Hi!
What I* have:
- a Raspberry Pi 3B
- a solar PV system with Modbus output
- a heat pump with Modbus output
What I want:
- energy stats of the PV and the heat pump, going back for a few years, without needing cloud access
- trigger the heat pump into overdrive when there's excess solar
- something that works well on a RPi 3B
- usable phone frontend (not necessarily an app, but kinda like it)
What I tried: Home Assistant -- which works but is very complicated and behaves rather funkily on the hardware. I suspect that putting a whole bunch of Docker containers on a lowly RPi is kind of a bad idea. But also, with Home Assistant, there appears to be a rather steep learning curve because there's just so much stuff.
What I've superficially considered but haven't tried: OpenHAB. Would be interested in learning if that's better.
(* actually none of these are mine, but for the purposes of this post, let's assume I have control of all this stuff.)
You can also simply copy the current install on a USB stick and boot from there - once you have the SD card running that's also an option. Tutorial: https://pimylifeup.com/raspberry-pi-boot-from-usb/