CIRCUIT DIAGRAM EXPLANATION

CIRCUIT DIAGRAM EXPLANATION

Here we are using PIC16F877Aas the major component. Which will control all actions and provide basic protection based on the program.

The current produced by the solar panel is flowing to the battery through a relay switch RL1.  When the battery is fully charged RL1 will be energised and disconnects the solar panel from battery .The relay switch RL2 is used to protect the battery from over load. When an overload is occurred, the relay switch RL2 is energised and it disconnects load from battery.

The relay will be de-energised when the overload reset switch is pressed. The voltage at the battery is continuously displayed on the LCD using the built-in ADC module in the PIC 16F877A. The voltage is divided by 3 by using 3 equal value resistors and 1/3 voltage is send to ADC input. The analogue voltage is converted into digital and it is displayed on LCD after multiplying with 3. The reference voltage for the ADC conversion is taken from the VDD supply.

            The rated current of the power supply is chosen as 3A. At full load, the load voltage will be 9.6V (full load resistance = V/I = 12V/3A = 4Ohm. Therefore Load voltage = 12 x 4/5 = 9.6V using voltage divider rule) it is divided by 3 using resistive network and given to ADC channel 2(AN2). The voltage is continuously measured by the pic. If over load occurs, the voltage at load reduces. It is detected by the pic and energises relay switch 2 and disconnects load from over current.