Vanderpaco

As non essentials can only be fed when the grid is on this portion cannot cause the inverter to go into overload. The inverter will only feed as much as it can and if the non essential load is higher than what the PV via inverter can supply to non essential loads will be drawn from the grid so no tripping the inverter.

No. I found a way.

First, when you are allowing the inverter to send power out to non-essential load, then the GRID reading is equal to what the CT reads. In other words it should match what your GRID meter is reading.
Second, when you are allowing the inverter to send power out to non-essential load, then the LOAD reading INCLUDES all consumption (LOAD and export through the GRID port).

Now, since all load is in one number, the frustrating part is to answer: "How much load is essential load, and how much is non-essential?". 

So I found after much experimentation that in the custom graph for the Inverter there is a value called "P-L1" which reveals the "Load" (kw) passing through the Inverter's grid port. This will show positive values when grid power is flowing INTO the inverter, and will show negative values when the inverter is exporting power to the non-essential load.

Here's my graph for this morning - look carefully at the period 10-11am. My geyser kicked in (non-essential), and you can see that PV and Battery power were blended by the inverter to EXPORT to the geyser during that period (P-L1 goes negative). Apart from a short spike in load about 10:35am, the GRID (at the CT) stayed on zero while the inverter supplied the geyser. During that spike you can see that the export also reduced, indicating that the load spike was caused by something inside (essential load), maybe a kettle or something.



Also note the small spike about 5am. Battery was on minimum SoC, so the load, grid and P-L1 were all tracking together. When the battery needed a little charge from grid, you can see battery goes negative, but this time P-L1 is positive (with grid), indicating IMPORT through the CT and through the inverter grid port.

For those running "Limit to load", and you want to know how much the nomn-essentials are taking from the Grid - look at the "P-External-CT-Total" setting (disabled in my image above). this will show import from the grid through the CT, while the "P-grid" in that mode will only show what passes through the Inverter's grid port.
 
I hope this helps...