So I was wrong. The little bumblebee inverters who should not be able to fly are still flying! We gave the batteries a deep charge yesterday (and warmed them up good) so the system is happy enough to keep going a bit longer! The problem is that when the batteries are happy, we get about 130 volts of elec coming through the system. When the batteries are drained, we might only get 100 volts coming through - with virtually no load! That's the time when the system will go down if anything turns on. So we're still able to use the system for now, but we just need to keep a closer eye on it. Based on past experience, this deep charge ought to hold us relatively steady until we can get the new inverter. Hopefully. ;)