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الأربعاء، 22 سبتمبر 2010

What is Solar Energy?

Solar power is a renewable energy source, which is energy from sunlight. What is so attractive about solar power is that it is clean, free energy from the sun. It is on the path to living a more sustainable, environmentally friendly lifestyle. There are two types of solar energy: thermal energy and electric energy.
Thermal energy is everywhere; it heats up Earth, our bodies, and homes. It’s also used to heat water for domestic use. There are two ways in which water can be heated: actively, when a conventional heating element within the solar hot water system heats water on hot days, and passively, when water is preheated before it is delivered to the cold inlet of a conventional gas/electric water heater.
Electric energy uses the power of the sun to produce electricity through solar cells, otherwise known as photovoltaics (PV). It can be applied in three ways: stand-alone, grid-connected, and back-up. Stand-alone, also called Solar Home System is a system not connected

to the grid. These systems are installed in remote areas where there is no utility-supplied power. A solar home system consists of solar panels, an inverter, a battery, a charge controller, wiring, and a support structure. It is cheaper to install a solar energy system than lay electricity cables o the site. Excess energy can be stored in a battery for use during times where there is no sunlight. Grid-connected is a system where utility supplied electricity is connected to the property, but the owners wish to harvest clean, free energy from the sun. Electricity is supplied firstly from the solar energy system, then the connected battery, if one has been installed, and finally from the grid is there is still a need for energy. Back-up is a system connected to an unreliable grid or one of poor quality. These types are usually installed in areas where a lot of power blackouts occur. A small system will service the most important electrical appliances and lights, but a bigger system will be required to keep the fridge running during a blackout.
Solar power has the potential to provide over 1,000 times the total world energy consumption according to figures in 2008. However, in 2008, solar power only supplied 0.091 quadrillion btu, which is 0.02% of the world’s total energy supply. Solar power plants face high installation costs, although this has been decreasing over time.  Hopefully, solar energy would become the dominant energy source within a few decades. With the increase in availability, solar e
nergy is becoming more economically accessible. There are increases in the production and installation of solar energy systems throughout the United States as well as globally (U.S. EIA, 2009). With the increase in solar energy systems, energy coming from renewable energy sources will go up, decreasing the United States reliance on other depleting natural resources: oil and petroleum. In addition, relying more on a renewable energy source will coincide with the country’s sustainability efforts.

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