Hi John, sorry to hear you have admitted defeat for now. I am hoping that you can leave it for a bit in the box, and take a fresh look at the project a little later.
From what I can understand from the post linked to, is that you can add this to the HA via a custom repository, and once you input account details or whatever it needs, it can allow you to have control over your Inverter.
So, fingers crossed you take a look again, with fresh eyes/mind.