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How are Silicon,Thin Film Photovoltaic Solar Cells Made and Different Types

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What is a Solar Cell

A solar cell is an electrical device that converts light energy directly into electricity by the photovoltaic effect.Note Solar Cells can be made of many materials like Silicon,Cadmium Tellerium,CIGS and even on Organic Substrates.However almost 90% of the Solar Cells produced in the world currently are made of crystalline silicon.The drastic fall in prices of silicon solar cells has seen an explosive growth in demand with solar cell supply increasing by almost 50% per year in the last decade.

How Silicon Solar Cells are Made

The basic component to make a solar cell is silicon, which is not pure in its natural state. The silicon to be used should be 99.999999999% pure. So the first step involves purifying the silicon. The most common method is Czochralski method.

The major steps involved are:

Step1) To purify, it is first placed into a cylindrical electric arc furnace, where a carbon arc is applied to it. The pure silicon collects on the rod situated in the middle of the cylinder. However the silicon is still not that pure to be used any further.

Step2) Hence the rod of impure silicon is passed through a heated zone several times in the same direction. This procedure drags the impurities towards one end. At a specific point, the silicon is deemed pure, and the impure end is removed.

Step3) From the silicon boule, thin square slices are cut. Each such unit is the solar cell.

Step4) Electrical contacts connect each solar cell to another and to the receiver of produced current. The contacts must be very thin so as not to block sunlight to the cell.

Step5) Silicon is a very shiny material, hence very reflective. For this reason, an anti-reflective coating is applied to the top of the cell to reduce reflection losses to less than 5%.

Step6) The cells are encapsulated and placed in an aluminum frame that has a glass cover. Assemblies of cells used to make solar modules are known as solar panels.

Quality control is important in solar cell manufacture otherwise there can be adverse affect on the overall efficiency of the cells. During the entire silicon disk manufacturing process, the temperature, pressure, speed and other such factors should be continuously monitored.

Types of Silicon Solar Cells

Solar Cells are of 2 types a) Multicrystalline b) Monocrystalline. Multi Solar Cells have lower efficiency than the Solar Cells made from monocrystalline Solar Cells.

Monocrystalline Solar Cells

Solar Cells Efficiency can vary from 18% to 24% for the normal monocrystalline silicon technology.

Multicrystalline Solar Cells

Multicrystalline Solar Cells have lower efficiency and costs than monocrystalline solar cells.However they are currently the more popular though that is changing.They have an efficiency in the range of 14-17%.


Unlike Silicon Solar Cells,making of thin film photovoltaic solar cells are done at one place and at the same time.Therefore finding individual thin film solar cells is not possible as they are sold only in the form of solar panels.In a Thin Film Solar Cell Manufacturing Process,a Substrate made of Glass is usually passed through several pieces of equipment in which etching and deposition of materials is done.The process of putting electrical contacts,frames,anti reflecting coatings is all done in a single continuous process.


Thin Film Technology unlike crystalline silicon technology has a number of variants.Amorphous Silicon (a-Si),Copper Indium Gallium Sulphide (CIGs) and Cadmium Tellurium (Cd-Te) are the 3 main types of Thin Film Technology.There are a number of manufacturers of all of these 3 types of Technology.CIGs Technology is said to have the most potential in improving efficiency and competing with c-Si,however Cd-Te is currently the top dog as the world’s biggest solar producer First Solar currently uses this technology.a-Si Technology is not that hot with low efficiencies however Oerlikon and Sharp are pushing ahead with developing this technology.

Amorphous Silicon Technology (a-Si)

This Thin Film Technology has the lowest average efficiency of all the solar cell technologies except immature ones like Organic Dye Cells.With most of the a-Si thin film competitors bankrupt or in a moribund state,Sharp is the only big player remaining claiming a 10% efficiency.Oerlikon has said that its new generation equipment will cuts cost to 70c/watt and improve efficiency to 10% from the current 9%.

Copper Indium Gallium Diselenide (CIGs)

This Thin Film Technology has the highest Solar Cell Efficiency and a number of established companies like TSMC,Q-Cells,Honda and startups like Miasole,Nanosolar,Solyndra are using this technology.However its production is not easy as four different materials are used.Miasole has been claiming to have achieved an efficiency of 13.8%.General range is between 11-14%.

Copper Indium Selenium (CIS)

Solar Frontier claims 11.5% efficiency for its CIS modules which are expected to go upto 14% by 2014.Note it is very closely related to the CIGs Technology differing only in the fact that it does not use Gallium.

List of Top Global Crystalline Silicon Solar Cell Suppliers :

1) JA Solar – This Chinese company is not only the biggest solar cell producer in the world but is also the lowest cost one as well.The company has grown much faster than the industry due to its low costs and good quality.The company is looking to ship more than 2 GW of Solar Panels and Cells in 2011 with  50% growth.The company has small wafer and module facilities as well but continues to be primarily a solar cell producer

2) Gintech – This Taiwanese company has become the biggest solar cell producer in the country overtaking Motech.The company continues to expand aggressively as it uses its high quality to win more contracts from Japanese and European customers.

3) Motech – The company which used to be a pure play cell producer has expanded into polysilicon, modules and wafers.It is one of the oldest solar cell companies in Taiwan and faced tough times in 2008 post the GFC. TSMC owns a stake in this company.

4) Neo Solar – This is one of the fastest growing companies in Taiwan and has focused on solar cells.It has managed to grow revenues and shipments despite tough competition from domestic as well as international competition.

5) Q-Cells – The largest solar producer of cells in 2008 faced a horrendous 2009 running losses of as high as Euro 1 billion.After restructuring it has moved its factories to Malaysia and has diversified into solar modules and systems.The German company has seen its stock price drop more than 95% from the peak levels.It is using Flextronics as an outsourced module producer for its cells.

6) Del Solar – This company is another Taiwanese one with big operations in solar cells like the others.The company is also a new one like Neo Solar and has given strong competition to others like Motech.

7) China SunEnergy – This is a small Chinese Company which primarily engages in solar cell production.However industry cost pressures have made it get into module production as well.It bought 2 small Chinese panel companies in order to survive the onslaught.It has drastically reduced costs in the last one year to become competitive.

8 E-Ton – This Taiwanese Solar Cell Producer used to be one of the biggest pre 2008,however currently it faces huge headwinds.The company faces financial problems from a US acquisition that went wrong.It was on the verge of selling itself to Foxconn but the deal did not went through.

The other Solar Cell Producers who sell Modules are Suntech,Trina Solar,Yingli, Sharp are big producers of solar cells as well. Thin Film Technology does not require the intermediate step of solar cell production so there are not thin film cell companies.

You would  also want to read about

a) Efficiency of Solar Cells

b) Guide on Buying Solar Cells

c) Solar Panel Manufacturers


Abhishek Shah

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