a lot of solar panels, but the most used are: photovoltaic panels and solar hot water panels.
The first produce electric energy for domestic use, while the second heats sanitary water for daily use, without using gas or electricity.
Most solar water heating systems for buildings are made of two parts: a solar collector and a storage tank. The most common collector is called a flat-plate-collector. Flat-plate solar collectors are typically installed on a rooftop facing south. In the flat-plate collectors there is a fluid, that has to be heated by solar energy.
For more technical information, please see the following site from which I have taken some relevant notes: http://www.nrel.gov/learning/re_solar_hot_water.html
The common questions people asks regarding solar panels are: “but and when it rains?”, “and when it’s cloudy?”, “and during the night?”. Solar panels produce a lot of solar energy, and suppose we don’t use it all, the rest is stored inside for the night or when there is bad weather.
In Italy we have an average insolation of 1500 KWh/m2 every year, and if we install 160.000 m2 of solar panels in an Italian region, families save 8 million m3 methane for the heating of water or about 80 GWh of electric energy. This information comes from the site: http://www.ecoage.it/pannelli-solari.htm; it is an Italian site because I wanted to share some information about Italy.
But solar panels aren’t only used in buildings and houses, there are also some games for children or calculators that work with solar energy. And in some streets with luminous signals, there are little solar panels that make them work.
The most important thing of solar energy is that it’s natural and it does not pollute.