Arduino Solar Tracker | Science Project

Summary

In this video, Dr. Benino from Science Buddies demonstrates how to build an automatic solar tracker using Arduino. The project uses a solar panel mounted on a servo motor, controlled by two light-dependent resistors (LDRs). As the sun's position changes, the Arduino rotates the panel to optimize energy capture by aligning it perpendicularly to the sun's rays. The tutorial covers the circuit design, Arduino code, and practical considerations such as resistor values and sensor calibration. This simple yet effective project enhances solar panel efficiency by dynamically tracking the sun.

Takeaways

• 🔧 The video demonstrates how to make an automatic solar tracker using Arduino.
• ☀️ The solar panel is mounted on a servo motor and tracks sunlight using two photoresistors.
• 📉 Photoresistors, also known as light-dependent resistors, change resistance based on the amount of light hitting them.
• 🔄 The Arduino code uses the difference in light intensity between the two sensors to rotate the solar panel toward the light source.
• ⚙️ The solar tracker adjusts the panel to remain perpendicular to the sun’s rays, maximizing energy production.
• 🌞 The setup is designed to follow the sun’s east-to-west movement throughout the day, optimizing the panel’s output.
• 🔍 A dual-axis tracker can also be built, adding a second motor for vertical adjustments.
• 🛠️ The project uses simple materials like popsicle sticks and hot glue for the solar panel's structure.
• 💡 The video explains how to wire the circuit, which includes the solar panel, servo motor, and photoresistors connected to the Arduino.
• 📈 The Arduino reads voltage from the solar panel, but it still requires an external power source.

Q & A

What is the purpose of the automatic solar tracker project?

The automatic solar tracker project is designed to optimize the energy output of a solar panel by adjusting its orientation to follow the sun's movement throughout the day, ensuring the panel remains perpendicular to the sun's rays for maximum energy production.

What components are used in this solar tracker setup?

The solar tracker setup includes a solar panel, a servo motor, photo resistors (light-dependent resistors), a support structure made from popsicle sticks and hot glue, an Arduino, and resistors to form a voltage divider.

How do photo resistors (light-dependent resistors) work in this project?

Photo resistors change their resistance based on the amount of light they receive. In this project, they are used to detect light from the sun. When one of the two sensors is shaded, the Arduino compares the readings and rotates the solar panel to align it with the sun.

Why is it important to orient the solar panel perpendicular to the sun’s rays?

A solar panel produces maximum power when it is oriented perpendicular to the sun’s rays. If the sun’s rays hit the panel at a steep angle, the panel will generate less power, especially in the morning and evening.

What is the difference between a single-axis and a dual-axis solar tracker?

A single-axis tracker moves the solar panel left and right to follow the sun’s east-to-west movement throughout the day. A dual-axis tracker, on the other hand, adjusts the panel both horizontally and vertically to account for seasonal variations in the sun’s position.

What is a voltage divider, and why is it used in this project?

A voltage divider is a circuit with two resistors in series that converts the resistance of a photo resistor into a measurable voltage. The Arduino cannot measure resistance directly, so this technique is used to measure the light sensor readings.

Can the solar panel power the Arduino directly in this project?

No, the solar panel does not power the Arduino directly. The solar panel's voltage is measured using one of the Arduino’s analog input pins, but the Arduino still requires external power.

What precautions must be taken when connecting a solar panel to an Arduino?

It is important to ensure that the solar panel outputs less than 5 volts. Connecting a panel with a higher voltage can damage the Arduino, which is designed to operate at 5 volts.

How does the Arduino control the movement of the servo motor in this project?

The Arduino reads the difference between the two light sensors. If the difference exceeds a certain threshold (e.g., greater than 50), the Arduino adjusts the servo motor's angle to rotate the solar panel towards the sensor receiving more light.

What role does the delay function play in the Arduino code for this project?

The delay function controls how frequently the solar panel adjusts its position. A longer delay can prevent the panel from jittering back and forth, especially on partly cloudy days when light conditions change rapidly.

Outlines

00:00

🌞 Introduction to Solar Tracker with Arduino

In this introduction, Dr. Benino from Science Buddies explains the objective of the video: creating an automatic solar tracker using an Arduino. He starts by showcasing the setup with a solar panel mounted on a servo motor, supported by popsicle sticks and hot glue. The system uses photoresistors (light-dependent resistors) to detect light and adjust the panel's direction. Dr. Benino also briefly mentions the importance of the voltage divider, and how the Arduino controls the panel’s movement by comparing light intensity on the sensors.

