I don’t believe so, unless I got that incorrectly.
Backup Reserve is similar, but still different concept. It limits how much you can use, and the buffer you’d keep in the case of an outage.
AFAIK, when you have GC turned on, it will always aim for a 100% charge, but it doesn’t specify which source. The Tesla PW algorithm does start to “learn” your habits of usage, and also semi-predicts excess solar the next day…but that is really a black box, and it’s definitely not consistent.
Since PG&E (not sure about others) charge a non-insignificant amount for each kWh imported, the so called NBC’s or non-bypassable-charges, then it’s in your interest (and hopefully Tesla’s to allow it) to reduce grid charge imports to as little as necessary.
It would be nice to say charge (via grid, at off-peak rates) to say 50% each night (mine usually goes all the way to 80-90% SoC) and then wait for the sun the next day. I’m routinely producing 40-60kWh from PV, and no usage during the day, so this would drastically reduce my NBC’s (which are now the dominant amount of my true up $ as some have noted).
I could turn of GC, and just fill up the PW with PV…but then I don’t think I would be able to max out my 4x PW’s at 54kWh capacity (accounting for 5% one way loss from PV->PW).