Solar Powered WiFi Weather Station V2.0

This tutorial is a continuation of my earlier weather station project. It was quite popular on the web, people around the globe made their own by following it and given valuable feedback for improvement. By taking consideration of the comments and Q&A section of my earlier project, I decided to make this new version Weather Station. I also made a custom PCB for this project, so anyone with little knowledge on electronics circuit can be made this project. My V-2.0 PCB can also be used for any application in the Arduino platform. The following are the salient features of the new weather station.

Features:

1. Connect to Wi-Fi, and upload the data to the web ( Blynk App and Thingspeak )

2. Monitoring Weather parameters like Temperature, Pressure, Humidity, altitude and UV level, etc.

3. Extra ports to add more sensors

4. Remote Battery Status Monitoring

5. Uses a powerful Li-Ion Battery ( 3400 mAh ) and Solar Panel ( 1 Watt )

6. Independence from the external power source

7.Can be installed in remote sites or geographically challenging environments

8. Being Solar powered, it is an environment-friendly device.

Step 1: Components and Tools Required

Update 05.08.2019

Now you can buy the PCB and all the components in a single Kit from PCBway.

Note:Battery and 3D printed enclosure is not included in the kit

Components Used :

1. Wemos D1 Mini Pro (Banggood / Amazon )

2. TP 4056 Charging Board (Banggood / Amazon )

3. BME 280 sensor ( Amazon / Bangood )

4. BMP280 ( Banggood / Amazon )

5. DS18B20 Sensor ( Banggood / Amazon )

6. Switch ( Banggood / Amazon)

7. Screw Terminals ( Banggood)

8. PCB standoffs ( Banggood / Amazon )

9. 18650 Battery ( Aliexpress)

10.18650 Battery Holder ( Banggood / Amazon)

11. Solar Panel ( Banggood )

12. Straight Headers Pin ( Banggood / Amazon )

13. 22 AWG wire ( Banggood / Amazon )

14. Weather Station V2.0 PCB ( PCBWay )

15. Super Glue ( Amazon )

16. 3D printing filament -PLA ( GearBest )

Tools Used :

1. 3D Printer ( Creality CR-10 )

2. Soldering Iron ( Amazon )

3. Glue Gun ( Amazon )

4. Wire Stripper ( Amazon )

5. Wire Cutter ( Amazon )

Step 2: Power Supply

My plan is to deploy the Weather station at a remote place ( my farmhouse).To run the Weather Station continuously, there must be a continuous power supply otherwise the system will not work. The best way to provide continuous power to the circuit is by using a battery. But after some days the battery juice will run out, and it is a really difficult job to go there and charge it. So a solar charging circuit was proposed to user free energy from the sun to charge the batteries and to power the Wemos board. I have used a 18650 Li-Ion battery.

The battery is charged from a Solar panel through a TP4056 charging module. The TP4056 module comes with a battery protection chip or without the protection chip. I will recommend buying a module that has a battery protection chip included.

About the TP4056 Battery Charger

The TP4056 module is perfect for charging single cell 3.7 V 1 Ah or higher Li-Po cells. Based around the TP4056 charger IC and DW01 battery protection IC this module will offer 1000 mA charge current then cut off when charging is finished. Furthermore, when the battery voltage drops below 2.4 V the protection IC will cut off the load to protect the cell from under-voltage. It also protects against overvoltage and reverse polarity connection.

Step 3: Monitoring Temperature and Humidity by BMP/E280

In the earlier days, weather parameters like ambient temperature, humidity, and barometric pressure were measured with separate analog instruments: thermometer, hygrometer, and barometer. But today the market is flooded with cheap and efficient digital sensors that can be used to measure a variety of environmental parameters. The best examples are sensors like DHT11, DHT 22, BMP180, BMP/E280, etc.

In this project, we will use BMP280 / BME280 sensor.

