Thanks! Though there is something not quite adding up for me. Please correct me if I am misunderstanding, but it sounds like you have you EV charger(s) on same circuit as the Powerwalls. It looks to me like the app is a blunt tool that lets you choose when to use the batteries not how. So, if I have it right based on your description you won’t be using your batteries for your system/configuration at all while you are charging your car(s). This doesn’t seem ideal to me. I would want to be running my AC at night (since it gets pretty hot in our home at night) using the Powerwalls, but not run down the Powerwalls for the EV charging. The setup that woferry described sounds great to me.
First, there is no such thing as having large loads "on the same circuit". That just isn't allowed. Each large load must have its own circuit breaker. A circuit is generally defined as everything fed by one circuit breaker.
What
@woferry described was arranging your loads in the breaker panel(s) so that the energy measurement would be blind to certain loads. This is one approach and my system used to work like that. When it was originally installed, it was blind to all the loads that were not backed up. However, separating it along these lines is not ideal because it prevents you from doing things like offsetting A/C use during Peak hours. It can't be offset because it's not being measured and it's not being measured because the startup load is too big when the grid is down. Certainly, if there was significant benefit to this methodology, you could separate the measurement of loads along a different dividing line than backup / non-backup. I am saying that this is not the right approach.
You say that you want to power your nighttime AC use from Powerwalls, but not your EV charging. This is illogical. Whether you use the Powerwalls or not to power a load should be based on the cost of power at the time that it is consumed. I am on the PG&E EV-A rate schedule. This means that there is no Off-Peak solar generation on weekdays. Since the Powerwall batteries are only charged from solar, the value of the energy in the batteries during the week is effectively my Part-Peak rate of ~$0.28/kWh Summer and $0.22/kWh Winter. If I discharge any of that energy during Off-Peak, I'm essentially giving away $0.15/kWh or $0.09/kWh because the Off-Peak price is ~$0.13/kWh. It doesn't matter if I'm using that Off-Peak energy for the refrigerator, the A/C, or charging the car.
Time Based Control uses your Time-Of-Use rate schedule to decide when to charge and discharge the Powerwalls. If you use the A/C during Peak, it will draw power from the Powerwalls, if you use the A/C during Off-Peak, it should come from the grid. My cars are charged from only grid power because I have them programmed to only charge during Off-Peak hours and because of TBC, the Powerwalls never discharge during Off-Peak.
I will freely admit that the way TBC works is really optimized for exactly my situation with net metering and no NBC (Non-bypassable charges). Other people have different utility rules. Some people don't have time of use and get no or very low reimbursement from energy fed into the grid. Those people want to self consume as much of their solar as possible, regardless of time of day. I agree with
@Ampster above who said that NBCs in California are not sufficient to cycle the Powerwalls more than you otherwise would.
