I asked around some time back looking for a meter that would show inverter output in the same way that
these little things show and display rectified output. Didn't have a lot of luck. Some people provided me instructions for how to build one, but the cost and effort didn't really justify what I was doing...it wasn't required information, just something I thought would be neat to know.
I saw a few people in youtube videos using
a gadget similar to this to show inverter output going back into either the grid or to AC appliances being currently powered. So I picked out up. Turns out some of them are reversible, but most of them seem to be usage meters only...one way flow. When I plugged the inverter into it all it showed was overload.
I tried wiring it in backwards, though, and it works very well. I was able to improvise the "backwards" bit by cutting and splicing some old cables and caps I already head...if you had to go to the store and buy materials to do it it'd be less than $20 worth of stuff. So for under $30 you can have one of these things showing inverter output, max/min watts, max/min amps, current voltage, and even calculate kwh cost if you're plugging it back into the grid.
just found it to be a neat tool and thought I would share.