05:01

💡 How Photoresistors Help Track the Sun

This section delves into how photoresistors function within the solar tracker. Photoresistors alter their resistance based on light intensity, and by placing two sensors on opposite sides of a vertical piece of cardboard, the Arduino can detect discrepancies in sunlight hitting them. The tracker adjusts the solar panel’s position to keep it perpendicular to the Sun for optimal energy capture. Dr. Benino demonstrates the process using a flashlight, highlighting how the tracker adjusts its position to balance the light on the sensors.

10:03

🔧 Circuit Setup and Wiring

Dr. Benino explains the circuit setup, utilizing a solar panel, servo motor, and two photoresistors. He clarifies that the solar panel doesn't power the Arduino directly; instead, its voltage is measured by the Arduino. The servo motor has three wires (ground, power, and control), which are connected to a breadboard along with the photoresistors. The photoresistors are part of a voltage divider circuit that converts resistance into voltage, which the Arduino can read. The correct wiring ensures that the system can control the solar panel’s movements accurately.

🛠️ Servo Motor Control and Code Explanation

In this paragraph, Dr. Benino walks through the Arduino code that controls the solar tracker. He introduces the Servo library and explains how the code reads analog values from the sensors to determine the light intensity. Based on the difference between sensor readings, the code adjusts the servo angle to point the solar panel toward the Sun. He also discusses how the margin variable helps prevent the servo from jittering due to small fluctuations in light intensity. Lastly, he shows how to calculate the actual voltage from the solar panel for experimentation purposes.

🔄 Fine-Tuning and Debugging the Solar Tracker

Dr. Benino discusses calibration and fine-tuning of the solar tracker. He emphasizes adjusting the resistor values and the position of the cardboard to ensure the system accurately tracks sunlight. The importance of monitoring light sensor readings during setup is highlighted, as it allows for better design adjustments. He also mentions how adding delays between rotations can prevent constant movements caused by passing clouds. The section wraps up with a TinkerCAD simulation demonstration, showing how light sensor values impact the servo motor’s rotation.

🔚 Conclusion and Project Resources

In the final segment, Dr. Benino provides concluding remarks and encourages viewers to try the solar tracker project using real sunlight. He reiterates the need for real-world testing due to the differences in sensor readings compared to the simulation. Lastly, he points viewers to additional resources for written instructions, the code, and over a thousand other STEM projects on the Science Buddies website.

Keywords

💡Arduino

Arduino is an open-source microcontroller platform used for building electronic projects. In the video, the Arduino is central to controlling the automatic solar tracker by reading sensor data and adjusting the position of the solar panel. It acts as the brain of the project, executing the code that directs the servo motor based on input from light sensors.

💡Photoresistor

A photoresistor, or light-dependent resistor (LDR), is a sensor that changes its resistance based on the amount of light hitting it. In the video, two photoresistors are placed on opposite sides of a cardboard to detect the intensity of sunlight. The Arduino uses the difference in readings from the two sensors to determine which direction to move the solar panel.

💡Servo Motor

A servo motor is a motor that precisely controls angular movement. In the video, the servo motor is used to rotate the solar panel to align it with the sun’s position based on the signals from the Arduino. The rotation allows the solar panel to track the sun's movement from east to west throughout the day.

💡Solar Panel

A solar panel is a device that converts sunlight into electricity. In this project, the solar panel is mounted on a support structure and moves with the help of a servo motor to track the sun, optimizing its energy output by maintaining a perpendicular angle to the sun’s rays. The panel’s voltage is also measured to compare performance between a fixed and movable setup.

💡Voltage Divider

A voltage divider is a circuit that reduces a high voltage to a lower voltage, making it safe to measure or process. In the video, a voltage divider is created using photoresistors and regular resistors so that the Arduino can measure changes in light intensity by reading voltage, since the Arduino cannot measure resistance directly.

💡Analog Input

Analog inputs on an Arduino are pins that read varying voltage levels, typically between 0 and 5 volts. In the video, the analog inputs are used to measure the voltage from the photoresistors, which changes based on light intensity, and from the solar panel, allowing the system to monitor how much sunlight is being captured.

