My thoughts on efficiency of the Kill-A-Watt approach. The converter is only used to supply house loads while on shore power so the Kill-A-Watt power used by the house loads would be higher the power used from the battery for the same loads. I’d probably use 10% for the converter. My Magnum ME2012 specification says 95% peak efficiency so I’d probably use 10% for it.
There are also efficiency in the solar system to consider like controller efficiency and weather, mounting, location, etc.
If I was going to consider efficiency I'd add 10% but overall I’d likely just ignore efficiency because I’d add a margin for the solar panels anyway. :R
