Minor Project Work
“SOLAR TRACKER AND CHARGING MONITOR”
Bachelor of Technology
Electronics and Communication Engineering
NAME ROLL NO.
LOGO OF THE INSTITUTE
NAME OF THE INSTITUTE
SOLAR TRACKER AND CHARGING MONITOR
A Solar panel (also solar module, photovoltaic module or photovoltaic panel) is a packaged,
connected assembly of photovoltaic cells. The solar panel can be used as a component of a larger
photovoltaic system to generate and supply electricity in commercial and residential applications
thereby effectively Producing renewable Energy. Each panel is rated by its DC output power
under standard test conditions, and typically ranges from 100 to 320 watts. Generally, solar
panels are stationary and do not follow the movement of the sun and hence cannot obtain
maximum sun light throughout the day. There is another major problem to check whether the
storage battery of a solar power unit is being charged or not.
The objective of this project is to provide solution to above problems as solar energy is one of
the abundant sources of energy provide by nature and one of the most efficient form of
renewable energy. In above problems mentioned we will use a Solar Tracker System that tracks
the sun’s movement across the sky and tries to maintain the solar panel perpendicular to the
sun’s rays, ensuring that the maximum amount of sunlight is incident on the panel throughout the
day. The solar tracker starts following the sun right from dawn, throughout the day till evening,
and starts all over again from the dawn next day. Along with the Solar Tracker we will use a
simple Charging Monitor that indicates whether the storage battery of a solar power unit is
being charged or not.
STUDY AND ANALYSE PHASE
The solar tracker comprises comparator IC LM339, H-bridge motor driver IC L293D (IC2) and a
few discrete components. Light-dependent resistors LDR1 through LDR4 are used as sensors to
detect the panel’s position relative to the sun. These provide the signal to motor driver IC2 to
move the solar panel in the sun’s direction. LDR1 and LDR2 are fixed at the edges of the solar
panel along the X axis, and connected to comparators A1 and A2, respectively. Presets VR1 and
VR2 are set to get low comparator output at pins 2 and 1 of comparators A1 and A2,
respectively, so as to stop motor M1 when the sun’s rays are perpendicular to the solar panel.
When LDR2 receives more light than LDR1, it offers lower resistance than LDR1, providing a
high input to comparators A1 and A2 at pins 4 and 7, respectively. As a result, output pin 1 of
comparator A2 goes high to rotate motor M1 in one direction (say, anti-clockwise) and turn the
When LDR1 receives more light than LDR2, it offers lower resistance than LDR2, giving a low
input to comparators A1 and A2 at pins 4 and 7, respectively. As the voltage at pin 5 of
comparator A1 is now higher than the voltage at its pin 4, its output pin 2 goes high. As a result,
motor M1 rotates in the opposite direction (say, clock-wise) and the solar panel turns. Similarly,
LDR3 and LDR4 track the sun along Y axis. Fig(1) below shows the proposed assembly for the
solar tracking system.
The circuit consists of two common ICs, an npn transistor, ten 5mm red LEDs and a few discrete
components. It can be divided into two parts: voltmeter and display controller.
The voltmeter, built around IC LM3914 (IC1), is a low-power, expanded-scale type LED
voltmeter that indicates small voltage steps over the 7-16V range for 12V solar panels. The meter
saves power by operating in a low-duty-cycle 'flashing' mode where the LED indicators are on
(and hence consuming power) briefly. The circuit may be switched to steady mode where the
active indicator remains on at all times.
The input for IC1 (LM3914) is derived from the solar panel voltage via a potential divider
network comprising preset VR1 and resistors R1 and R2. This variable input is about 3V for a
DC potential of 12V.
The display range depends on the internal voltage reference and resistors R3-VR2-R4. The
lowest LED (LED1) glows when the input voltage at pin 5 of IC1 is 1.8V and the top most LED
(LED10) glows when the voltage exceeds 4V. as the input signal is divided by 4, the display
ranges should be multiplied by this figure. So the actual display range is 7-16V, i.e., 1V per
The display controller is built around IC LM555 (IC2) that is wired in astable (free-running)
mode with a narrow-pulse output. The duty-cycle of IC2 is controlled by the ratio of resistors R6
and R7. If you want faster blinking, use a smaller value of resistor R7. A preset may be
substituted for R7 if a rate adjustment is desired. Increase the value of resistor R6 to get a longer
'on' time for LED indicators. The frequency of oscillations is determined by the combination of
capacitor C4 and resistors R6 and R7.
The output of timer IC2 is fed (through current-limiting resistor R5) to transistor T1 ,which, in
turn, controls the power to IC1. Capacitor C1 filters the control voltage input to IC1 and
capacitor C3 provides DC filtering for the entire circuit. When you press switch S1 across
capacitor C4, the output of IC2 remains high, and the display switches to steady mode from
flashing mode .Switch S2 is the master power-on/off switch.
For calibration, lock preset VR1 at the centre position and then set VR2 to its maximum
resistance with the help of a digital multimeter. Now close both the switches (S1 and S2) and
connect the circuit to a variable-voltage DC power supply unit with its output level set to 12V
(1%). Adjust VR1 until LED6 (at pin 14 of IC1) lights up. Finally, lock presets VR1 and VR2
The primary step is towards the search of components and IC’s which will be required. For the
designing of our project we require some specific hardware and software followed by
interfacing the components to accomplish the task required by our project.
In secondary phase for Hardware section we will implement circuit on PCB. After PCB
designing, we will place all the components on PCB. A Charger Controller will also be placed
with the Charging Monitor circuit along with different IC’s and components.
IC1(A1-A4) – LM339
R1 - 50-kilo-ohm
R2 - 12-kilo-ohm
R3 - 12-kilo-ohm
R4 - 50-kilo-ohm
R5 - 22-kilo-ohm
R6 - 22-kilo-ohm
R7 - 10-kilo-ohm
R8 - 10-kilo-ohm
R9 - 10-kilo-ohm
R10 - 10-kilo-ohm