Measuring and Displaying Solar Panel Voltage on an LCD using Arduino

 Measuring and Displaying Solar Panel Voltage on an LCD using Arduino

Step 1: Components Required

1. Arduino Board (e.g., Arduino Uno)
2. Solar Panel (small panel with known voltage range)
3. Voltage Divider Resistors (e.g., 15kΩ and 5kΩ)
4. 16x2 LCD with I2C Interface
5. Jumper Wires
6. Breadboard (optional for ease of connections)

Step 2: Circuit Diagram

1. Connect the Solar Panel:

   • Connect the positive terminal of the solar panel to the input of the voltage divider circuit.
   • Use resistors R1 (15kΩ) and R2 (5kΩ) to step down the voltage to a range readable by the Arduino (0-5V).

2. Voltage Divider Connections:

   • Solar Panel + connects to the junction between R1 and R2.
   • R2 connects to GND.
   • The voltage reading point (junction between R1 and R2) goes to A0 (analog input) of the Arduino.

3. Connect the LCD:

   • If using an I2C LCD, connect the LCD pins as follows:
     • GND to Arduino GND
     • VCC to Arduino 5V
     • SDA to Arduino A4
     • SCL to Arduino A5

Step 3: Arduino Code

Use the following code to read the solar panel voltage, compute it, and display it on the LCD.

cpp

#include <Wire.h>
#include <Adafruit_LiquidCrystal.h>

// Initialize the LCD using the I2C interface, address 0x20 (adjust if necessary)
Adafruit_LiquidCrystal lcd(0);

const int analogPin = A0; // Analog input pin
const float R1 = 15000.0; // Resistor R1 value in ohms
const float R2 = 5000.0;  // Resistor R2 value in ohms
const float referenceVoltage = 5.0; // Reference voltage of Arduino

void setup() {
  lcd.begin(16, 2);        // Initialize the LCD for 16 columns and 2 rows
  lcd.setBacklight(1);     // Turn on the backlight
  lcd.setCursor(0, 0);     // Set cursor to first column, first row
  lcd.print("Solar Voltage:"); // Display a static label
  
  Serial.begin(9600);      // Begin Serial for debugging
}

void loop() {
  int analogValue = analogRead(analogPin);
  float voltage = analogValue * (referenceVoltage / 1023.0); // Convert ADC value to voltage
  
  // Calculate the actual voltage of the solar panel
  float panelVoltage = voltage * ((R1 + R2) / R2);

  lcd.setCursor(0, 1);      // Set cursor to first column, second row
  lcd.print(panelVoltage);  // Display the panel voltage
  lcd.print(" V      ");    // Add units and clear remaining characters

  Serial.print("Panel Voltage: ");
  Serial.print(panelVoltage);
  Serial.println(" V");

  delay(1000); // Wait for 1 second before the next reading
}

Step 4: Explanation of the Code

1. Voltage Reading: The Arduino reads the analog signal from the voltage divider using the analogRead(A0) function. This value ranges from 0 to 1023 and represents 0V to 5V.
2. Voltage Conversion: The analog value is converted to a corresponding voltage by multiplying with the reference voltage (5V) and dividing by 1023.
3. Voltage Divider Adjustment: The actual voltage of the solar panel is computed using the voltage divider formula: $$V_{panel} = V_{out} \times \frac{R1 + R2}{R2}$$
4. Display on LCD: The voltage is displayed on the second row of the LCD screen using the lcd.setCursor() and lcd.print() functions.

Step 5: Testing the System

1. Power the Arduino by connecting it to your computer or an external power supply.
2. Observe the LCD: The measured solar panel voltage should be displayed on the LCD.
3. Adjust the Solar Panel's Exposure to Light: By exposing the solar panel to more or less light, observe how the voltage reading on the LCD changes accordingly.

Step 6: Debugging (if needed)

• Serial Monitor: Open the Serial Monitor in the Arduino IDE to see real-time voltage readings printed for further debugging and verification.
• Check Connections: Ensure all connections (solar panel, voltage divider, and LCD) are correct, and verify resistor values in the voltage divider.