The gadget has worked for 2 years but that was before your solar install... it's different now, hopefully I can explain why.
Where you have positioned the clamp meter, it won't show you your usage only now. The clamp is bi-directional, it can never show a negative. So will show what current is flowing through the wire, irrespective of direction.
As you have this on the Live wire going into or out of your import meter, it will show you either:
a) Net amount being imported: Usage minus generation or
b) Net amount being exported: Generation minus usage
In your example, this could be either
a) 200W being imported = 2.2kW usage minus 2kW generation
b) 200W being exported = 1.8kW usage minus 2kW generation
You can test this by turning off all the mains whilst the PV is still generating. The E.ON gadget should say a little bit less than your SunnyBeam (as it is assuming a lower voltage to what your inverter is generating) but should be roughly the same, so I would expect 2kW generation to show about 1.8kW on your E.ON gadget, the generation meter to be flashing and going up and the import meter to not be going up.
You can get the gadget to measure usage only, if you are able to position the clamp inbetween the consumer unit and the junction where the solar pv and grid mains meet. On a lot of installs though, this is inside the consumer unit, so not really possible.
Admittedly, this might be a red-herring to your problem, which sounds the case if you only had the fridge on.