BMP 280 :

BMP280 is a sophisticated sensor that very accurately measures barometric pressure and temperature with reasonable accuracy. The BME280 is the next-generation of sensors from Bosch and is the upgrade to the BMP085/BMP180/BMP183 - with a low altitude noise of 0.25m and the same fast conversion time. The advantage of this sensor is that it can use either I2C or SPI for communication with the microcontroller. For simple easy wiring, I will suggest buying the I2C version board.

BME280 :

The new BME280 sensor, an environmental sensor with temperature, barometric pressure, and humidity. The BME280 is the next-generation of sensors from Bosch and is the upgrade to the BMP280. This precision sensor from Bosch is the best low-cost sensing solution for measuring humidity with ±3% accuracy, barometric pressure with ±1 hPa absolute accuracy, and temperature with ±1.0°C accuracy. It can be used in both I2C and SPI.

Note: BME280 can measure humidity but BMP280 can't. In the market, BMP280 is also available by the name of BME280. So be sure whether it is a BMP280 or BME280.

Step 4: Additional Ports for More Sensors

The Weather Station V2.0 board has 5 additional ports to hook up more weather sensors. The following additional sensors can easily be hooked up :

1. GY-1145 Sensor: for measuring UV Index

The SI1145 is a sensor with a calibrated UV sensing element that can calculate the UV Index. It can communicate via I2C communication (address 0x60). You can hook up this sensor with I2C port on the board which is located just side to the power switch.

You can read this article to know more about this sensor.

You can buy this sensor from Banggood.

2. HDC1080: for measuring temperature and humidity

The HDC1080 is a digital humidity sensor with an integrated temperature sensor that provides excellent measurement accuracy at very low power. It can also communicate via I2C communication.

You can read this article to know more about this sensor.

You can buy this sensor from Banggood.

3. DS18B20: for measuring temperature

It can measure temperature with a minimal amount of hardware and wiring. These sensors use a digital protocol to send accurate temperature readings directly to your development board without the need for an analog to digital converter or other extra hardware. It uses a one-wire protocol to communicate with the microcontroller. It can be hooked up in port-P2 on the board which is located on the right side of the Wemos board.

You can read this article to know more about this sensor.

Step 5: Using an External Antenna ( 3dBi )

The Wemos D1 mini Pro board has an inbuilt ceramic antenna along with provision for connecting an external antenna to improve the range. Before using the external antenna, you have to reroute the antenna signal from the built-in ceramic antenna, to the external socket. This can be done by rotating the small surface mount (0603) Zero Ohm resistor (sometimes called a link).

You can see the above picture, how I have done this.

You can also watch this video made by Alex Eamesto to rotate the zero ohm resistor. Then snap the antenna SMA connector into the Wemos Pro mini antenna slot.

Step 6: Monitoring Battery Voltage

The weather station is run by a 18650 Li-Ion battery, so it is very important to monitor its status. The max voltage input to the Wemos board is around 3.2~3.3V but a fully charged 18650 battery voltage is 4.2V. So to measure this voltage we have to step down the voltage by using a voltage divider network.

The Wemos D1 mini already has an internal voltage divider that connects the A0 pin to the ADC of the ESP8266 chip. The voltage divider is made up of 220k (R1) and 100k (R2). So, we have to add an external resistance with the inbuilt 220k resistor to read the battery voltage. By using a 100k resistance we can measure the max voltage of the battery, but taking some margin, a 220k resistor is selected. It is named R1 on the PCB board and located just above the battery holder.

To select the voltage divider resistance values, you can use this online calculator.

You can also read this article on battery voltage monitoring.

Step 7: Implimenting Deep Sleep Mode

The heart of the Wemos Board used in our Weather Station is an ESP8266 SOC which is a power hungry chip. Our objective is to run the device by using a 18650 battery but the demand for power usually makes battery operation impractical.

Another problem is that as the device will run continuously, it is quite obvious that the device will experience warming, and therefore the measured temperature will be higher than the ambient temperature.

From the above, it is clear that we have to lower the power consumption of the ESP8266 WiFi chip. To do that, we’ll use the Deep Sleep mode which is the most power efficient option for ESP chip. It allows to put the ESP8266 into hibernation and saves the battery. You can wake up at regular intervals to make measurements and publish them.

