mppt-2420-hpx

Libre Solar MPPT 2420 HPX

First prototype board ordered.

Schematic: PDF file in repository

Concept description

The battery port voltage can be 12V or 24V.

The MPPT port is connected to the battery via the DC/DC converter. This port is typically used as the solar panel input.

If building a hybrid system, the MPPT port can be used for wind generator input (after rectification) and the solar panel is connected to the PWM port. For a pure wind energy system, the PWM port can be used for controlling a dump load.

The load output protects the battery from deep-discharge if there is not sufficient power from solar panel or wind turbine. It is switched on the high-side to prevent issues with second GND paths e.g. via USB or audio cables.

Features

• MPPT terminal
  • Max. 80V (using 100V MOSFETs)
  • DC/DC converter inductor current max. 20A, resulting in approx. 560 W maximum power for 24V systems
• Battery terminal
  • 10 V - 32 V (supporting 12 V and 24 V battery systems)
  • Max. current: 20A
• High-side load output switch
  • Max. current: 20A
• PWM input/output terminal
  • Max. current: 20A
• Fast inductor current measurement (sample rate > 300 kHz) to allow implementation of digital DC/DC control algorithms
• New STM32G431 ARM MCU with advanced digital power conversion features
• Expandable via Olimex Universal Extension Connector (UEXT)
• Peripheral power connector for power-hungry extensions like GSM boards
• Only single LED as power indicator. Additional user interface (LED gauges, displays, etc.) will be included in separate PCB in front panel housing and connected via UEXT
• Optional EXT PCB on socket in bottom right corner
  • Dual USB charging port
  • CAN interface
  • Serial interface
• Optional USB Micro B connector for firmware upgrades and settings via virtual COM port.
• Optional ESP32 module for WiFi / Bluetooth
• Optional external temperature sensor (10k NTC)

Housing design

• MOSFETs need to be attached to an external heat sink (preliminary solution with thick aluminum sheet metal, final solution with aluminum extrusion profile)
• Panel for screw terminals and communications ports might be made from plate material to allow easy adjustment to different features.

First draft sketch of a housing with LED UI module: