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.

BLOCK DIAGRAM

BLOCK DIAGRAM

Figure1:block diagram.

2.1) BLOCK DIAGRAM EXPLANATION

Here we are using PIC16F877A as the major component. Which will control all actions and provide basic protection based on the program.

We have a 12V rechargeable battery and a 12V  solar panel ,on day time the solar panel will provide 12V ,which will charge the battery and provide 12V constant load.The charging is controlled by the Relay 1.If the battery is full then the relay get energized. So Relay 1 will provide over charge protection.

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.

INTRODUCTION

As the sources of conventional energy deplete day by day, resorting to alternative sources of energy like solar and wind energy has become need of the hour.

Solar-powered lighting systems are already available in rural as well as urban areas. These include solar lanterns, solar home lighting systems, solar streetlights, solar garden lights and solar power packs. All of them consist of four components: solar photovoltaic module, rechargeable battery, solar charge controller and load.

In the solar-powered lighting system, the solar charge controller plays an important role as the system’s overall success depends mainly on it. It is considered as an indispensable link between the solar panel, battery and load.

The microcontroller-based solar charge controller described here has the following features:

1. Built-in digital voltmeter (0V-20V range)
2. Overcharge protection
3. System status display on LCD
4. Low current consumption
5. Highly efficient design based on microcontroller

LCD module: The system status and battery voltage are displayed on an LCD based on HD44780 controller. The backlight feature of the LCD makes it readable even in low light conditions. The LCD is used here in 4-bit mode to save the microcontroller’s port pins. Usually the 8-bitmode of interfacing with a microcontroller requires eleven pins, but in 4-bit mode the LCD can be interfaced to the microcontroller using only seven pins.
     

Solar panel: The solar panel used here is meant to charge a 12V battery and the wattage can range from 3 to 40 watts. The peak unloaded voltage output of the solar panel will be around 19 volts. Higher-wattage panels can be used with some modifications to the controller unit.
     
Rechargeable battery: The solar energy is converted into electrical energy and stored in a 12V lead-acid battery. The ampere-hour capacity ranges from 5 Ah to 100 Ah.

Charge control: Relay RL1 connects the solar panel to the battery through diode D1. Under normal conditions, it allows the charging current from the panel to flow into the battery. When the battery is at full charge (12.0V), the charging current becomes ‘pulsed.’ To keep the overall current consumption of the solar controller low, normally-closed (N/C) contacts of the relay are used and the relay is normally in de-energised state.
     
Load control: One terminal of the load is connected to the battery through a relay.  This relay will control the load providing. That is if the resistance of load is below 3ohms(high current) then the relay get energised and cut off the load.

ABSTRACT

ABSTRACT

As the sources of conventional energy deplete day by day, resorting to alternative sources of energy like solar and wind energy has become need of the hour.

Solar-powered lighting systems are already available in rural as well as urban areas. These include solar lanterns, solar home lighting systems, solar streetlights, solar garden lights and solar power packs. All of them consist of four components: solar photovoltaic module, rechargeable battery, solar charge controller and load.

In the solar-powered lighting system, the solar charge controller plays an important role as the system’s overall success depends mainly on it. It is considered as an indispensable link between the solar panel, battery and load.

The microcontroller-based solar charge controller described here has the following features:

1. Automatic dusk-to-dawn operation of the load
2. Built-in digital voltmeter (0V-20V range)
3. Overcharge protection
4. System status display on LCD
5. Low current consumption
6. Highly efficient design based on microcontroller