Component Operation mode ----- Sleep mode

1. ESP8266 170 mA -------- 10 uA

2. CH340 12 mA --------- 50 uA

3. Built-in LED 3 mA ----------- 0 uA

4. Voltage monitor 0.006 mA ----- 6 uA

-----------------------------------

Total185 mA ---- 66 uA

If the sleep-wake cycle is 10 minutes, with a 30 second wake time, the energy consumption budget looks like this:

Wake time 185 mA for 0.5 minutes = 92.5 mA-minutes

Sleep time 0.066 mA for 9.5 minutes = 0.627 mA-minutes

Total in 10 minutes = 93.13 mA-minutes

Thus the average current consumption is 9.3 mA.

Image credit: http://brainpoweryoutube.blogspot.com/2015/12/the-...

Step 8: Selecting the Solar Panel

From the previous step, it is concluded that the average current consumption is 9.3 mA

Charge required for running the device for the whole day = 9.3 mA x 24 Hours = 223.2 mAh

There is no current gain in the linear regulator used in the WeMos, so any current used at 3.3V results in the same current at 3.7V or whatever voltage the battery is at.

The amount of solar insolation varies according to which part of the globe you are located at. To find out the amount of solar insolation in your area, you can use the Global Solar Atlas. By taking consideration into a minimum of 1 hour of full sunlight, we are going to select the solar panel.

So, our target is to generate 223.2 mAh in 1 hour.

To charge a 3.7V Li-Ion battery, a solar panel of voltage 5 to 6V is adequate.

Required Solar Panel rating = 223.2 mA at a voltage of around 5 to 6 volts.

Solar panel rating = 223.2mA x 5V = 1.1W

Solar Panel Selected : 1W / 5V to 6V

In this project, I have used a 5V, 200mA Solar Panel ( 99 x 69 mm)

So a 1W panel should be enough to run the project even in winter in places with a high latitude.

Note: If your location receiving an ample amount of sunlight, then a 0.66W solar panel which I have used in my earlier version also works.

Step 9: PCB Design

I have drawn the schematic by using EasyEDA online software after that switched to the PCB layout.

All of the components you added in the schematic should be there, stacked on top of each other, ready to be placed and routed. Drag the components by grabbing on its pads. Then place it inside the rectangular border line.

Arrange all the components in such a way that the board occupies minimum space. Smaller the board size, the cheaper will be the PCB manufacturing cost. It will be useful if this board has some mounting holes on it so that it can be mounted in an enclosure.

Now you have to route. Routing is the most fun part of this entire process. It’s like solving a puzzle! Using the tracking tool we need to connect all the components. You can use both the top and the bottom layer for avoiding overlap between two different tracks and making the tracks shorter.

You can use the Silk layer to add text to the board. Also, we are able to insert an image file, so I add an image of my website logo to be printed on the board. In the end, using the copper area tool, we need to create the ground area of the PCB.

Now the PCB is ready for manufacturing.

You can order it from PCBWay Sign up PCBWay now to get a US $5 coupon. That means your first order is free of cost only you have to pay the shipping charges.

When you place an order, I will get 10% donation from PCBWay for acontribution to my work. Your little help may encourage me to do more awesome work in the future. Thank you for your cooperation.

Once we are completed the PCB design we just need to click the “Gerber Output” button, save the project and we will be able to download the Gerber files which are used to manufacturing the PCB.

Step 10: PCB Fabrication

Once we are completed the PCB design we just need to click the “Gerber Output” button, save the project and we will be able to download the Gerber files which are used to manufacturing the PCB.

Step 11: Assembling the PCB

After receiving the board from the PCB fab house, you have to solder the components.For Soldering, you will need a decent Soldering Iron, Solder, Nipper.

First I cut the straight male and female headers pin for Wemos Board, TP4056, BMP/E 280 and for all the ports.

