Solar Panel Voltage Measure project using Arduino

Solar Panel Voltage Measure project using Arduino

Project Overview

The core idea is to use a voltage divider circuit to scale down the solar panel's output voltage (which can be 12V or more) to a safe range (0-5V) that the Arduino's Analog pin can read. The Arduino then converts this analog reading back into the actual voltage value and displays it on the Serial Monitor.

Components Required

According to the article, you will need:

Arduino Uno (or any other Arduino board)

• Arduino Uno (or any other Arduino board)

Solar Panel (The project suggests a small 3V, 6V, or 12V panel)

• Solar Panel (The project suggests a small 3V, 6V, or 12V panel)

Resistors for the voltage divider (1x 10kΩ and 1x 1.5kΩ)

• Resistors for the voltage divider (1x 10kΩ and 1x 1.5kΩ)

Breadboard

• Breadboard

Jumper Wires

• Jumper Wires

Multimeter (for verification and troubleshooting)

• Multimeter (for verification and troubleshooting)

Circuit Diagram & Connection

The circuit is simple but must be built correctly for accurate and safe measurement.

The Voltage Divider is Key:

Connect the 10kΩ resistor and the 1.5kΩ resistor in series on the breadboard.

• Connect the 10kΩ resistor and the 1.5kΩ resistor in series on the breadboard.

The connection point between these two resistors is where the voltage is "divided."

• The connection point between these two resistors is where the voltage is "divided."

Connections:

Solar Panel Positive (+) → One end of the 10kΩ resistor.

• Solar Panel Positive (+) → One end of the 10kΩ resistor.

Solar Panel Negative (-) → Arduino GND (This common ground is essential).

• Solar Panel Negative (-) → Arduino GND (This common ground is essential).

The other end of the 1.5kΩ resistor → Arduino GND.

• The other end of the 1.5kΩ resistor → Arduino GND.

The junction between the 10kΩ and 1.5kΩ resistors → Arduino Analog Pin A0.

• The junction between the 10kΩ and 1.5kΩ resistors → Arduino Analog Pin A0.

This setup ensures that only a fraction of the solar panel's voltage reaches the sensitive Arduino pin.

How the Code Works (The Core Logic)

The code performs two main tasks: reading the scaled-down voltage and calculating the actual solar panel voltage.

Analog Read: The analogRead(A0) function reads the voltage at pin A0. It returns a value between 0 (0V) and 1023 (5V).

• Analog Read: The analogRead(A0) function reads the voltage at pin A0. It returns a value between 0 (0V) and 1023 (5V).

Convert to Scaled Voltage: This value is converted to the actual voltage seen by the Arduino pin.

voltage = sensorValue * (5.0 / 1023.0);

• voltage = sensorValue * (5.0 / 1023.0);

• Convert to Scaled Voltage: This value is converted to the actual voltage seen by the Arduino pin.voltage = sensorValue * (5.0 / 1023.0);


Calculate Actual Solar Voltage (The Crucial Part): This is where the voltage divider formula is applied.

The formula for a voltage divider is: Vout = Vin * (R2 / (R1 + R2))

• The formula for a voltage divider is: Vout = Vin * (R2 / (R1 + R2))


We know Vout (the voltage we measured at A0) and we need to find Vin (the solar panel voltage).

• We know Vout (the voltage we measured at A0) and we need to find Vin (the solar panel voltage).

Rearranging the formula: Vin = Vout * ( (R1 + R2) / R2 )

• Rearranging the formula: Vin = Vout * ( (R1 + R2) / R2 )


In the code, this becomes: solarVoltage = voltage * ((10000 + 1500) / 1500.0);

• In the code, this becomes: solarVoltage = voltage * ((10000 + 1500) / 1500.0);

• Calculate Actual Solar Voltage (The Crucial Part): This is where the voltage divider formula is applied.The formula for a voltage divider is: Vout = Vin * (R2 / (R1 + R2))

We know Vout (the voltage we measured at A0) and we need to find Vin (the solar panel voltage).Rearranging the formula: Vin = Vout * ( (R1 + R2) / R2 )

In the code, this becomes: solarVoltage = voltage * ((10000 + 1500) / 1500.0);


Example Code Snippet (Based on the Article)

Here is the essential code structure with explanations:

cpp

// Define the resistor values for the voltage divider
const float R1 = 10000.0; // 10k ohm resistor (R1)
const float R2 = 1500.0;  // 1.5k ohm resistor (R2)

