Introduction

This tutorial demonstrates how to power your Arduino Uno with a solar cell. Solar cells can be a useful solution for powering projects that require portability or remote monitoring. This tutorial uses concepts drawn from the following resources:

Parts

This project requires the following components:

Wiring

he following steps describe how to set up your Arduino Uno with solar power. As a note, components should be soldered together for stability.

Step 1: Solder M-M jumper wires to the positive (+) and negative (-) terminals of the solar cell.

Step 2: Solder the other end of the M-M jumper wires to the input terminals of the TP4056 battery charge controller.

Step 3: Solder the output wires from the battery holder to the TP4056 battery charge controller B+ and B- terminals.

Step 4: Solder a second set of M-M jumper wires to the output terminals of the TP4056 battery charge controller.

Step 5: Solder the other end of the M-M jumper wires to the input terminal of the XL6009 – Voltage Adjustable DC-DC (5v-35v) Boost Converter. Use a voltmeter connected to the output terminals to determine the output voltage. Powering the Arduino Uno through the Vin port requires an input between 7 and 12 Volts, so the desired output from the Boost Converter is 9V. The voltage output can be adjusted by turning the knob located on the blue rectangle.

Step 6: Solder another set of M-M jumper wires to the output terminals of the Boost Converter. Insert the other end of the M-M jumper wires to the Arduino Uno with the positive terminal connected to the Vin pin (+) and the negative terminal connected to the GND pin (-).

If working properly, the green light of your Arduino Uno should light up and it should now be ready to use!

Important Notes

Can I connect the solar cell directly to the Arduino Uno?

This is not a good idea for several reasons. Due to variability in sun This is not a good idea for several reasons. Due to variability in sun exposure, the solar cell may not provide a steady stream of power. The Arduino Uno may not be able to draw the maximum power at any given instant from the solar cell. Additionally, the power demands from the Arduino Uno may overload the solar cell. Using a rechargeable battery provides a constant, reliable energy source.

Are lithium-ion batteries safe to work with?

Lithium-ion batteries are extremely sensitive to charging characteristics and can easily catch fire or explode. It is necessary to take precautions when working with these batteries, considering they contain a high amount of energy and volatile chemical content.

The TP4056 battery charge controller works to mitigate the risks of working with lithium-ion batteries. The controller regulates the current produced by the solar cell to protect the batteries from overcharging. The controller detects when the battery is fully charged and can stop or limit the current received by the battery. Additionally, the controller also protects the solar cell by stopping reverse current flowing back from the batteries when there is no sunlight.

How do I choose a solar cell and battery?

The TP4056 battery charge controller has a maximum input of 6V, thus, the solar cell should be at maximum 6V. The voltage of the solar cell should be at least 1.5 times the voltage of the battery. So a 3.7V lithium-ion battery needs a solar cell of at least 5.55V. The current of the solar cell should have 1/10th of the capacity of the battery divided by 1 hour . So a lithium-ion battery of 2000 mAh, should be supported by a solar cell with around 200 mAh.

Why do I need a boost converter?

The power source that connects to the Vin pin on the Arduino Uno has to be 7 to 12 volts for the regulator to work reliably. The Vin pin converts unregulated input voltage to a stable 5V. The output voltage from the lithium-ion battery is 3.7V. A boost converter converter can step up the voltage from its input to its output to meet the desired input range of the Vin pin of between 7 and 12 volts.