Our system was spec'd to cover 82% of estimated usage (we had it installed before the house was 12 months old, so we did not have a full year of usage). Now that we've been here for coming up on 2 years, our actual usage is lower that that estimate. For May, the system gave us 89% coverage, but was over 100% from Nov to April. I suspect we'll end our first full year on Solar in August at 90%+
As for the price jump, I would look at it and wonder if it really matters. In our case, 98%+ of our grid draw is during the free nights period (and the Tesla app show 0% grid draw on-peak, although if I go to the GM site, I see we were charged anywhere from 1 to 4 cents per day. Our renewal plan has rates about 6 cents higher than the plan that expires in a couple weeks -- and I estimated that will cost us at most an extra $1 per month. So we go from $5-7 per month to $6-8. Not a big deal.
The only thing you have to do is be aware of your daytime draw and plan things like charging to minimize grid draw. We occasionally charge the cars during the day, but only if we have excess solar so we minimize Powerwall draw. But if we need to charge one of the cars for an hour or so, even on a cloudy day, we can (that's part of what the Powerwalls are for...). We now have the option to grid-charge the Powerwalls -- I haven't activated that due to tax credit (I'll wait until the audit period is up on our 2021 tax return...).
