Thin film solar cells are the new generation solar cells that contain multiple thin film layers of photo voltaic materials. The thin film solar cells (TFSC) are also known as Thin Film Photo Voltaic cell (TFPV). The thicknesses of thin film layers are very less as (few nano meters) compared to traditional P-N junction solar cells. According to the type of photo voltaic material used, the thin film solar cells are classified into four types. They are
1) Amorphous silicon (a-Si) and other thin-film silicon (TF-Si)
2) Cadmium Telluride (CdTe)
3) Copper indium gallium deselenide (CIS or CIGS)
4) Dye-sensitized solar cell (DSC) and other organic solar cells
Thin film soar cells provide better ways to produce electricity from sunlight than any other method. We can implement these panels in forest areas, solar fields, traffic and street lights, and so on. The cost of this panel is very less as compared to the older silicon wafer cells.
Structure of Thin Film Solar Cell
The structure of thin film solar cell is shown below. The structure and functioning of thin film solar cells are almost same as that of normal silicon wafer cells. The only difference is in the thin flexible arrangement of the different layers and the basic solar substance used. The thin flexible arrangement of the layers helps to produce very thin form of cells that is much more efficient than the conventional silicon wafer cells.
The basic substance of a photovoltaic cell is semiconductors. The semiconductor doped with phosphorus develops an excess of free electrons (usually called N type material) and a semiconductor doped with boron, gallium or indium develop a vacancy( called holes) and this doped materials known as P type materials. These n type and p type materials combine (join) to form a Photo voltaic cell. During the absence of light, a very small amount of atoms are excited and move across the junction. This causes a small voltage drop across the junction. In the presence of light, more atoms are excited and flow through the junction and cause a large current at the output. This current can be stored in a rechargeable battery and used for several applications based on our requirement.
The old solar panel technology use silicon semiconductor for the production of p-type and n-type layers and has several disadvantages. But in the case of Thin Film Layer technology , the silicon semiconductor materials is replaced by either cadmium telluride(CdTe) or copper indium gallium deselenide (CIGS).
1) Easy to handle
2) More flexible than conventional solar cells
3) Available as thin wafer sheets
4) Cheaper than traditional panels
1) Less efficiency (20 to 30% of light converted into electricity)
2) Complex structure
3) Need to be very careful in handling
4) Can’t be used in astronomical devices.
1) Electronic powering circuits
2) Home light applications
3) Used in Solar fields