3 Ways to Power an Arduino With Solar Power

To power an Arduino board using solar power, you need a solar panel to generate solar power, a rechargeable battery to store and supply power to your Arduino, and a method to regulate the voltage from the solar panel and prevent overcharging. You can select a solar charge controller with a voltage regulator, a solar charge controller with a USB port, or a specialized solar power manager board to regulate the voltage from your solar panel to power your Arduino board.

The board’s required power and voltage are the first factors to consider before getting started with your solar-powered Arduino project. Let’s start by looking at that.

Arduino Power Consumption

When choosing the best Arduino board for your solar-powered project, it’s important to consider Arduino’s power consumption.

Here’s a comparison of the power requirements for three popular Arduino boards:

I. Arduino Uno

The power consumption of Arduino Uno is about 50mA.

The recommended input voltage range for Arduino Uno is 7-12V, with a maximum current draw of around 800mA from the 5V pin when using an external power supply. Any external power supply or a USB connection can power Arduino Uno easily.

II. Arduino Nano

The Arduino Nano is similar to the Uno but with a smaller form factor. A Mini-B USB connection or an external power source has the capability to power Arduino Nano.

The recommended input voltage range is 7-12V, with a maximum current draw of around 800mA from the 5V pin when using an external power supply.

The power consumption of the board is about 19mA.

III. Arduino Pro Mini

The Arduino Pro Mini is a smaller, more efficient version of the Uno. It can be powered via the RAW pin or a regulated voltage applied to the VCC pin.

The prescribed range of input voltage for the 3.3V variant is 3.3-12V, while for the 5V variant, it is 5-12V.

The power consumption of the board is only about 4.7mA.

Based on power consumption alone, the Arduino Pro Mini is the most efficient choice for a solar-powered project, while the Arduino Uno is the most powerful.

Required Components and Material

The necessary components and materials will vary depending on the method you choose to power your Arduino with solar energy. Nonetheless, certain items are commonly required for all methods, including:

• A solar panel (5V or higher) to generate solar power
• Rechargeable batteries to store and supply power to your Arduino
• An Arduino board (with a USB port for power) to run your project
• A USB cable to connect your Arduino Uno to a power source
• A multimeter (optional) to measure voltage and current in your circuit
• And, wires to connect components

Each solar-powered Arduino method entails additional required components discussed in the corresponding sections below.

Method 1: Using a Charge Controller With a Voltage Regulator

This method involves using a voltage regulator to stabilize the output voltage from the solar panels, ensuring that it is safe to use with the Arduino.

For this method, you will also need:

• A solar charge controller
• A voltage regulator (LM7805 7805 Voltage Regulator 5V) to regulate the voltage output from your rechargeable battery.
• Capacitors (100 uF and 100 nF) to stabilize the voltage output from the regulator.
• Jumper wires to connect components on a breadboard
• Breadboard to build and test your circuit system
• An LED (any color) to indicate the power and status of your circuit

Once you have all the required components, you are ready to power your Arduino board with solar energy. Here are the steps to do so.

Step 1. Connecting the Solar Panels to the Charge Controller

Identify the positive and negative terminals of the solar panel (marked with + and – symbols).

Connect the solar panel’s terminals to the charge controller’s solar input terminals. The terminals on the controller may be labeled as SOLAR IN or PV IN. Some controllers also use the symbol of a solar panel to label the terminals.

Solar Panel Power Management Connection

Step 2. Connecting the Charge Controller to the Battery

Locate the battery’s positive and negative terminals. (marked with + and – symbols).

Connect the battery’s positive and negative terminals to the appropriate terminals on the charge controller. The terminals may be labeled as either BAT IN, BATTERY IN, or a symbol of a battery.

Step 3. Connecting the Voltage Regulator to Arduino

The voltage regulator regulates the voltage generated by the solar panels and provides safe, stable power to the Arduino.

First, identify its input (Vin), output (Vout), and ground (GND) pins. These pins are typically labeled on the voltage regulator.

Connect its input pins to the battery terminals, ensuring that you connect Vin to the positive terminal and GND to the negative terminal.

Connect its output pins to your Arduino and the out of the voltage regulator to the Vin terminal on your Arduino. Then, connect the GND on your voltage regulator to one of the GND pins of your Arduino.

Step 4. Stabilizing the Voltage Regulator Output

To prevent voltage fluctuations, use capacitors by connecting one capacitor between the Vin and GND pins of the voltage regulator and another between Vout and GND pins. A common capacitance value that can be used is 10uF.

Method 2: Using a Solar Charge Controller with a USB Port

The second method involves using a solar charge controller that can provide an output voltage of 5V using a USB port to power the Arduino.

For this method, you will need:

• A solar charge controller with a USB port to regulate the charging of your rechargeable battery and provide a stable 5V output to your Arduino.

Step 1. Connecting the Solar Panel and Battery to the Solar Charge Controller

Connect the solar panel and the battery to the appropriate terminals of the charge controller.

Make sure you connect the positive and negative terminals correctly. You can follow the same steps mentioned in Method 1 to do so.

