Small PCB that can be directly mounted onto the Raspberry Pi's pin header. Isolating GPIO 24 using an optocoupler.
Included is a rust program to to switch on or off a PV inverter based on the voltage of the battery bank.

hardware design

The hardware design was done using the open source EDA KiCAD 10.0 based on a 2.54mm prototype board.
Used components:

2x20 pin socket header
200Ohm metal film resistor (2.5mmx6.3mm)
optocoupler PC817
output connector: 2-pin JST XH board connector
20x16 hole 2.54mm prototype board

software

As a sample implementation, there is a rust program included that is switching a PV inverter on and off based on the voltage of the battery bank.
The data is read from a database that is updated regularly using VE.Direct-Text-Reader.
The actual control the pin is done using the crate rppal.
Developed and tested on a Raspberry Pi 5, with Raspberry Pi OS running rustc and cargo version 1.96.0.