weekly3-V2

weekly3-V2 - Bi Weekly Report I I I May 20-26, 2011 Azraf...

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Unformatted text preview: Bi Weekly Report I I I May 20-26, 2011 Azraf Hipni ( 260278238 ) Nurul Hanim Hashim ( 260278238 ) Sivapriya Prem Kumar ( 260261057 ) Violet Kharadabineh ( 260159150 ) Tasks Done This Week : Azraf H ipni 1- Research in PV shading, its effects and solution to problem. Shading is an unavoidable problem in PV system. Since the PV panels are connected in series, if one panel is shaded, it will pull the output of the whole system down. This is because the shaded cells can act as a power consumer produced from the other cells. With new technology, this problem is gradually solved. The solution will be explained later on. As for now, let us understand more about PV shading. There are two sources of shading; the soft sources shading and the hard sources shading. As the name implied, soft sources shading reduce the amount of sunlight reaching the cell. This is basically objects that block the sunlight from reaches the panel from a distance. While there is still sunlight, the amount is too small. Hard sources shading are those that completely block the sunlight from reaching the sun. Examples include bird dropping or tree leaves that sit on top of the PV cell. Although in partial shading, sunlight is still available, output will also decrease. If half a cell or a row of cells ( as depicted in figure 1 below ) is screened, the power output of each individual shaded cell will be cut by half. But if one whole cell is shaded, it can reduce the total power output of the panel by half of it maximum output. This is because, as mention earlier, this cell becomes an energy consumer. If one whole row is shaded, total power output can be reduced to zero. Therefore, it is most favourable to install the PV panel where shading is less probably to occur. Modern PV panels have a way to reduce the effects of shading. As mentioned earlier, when a particular cell is shaded, it tends to be the power consumer. One of the features built into these PV panels is the by-pass diodes. When a cell ( or row of cell ) is shaded, it will t rigger the by-pass system of the PV panel and exclude the shaded part of the cell from consuming power produced from the other cells. Therefore, instead of having power being consumed, it eliminates the consumer from the system, and continue to produce a slightly reduce output. Figure 1 : partially shaded pv cell. a) is for a case where half a cell is shaded....
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weekly3-V2 - Bi Weekly Report I I I May 20-26, 2011 Azraf...

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