Wawa:
Long time ago that I played with this, but I don't remember it dropping to unreadable.
When output of a big 5Amp panel drops to a useless 5mA, who cares.
Leo..
It depends on what is your aim. If you just want to harvest as much as possible to feed into mains, you won't care.
If you need a 24/24/365 off-mains power supply in a maritime region northern of the 45th parallel, you will be more than 80% of the time in the 5ma region.
I had a (real)5W panel, backed by a 20 Ah battery just to feed a Nano+RF24+a couple of sensors that drew an average of 12mA. It was not enough to pass the last winter. 