SunAirPlus3 - Solar Controller / Charger / Sun Tracker / Data Gathering Grove/Header
SunAirPlus3 - Solar Controller / Charger / Sun Tracker / Data Gathering Grove/Header

SunAirPlus3 - Solar Controller / Charger / Sun Tracker / Data Gathering Grove/Header

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SunAirPlus3 - Solar Cell Controller Board and Sun Tracker for Arduinos / Raspberry Pi / Cell Phone Charging. Plus open source software. Includes high quality ADC and Current and Voltage Data Gathering. Supports Grove Connectors and Pin Headers.

Ever wanted to build your own Solar Powered Raspberry Pi or Arduino system? SunAirPlus3 is a 5th Generation Solar Charging and Sun Tracking Boards designed by Dr. John C. Shovic at SwitchDoc Labs.  Also known as SunAirPlus 3.

SunAirPlus3 is customizable with your software and hardware. Note that the battery and solar panel plugs on SunAirPlus2 are of type JST-PH 2 pin.   The USB port is a USB Micro port

Differences between SunAirPlus2 and SunAirPlus3

  • Removal of stepper motor and limit switch interfaces
  • Addition of hysteresis and shutoff of load USB.  ~3.7V turn on / ~3.2V turn off.
  • VSS is cutoff to USB Out and I2C Grove port when board is powered down
  • INA3221 I2C Address is 0x41


The major features of the SunAirPlus3 board are:

  • Uses 6V Solar Cells
  • Use 3.7V LiPo Cells for batteries
  • Has Hysteresis built in to protect battery and load.   Turn on at battery voltage of ~3.7 and turns off at battery voltage of ~3.2
  • Has LiPo to 5V voltage boost built in
  • Directly powers Raspberry Pi / Arduino
  • Grove I2C Connector
  • Works Raspberry Pi (3.3V) GPIO and Arduino (5.0V) GPIO
  • Built-in data gathering chips for system currents /voltages
  • Charges iPhones and other phones or devices
  • Approximates an MPPT (Maximum Power Point Tracking) charging system


  • Put it with your favorite project and make it solar powered!
  • Make a Solar Powered Robot
  • Install a servo motor or stepper motor and track the sun
  • Add a SwitchDoc Dual WatchDog Timer to recover from failures, bad code or brownouts!
  • 3D Print your own SunAirPlus2 solar tracker


    Full SunAirPlus3 Specification Coming Soon

    Arduino SunAirPlus2 INA3221 Current Measuring Drivers

    Raspberry Pi Python SunAirPlus2 INA3221 Current Measuring Drivers

    ESP8266 SunAirPlus2 INA3221 Library (Change I2C address to 0x41)

    node + mraa library for reading from SwitchDoc Labs SunAirPlus2 or INA3221 Breakout Board (Change i2C address to 0x41)

    3D Printed Sun Tracking System for SunAir Application Download OpenSCAD files and STL Files Here.


    What are Grove Connectors?

    Check out this Grove Connector tutorial.


    Wire Colors on Grove Connector

    Wire colors on standard Grove Cables are always the same.

    Pin 1 - Yellow (for example, SCL on I2C Grove Connectors)

    Pin 2 - White (for example, SDA on I2C Grove Connectors)

    Pin 3 - Red - VCC on all Grove Connectors

    Pin 4 - Black - GND on all Grove Connectors

    What are the LEDs next to the Battery Plug?

    Charging State LEDs

    CH pin level(Red LED state) OK pin level(Green LED state) Statements
    low level(on) high level(off) Charging
    high level(off) low level(last on) Complete
    pulse signal(flash) pulse signal(on) The battery doesn't exist or has been deeply discharged
    high level(off) high level(off) No charging is taking place as the solar cell input voltage is too low

    USB OUT LED1 - On when power is supplied to the USB OUT port and Grove Port


    Data! Data! Data! More Cowbell!

    SunAirPlus2 includes an I2C INA3221 3 Channel Current / Voltage Monitor and a I2C 4 channel 12 bit Analog to Digital Converter (ADS1015). The INA3221 allows you to monitor all of the major currents and voltages in the system (Battery / Solar Panels / Load - Computer ). You can tell what your solar power project is doing in real time. Here are some results from the SunAirPlus2 board using the onboard INA3221. You can see that the battery is almost fully charged and the solar cell voltage (actually a variable power supply on the test bench) is 5.19V and it is supplying 735mA. The Output voltage is 4.88V because we are fiddling with the board. The Library works like a champ. (Set I2C Address to 0x41).


    Test SDL_Pi_INA3221 Version 1.0 - SwitchDoc Labs
    Sample uses 0x40 and SunAirPlus2 board INA3221
    Will work with the INA3221 SwitchDoc Labs Breakout Board
    LIPO_Battery Bus Voltage: 4.15 V 
    LIPO_Battery Shunt Voltage: -9.12 mV 
    LIPO_Battery Load Voltage:  4.14 V
    LIPO_Battery Current 1:  91.20 mA
    Solar Cell Bus Voltage 2:  5.19 V 
    Solar Cell Shunt Voltage 2: -73.52 mV 
    Solar Cell Load Voltage 2:  5.12 V
    Solar Cell Current 2:  735.20 mA
    Output Bus Voltage 3:  4.88 V 
    Output Shunt Voltage 3: 48.68 mV 
    Output Load Voltage 3:  4.93 V
    Output Current 3:  486.80 mA

    You can use this board to power your projects and add a servo or stepper motor to allow it to track the sun to generate even more power! It incorporates a number of outstanding features in a very compact, inexpensive single fully assembled and tested PC Board.

    3D Printing Files for SunTracker

    Solar Power

    3D Printed Sun Tracking System for SunAirPlus2 Application Download OpenSCAD files and STL Files Here.