Bear with me, because I don’t know exactly what this all means, but I understand the result. PG&E charges us in tiers. “Baseline” tier costs a little more than 13 cents per kWh. If you go up to 30% over the baseline in a billing period (Tier 2), the extra costs around 15 cents per kWh. But if you go 31-100% over baseline (Tier 3), everything over 30% costs around 32 cents per kWh. If you go still higher (Tier 4), the extra costs around 36 cents per kWh.
So the idea with the solar panels, as we planned it, was to bring our usage down to no more than 30% over baseline, because that would eliminate the most costly part of the bill. On the last bill before solar, we spent as much on Tier 3 as we did on Tiers 1 and 2 combined. And we spent about 30% more on Tier 4 than we did on Tier 3. In short, those top two tiers constituted about 3/4 of our bill.
And those two tiers have disappeared thanks to the solar panels. That is, we’re using the same amount of energy, more or less, but a good chunk of it is being created by us, not by PG&E (to say nothing of the excess solar energy we sell back to PG&E), and what electricity we use from PG&E is low enough now that we’re out of the “Tier 3/4” zone.
I’m pretty sure I’ve confused things rather than clarified them. Suffice to say that so far, the solar panels are doing exactly what we were told they would do.