Tesla is shutting off the old solar city app/web site in august and is forcing the tesla app to collect data on tesla/solar city solar panels. It basically sucks because it doesn't allow any data export nor seeing more than 1 year of history.
As you have already reverse engineered tesla APIs for the cars, it might be trivial to do the same for the solar panels. Goal would be to scrape data similar to what solarcity.com does today, which is production snapshot every 15 minutes for export, and any other features others request.
Customer support service by UserEcho