Photovoltaic Efficiency

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Photovoltaic is a semiconductor material that functions to generate electricity, so photopoltaic on this, the semiconductor material is processed in such a way when exposed to sunlight or the light will produce direct current electric voltage (dc). Photovoltaic is also a kind of structured dioda on PN Junction.

Symbols such as its figure-1 below:

figure-1

Current versus voltage characteristics for the radiation that is different for the photovoltaic can be seen in the figure-2,

figure-2

the image-2 can be seen that the open circuit voltage that occurred (Voc) is approximately constant, but the flow will change in accordance with the amount of radiation the mengenainya. With advances in technology that has been achieved in making the photovoltaic current, effisiensinya was only able to achieve about 10% ~ 20%. So, for example, power (P) radiation from the sun is 1000 watt/m2, the power generated by photovoltaic is 100 ~ 200 watt/m2. Photovoltaic efficiency is also dependent on its temperature cells. Efficiency will be reduced at higher temperatures. Temperature measurement in the standard of efficiency is 25 degrees Celsius. Graphic efficiency for a solar cell can be seen in the figure-3.

Figure-3

To get maximum power from a photovoltaic, then the burden should be located at the point called a Maximum Power Point (MPP), which at this point is knowledgeable = V x I = maximum power (see figure-4).

figure-4

To load a constant, the point MPP can not be achieved by all the radiation. This requires a series regulator that is capable of carrying the burden to point to its MPP. This series is known as the series of the MPP (MPP regualtor circuit). But when the photovoltaic is used to charge the battery, then almost all point to the MPP approach, is to design a photovoltaic that approximately the same as the voltage is the battery voltage.

Generally, one unit solar cell able to produce only a small power. Power generated can be enlarged with the connective-connect several solar cell in series and parallel. The module is the order of several solar cell, while some of the modules will produce an array. For example in the figure-5 series parallel relationships depicted in the photovoltaic.

Figure-5

For example there are N photovoltaic units connected in parallel to M series units are linked. Consider each module has its Iout = Io and Vo = Vout for maximum radiation. So it can be said that the module or array has peak power (watts peak) of M x N x Vo x Io watt. With the output voltage of M x Vo volt current and a maximum of N x Io ampere.