Following are the details about the headers :

1. Wemos Board - 2 x 8pins Female

2. BMP280 - 1 x 6pins Female

3. I2C Port - 1 x 4pins

4. Port P1 - 1 x 4pins

5. Port P2- 1 x 3pins

6. Port P3- 1 x 4pins

7. Port P4- 1 x 3 pins

It is good practice to solder the components according to their height. Solder the lesser height components first.

I have started by soldering the resistors, switch and then moved towards the bigger components like headers pin, screw terminal and battery holder.

Step 12: Adding the Modules and Battery

After assembling the header pins, switch and screw terminal, it is time to insert the boards into their respective headers. The headers are clearly labeled on the PCB, so there is no chance of confusion.

First I place the TP4056 board and solder all the pads.

Then I added the Wemos Board and BME280 Sensor.

Finally, I inserted the 18650 battery into the battery holder.

Step 13: Mounting the Standoffs

After adding all the parts, mount the standoffs at 4 corners. I used M3 Brass Hex Standoffs.

The use of standoffs will provide sufficient clearance to the soldering joints and wires from the ground.

Step 14: 3D Printed Enclosure

To give a nice commercial product look, I designed an enclosure for this project. I used Autodesk Fusion 360 to design the enclosure.

The enclosure has two parts:

1. Main Body

2. Cover Lid

The Main Body is basically designed to fit the Weather station V2.0 PCB (85mm* 83mm).

The Cover lid is to cover up the main body opening.

I used my Creality CR-10 printer and 1.75 mm green PLA filament to print the parts. It took me about 11 hours to print the main body and around 3 hours to print the top lid.

My settings are:

Print Speed : 60 mm/s

Layer Height: 0.2mm ( 0.3 also works well)

Fill Density: 25%

Extruder Temperature: 200 deg C

Bed Temp: 60 deg C

Download the STL files from Thingiverse

You can also have a look into the enclosure designed by 3KU_Delta.

Download the STL file of his design from Thingiverse

Step 15: Put the PCB Inside the Enclosure

First, insert the M-F hex standoffs into the four mounting slots in the enclosure.

Then fix the PCB board over the standoffs by aligning its four screw holes at the corner.

After inserting the four standoffs, I have faced difficulty to fix the PCB due to small misalignment. So I am thinking to modify the mounting stand to fix the 3M screw directly instead of hex standoffs.

Step 16: Installing the Components

Solder a 22 AWG red wire to the positive terminal and black wire to the negative terminal of the Solar panel.

Insert the two wires into the holes in the roof of the main enclosure body.

Use super glue to fix the Solar Panel and press it some time for proper bonding.

Seal the holes from the inside by using hot glue.

Step 17: Installing the Solar Panel

After mounting the PCB, you have to install the BME280 module and Wemos board.

Then insert the jumper JP2.

Insert the SMA connector into the holes provided in the enclosure. Then tighten the nut along with the washers. Now install the antenna by properly aligning with the SMA connector.

At last, put the 18650 battery inside the battery holder. Make sure you have to insert the right polarity. The polarity is marked on the battery holder, PCB as well as on the battery.

Step 18: 3D Printed Stevenson Screen

My earlier enclosure design was a decent looking enclosure but it was not ideal for the weather station. The ideal enclosure for keeping the weather sensors is the Stevenson Screen. A Stevenson screen is an enclosure for weather sensors against rain and direct heat radiation from outside sources, while still allowing air to circulate freely around them.

The Stevenson Screen for Solar Weather Station V2 is designed by my friend Glen. This has a simple wall mount and a 2 part cover to isolate the heat transfer from the solar panel. I really appreciate his work.

You can download the.STL files from Thingiverse

TIP: Spray the fully assembled PCB with Lacquer Sprayto protect the board and components, but you do need to put a little tape over the BME280 temp sensor hole to not block it.

Step 19: Interfacing With Blynk App

Step-1: Download the Blynk app

1. For Android

2. For iPhone

Step-2: Get the Auth Token

In order to connect the Blynk App and your hardware, you need an Auth Token.

