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AU Solar import export to grid 3 phase balancing circuits- no battery

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exup:
Hi

I have a 10kW solar with 10kW inverter but no battery. So I am consuming solar as its produced and surplus going to the gird. I understand that its more economical to use the solar versus the rebate I get back.

Are my assumptions correct

* If my solar is producing 9kW of power that would be spread evenly across the three phases evenly so 3kW each.
* Surplus power is then feed into the grid via the three phases at varying values due to how much load is being used on each phase in the house
Now if one phase that is connected to one circuit in the house like power points and I started to draw power on that circuit that exceeded the solar supplied on that circuit, am I correct in saying that I would start to draw power from the grid and therefore charged by my utility provider. Even if the other 2 phases were still supplying excess solar into the grid.

Eg L1 is drawing 5Amps but L2 and L3 is supplying 10 Amps each into the grid. Currently I get 12cents/kWh for supply to grid and at peak times charged 48 cents/kWh when drawing.

Watching my utility smart meter I can see the three phases current and if its being drawn or supplied to the grid. There is a little arrow showing supply and draw directions I am assuming for each phase.
As an experiment I load up one circuit in my house with a few heaters and can see when I toggle them off and on that that phase is drawing and supplying in line with the load, the other 2 phases remain supplying.

So after all that does it make sense to ensure I spread the load across each circuit in the house which means I maximise the spread of the loads and reduce the likelihood of one phase drawing power leaving the other supplying power to the grid (which is not as cost effective)

Sorry if that is all confusing :o

David_AVD:
Isn't your electricity retailer charging you for the sum of the 3 phases imported / exported?

That is, they don't charge per phase, or even have any idea on the split.

swingbyte1:
If you have three phase power you should distribute the solar over the three phases.  If you have a single phase inverter onto one phase that is not sinking i.e. solar will be exported, your power bill will reflect that small feed in tarrif rather than offesetting your three phase use.  The power company will charge for the power on the other phases so you will pay more than you offeset

Someone:

--- Quote from: David_AVD on August 03, 2022, 08:03:27 am ---Isn't your electricity retailer charging you for the sum of the 3 phases imported / exported?

That is, they don't charge per phase, or even have any idea on the split.
--- End quote ---
Its all a bit murky, what's reported to the customer is an accumulated figure of exports and imports. Depending on the meter that can be per phase, per cycle, accumulation of each of those flows, or pre summed over some longer period.

Would need some experimentation while looking at the finest data the retailer will export/provide (likely only 15 minute data). Say disconnecting enough loads so that a reporting period is 100% export, then drawing a significant load on one phase with the inverter disabled/off for a short time in otherwise 100% export.

Faringdon:
exup i think what you say is correct, because as far as i can tell, your three phase solar inverter has no way of knowing  if the load that it sees on each phase is  in your house, or out on the grid.
To sort this out you would need current measurement devices on the phases coming into your house, and on the solar.
When i worked in a Battery/Inverter place, we needed those current measurement  devices, and a load of software to "zero the customer meter".... ie ensure that as little as possible electricity was exported.

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