Tesla is already lower in price than the Independents that are selling Powerwalls. And it seems they are prioritizing their orders over those of the Independents. The Battery installers are a separate group from the Panel installers. However, when a full panel and battery install is scheduled, both of those groups show up on the job. The battery guys typically do a full battery install in a day. Roof installs could be a couple days, so both are scheduled separately but coordinated.
Tesla has tried to streamline their system to reduce cost. That is why they have no salesmen. They get a good percentage of their business from referrals and compensate owners who give referrals. This is also why when it comes to their systems, they are not custom. Basically 4 solar panel systems with 4 power configurations. This also makes it easy for them and the building departments as they see the same configurations over and over. That reduces cost as there is not a lot of back and forth between Tesla engineers and Building departments. Is the supply line strained? Absolutely, the guys on my job said they are even having trouble getting Square D breakers for the panels. I am kind of rambling here but thought I would pass on what I was able to dialog about during my install.