💡Single-Axis Tracker

A single-axis tracker allows movement along one axis, in this case left to right, to follow the sun’s movement from east to west. The solar tracker in the video is a single-axis tracker, which adjusts the solar panel horizontally to maintain optimal exposure to sunlight throughout the day.

💡Servo Angle

The servo angle refers to the angular position of the servo motor, which can range from 0 to 180 degrees. In the video, the servo angle is adjusted based on the difference in light readings from the two photoresistors, allowing the solar panel to rotate and follow the sun. The code controls these angle changes, ensuring the panel stays aligned with the sunlight.

💡Light Sensors

Light sensors are devices that detect light intensity. In this video, photoresistors act as the light sensors, and their readings help determine the position of the solar panel. By comparing the readings from two light sensors mounted on opposite sides of a cardboard, the Arduino decides in which direction to move the solar panel for maximum sunlight exposure.

💡Tinkercad

Tinkercad is an online platform for creating and simulating electronic circuits. In the video, the presenter uses Tinkercad to simulate the circuit before physically building it. This allows for testing the servo motor, light sensors, and solar panel interactions in a virtual environment, which is helpful for debugging and designing the project before actual assembly.

Highlights

Introduction to making an automatic solar tracker using Arduino.

Demonstration of solar tracker setup with servo motor, solar panel, and light sensors (photo resistors).

Explanation of how photo resistors work by changing resistance based on light exposure.

Arduino uses analog input pins to measure voltage from photo resistors and track sunlight.

Servo motor rotates the solar panel based on the difference in light hitting two photo resistors.

Single-axis solar tracker adjusts solar panel left and right to follow the sun's movement.

Comparison of single-axis and dual-axis trackers, which follow both east-west and seasonal sun movements.

The purpose of a solar tracker is to maximize power output by keeping the panel perpendicular to the sun's rays.

Overview of the circuit assembly using an Arduino, breadboard, servo motor, and photo resistors.

Important safety note: solar panel voltage should not exceed 5V to avoid damaging the Arduino.

Code logic for reading photo resistor values and adjusting the servo angle based on the difference in light.

Servo movement is restricted between 0 and 180 degrees to prevent over-rotation.

Photo resistor readings are stabilized by setting a margin to prevent small fluctuations from causing servo jitter.

Code explanation for converting analog inputs into actual voltage values for measuring solar panel efficiency.

Simulating the solar tracker setup in Tinkercad and showing how the light sensor readings affect servo movement.