Step 2. Connecting the Arduino

Connect the Arduino to one of the USB ports on the charge controller using a compatible USB cable and an output port with appropriate voltage and current ratings for your Arduino.

If everything is correctly connected, your Arduino should be powered on.

Method 3: Using a Specialized Solar Power Management Board

This method involves using a specialized solar power management board with an onboard voltage regulator to stabilize the output voltage from the solar panel and ensure that it is safe to use with the Arduino.

For this method, you will need to get:

• A specialized solar power management board (e.g. DFRobot Solar Power Manager 5V).

Step 1. Connecting the Solar Panel to the Power Manager Board

Locate the solar panel’s positive and negative terminals. (marked with + and – symbols).

Connect the positive terminal of the solar panel to the SOLAR IN+ input terminal of the power manager board.

Connect the negative terminal of the solar panel to the SOLAR IN – input terminal of the power manager board.

Step 2. Connecting the Power Manager Board to the Battery

Identify the positive and negative terminals of the battery, marked with + and -, respectively.

Connect the positive terminal of the battery to the BAT IN + output terminal of the power manager board.

Connect the negative terminal of the battery to the BAT IN – output terminal of the power manager board.

Step 3. Connecting the Arduino

Connect the Arduino board to the USB port on your power manager board using a compatible USB cable.

Testing Your Circuit

To ensure proper and safe operation, testing your solar-powered Arduino circuit after setting it up is important. This involves using a multimeter to measure the voltage at various points in your circuit and verifying that all components are functioning correctly.

Step 1: Measuring Voltage at the Solar Panel’s Output Terminals

Use a multimeter to measure the voltage at your solar panel’s output terminals. This will verify whether the solar panel is generating power or not.

Step 2: Measuring Voltage at the Battery’s Terminals

Use a multimeter to measure the voltage at your battery’s terminals and verify that the battery is being charged by your solar panel.

Step 3: Measuring Voltage at the Output of Your Power Regulation Component

Depending on which method you used, this step will vary:

• For Method 1 (Using a Charge Controller with a Voltage Regulator), use a multimeter to measure the voltage at your voltage regulator’s input (Vin) and output (Vout) pins.
• For Method 2 (Using a Solar Charge Controller with a USB Port), use a multimeter to measure the voltage at one of your charge controller’s USB ports (positive and negative).
• For Method 3 (Using a Specialized Solar Power Manager Board), use a multimeter to measure the voltage at the USB output pins on your solar power manager board.

Troubleshooting for Arduino Solar Power Management

You may encounter some unexpected challenges when powering your Arduino with solar energy. Here are a few common issues and their solutions:

A. Inefficient Voltage Regulation

The use of a linear voltage regulator (Method 1) may result in inefficiency and heat generation.

Utilizing a switching voltage regulator or a step-up boost converter, such as TPS61200 or TPS61202 chips, is recommended. The boost converter is a voltage-boosting device that is more efficient than linear regulators.

C. Insufficient Power Output From the Solar Panel

Insufficient power output from a solar panel can be addressed using multiple panels or selecting a panel with a higher power output.

Also, ensure the solar panel’s voltage and current output are compatible with your charging circuitry.

D. Battery Not Charging

To troubleshoot a battery that is not charging, ensure all connections are secure, and all components are functioning correctly.

Ensure adequate sunlight is reaching the solar panel and verify the proper functioning of the charge controllers (Method 1 and Method 2) or power manager board (Method 3).

It is important to ensure that the battery capacity is suitable for the power needs of your Arduino board. Since Arduino boards have low power requirements, this is not normally an issue.

E. Overheating

To prevent overheating of components, ensure proper ventilation and avoid direct exposure to sunlight. It is recommended to utilize components that have protection against overcurrent and overheating.

Power Management Tips

To ensure efficient power management in your Arduino solar-powered projects, follow these tips:

1. Optimize Your Solar Panel Setup

Choose solar cells with suitable power output, battery voltage, and capacity. If you are using very small solar panels, you may need multiple panels to generate enough voltage and power for your Arduino.

Orient the solar panel towards the true south (in the Northern Hemisphere) or the true north (in the Southern Hemisphere) to ensure maximum exposure of the solar cell to direct sunlight throughout the day.

Adjust the slope of the solar panel. The optimal angle for a solar panel is equal to the latitude at which it is located.

Use a good quality charge controller to regulate the voltage and current from the solar panel to safely charge the battery and prevent overcharging. Make sure the charge controller is compatible with your battery capacity and voltage.

2. Choose Low-Power Components

Choose low-power microcontrollers, sensors, and other components to minimize power consumption in your project.

Search for components that have low quiescent current and power-down modes to minimize power consumption.

3. Implement Power-Saving Techniques

Reduce data logging frequency in your Arduino to save power.

Configure sleep mode for your microcontroller and other components to minimize power consumption during idle periods.

Use interrupts to wake up the microcontroller only when necessary to perform tasks.

4. Monitor Power Usage

To monitor the power consumption of your circuit, utilize a multimeter.

Identify potential areas for reducing power consumption and optimizing setup efficiency. It is recommended to upgrade the battery capacity and voltage if necessary.