Monday, May 13, 2013

What are Solar Panels

Solar Panels are Eco Friendly electric generators.  The solar panels generate free power from sun light by converting sun light into electrical energy.  You can see a collection of individual silicon  cells in each solar panel.  The solar panels generate electricity with no moving parts, zero emissions and no maintenance. 

The photos ( light particles) produce electric current as they strike the surface of the thin silicon wafers.  A single solar cell generates about 0.5 volts.  A normal 12 Volts solar panel has 36 cells wired in series to produce about 17 to 18 volts peak output.   A 24 Volts Solar Panel contains about 72 cells.  When a solar is charging the battery, this 17 volts drops to around 12 to 14 volts ( for a 12 V solar panel) which results in 75 to 100 watts for a panel of this size.  A solar panel of 12 V has dimensions of 25 inches by 54 inches.

If you want to increase the current capacity ( more power) of a solar panel, you need to wire multiple solar panels in parallel.  If you want to increase the voltage for 24 V, 48 V or so, you need to connect the solar panels in series.  One advantage of using higher voltage output solar panels is that you can use small wire sizes for transferring electric power from panels to the charge controller or battery.  

Types of Solar Panels

 Basically there are three types of solar panels available in the market.  The details of three types of solar panels is listed below.

Monocrystalline Solar Panels :  These are the most efficient and expensive solar panels and made with Monocrystalline cells.  These solar cells uses pure silicon and it involves a crystal growth process.  Long silicon rods are cut into slices of 0.2 to 0.4 mm thick discs or wafers which are then processed into individual cells which are wired together in a solar panel.





Polycrystalline Solar Panels:  These Solar Panels are also called as Multi-Crystalline Solar Panels are made with Polycrystalline cells and are a little less expensive and less efficient compared to Monocrystalline type.  This is because the cells are not grown on single crystals but in large blocks of many crystals.   These are also sliced into wafers to produce individual cells which make up the solar panel.





Amorphous Solar Panels :  The third type of solar panels is the Amorphous solar panels which are not really crystals but a thin layer of silicon is deposited on a base material like metal or glass to create a solar panel.  These solar panels are very much cheaper but their energy efficiency is very less and so more area is required to produce the same power compared to above two types.  


Location to install Solar Panels

When you decide to install Solar Panels, the location has to be planned properly in order to get the maximum sun light on them. You should make sure that no shadows fall on the solar panels installed during the peak sun light hours ( say between 10.00 AM to 04.00 PM).  The shading of solar panels reduce their output drastically but it could also damage them.  Some suppliers  say that their solar panels can withstand shading.  So it is very important that choosing a good location without any shadows is essential requirement for a solar panel installation.  So if there are any obstacles which give shadows on the panels can be removed.

The temperature and wind loads are also important factors to be considered.  We know that we have to install solar panels in sunny and non-shady locations to get maximum output.  But heat building up is also a problem for solar panels.  The efficiency of solar panels reduces as temperature rises.  So the solar panel mounting system must allow for spacing around individual panels for air circulation so that it allows air cooling in the hot sun to reduce temperature of panels.  By allowing air flow around the solar panels, they not only become cooler  but the wind resistance also reduces.

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