1. Create a new account in the Blynk App.

2. Press the QR icon on the top menu bar. Create a clone of this Project by scanning the QR code shown above. Once it detected successfully, the whole project will be on your phone immediately.

I've made the Solar Weather Station app. You are welcome to try it out!

To start using it: 1. Download Blynk App: http://j.mp/blynk_Android or http://j.mp/blynk_iOS 2. Touch the QR-code icon and point the camera to the code below 3. Enjoy my app!

3. After the project was created, we will send you Auth Token over email.

4. Check your email inbox and find the Auth Token.

Step-3: Preparing Arduino IDE for Wemos Board

To upload the Arduino code to Wemos board, you have to follow this tutorials

Step-4: Arduino Sketch

After installing the above libraries, paste the Arduino code given below.

Enter the auth code from step-1, ssid, and password of your router.

Then upload the code.

Step 20: Uploading Sensor Data to ThingSpeak

First, create an account on ThingSpeak.

Then create a new Channel on your ThingSpeak account.

Find How to Create a New Channel Fill Field 1 as Pressure, Field 2 as Temperature, Field 3 humidity, Field 4 as altitude and Field 5 as Bat Voltage.

In your ThingSpeak account select “Channel” and then “My Channel”.

Click on your channel name.

Click on “API Keys” tab and copy the “Write API Key”

Open the Solar_Weather_Station_ThingSpeak code.

Replace the “WRITE API ”with the copied “Write API Key”.

You can see my live feed.

Step 21: Software and Libraries

To use Wemos D1 with the Arduino library, you'll have to use the Arduino IDE with ESP8266 board support. If you haven't already done that yet, you can easily install ESP8266 Board support to your Arduino IDE by following this tutorial by Sparkfun.

Following settings are preferable :

PU Frequency: 80MHz 160MHz

Flash Size: 4M (3M SPIFFS) – 3M File system size 4M (1M SPIFFS) – 1M File system size

Upload Speed: 921600 bps

Library

Before uploading the code install the following libraries :

1. ESP8266

2. BMP280

3. Blynk

You can read this tutorial by Sparkfun to install the Arduino libraries.

In my earlier version, there are two separate codes for Blynk and Thinspeak but in this version, we have written a single piece of code. The user has to only comment out a single line of code for Blynk or Thingspeak. For example, if you are using it for Blynk App, the code should be as below:

const String App = "BLYNK";         //  alternative is line below
// const String App = "Thingspeak";    //  alternative is line above

Credit: I want to give a lot of credit to Keith Hungerford, who has guided me to make this project more powerful. The software library for BMP280 is also written by him. You can read his Instructable on BMP280 power saving mode.

Note: Before using the deep sleep feature, Wemos D0 pin must be connected to the RST pin. This can be done by shorting the jumper JP2.

Update : 15.05.2019

You can also see excellent work done by 3KUdelta on his GitHub Page. In his V2.3 code, he included the famous Zambretti forecaster. I really appreciate his hard work for the improvement of the project.

The software provides short term forecast in words (4-6 hours) using the famous Zambretti forecast model :

• 4-6 hour forecast in words
• Trend in words
• Temperature
• Dewpoint
• Heat Index
• Humidity
• Absolute Pressure
• Relative Pressure
• Battery Voltage (V)

Step 22: Conclusion

In the future, my plan is to add wind and rainfall measuring sensors like this project

I am thinking to make a DIY kit for this project, but not finding a suitable vendor who can do this for me. Be in touch for more updates.

Update on 15.02.2019 :

Now you can order the PCB from PCBWay Sign up PCBWay now to get a US $5 coupon. That means your first order is free of cost only you have to pay the shipping charges. When you place an order, I will get a 10% donation from PCBWay for a contribution to my hard work. Your little help may encourage me to do more awesome work in the future. Thank you for cooperation.

Update on 05.08.2019Now you can buy the PCB and all the components in a single Kit from PCBway.

Note: Battery and 3D printed enclosure is not included in the kit

Thanks for reading my tutorial.

If you like my project, don't forget to share it.

Comments and feedback are always welcome.