What is the difference between amorphous and polycrystalline solar modules?
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I am looking at your website and noticed your different pre-packaged, grid interconnect systems. Some of your kits utilize solar modules, which are amorphous while others use polycrystalline. While the power outputs are comparable for some of the systems, why the large difference in cost?
This question is often asked of us so lets take a look at the two technologies and break down their differences.
Technical:
Polycrystalline solar cells are manufactured by taking raw silicone and forming it into a block or "ingot". Once this ingot is formed, the cell slicing process begins. Now, in order to make a nominal 12-volt solar panel at 18 volts, you will need 36 solar cells connected in series. Each solar cell produces .5 volts with the current output of the cell directly related to the physical size of the cell. The larger the cell the more power it puts out and the larger the finished module will be. With this in mind, the ingots go into a slicer, which cuts off the thin cells that make up the solar panel. Once these cells are produced, one side of the cell is printed with a positive material and the other a negative. These cells are then connected in series and continue on to become a complete solar panel.
Amorphous solar panels contain no cells per say but are created rather through a deposition process which actually forms the silicon material directly on the glass substrate. To understand this a bit clearer, think of it as spraying the silicon onto the glass in very thin layers. This film which gives amorphous panels the "thin-film" nick name, is laser patterned which interconnects instead of physical connecting tabs which eliminates a mechanical connection that can break down and fail. The amount of silicon used in this process produces a film, which is often up to 100 times less the thickness of a polycrystalline cell.
Performance
Polycrystalline cells are generally 13-15% efficient. Efficiency ratings are a calculation of the amount of power produced compared to the physical size of the panel. Amorphous panels are in the 8-9% efficiency range.
Conclusion:
If you're looking to get the lowest cost system, then amorphous is the way to go. As these modules are easier and less expensive to manufacture, it allows producers to pass the savings down to the end user of the product. The down side to amorphous systems is the amount of real estate needed to mount the panels. Since the efficiency of the amorphous panels are not as high as those made of the polycrystalline cells, they often require 50% more room than that of an equivalently powered polycrystalline system. If your restricted in area and your looking to produce the most power in the area you have to work with, the crystalline cells are the definite choice. Let me give an example:
Example:
http://www.mrosolar.com/page/MSOS/CTGY/ce/
CP6043, amorphous silicone package utilizes 60 MST-43, 43-watt Solar panels for an array output of 2580 watts. This system requires approximately 517 sq. ft of roof space and the MrSolar price for this system is $11,250.00 or $4.36 per watt.
CP24120, polycrystalline package utilizes 24 MSX-120, 120-watt solar panels for an array output of 2880 watts. This system requires approximately 288 sq. ft of roof space and the MrSolar price for this system is $16,527.00 or $5.74 per watt.
So the choice is yours as to which system best suites your needs whether its power, size, aesthetics or cost there is a system to fit your requirements.