• We’d like to develop a portable power solution using solar energy to power our Smart Irrigation Controller.
  • We intend for the Smart Irrigation Controller to be connected to a rechargeable battery, which would supply it with 5V. The rechargeable battery will be in turn connected to a portable solar panel, which would provide it with enough electrical energy to run our Smart Irrigation Controller.
  • Important : The Pi supports a 5V@2A input power. If our battery supplies more than 5V input voltage, we might have to use additional circuitry (i.e. Voltage Divider Circuit, DC/DC Power Converter, Linear Voltage Regulator) to reduce its input power to the Pi. Also, we might want to include a Current Regulator circuit to control the input current based on the boards’ needs.

Solar Energy Solution Diagram

Selecting components

  • Solar Panel : We need a solar panel able to support a battery outputting 5V @ 2A. A close match would be this model from Adafruit.
  • Battery : We’d like to provide an input power of 5V @ 2A to the Raspberry-Pi. There are many battery models available, but we’d likely have to add some voltage/current limiting circuits in-between the battery and the Raspberry-Pi.
  • Interface with the Raspberry-Pi : To power the Pi, we can connect our battery to either the Micro-USB port , or through specific pins of its GPIO interface. We need to see what interfaces is more suitable to our implementation.