9 Figure 47 Left Aerial view of Apple Park the corporate headquarters of Apple

9 figure 47 left aerial view of apple park the

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Figure 4.7 . Left: Aerial view of Apple Park, the corporate headquarters of Apple Inc., located in Cupertino, California, one of the biggest solar roofs in the world as of 2018 (Credit: Daniel L. Lu CC BY-SA 4.0 ). Right: Closer image of solar panels made of photovoltaic cells on a flat roof (Credit: AleSpa CC BY-SA 3.0 ). Figure 4.8 . Flat plate solar thermal collectors used for heating water deployed on the roof of a hotel in Santorini, Greece (Credit: 23x2 CC BY-SA 3.0 ). Solar thermal collectors An alternate type of active solar power device, solar thermal collectors may require the input of some energy to pump a heat-absorbing fluid medium through a collector to store and distribute the energy. Fans or pumps circulate air or heat-absorbing liquids through collectors and then transfer the heated fluid directly to a room or to a heat storage system. The collectors absorb and transfer heat to a fluid (water or air) which is then circulated to provide heating to a 10
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building. The solar collectors are either concentrating or non-concentrating. In the non- concentrating collectors , the surface area that intercepts the solar radiation is the same as the area absorbing the radiation. Flat-plate collectors are the most common type of non- concentrating collectors and are used to heat air or water to temperatures of less than 100°C. This type of solar thermal collector is shown in Figure 4.8. In concentrating collectors , the surface area intercepting the solar radiation is greater, sometimes hundreds of times greater, than the absorber area. The collector focuses or concentrates solar energy onto an absorber. The collector usually moves so that it maintains a high degree of concentration on the absorber. Solar thermal systems Solar thermal systems , like the one in Figure 4.9b use concentrating solar collector systems to collect and concentrate sunlight to produce the high temperature heat needed to generate electricity. All solar thermal systems have solar energy collectors with two main components: reflectors (mirrors) that capture and focus sunlight onto a receiver . In most types of systems, a heat-transfer fluid is heated and circulated in the receiver and used to produce steam. The steam is converted into mechanical energy in a turbine, which powers a generator to produce electricity. Solar thermal power systems have tracking systems that keep sunlight focused onto the receiver throughout the day as the sun changes position in the sky. Figure 4.9: (left photo) Rooftop Solar Installations on Douglas Hall at the University of Illinois at Chicago has no effect on land resources, while producing electricity with zero emissions. Source: Office of Sustainability. (right photo) Solucar PS10 solar power tower in Andalusia, Spain, is a solar thermal system that generates electricity commercially. (Photo by Afloresm Solucar PS10 CC BY 2.0) 11
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4.2.2 Environmental impacts of solar energy Solar energy has minimal impact on the environment, depending on where it is placed. The
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