 Everyone. Welcome to this video lecture. Myself Deepali Vadkar working as assistant professor at W提 солapsake. In this video lecture we will studyedsolarDrations. At the end of this video lecture students will be able to examine andER and studying solarござL buenaE छने चराथ sesleri worker. Students will be able to state applications of solar cells. Solar cell , it is the device which converts the solar energy i.e. energy obtained from the sun directly into postero-electrical energy. It is also called as photogalonic sale. The basic principle behind the working of solar sale is depend upon photo-holtec effect. Now what is the photo-holtec effect? Whenever light energy is allowed to fall on solar sale, solar cells generate voltage across its terminal. So this is called as photo-holtec effect. As the intensity of light increases, the voltage also increases. Now this is the constructional diagram for solar sale. Mainly, solar sales are constructed by using crystalline silicon, which consists of P-type and N-type semiconductor. These P-type and N-type semiconductors are sandwiched to each other. Due to this, there is a P- end junction between P and N-type semiconductor. The upper layer that is here, the N-type semiconductor, its layer is thin so that light can easily enter inside the material. Solar sales are metallized with thin strips which are painted on front and rear contact. These strips are called as a finger and these strips are called as a bus bar. Its purpose is to conduct the DC power which is generated by this solar sale. The single solar sale generates a voltage across it. That voltage is in the range of 0.5-0.8 V. So this voltage is very small. So this different combination of solar sales are used to increase its efficiency. So there may be parallel combination, there may be serial combination, there may be parallel and serial combination. So these combinations of solar sales is called as a solar model. On the both sides of this solar sale, these EVA sheets are used which are used to protect this solar sale from shocks, from vibration as well as from dust. So this is the construction of solar model. The single solar sale, by using its different combination, there is a solar module. By using different combination of solar module, there is a solar panel and by using different combination of solar panel, there is a solar array. Now the working principle behind the solar sale. This is the n-type semiconductor which consists majority charge carrier electron. This is the p-type semiconductor which consists majority charge carrier holes. When n-type and p-type semiconductor connected to each other, the electrons from n-type start diffusing into the p-type. And due to this, they start neutralizing the atom and there is a formation of depletion region. First the depletion region generated, here the potential barrier generated across, that is the electric field generated and due to that the majority charge carriers cannot cross the junction. So once this depletion region generated, majority charge carrier stays on their position. Now question, when external energy is applied to depletion region, what is the effect on depletion region? So in the previous lecture we have seen, so what is the effect of external energy on the depletion region? Pause the video for a while and think, yes, whenever the external energy, that is the sunlight strikes on the depletion region, the whole electron pair generated. That is due to the photons, the silicon atoms get excited and the free electrons generated and hence the holes also generated. Now due to this electric field, these electrons cannot cross the junction. So these electrons stays on the n-side and the holes stays on p-side. So large number of excess electrons present here at the n-side and large number of excess holes present here the p-side. So get your charge is generated towards the n-side and positive charge is generated towards the p-side. Now when these two terminals connected to each other by using single cable, then these electrons from n-side start attracting towards the p-side and due to this this electron flows through the cable and due to this the current is generated. So the current flows through this cable. So in this way, whenever the light strikes on the solar cell, the voltage across the solar cell generated or electric field is generated. Now the types of solar cell, there are basically two types of solar cell, monocrystalline and polycrystalline. Monocrystalline solar cells, they are the premium solar cells. So these solar cells uses a single crystal. So it is called as a monocrystalline. So to make the cells of monocrystalline panels, the silicon is formed into bars and cut into wafers. Now second type that is the polycrystalline. The efficiency of polycrystalline solar cell less as compared to monocrystalline but its advantage that its cost is low. So to make the cells of polycrystalline panels, fragments of silicon are melted together to form the wafers. It is also called as a multi-crystalline. Next that is the application of solar cell. The solar cells which are connected to the inverter, so this system can be used for home appliances. The inverters which converts the DC from solar cell into AC energy and this AC energy is now then distributed to the home appliances and lightning system. Now in case of solar cell, it is not necessary that separate structure should be there but the solar cell can be structured on the surface of home. Solar cell with battery storage system can be used for a lightning purpose. The solar cell used in a communication system that is some of the towers are far away from a power distribution system. So in that case the solar cell is an alternative energy source. Solar cells can be used in a remote areas where distribution system or power lines are far away from that area. So in that case provide the electricity. The solar cell is an alternating way. Antifree experiment setups are far away from a power distribution system. So to provide the electricity for such system, the solar cells are used. Now in navigational systems such as light houses, highways and aircraft warning signals can be far away from electricity grid. So in that case to provide the electricity the solar system or PV systems are used. The vehicles running on electric power can be charged by PV powered stations. So this is one of the examples how the vehicles are get charged with the help of solar system. Then solar system can be used for applications like storage and transport of medicines and vaccines. That requires a refrigeration. The solar systems used in a public utilities like in telephone booth or teller system. The solar systems becomes a perfect candidate for agriculture and livestock purposes due to need for water during the periods with the bright sunshine. Now next, the advantages of solar system. It is clean and non-polluting. It is renewable energy. Solar cells do not produce noise and they are totally silent. They require very little maintenance. There are no fuel cost or fuel supply problem. Next, disadvantages. Solar power can't be obtained in nighttime. Solar panels are very expensive. Energy has not to be stored in battery. Air pollution and weather can affect the production of electricity. They need large areas of land to produce more efficient power supply. Now these are the references. Thank you.