Tame the Beast! Make a Solar Powered Arduino Unit

This solar powering unit is a time switching battery powered solar charged circuit, used to power an Arduino Uno and some peripherals. The solar powering unit presented here is energy efficient. When we talk about Arduino, it consumes lots of energy in displays and other work that are not important. The solar powering unit presented here has a timer which turns on the Arduino in regular intervals. When you have a project like weather station, remote data logger, etc. or applications like this, you do not have to keep your Arduino on all the time. And of course in all this applications, powering is the major issue. If you turn on the Arduino in 1 minute or any interval, it can save a lot energy. This unit is variable i.e. you can decide the time delay! The unit can also power your Arduino when there is no sunlight(at night) as it has a rechargeable battery inside.

The unit consists of two solar panels, one is for the timer circuit and another is for output. The timer circuit contains an Arduino which is converted into a variable timer with the help of code. It is connected to relay module. The unit also consists of rechargeable cells which are charged by solar panel. When you want to use power from them, you need to just toggle the switch.

Go through the instructions for building you own solar powering unit and taming the beast!

Step 1: Components and Materials

The materials and components you need for building this unit are as follows:

1. 2 x Arduino UNO R3 Boards

2. 2 x 6V 100mA Solar panels

3. DC-DC Boost Converter Module

4. A 4.5" x 6.5" x 2.75" enclosure

5. 2 x Rechargeable cells

6. Female USB Port

7. Relay module

8. 50k Potentiometer

9. 1N4007 diode

10. 2 AA Batteries Holder

The supplies needed for a simple solar powering unit are:

1. 6V 100mA Solar Panel

2. 7805 Voltage regulator IC

3. 1000uF Capacitor

4. Female USB Port

5. DC-DC Boost converter module(Optional)

6. A 2.25" x 3.5" x 1" Enclosure

Note: All this supplies can be found on Sparkfun/Digikey except enclosures!

Step 2: Making a Simple Solar Powering Unit!

If you don't want the complex powering system, then this simple solar powering unit is ideal and you have to just plug your Arduino and it is ready to play!

Step 3: Make the Circuit

Assemble the components as shown in circuit diagram. The circuit used for charging is a simple voltage regulating circuit. I have used 7805 voltage regulator IC to give 5V output and a 1000uF Capacitor is connected in parallel to output voltage. The output is done through female USB port. Connect the VCC of solar panel to Pin 1 of 7805 and GND to 2nd pin of 7805.

Note: 1. Please study the pinout diagram of female USB port carefully before connections!

2. Just connect the circuit to test whether it is working because you have to disconnect it when arranging in enclosure.

Step 4: Or Just Use DC-DC Boost Converter

If you do not want to make the circuit, just use DC-DC boost converter module. Connect red wire of solar panel to + polarity of module and black wire to -.

Note: Just connect the module to test whether it is working because you have to disconnect it when arranging in enclosure.

Step 5: Getting Enclosure Ready!

Make a small hole on the top of the front side of enclosure to pass the wires in and a square hole in the side for the USB female port.

Step 6: Final Assembly

Assemble the circuit inside the enclosure and make sure you place in such a way that the female USB port is exposed to the hole you made for it and also do some necessary arrangements to place the circuit in its place and do not move.

Step 7: Time for the Big Thing!

After making the basic solar powering unit, its now time to make the power efficient unit. In this we will make first of the timer circuit and then we will do some necessary connections to solar panel, switch and output ports.

Step 8: The Timer Circuit

The timer circuit has arduino as its main component. The relay module is attached to it which actually lets the voltage flow when the timer activates. The potentiometer is used for variation in time delay.

Here the relay module has 3 pins which are Signal, VCC and Ground. On the VCC pin we have to supply +5V and the other one is ground. Now, the signal pin is the pin which helps us to trigger the relay. This signal pin is kept at the source where voltage is high at regular time delay. So we use arduino for the same purpose. In Arduino we will upload the code which will read the potentiometer and delays accordingly. The relay module has NO, NC and Common pin in the front portion. The Common terminal is in the center of No and NC. The NO pin is open. If you turn your multi meter into continuity testing mode and put the probes on NC and common, it beeps. Means they are connected. when the signal triggers the relay, NO and Common terminal gets connected and thus switching occurs. At that time NC and Common terminal is disconnected. thus in this way we have used Arduino and Relay module for switching at regular intervals.

The circuit diagram shown here is the diagram of whole unit.

Step 9: Potentiometer Connections and Code

Now, the potentiometer we have used is 50Kohm. It has three pins. The center pin is to be connected to Analog pin 2 of Arduino UNO. The either of the remaining two pins is to be connected to +5V and the other one to GND.

The code written is very simple and easy to undersatnd.

Code:

int potPin = 2;
int ledPin = 13; void setup() { pinMode(ledPin, OUTPUT); } void loop() { val = analogRead(potPin); delay(1000); digitalWrite(ledPin, LOW); delay(val*10); }

sketch_jan11a.ino
Download

Step 10: Make Holes and Insert Solar Panels

Make holes as seen in first photo. The two on both the sides are for solar panels and the two in center are for switch and potentiometer. Then insert both the solar panel and fix them.

Step 11: Powering the Timer Circuit

We will power the timer circuit with the help of circuit we made in step 3. Connect the VCC of solar panel to Pin 1 of 7805 and GND to 2nd pin of 7805. Then Connect the timer circuit with the help of small Arduino cable. Then insert the Potentiometer in the hole and tighten it with nuts from outer side.

Step 12: Connecting Rechargeable Batteries

Here we are using two AA Rechargeable batteries which are connected to solar panel. Now first of all connect diode 1N4007 in such a way that the Negative terminal of diode is connected to positive terminal of Cell Holder. Then Connect the red wire of solar panel to positive terminal of diode and black wire of solar panel to negative terminal of Cell Holder.

Step 13: Connect DC-DC Boost Converter

For using the voltage of Batteries, we are using a 5V DC-DC Boost converter. First of all connect positive terminal of battery to the switch and the other terminal of switch to Positive terminal of Boost Converter and connect negative terminal of cell holder to negative terminal of boost converter. Take the help of circuit diagram if any confusion.

The big problem here is attaching DC-DC Boost Converter on its place. So first of all, make a square hole. I have made all the holes wit the help of Drill machines and if you are not expert in it please take help of anyone who have enough experience. Then I have kept some plastic pieces for mantaining height and then stuck the USB port of converter with the help of hot glue. Now its fixed!

Step 14: Output

Now, the output voltage should be switched with the help of relay module. So first of all connect the positive terminal of second solar panel to which cells are connected to Common pin of relay module and take a wire and connect its one end at NC pin of relay module and other one to output USB port. Then connect the negative terminal of solar panel to USB port. Then fix the port as we fixed DC-DC Boost converter earlier.

Note: Please refer USB port pinout diagram before making connections.

Step 15: Nailed It!

Just assemble everything properly inside the enclosure. Tighten the box with screws and then hurray!! you have just built your own solar powering unit.