So for a better understanding of this important technology, this section shall explore how Electricity is generated from rays of light coming from the sun as bases for understanding the working principles of Solar power system.
PHOTOVOLTAIC CELLS: ELECTRIC GENERATOR
You must have heard people talk about Solar Panel or PV Modules before; well they are referring to the same thing. PV actually means Photo Voltaic Modules. In actual fact, the solar panels you may have installed on your roof top or may have seen, is made up of many PV cells arranged together in a way to achieve highest possible efficiency for desired application.
Here is how the technology works.
We explained earlier that all materials have atom as their smallest indivisible part; but each atom contains nucleus and electrons. The electrons move freely around the nucleus and it is negatively charged.
When light particles (called Photon) -which is the positively charged rays of light from the sun, hits some materials, the electrons get excited and moves faster. Some even attempts to jump out. The rate of movement of the electrons, relative to the position of the nucleus in the atom and resultant effect, varies from materials to materials. In some materials, this produces intense heat, which is harnessed, preserved and used for food preservation, water heating and other applications.
For production of electricity, some special materials called semi-conductors are used. Semi-conductors as we explained earlier in this series are materials that permit the flow of electron in one direction only, until certain conditions are changed. In this particular application, two different types of these materials are fused (combined) together to accentuate the flow of electrons (creating current) in a particular direction when excited.
Thus, when the sun rays hit the semiconductor materials, the electrons get excited and tend to flow towards a particular direction, thereby producing Direct Current or what is called Photovoltaic effect. The currents of electrons flowing from a combination of these materials are then connected together and so, electricity is generated. These combinations of semiconductor materials are grouped together to form PV cells. Typically, 40 of them are then combined into modules. Several PV modules (10?) are then connected together in particular format to get the desired flow of electrons, called current at the right pressure or voltage, to produce the desired energy or Power.
A flexible glass material that would enhance the impact of rays of light on the cells is then mounted with aluminum frames to solidify the panel.
As long as sunlight shines on the surface of the PV cells, at the right intensity and angle, electrons would be liberated to flow towards certain direction, which leads to production of electricity.
This process is similar to the way battery produces electricity; the only difference is that batteries uses chemical actions to produce electricity. At a later time, we shall deal with this process in this part 6 of EMS series.
Whether Battery or PV, take notice that electricity been produced is DC (Direct Current) not AC (Alternating Current). Also note that AC is used in our homes, not DC.
We shall later get to how the DC is eventually converted to AC to be used in our homes and offices.
NEXT: Solar Panel Types and Sizing
©Tunde Y. Salihu, 2017
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