Solar cells convert sunlight into electricity through the photovoltaic effect. They consist of a semiconductor material with a positive and negative layer that generate electrons and holes when exposed to light. Multiple solar cells are connected together in a panel to increase voltage or power output. The efficiency of solar cells can be improved with anti-reflective coatings and the maximum efficiency so far is 18.7%. Solar cells come in crystalline types like mono and multicrystalline, and amorphous thin film types. They have applications for powering homes, buildings, consumer electronics, and remote areas without access to electricity grids.

1. SOLAR CELL ANJALI PATRA ANKITA TRIPATHY BRANCH-EEE PRESENTED BY

2. What is a solar cell? Construction Storage of power Efficiency of solar cell Power control Types of solar cell Different types of solar cell Types of crystalline solar cell Cell packaging Solar cell applications Conclusion CONTENTS

3. A solar cell is a semiconductor device which converts electromagnetic radiation into electrical signals. It is a device which generates electricity directly from Sun’s radiation by means of the photovoltaic effect so it is also called Photovoltaic cell. In order to generate useful power, it is necessary to connect a number of cells together to form a solar panel, also known as a photovoltaic module. The nominal output voltage of a solar panel is usually 12 Volts, and they may be used singly or wired together into an array. The number and size required is determined by the available light and the amount of energy required.

4. It consists of p-n junction diode in which electrons & holes are generated by the incident photons. When an external is connected through the p-n junction device a current passes through the circuit & generates power when light is incident on it. Large area p-n junction is used for effective power generation. Incident photons p Load resistance

5. The amount of power generated by solar cells is determined by the amount of photons absorbed by it. Several solar cells are mounted on a common panel connected in series or parallel for increasing the voltage or power respectively. This type of device is called Solar Panel. In this type of system the usual choice for energy storage is the lead-acid battery. The number and type of batteries is dependent on the amount of energy storage needed.

6. Efficiency of a Solar cell is the ratio of the electrical power output to the light input. The Efficiency can be increased by using an anti-reflection coating on the thin heavily doped surface. The maximum efficiency so far is 18.7% .

7. The battery will be damaged if it is allowed to be overcharged or over discharged, so a controller is needed to protect it. The smallest systems may have only a few 12 Volt lights, but in bigger systems 230 Volts will probably be needed. An inverter is used to transform the low voltage DC generated by the solar panels into mains voltage AC. The power output is maximum for a particular load resistance. The output voltage increases with increasing light intensity but beyond a certain intensity the voltage remains constant.

8. Two solar cell types are currently in use. They include amorphous solar cells & crystalline solar cells . Amorphous solar cells are prepared by attaching a thin silicon film onto a durable material such as steel. Amorphous cells have been used for a long time in products like solar powered calculators, and garden lamps. The entire panel consists of one piece, making individual solar cells less identifiable. This has long been the least efficient solar cell type, but they have begun to improve to the point where they may become a viable alternative to crystalline solar cells. Crystalline cells use a series of cells combined in a circuit to generate power. A panel of 36 cells typically produces about 20 watts, or enough to charge a 12volt battery. Crystalline cells come in two types: Monocrystalline & Multicrystalline. For the purposes of Solar Power Industries, multicrystalline solar cells represent the greatest efficiency for manufacturing and the greatest value to the customer. Theoretically, monocrystalline cells are the most efficient cell type, but in practice poly-crystalline cells produce nearly the same energy output.

9. Amorphous Solar Cell Crystalline Solar Cell

10. Single Crystal Solar cells Polycrystalline Solar Cells Multicrystaline solar cell Monocrystaline solar cell

11. Solar cells also are available in a variety of packages. Most common are "raw cells," often with some cover sheet attached. One popular line of cells, the Panasonic Suncerams , consist of amorphous silicon cells, deposited on the back of a glass substrate (in this case, the glass functions as both substrate and cover sheet). These are durable and cost-effective cells, it is a bit heavy due to the thickness of the glass. Encapsulated solar cells are also sold -- as the name implies, an enclosure (often plastic, often with some sort of concentrator lenses built into the cover sheet) contains a regular (generally multicellular) solar cell or cells. These are extremely durable, if heavy and none too efficient. Recently, flexible solar cells have become available. These are amorphous cells on a thin plastic substrate -- low efficiency, fairly high cost, but light and a very useful package for some applications.

12. A variety of solar cell applications are currently in use and the potential for a great deal more uses still exist. Currently, solar cell applications fall into four basic categories: Utility grid connected solar cell applications supplement the energy needs in both residential and commercial capacities. Grid interactive systems act to charge a battery back-up systems for a building or structure. Remote solar cell applications power buildings and structures that are far away from existing power grids. Consumer products applications include many products that were previously powered by batteries since it is both cleaner and renewable. A more recent development in solar cell applications, consumer products include children’s toys that require electricity, or other novelty items such as ball caps with built-in fans.

13. Specially solar cell can be used in rural & desert areas where supply of electricity is very less. Gas stations could power their pumps through the use of solar cells. Anything that requires electricity could utilize photovoltaic energy as it will reduce electricity expense. Solar cell is mainly used as a voltage generator. It is also eco friendly as it does not produce any pollution that will make any harm to environment. It can also be used as photo-detectors to detect optical signals.

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