Transcripts

hi this is Dr benino with science

buddies and in this video I will show

you how to make an automatic solar

tracker using an Arduino now that

previous clip was a time lapse of the

setup working outside in direct sunlight

here I have it set up indoors so I can

demonstrate its use with a flashlight so

first let's take a look at the physical

setup I have a solar panel mounted on a

Servo motor and a support structure

built from popsicle sticks and hot GL

blue here that holds the solar panel at

an angle and most importantly up here

above the solar panel I have two light

sensors these are called photo resistors

or light dependent resistors they are

resistors that change their resistance

value depending on the amount of light

that hits them the resistance gets lower

when there's a lot of light and higher

when it's dark and we have a separate

tutorial video all about using these

sensors with an arduinos I'm not going

to go over all those details again in

this video but long story short you

can't measure their resistance directly

but you can measure the voltage from the

arduino's analog input pins by

connecting them to another resistor

forming something called a voltage

divider again go check out our other

video Linked In the description of this

one if you want to learn more about

these light sensors and how they work

what we are doing with them in this

project is using two of them mounted on

opposite sides of this vertical piece of

cardboard so so what happens is

depending on the location of the Sun in

the sky if the Sun is slightly off to

one side one of these will be shaded

while the other one gets hit directly

with light and the Arduino code looks at

the difference between these two sensor

readings and will rotate the solar panel

until the readings are approximately

equal meaning that this piece of

cardboard is pointed directly at the Sun

and both of the light sensors are

getting hit by light so you can see that

if I demonstrate with the flashlight

here right now just based on the ambient

internal Lighting in the room I'm in

this has kind of found its equilibrium

position but if I take the flashlight

and add more light on one of the sensors

it is going to rotate the solar panel

towards that side and then if I switch

to the other side it's going to rotate

back in that direction so again I am

just using a flashlight here to quickly

demonstrate this if this was outside you

would have the sun gradually moving

through the sky throughout the day so

moving much more slowly and as it moves

it's slowly going to start shading One

of Those sensors and rotate the solar

panel to track the sun now the reason

for doing this is that a solar panel

produces maximum power when it is

oriented perpendicular to the sun's Rays

so for a fixed solar panel installation

where the panel does not move the panel

is going to produce less power early in

the morning and later in the evening

when when the rays are hitting the solar

panel at a very steep angle so this is a

single axis tracker that rotates the

panel left and right to follow the sun's

east to west movement throughout the day

you can also make a dual Axis or two

axis tracker with a second motor that

has motion to adjust the panels up and

down to account for seasonal variation

in the sun's position as it moves up and

down in the sky throughout the year what

I will do in the rest of this video is

show you how to assemble the circuit and

code for a single AIS tracker with a

single Servo motor and two photo

resistors but you could duplicate this

setup and add another motor and another

pair of photo resistors to make a two

AIS tracker let's switch over to the

computer to take a closer look at the

circuit diagram and the code so here we

have the circuit built in a simulation

program called Tinker cat we also have a

tutorial about this software Linked In

Our Arduino tutorial playlist in the

description of this video so in the

circuit we have the four main components

spread out here since we can't do the

physically physical assembly in the

simulation we have the servo motor the

two photo resistors and the solar panel

which again are all connected together

with hot glue and popsicle sticks you

can check out the link to the project

for more pictures of that setup they are

all wired to a breadboard and connected

to our Arduino one note the the solar

panel itself is not actually powering

the Arduino in this project we are

measuring the voltage from the solar

panel using one of the arduino's analog

input pins this allows you to do an

experiment for example to compare the

voltage throughout the day with a fixed

panel and a movable panel mounted on the

servo but it is not powering the Arduino

the Arduino still requires external

power one very important note if you

connect your solar panels output

directly to an Arduino like this you

must have a small solar panel that will

output less than 5 volts trying to send

a higher voltage into your Arduino can

damage it it is only designed to operate

at 5 volts and measure up to 5 volts on

the analog input pin you can use

something called a voltage divider to

lower the voltage of your solar panel

and measure the voltage from a bigger

panel but I'm not going to cover that in

this video for purposes of a science

project we just recommend a smaller

panel that outputs less than 5 Vols and

then you don't need to worry about it

looking at the connections on the

breadboard here we have the ground or

black wire from the solar panel going to

the ground bus on the breadboard we have

the positive wire from the solar panel

going to one of the uo's analog input

pins we have the servo motor which has

three wires now depending on where you

buy your Servo the colors of the wires

may vary for this common type of Servo

we have brown which is is ground and

going to the ground bus on the

breadboard red which is power going to

the positive BR bus on the breadboard

which is connected to 5 Vols from the

Arduino and orange which is the control

signal in this case going to Arduino pin

9 we then have the two photo resistors

each photo resistor has two pins one of

those pins is connected to 5 volts and

the other pin is connected to one end of

a resistor and that resist

then goes to ground the size of this

resistor is going to depend on the

resistance of your photo resistors you

might have to tweak this and try

different resistor values to get the

best readings but 10 kiloohms is

generally a good place to start I should

have mentioned that you can also find

this diagram and a link to the tinkercad

Circuit simulation in the description of

the

video finally we have two more wires

going over to other analog inputs we

have a connection on the breadboard

between this fixed resistor and the one

leg of the photo resistor that goes over

to an analog input and again that is

taking the voltage from this circuit

called a voltage divider where you have

two resistors in series converting the

resistance of this photo resistor to a

voltage that can be measured directly by

