I have such a fear about this and I don't need the grid very often, that I had the installer put a breaker in the house (for convenience) between the pole and the inverter for my utility wire. I leave it turned off. In the case I need it (super cold mornings and have to run the central heat system), I shut off the PV, shut off the batteries and run off of utility power. I don't have enough confidence in this system yet that it won't feed back to the grid. There is a problem with mine, either in the monitoring software (likely) or the inverter (less likely) so that when I'm running on the grid, even though I have the CTs set up correctly, it shows me exporting energy to the grid. That can't possibly be the case because in this example, you can see the batteries are turned off and you can also see there is nothing coming from the PV. But, still it shows me exporting instead of importing.
GSL has had me flip the direction of the CTs (pointing them to the power pole, instead of to the inverter), which worked for a while. But, now it is showing that the power is going to the grid again. It IS possible that Lux fixed the website now. But, I'm still leary until I hear exactly what has changed and what is going on now