SunAirPlus2 - Solar Controller / Charger / Sun Tracker / Data Gathering Grove/Header
SunAirPlus2 - Solar Controller / Charger / Sun Tracker / Data Gathering Grove/Header
SunAirPlus2 - Solar Controller / Charger / Sun Tracker / Data Gathering Grove/Header
SunAirPlus2 - Solar Controller / Charger / Sun Tracker / Data Gathering Grove/Header

SunAirPlus2 - Solar Controller / Charger / Sun Tracker / Data Gathering Grove/Header

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SunAirPlus2 - 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? SunAirPlu2 is a 4th Generation Solar Charging and Sun Tracking Boards designed by Dr. John C. Shovic at SwitchDoc Labs.

SunAirPlus2 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 major features of the SunAirPlus2 board are:

  • Uses 6V Solar Cells
  • Use 3.7V LiPo Cells for batteries
  • 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
  • Built-in Interface for Servo motor or Stepper motor
  • Built-in Interface for Limit Switches
  • 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

New Application Note Published *Secrets of SunAirPlus2*

  • Stepper Motor Controller / SunTracker
  • Turn off A USB Power Control with SunAirPlus
  • Directly Charge an iPhone / Android Phone from SunAirPlus
  • More More More Analog to Digital Inputs


You can download the current Full SunAirPlus2 (version 1.2)  Product Specification here.

Arduino SunAirPlus2 INA3221 Current Measuring Drivers

Raspberry Pi Python SunAirPlus2 INA3221 Current Measuring Drivers

ESP8266 SunAirPlus2 INA3221 Library

node + mraa library for reading from SwitchDoc Labs SunAirPlus2 or INA3221 Breakout Board

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

EXTPOWER LED1 A External Power Connected to VDD from Computer
GP0 STATE LED2 A Driven by EXTGP0 from Computer. Buffered

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.

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.