I don't think you will see any peak demand reduction, APS peak period is 3pm - 8pm and your solar pretty much stops producing by 4pm in the winter. Peak demand is your highest 1 hour of use so cutting demand from 3pm - 5pm doesn't help your demand during the other 3 1 hr periods.
I am on the same APS rate plan as you and also use Hubitat and smart thermostats to control my peak demand, without a PowerWall I don't think solar is at all effective in peak shaving in Arizona other than possibly giving you an extra hour in the summer (3-4pm) where you can run your AC without drawing from the grid and without some smarts to monitor solar output you run the risk of a cloudy day cutting 3-4pm output and your AC still running and driving up your peak demand charge.
Solar in the summer should allow me to pre-cool my house later into the peak period (I'm hoping to be able to run it until somewhere around 5pm), then shut the A/C off for the remainder of the peak period. Trying to go without A/C from 3-8pm in the summer is a non-starter, but I think from 5-8pm may be doable if I can get the inside temp down to upper 60s or so. I started doing this late summer last year (highs near 100) and it was tolerable with inside temps near 80 by 8pm, but I can't see it working for the full 5 hour period when it's 115 outside unless solar adds a couple hours to the A/C run time.
That's the plan anyway, we'll see how it works in practice. In the winter I'm not running the A/C and we try to be conscious not to run more than one appliance at a time to keep the peak down. I've accepted that I'm going to get hit with a 3-4kw peak charge each month, but would like to limit it to that. I had a month or two last summer where I peaked at 9kw, that was expensive.
I use Hubitat too. Are you monitoring panel output with Hubitat? I need to figure out how to do that. If I can't figure it out I think getting lux value from a weather site could work, but I'd prefer to monitor directly.