First, in order for you to claim the 30% federal tax credit, your Powerwall can only charge from solar power. The only exception is for storm watch mode.
The only time you can export solar is the "instant" it is produced. How much is exported depends on the mode you are in, the state of the battery, and the household loads covered. Currently you can not export solar power in the evening as the battery is programmed to only cover household loads at that time.
To maximize savings, use the Advanced - Time-based control and set it to cost savings. Form other posts, you are on SCE TOU-D-4-9PM. I suggest adjusting your peak and off-peak times to match. If you want to encorage the Powerwall to cover other times (9 PM until 8 AM), set part-peak for that time.