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. 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. This microcontroller based solar charger controller consists of
Microcontroller, serial ADC, LCD display, solar panel, battery, dusk dawn
sensor.
The microcontroller monitors the
battery voltage with the help of an analogue-to-digital converter. The system
status and battery voltage are displayed on an LCD. The solar energy is
converted into electrical energy and stored in a lead-acid battery. The
microcontroller needs to know the presence of the solar panel voltage to decide
whether the load is to be connected to or disconnected from the battery. This
will be done by using simple dusk-to-dawn sensor circuit build by potential
divider, zener diode and transistor.
The microcontroller monitors input
signal from sensor and activates the load or charging the battery. When the battery
voltage reaches maximum, the microcontroller interrupts the charging current by
energizing the relay and disconnects relay from panel. After five minutes, the
relay reconnects the panel to the battery. This way, the charging current is
pulsed at the intervals of five minutes and the cycle repeats until the panel
voltage is present. When the panel voltage falls below the zener diode voltage
of the dusk-to-dawn sensor, the microcontroller senses this and activates the
load. When the battery voltage drops below 10 volts, microcontroller turns off
the load and entering into ‘lock’ mode to avoid, the load oscillates between
‘on’ and ‘off’ states. It will come out of the lock mode when the dusk-to-dawn
sensor receives the panel voltage (the next morning).
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