Garlan I am not questioning your description of your particular installation, but where I live a critical loads ("essential") panel is required by code. I think that is the case in many parts of the US. When you make absolute statements like "You don't need an essential panel" I suggest keeping in mind that there are other factors that negate that statement.
If anyone knows how to perform that type of direct purchase, I'd sure love to hear the details as I've called Tesla many times and have been told , "No, we sell through installers only" and "We may, one day". The last time I had a Solar City guy out to discuss the matter, the cost was huge, to the point of being eye brow raising, something like '$11,000 for a 10 year lease'.
The firmware that controls all aspects of the system operation including the Powerwall is all in the SolarEdge inverter. Some of that firmware was written by Tesla Energy, some by SolarEdge.
My system has no provision for connecting to a portable generator as far as I know, and I have no interest in connecting a portable generator to it. If that is what you want I suggest you contact Solar Edge or a solar installation company local to you to see if they can handle that.
All I can tell you is that when Tesla Energy contacted me early this year to tell me that a Powerwall was available for me to purchase, they were willing to sell it to me directly. As it turned out, my solar installer wanted to be responsible for buying and installing all the system components themselves so they bought the Powerwall and it was shipped to them. My installer did not mark up the Powerwall price to me, they just passed it on.
I believe that is what I was told was an "auto transformer".
