Arduino / ESP32
Microcontroller builds — ESP32, ESPHome, and the firmware that glues hardware to the network.
A living reference for adapting the ESP32 local inverter control build to other brands: what transfers as-is, what changes per brand, where to find register maps, and the quirks that bite.
My heat pump was invisible to the inverter and my EV charger was confusing it. Moving one CT clamp fixed the first problem with zero software; a small Home Assistant automation driving the part 1 ESP32 fixed the second.
Wire a cheap ESP32 and RS485 transceiver to a Growatt SPH5000 inverter, flash ESPHome, and get a local Modbus web UI for monitoring and control — no cloud, no app.