My installers connected the solar inverter to the home WiFi. I soon fixed that by changing the WiFi password, but I also discovered that inside the inverter is a stange-looking metal sim card, very small, but thankfully removable. I removed it. No-one is mucking about with my setup! (Except me 😀)

Surely Sheldon should be here commenting on this?

Are they working all through the night? One man working 40 hours a week with no sickness but including 5 weeks holidays per year works 1880 hours. A year of hours is 8760.