I started to build a custom integration for the LG ESS Inverter:
https://github.com/dkarv/hacs-lg-ess
It allows watching your home energy consumption, solar and battery statistics.
It is built with the python library pyess. I currently publish all data points I receive from the device and calculate two more for positive and negative grid and battery flow, to support various custom cards.
It is automatically discovered on the network once the integration is added, only a password is needed. The README explains how to get it.
I hope this turns out useful for somebody else. Some adjustments might be needed for other configurations, please tell me if you find any issue.