// Arduino pin and variables
const int sensorPin = A0;
int sensorValue = 0;
float voltage = 0;
float solarVoltage = 0;

void setup() {
  Serial.begin(9600); // Start serial communication to display results
  Serial.println("Solar Panel Voltage Measurement");
}

void loop() {
  // 1. Read the analog value (0 - 1023)
  sensorValue = analogRead(sensorPin);
  
  // 2. Convert it to the voltage at the Arduino pin (0V - 5V)
  voltage = sensorValue * (5.0 / 1023.0);
  
  // 3. Calculate the actual solar panel voltage using the divider formula
  solarVoltage = voltage * ((R1 + R2) / R2);
  
  // 4. Print the results to the Serial Monitor
  Serial.print("Analog Read: ");
  Serial.print(sensorValue);
  Serial.print(" | Scaled Pin Voltage: ");
  Serial.print(voltage);
  Serial.print("V | Actual Solar Voltage: ");
  Serial.print(solarVoltage);
  Serial.println("V");
  
  delay(1000); // Wait for a second before the next reading
}

Advantages and Limitations

Advantages

Limitations

Safe for Arduino: Protects the microcontroller from high voltages.

No Current Measurement: This setup only measures voltage, not power (Wattage).

Low Cost & Simple: Uses very cheap and common components.

Power Consumption: The voltage divider constantly draws a small amount of current from the panel (I = V/(R1+R2)).

Excellent for Learning: Demonstrates a fundamental electronics principle (voltage divider) in a practical context.

Accuracy Depends on Resistors: The accuracy of the measurement depends on the precision of the resistors (standard 5% tolerance resistors have a margin of error).

Foundation for Advanced Projects: Can be extended to data logging, charge controllers, or IoT monitoring.

Not for High Power/Voltage: This specific resistor combination is for lower-voltage panels. Measuring grid-tier solar panels requires more sophisticated instrumentation.

How to Improve This Project

The basic project is a starting point. Here are ways to make it more advanced and useful:

Add an LCD Display: Connect a 16x2 LCD to show the voltage in real-time without needing a computer and the Serial Monitor.

• Add an LCD Display: Connect a 16x2 LCD to show the voltage in real-time without needing a computer and the Serial Monitor.

Measure Current: Add a Hall Effect sensor (ACS712) or a small shunt resistor to measure current. With voltage and current, you can calculate Power (P = V * I).

• Measure Current: Add a Hall Effect sensor (ACS712) or a small shunt resistor to measure current. With voltage and current, you can calculate Power (P = V * I).

Data Logging: Add an SD card module to log the voltage, current, and power over time to track solar panel performance.

• Data Logging: Add an SD card module to log the voltage, current, and power over time to track solar panel performance.

Create a Simple Charge Controller: Use the Arduino to control a relay or MOSFET to connect/disconnect a battery based on the solar voltage, preventing overcharging.

• Create a Simple Charge Controller: Use the Arduino to control a relay or MOSFET to connect/disconnect a battery based on the solar voltage, preventing overcharging.

Calculate Energy: By integrating power over time in the code, you can calculate the total energy generated (Watt-hours).

• Calculate Energy: By integrating power over time in the code, you can calculate the total energy generated (Watt-hours).

Important Considerations

Resistor Tolerance: For a more accurate measurement, use resistors with 1% tolerance instead of the standard 5%.

• Resistor Tolerance: For a more accurate measurement, use resistors with 1% tolerance instead of the standard 5%.

Maximum Voltage: With the given resistors (10kΩ & 1.5kΩ), the maximum measurable voltage is calculated as follows: Vin_max = 5V * ((10000 + 1500) / 1500) ≈ 38.3V. Do not exceed this voltage.

• Maximum Voltage: With the given resistors (10kΩ & 1.5kΩ), the maximum measurable voltage is calculated as follows: Vin_max = 5V * ((10000 + 1500) / 1500) ≈ 38.3V. Do not exceed this voltage.

Verification: Always verify your Arduino readings with a trusted multimeter.

• Verification: Always verify your Arduino readings with a trusted multimeter.

Conclusion

The Solar Panel Voltage Measurement Project is a perfect beginner-to-intermediate Arduino project. It successfully teaches a critical circuit (the voltage divider) and applies it to a real-world scenario. It's a foundational step towards building more complex renewable energy monitoring systems and provides a solid understanding of how to safely interface microcontrollers with higher-voltage sources.