After a few prototypes using Arduino boards and AVR 8-bit microcontrollers, the current version of the charge controller is based on 32-bit STM32 ARM MCU. This change was necessary in order to be able to implement a CANopen stack. In addtion to that, the used STM32F072 allows for some additional nice features like USB or a real-time clock.

Features

• 20A MPPT charger
• 55V max PV input
• 12V or 24V battery output
• 32bit ARM MCU (STM32F072)
• CAN communication interface with standard RJ45 jacks
• USB interface for firmware update and serial monitor
• Housing for DIN rail mounting
• Expandable via Olimex Universal Extension Connector (UEXT) featuring I2C, Serial and SPI interface (e.g. used for display, WIFI communication, etc.)
• Built-in protection:
  • Overvoltage
  • Undervoltage
  • Overcurrent
  • PV short circuit
  • PV reverse polarity (for max. module open circuit voltage of around 40V)
  • Battery reverse polarity (destructive, fuse is blown)

Development

The charge controller is under active development and you are welcome to participate.

Visit the GitHub page for schematics and board layout.