the Arduino because the Arduino cannot

measure resistance directly and again we

have another tutorial video All About

these photo resistors so you can learn

more about them in that video I'm not

going to going to cover it here we have

another wire that does the same thing

connecting from between this photo

resistor and this resistor over to one

of the aro's analog inputs so that is it

for the circuit let's take a look at the

code looking at the code and if you want

to copy paste this again you can find a

link to it in the description the first

thing we do is include the Arduino Servo

Library we then declare a bunch of

variables for the pins we are using so

we have two analog pins for the light

sensors we have one for measuring the

solar panel

and we have one for controlling the

servo we declare a variable for the

servo angle variables for the two light

sensor readings and the difference

between them and then we have a margin

variable where we are going to take

action to move the servo if the

difference is greater than this margin

but if it's less than that margin which

you'll see later we won't do anything

because we don't want the servo to

constantly Jitter back and forth due to

small

variations we also have a variable to

read the voltage from the solar panel

but the arduino's analog inputs as we

will see later do not directly give you

the voltage so we have another variable

to convert that to the actual voltage of

the panel and then we create a Servo

object that we are going to use to refer

to our servo motor using the Arduino

Servo library in our setup function we

attach our Servo object to the servo pin

we set the initial angle of the servo

motor and and we initialize serial

communication so we can print out some

information to the serial monitor later

in the loop function we use the analog

read command to get the value for both

of our light sensor pins we then

calculate the difference between them

and then again here is the key part of

the code that's going to move the servo

motor depending on this reading now if

you were watching very closely you might

have seen that I changed something there

which I will explain in a minute but

first if the difference is greater than

the margin variable that we declared

earlier so if the difference is greater

than 50 then we want to increase the

servo angle but the servo only has a

range of 0 to 180 so we only want to in

this case if I'm adding five to the

angle increase it if the angle is

already less than 176 so if the angle is

equal to 175 I will add five and get 180

but the angle can't go over 180 so I

don't want to add it if for example the

angle is 176 and I add five add five I

would get 181 I don't want that what you

may have noticed earlier in the video

this said

180 that would work if I was only

changing the angle by one at a time so

for example if the angle is

179 that would be less than 180 then

this would be true I would add one to

the angle and get 180 but if you were

changing it by larger increments you

need to change this value accordingly so

in this case 176

and then same thing down here if the

difference is less than negative margins

so if the difference is less than -50

then I want to decrease the angle but

again I only want to do that if I'm not

going to make the angle itself negative

because the angle should not go below

zero so again if the difference between

the two light sensor values is greater

than 50 I'm going to rotate the servvo

one way if it's less than -50 I'm going

to rotate the servo the other way but if

it's in between between -50 and postive

50 I'm just not going to do anything and

that is because I don't want the servo

to constantly Jitter back and forth just

due to very small fluctuations in the

light sensor reading I really only want

it to start rotating with larger

changes I'm then going to write the new

angle to the servo motor and I could

have done this earlier but I'm going to

get the reading from the solar panel and

the analog read command on the Arduino

gives you a number between 0 and

1,23 so you can convert that to a

voltage between 0 and 5 using this

formula here so again you can use this

to record your actual solar panel

voltage or you could also do this with a

multimeter if you have one available and

track that throughout the day comparing

the results with a fixed panel to that

with a movable panel finally I have a

bunch of Serial print commands to print

out the light sensor readings and the

solar panel voltage printing out these

readings is useful for calibration as

you adjust things like the size and

position of that piece of cardboard

where the sensors are mounted and maybe

changing the value of this fixed

resistor to make sure that you are

getting a difference in the two readings

when one of the sensors is shaded and

the other one is not so again that is

mostly useful for the initial setup and

debugging and design process and then

once everything is working you're going

to want to look at the solar panel

voltage print out finally in the actual

code running on the physical Arduino I

have a delay here I have that commented

out in Tinker CAD because the simulation

was running kind of slow but you don't

necessarily need to reposition the panel

every second especially maybe if it's a

partly cloudy day and you don't want to

be moving back and forth all the time

with clouds so you could add an even

longer delay here if we run the

simulation in tinkercad it will let us

click on the light sensors to simulate

the amount of light hitting them so it

starts with a default of very dark but

you can see if I

increase the amount of light hitting

this sensor it makes the servo rotate

towards that one if I click on the other

one and increase the amount of light

here as I

exceed that first sensor and then maybe

drop this one down a little bit it

rotates over towards this sensor and I

can look at that in the serial monitor

here you see it is printing out both

sensor readings and in this case I'm

getting 974 on One sensor 879 on the

other sensor so that difference was

greater than 50 so it was rotating but

if I move these back

down the servo is already at its maximum

position so it's not going to rotate

anyway but for example if I start

increasing this one again you see it's

not rotating yet because the difference

here is not greater than 50 yet but if I

increase this one all the way and drop

this one down a little bit as the

difference becomes greater than 50 the

servo is going to rotate back in the

opposite direction this is just a

simulation so clearly you will need to

try this with real sunlight on your

physical Arduino because the readings

you're going to get from your physical

photo resistors are going to be

different remember that for written

instructions for this project you can

check out the link in the video

description and for over a thousand

other projects in all areas of Science

and Engineering not just Arduino and

electronics check out the rest of our

YouTube channel and our website

www.sciencebuddies.org