It appears that you and I will be comparing notes as I shot myself in the head a few days ago, too. Get ready for the notoriously horrible customer support, impossible timelines, and horrible follow on support should something fail.
I'm setting my expectations to TSLA level. I don't expect this to go smoothly, on time or with any level of care. But I love saving money, and so here we are.
In case you need any reasons to back out, here are a few threads. One of the posts links to another thread with some relative "horror" stories, lol.
https://teslamotorsclub.com/tmc/threads/tesla-solar-vs-third-party-competitors.239004/
Share the links where they make these guarantees please. Don't believe anything they say unless YOU get it in writing for your specific build out because they are notorious for going back on their words. And it doesn't matter if they guarantee it and don't meet the deadline, PG&E (etc) won't give a rat's ass.