Hi! I created the DSMR Datalogger Add-on (https://dsmr-reader.readthedocs.io/en/v4/tour.html). It’s a solution to monitor your power usage with an USB P1 meter.
Here is my repository: https://github.com/sanderdw/hassio-addons which you can add in HA and where you can find further instructions.
17 December 2020: Updated to support v2 and v3 hardware
1 October 2020: Updated for v4 of dsmr-reader