Does a common neutral between solar inverter and utility affect current measurement?

Question

I have solar hybrid inverter at home that's connected to the mains using both, the line and neutral wires. However, to save the costs, I've connected the load to it using a common neutral i.e. I've daisy chained (or looped) the neutral input to the neutral output behind the inverter.

This works perfectly, but an electrician tells me that electrical meters (from the utility company) still measure the current when using the neutral as common, and this is the first time I'm hearing this.

Few points to note are:

1. My electricity from the utility company is single phase.
2. The inverter powers critical load in the house during the day using solar energy, while non-critical load is powered over utility.
3. Both critical and non-critical loads share the same neutral line.

Can someone please explain how current measurement in this scenario would work? Should I be running a separate neutral wire from the inverter to my critical load?

Update: Below is a diagram to better explain the above:

Answer 1

You don't mention where you are. However, in North America, the Incoming Neutral conductor is bonded to Earth ground.

The incoming phase conductors pass through the utility power meter. This meter measures both incoming voltage and the current on each phase. These measurements are used to calculate the amount of power consumed by your premises.

In other words, the amount of current in any Neutral conductor will not influence the utility power meter.

Your electrician may be thinking of the problems that will occur if one tries to share a Neutral conductor after a GFCI device. If the current on that Neutral conductor is not exactly the same as on the phase conductor coming out of that GFCI, the GFCI will trip.

You should still check both the relevant electrical codes and the manufacturer documentation to ensure that you are not inadvertently introducing a potential problem.

Provided you don't exceed the current rating of the Neutral conductor, you should be okay.

Answer 2

Actually , your technician is right i m am an electrical engineer from pakistan also , as these new ke or wapda meters run with reverse indication ie. you meter is running without line and using neutral which makes continue unit , so in generator or ups or solar system case you have to lay cable separate neutral to totaly cuttoff from wapda or ke , commoning neutral is not right approach ,

Answer 3

If the question is whether the utility energy meter would register the energy consumption from the inverter, just because the neutrals are connected, the answer is no.

It's the case with any back-up inverter, for its neutral to be connected to the utility neutral, to enable lighting loads to be automatically shifted to the inverter during a utility power failure.

The energy meter would, of course, register the energy drawn from the utility supply to charge the inverter battery.