What is Photo voltaic cell? Explain its construction and principle of working.
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In 1839, French physicist Alexander E. Becquerel discovered the photovoltaic effect involving conversion of solar energy into electrical energy in semiconductor element.
Photovoltaic cell consists of high-purity silicon. On the silicon, a PN (positive-negative) junction was formed as a potential barrier. Photons falling on the PN junction cause the rise of pairs of opposite electrical charge carriers (electron – hole), which as a result of the presence of PN junction are separated in two different directions. Electrons go to the semiconductor N and holes go to the semiconductor P. The voltage will arise on the junction. Because the separated electrical charges are redundant carriers, having so called, infinite life and a PN junction voltage is constant, the junction, on which the light falls acts as a stable electric cell
1. semiconductor n
2. p-n junction
3. semiconductor p
4. 5. metallic connection
6. anti-glare material
Construction of pv cell
Solar photovoltaic cells are made of polycrystalline silicon. The process of developing those cells start with a very pure semiconductor polysilicon. It is processed from quartz, which is used heavily within the electronics industry
Quartz mining in Arkansas [2]
Next, the polysilicon is melted by being heated to a temperature above the melting point. In order to create P-type semiconductor material, trace amounts of boron is added to the melted polysilicon. A block of silicon, also known as an ingot, is created in two different ways; one is to grow crystals from a seed crystal that originated from the melted polysilicon while the other is to cast melted polysilicon into a block. Each individual wafers are sliced from the ingots via wire saws before being cleaned as they are subject to the surface etching process. Once the wafers are cleaned, they become thin N-type semiconductor layers around the entire exterior cell surface by being placed into a phosphorus diffusion furnace. An anti-reflective coating is then placed at the top surface of the cell. Electrical contacts are marked on the top surface, which becomes a negative charge. On the positive (back) side of the cell, a conductive (aluminized) material is placed to restore the P-type properties of the back surface. This would later displace the diffused phosphorus layer. Before the cells become usable, it must be tested electronically to determine whether it works properly, based on the current output and electrical connection to other cells. This would then form cell circuits ready to be assembled. Below is a flow chart which shows the polysilicon manufacturing process.
Photovoltaic cell consists of high-purity silicon. On the silicon, a PN (positive-negative) junction was formed as a potential barrier. Photons falling on the PN junction cause the rise of pairs of opposite electrical charge carriers (electron – hole), which as a result of the presence of PN junction are separated in two different directions. Electrons go to the semiconductor N and holes go to the semiconductor P. The voltage will arise on the junction. Because the separated electrical charges are redundant carriers, having so called, infinite life and a PN junction voltage is constant, the junction, on which the light falls acts as a stable electric cell
1. semiconductor n
2. p-n junction
3. semiconductor p
4. 5. metallic connection
6. anti-glare material
Construction of pv cell
Solar photovoltaic cells are made of polycrystalline silicon. The process of developing those cells start with a very pure semiconductor polysilicon. It is processed from quartz, which is used heavily within the electronics industry
Quartz mining in Arkansas [2]
Next, the polysilicon is melted by being heated to a temperature above the melting point. In order to create P-type semiconductor material, trace amounts of boron is added to the melted polysilicon. A block of silicon, also known as an ingot, is created in two different ways; one is to grow crystals from a seed crystal that originated from the melted polysilicon while the other is to cast melted polysilicon into a block. Each individual wafers are sliced from the ingots via wire saws before being cleaned as they are subject to the surface etching process. Once the wafers are cleaned, they become thin N-type semiconductor layers around the entire exterior cell surface by being placed into a phosphorus diffusion furnace. An anti-reflective coating is then placed at the top surface of the cell. Electrical contacts are marked on the top surface, which becomes a negative charge. On the positive (back) side of the cell, a conductive (aluminized) material is placed to restore the P-type properties of the back surface. This would later displace the diffused phosphorus layer. Before the cells become usable, it must be tested electronically to determine whether it works properly, based on the current output and electrical connection to other cells. This would then form cell circuits ready to be assembled. Below is a flow chart which shows the polysilicon manufacturing process.
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