Abstract :
The solar energy is converted into electrical energy by photo-voltaic cells. This energy is stored in batteries during the day time for it to be utilized to run water pump for agriculture.
This project deals with a controlled charging mechanism with protections for over charge, deep discharge and under voltage of the battery. The project is designed to operate water pump at four different time slots. It overcomes the difficulties of switching the pump ON/OFF manually. This proposed system has an inbuilt real time clock (RTC) to keep tracking the time and thus to switch ON/OFF the pump accordingly.
This project consisting of a real-time clock (RTC) is interfaced to a microcontroller . While the set time equals to the real time, then microcontroller gives command to the corresponding relay to turn on the load, and then another command to switch off as programmed by the user. Multiple on/off time entry is the biggest advantage with this project.
A matrix keypad helps entering different time slots. A 7-sement display is interfaced to the microcontroller to display time. In this project, a solar panel is used to charge a battery. A set of op-amps are used as comparators to continuously monitor panel voltage, load current, etc.
Indications are also provided by a green LED for fully charged battery while a set of red LEDs to indicate under charged, overloaded and deep discharge condition. Charge controller also uses MOSFET as power semiconductor switch to ensure cutting of the load in low battery or overload condition. A transistor is used to bypass the solar energy to a dummy load while the battery gets fully charged. This protects the battery from getting over charged.
Furthermore, the project can be enhanced by interfacing a GSM modem to the existing project so that the complete control of the load can be done by sending an SMS to the control unit.