PV bloopers by the "professionals" - Part 1

I decided my solar panel setup could do with the help of an additional battery together with changing my tariff to Economy 7 (cheap nighttime electricity). I'd been drawing from the grid at night for a short time to get a feel for how it would all work. A meter change was required and an appointment was booked for the installation. 

Some time around 6 PM on the day of installation I went to my SolisCloud app. To my horror this is what I found:

Massive movements, something wasn't right. When I checked the meter I found that a clamp on one of the leads that reports import/export volumes to the system had been replaced the wrong way round! Put the clamp back the way it should be and, voila, back to normal:

Very disappointing. I dread to think of the consequences if I hadn't spotted the issue fairly quickly.