"Operations of Hybrid Energy System: - 1) PV Cell: - For the operation of PV hybrid system [4], we should know the operation of solarcells. The devices which are used to convert solar energy into electrical energy areknown as solar PV cells. These cells have many applications like street lightingsystems, railway signalling systems, and domestic lighting systems. Solar PV cellsconsist of P-type and N-type of Silicon layer that is placed in contact with each other.The electrons from the N-type material start diffusion with the P-type material. Theholes in the P-type material will accept the electrons coming from the N-typematerial,but there are usually more electrons in the N-side than the holes in the P-side. Now,these electrons and holes are combined to form a P-N junction. Due to this charge,will be there which will further generate the Electric field. Thus, during darkness ornight time PV cell will work in Reverse biasing mode. Solar cells are generally madeof Silicon as it is the best semiconductor material. The process of converting solarenergy to DC electricity using an array of solar panels is known as solar PV effect.Now, this DC electricity will be stored inbatteries, and this can further be fed directlyto the DC loads. These can be fed to AC loads by using an inverter which convertsDC electricity to 120V of AC power.2) Wind Turbines: -Wind energy is one of the best renewable sources available that can be used forgenerating electricity coupled with generators and wind turbines. When the wind isblowing, large wind turbines are rotated for generation of electricity. Cut in speed isthe major parameter which is defined as the minimum wind speed required for connecting the generator to the power grid. Another Important parameter is cut offspeed which is defined as the maximum wind speed required for the generator fordisconnecting the generator from the power grid. Generally, wind turbines work in therange of speed between a cut in and cut off speeds.Figure 1 Wind Power systemNow let us consider double fed induction generator (as shown in figure 5) which has3-phase wound rotor with 3-phase wound stator. When the 3-phase AC signal is fed torotor windings, an AC current is induced in the rotor windings. Now the rotor startsrotation and will produce a magnetic field, this all happens due to a mechanical forcewhich is produced by wind energy. The frequency of the AC signal applied to therotor, and the speed of the rotor are directly proportional to each other. Figure 2 Double fed induction generator3) Diesel Generator: - As we know that operation of Hybrid PV system depends onweather conditions. If someday there is poor sunshine and bad weather, then thehybrid PV system will not operate and will not that much efficient to satisfy the loadrequirement. So, to overcome all these issues we can use Diesel generator in PVHybrid system. The efficiency of the Diesel Generator is given as: -? = ? +? T B Gwhere ? total efficiency and ? , ? are the thermal and generator efficiencyT B G Modes of operation: -1) During day time: - In the presence of sunlight, Solar PV cell will start workingand generator will be off at that time. DC power is converted to AC power for theload.Figure 3 System during day time 2) During Night time: -During night time, PV cell will not work and the energy stored during daytime inbatteries is the only source. The converter converts DC power to AC power for load.Figure 4 System during night timeMaintenance issues of the Hybrid system: -Maintenance issues of the hybrid system due to all its components are as under [3]: -1) Batteries bank: - The lifespan of batteries depends on how we use them or on theiroperation criteria and need to take under care in changing temperature conditions.Let us consider the example of lead-acid batteries which lose their 15-20% of lifespanfor every 5°C change in temperature.2) Inverters: - This is high technology product, and when this product fails we requiresome high technicians from the supplying company to fix them again. This riskmainly occurs in the remote areas where it will take longer time for a technician toreach that place.3) Diesel generators: - They are highly unavailable equipment, and ofcourse,their cost istoo high, so proper maintenance of these should be undertaken.4) As we know, most of the electrical appliances work on AC current; it will be moredifficult to handle this if the output given by the system is DC current. 5) When the user uses the battery of 6V instead of 12V which is already designed, thismay lead to overcharge and will reduce the lifetime of the system.6) Lack of system observation and repairing of the system will take longer time, and itrequires some skilled technicians to overcome these issues.7) Due to bad and Corrosive environmental conditions, the system requires propermaintenance.8) The Project requires proper plot and full area for its installation, and it may requiretwo or more years of support.9) To install wind turbine systems, we need to disturb the hard-packed soil surface,which may lead to erosion in desert areas. So, here erosion is the big concern incertain habitats.10) When the wind turbines are rotating, birds and bats occasionally collide with windturbines, which may lead to endangered of species. "