Add remote monitoring to a Sunbather Sunswitch: https://sunbather.com.au/pool-products/automatic-sunswitch-solar-controller/
Included code is designed to be run on an ESP32 running Tasmota, then attached to the serial port of a sunswitch. The sunswitch internal psu can be used to power the ESP, so the whole module can be cleaned mounted inside the switch itself.
The code is written in Berry scripting language and will monitor the binary output of the sunswitch and relay the current pool temperature over MQTT.
The sunswitch outputs a binary blob every second, which contains lots of information about what is going on. Currently the included code only decodes the pool temperature, however there is lots more there that looks relatively simple to read (roof temperation, pump status, etc). I have not looked into sending/writing data.