The SGIP process is very complicated with numerous steps in the middle. The chance of a check randomly showing up in the mail without those steps being followed is zero.
At a bare minimum, you need an SGIP application number that SGIP has acknowledged is in the Reservation Request (RRF) phase. This means the designed/planned system qualifies for SGIP, and SGIP will acknowledge a place in line. You should consider that Tesla may not realize you wanted the large-scale-residential SGIP; and tried to put you in queue for the small-scale-residential SGIP. In the PG&E coverage area... large-scale still had a bit of funds in 2020/21. But small-scale was exhausted after 2019.
For me, SGIP initially refused to grant me RRF because PG&E refused to acknowledge that my system was "properly sized". So I had PG&E telling me 2x Powerwalls was too small and the plans would be denied PTO. And PG&E saying 3x Powerwalls was too much ESS for my house. But eventually I went straight to SGIP and got this issue resolved (zero help from PG&E because PG&E sucks).
At the time of RRF, the project will obtain a number and the funds place-held. The message the homeowner gets with a successful RRF starts out with:
If you don't have that number or a confirmed RRF, your SGIP may not even be in the queue.
As the system approaches completion, the RRF must be converted to an Incentive Claim (ICF) submission. At this time, the company installing the system will need to report to PG&E that the system is ready for inspection and provisioning. From here, SGIP will require PG&E to validate the system is what the installer claims it to be. The message the homeowner receives with a successful ICF starts out with:
During the ICF, there will be more steps. I had two separate surveyors come to my house to take pictures of the install and test the backup by opening my main PG&E disconnect. I believe SGIP had early problems with installers pretending to install ESS then claiming the systems for SGIP rebates. So now PG&E (the SGIP administrator in NorCal) will send folks from the likes of
Energy Engineering for Utilities and Industry | AESC Inc to your home to take pictures and confirm the system is operational (not just some cardboard cutouts on the wall).
SGIP also requires proof of data storage and export from the ESS. They usually obtain this data from Tesla (or the agent authorized to access Tesla's telemetry).
Assuming smooth sailing, the ICF will be approved. From here, it's about 3 weeks before a check shows up in the mail.
So yeah, if Tesla cannot provide you with an RRF number, you're likely not going to get the SGIP rebate.