Wednesday, May 15, 2013

How do the Solar Panels generate Electricity?

Most of us may be aware of the growing importance of Solar Energy in the modern era.  This is because of the shortage of the conventional energy available for all.  There are some remote villages in India where you do not see electricity.  Even if there is electricity connection, there are lot of power cuts now a days.  So the Solar electricity has attained a growing importance.  Many of you may not be knowing how the sun light is converted into electricity by the Solar Panels.  It is very important to know how the Solar Panels generate Electricity.

Solar Panels produce electricity (Direct Current) directly from the sun light.  The Sun light is directly converted to electricity by each solar cell in the panels.They do not need direct sun light to work - they still produce some electricity on some cloudy day also.  

The Solar Panels are made up of circular, rectangular or square shaped solar cells.  These solar panels have p-n junctions.  The solar cells are also called as Photovoltaic cells (PV) and the process of generating electricity from sun light is known as photo voltaic effect.  The P-N junctions are made of semi conductors.  The efficient of these solar cells must be as high as possible to produce more electricity and the efficiency depends on the type of material used for p-n junctions.   The present efficiency level is only 15 to 16 % and in future it may go beyond 25 to 30%.  

The sun light is made of photons.  The photons convert into electrical energy when the p-n junctions are placed in sun light.  When the photons of sufficient energy strike a solar cell, they knock out free electrons  in the silicon crystal structure and force them to travel in external circuit ( battery or a DC load) and then return them back to other side of solar cell to start the process again.

The voltage from a single solar cell is about 0.5 Volts with amperage output directly proportional to the cell's surface area.  It is roughly 7 amps for a 6 square inch area.  Normally 30 to 36 solar cells are wired in series in each solar panel.  This produces a solar panel with a 12 Volts nominal output ( 18 Volts peak output) which can be wired in series or parallel with other solar panels to form a complete solar array for charging a 12V, 24V or 48V Battery banks.  Here is a video showing how a solar panel generates electricity.,



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