Charge Controller For PV System
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Renewable energy sources, such as wind energy and photovoltaic (PV) energy, are widely used as stand-alone power systems supplying different electrical loads in rural and remote areas. Solar Energy, radiation produced by nuclear fusion reactions deep in the Sun’s core The Sun provides almost all the heat and light Earth receives and therefore sustains every living being. These sources are of intermittent nature and, therefore, the stand alone power systems should include storage battery banks. Therefor the implementation of the battery and the PV system should be done through a charge controller. An efficient charge controller can be used to do the battery charging and discharging process faster and better. The charge controller is designed with a view to decrease the battery charging time, protect the battery from over charge and deep discharge. Photovoltaic solar systems can be divided into two basic categories – On grid (connected to the electrical grid) and off-grid (also stand alone or isolated) solar systems. The grid connected systems feed the electricity produced by solar panels to the grid using an inverter. When the electricity is needed during night or periods with little sunlight, the energy is taken back from grid. In isolated systems, the excess electricity is usually stored in battery during the day and battery is used to power the appliances in times when photovoltaic panels do not produce enough energy. In this field must say that the most important component in the off-grid systems is the charge controller. The main responsibilities of the charge controller are performance and durability functions. Charge controller is also named a solar regulator as it coordinates and regulates the main components of the system which are the PV generator, battery and loads. Usually the voltage of the charge controller is 12/24V and 48V which matches the batteries' voltage. There are two main types of charge controllers: PWM and MPPT. The charging mode is the main difference between the two types. PWM charge controllers use the Pulse-Width-Modulation technique while the MPPT controller uses the Maximum Power Point Tracking technique which gives 30% more energy than the PWM controller. In this project, the PV system will be connected to the Charge controller that will be designed, then the battery will be connected to the charge controller, and the load (in this project will be a DC load) which will be connected to the charge controller also. The charge controller in this case will control the power flow from the PV system to the load and the power flow to and from the battery. Between the PV system and the charge controller will be a solid switches or a contractor, also a switches will be inserted between the charge controller and the battery and between the charge controller and the load, all these switches will be controlled from the micro controller that used in the charge controller, in this project will be Arduino. The aim from this project is to control the PV system through the internet and getting complete information about the battery state and the load power consumption, energy produced from the PV system, Energy saved in the batteries. The charge controller will protect the battery from over charge and deep discharge, if the battery reaches the full state of charge the controller will disconnect the power that comes from the PV cells, and when its charge falls down the controller will reconnect the PV system to the battery. Also when the charge of the battery falls down to the desired value the controller will disconnect the load to protect the battery from deep discharge, if the deep discharge occurs to the lead acid battery, the life time of this battery will be affected directly and it will be damaged. Voltage and current sensors will be inserted between the PV system, the battery, the load and the charge controller, which gives us the ability to deal with the system and controlling it.