外文翻译--太阳能发电的基础-精品.docVIP

The Basics of Solar Power for Producing Electricity Using solar power to produce electricity is not the same as using solar to produce heat. Solar thermal principles are applied to produce hot fluids or air. Photovoltaic principles are used to produce electricity. A solar panel is made of the natural element, silicon, which becomes charged electrically when subjected to sun light. Solar panels are directed at solar south in the northern hemisphere and solar north in the southern hemisphere (these are slightly different than magnetic compass north-south directions) at an angle dictated by the geographic location and latitude of where they are to be installed. Typically, the angle of the solar array is set within a range of between site-latitude-plus 15 degrees and site-latitude-minus 15 degrees, depending on whether a slight winter or summer bias is desirable in the system. Many solar arrays are placed at an angle equal to the site latitude with no bias for seasonal periods. The intensity of the Suns radiation changes with the hour of the day, time of the year and weather conditions. To be able to make calculations in planning a system, the total amount of solar radiation energy is expressed in hours of full sunlight perm, or Peak Sun Hours. This term, Peak Sun Hours, represents the average amount of sun available per day throughout the year. It is presumed that at peak sun, 1000 W/m of power reaches the surface of the earth. One hour of full sun provides 1000 Wh perm = 1 kWh/m - representing the solar energy received in one hour on a cloudless summer day on a one-square meter surface directed towards the sun. To put this in some other perspective, the United States Department of Energy indicates the amount of solar energy that hits the surface of the earth every +/- hour is greater than the total amount of energy that the entire human population requires in a year. Another perspective is that roughly 100 square miles of solar panels placed in the southwestern U.S. c