PG&E's minimum charges

This has taken me over a year to figure out, so I thought I should post about it.  The issue is--What does PG&E mean by minimum charge?  We pay $11 each month, of which about $6.50 is a meter reading fee and $4.50 is a minimum charge.

When I first heard about minimum charge, I thought that PG&E would make a minimum charge for months where our solar panels put out enough electricity so that there was no monthly bill.  But then I noticed that the $11 monthly fee kept appearing on our PG&E bill every month, both in summer when there was a negative bill, and in winter, when the bill was positive.  So then I assumed that the minimum charge was just added onto the monthly bill no matter what.

But it turns out that the minimum charge is compared to the amount due at the end of the one year "true-up" accounting. If the total bill is less than the minimum charge for the year (about $54), then the balance due is dropped.  If the total bill is greater than $54, then the customer must pay the difference.

This seems pretty simple, but I don't see it explained anywhere. I can only conclude that PG&E is not too interested in people understanding how to minimize their electric bill by sizing their solar panels to be just enough to reach the minimum charge.