> often had negative quarterly invoices (i.e. got paid by our retailer) ... esp. in winter months
"[I]n winter months"? My stupid northern hemisphere brain did a double take; I needed to remind myself that Christmas (December) is summer!Winter is the cold one down here too mate
It's got nothing to do with the hemisphere.
Most likely the aircon is running less in winter so they don't use as much power. There is not much of a winter in the tropics.