Can You Use A Single Phase Inverter If You’re On A Three-Phase Property?

Question: I have 3 phase power, and want to cover the power on each phase. However, I’ve been quoted for a one phase solar inverter. Will I have to pay for the power that’s consumed on the other two phases that solar doesn’t cover?

That’s a good question. Let’s take a closer look:

SMA 3-phase and 1-phase solar inverters

Whoever installs a solar energy system in their home probably worries about saving on their energy bill, and wants to do that in the most efficient manner as possible. As the amount paid for feed in tariffs in Australia lowers, it becomes a great idea to do your best the use the entirety of the solar power produced at your home, instead of sending the surplus back to the grid. On the Gold cost, we have been paying approximately 25 cents, including GST, for every kWh we get from the street – but we only get paid 12c for the surplus solar power that we send back, from retailer Click Energy. You won’t have to do much math in order to figure out it’s best to use that solar power instead of sending it back to the grid as surplus – but how exactly is it that surplus power works when you have a single phase system on a three-phase supply? Read on to find out more about the best to do in such situations.

Three-phase Power With Solar On One Phase – What Happens

If your inverter is single-phase and you have a three-phase supply at your home, then the surplus of the solar power you produce (the amount that exceeds your consumption) gets sent back to the grid. This is what happens physically, and this may make you think it’s best to either get a three-phase one or load up the phase that has has solar with everything that gets used in the day, so you make sure as little as possible gets sent back as surplus. If you’re billed for what physically happens, it would be entirely correct. The most important thing is what gets metered by you’re areas provider, and, consequentially, what you get billed for.

Single Phase Power On A Three Phase Meter – What Gets Metered

Emergex utilizes an Atlas EDMI 3 phase meter here on the Gold Coast. These are the meters utilized by Energex in many other areas of Australia as well – you can learn more about the Atlas EDMI polyphase meter and how to read it right here. When the meter gets programmed to handle surplus power, it makes sure to take into account power consumption on each of the three phases before considering any power surplus to what you need.

For example: If a home utilizes 400W of power on each of the three phases, it’s 1200W in total (400 watts times three) of power being consumed. Suppose a solar power system is connected to a phase of the house, and that it’s outputting 1500W into that phase.

If 400W power is being used on the phase where the solar energy is connected, and the inverter is producing a total of 1500W, it will consider 1100W surplus – 1500W minus the 400W used on the phase. This amount is going to be sent back to the grid, since the meter will consider it surplus power.

In such cases, the Atlas EDMI 3 meter would see the power getting consumed on each of the three phases – in our example, 1200W. It would only consider your energy a surplus after the combined consumption gets covered – in our example, the surplus would be of only 300W – the 1500W consumed, minus the 1200W produced. Only that amount would be sent back to the grid.

What Should You Do Then?

In the end, all of this means that, regarding using as much of your produced solar energy for consumption as possible, is that it does not matter whether you have a three-phase or single-phase solar inverter – it will cover all of your power consumption on all phases connected to your peak tariff either way, before considering your power surplus. Single phase inverters are significantly cheaper than 3-phase ones, so they tend to be the first choice – but there are cases in which a three-phase inverter would be the best for your system.

3 thoughts on “Can You Use A Single Phase Inverter If You’re On A Three-Phase Property?”

  1. Thank you for the information. I recently had a single phase inverter solar installed onto my 3 phase system, and now I am also on the Atlas EDMI 3 meter. Interestingly, when I am running my ducted air conditioning, I seem to notice one phase is on a negative cycle (i.e negative number), while the other two phases are on a positive cycle (i.e positive number). Of course the ‘negative number’ phase is connected to my inverter.

    Example: solar is generating 4kW and I am consuming say 6kW, phase 1 shows +2kW, phase 2 shows -2kW and phase 3 shows +2kW. Assuming what you have explained, despite displaying a negative number on phase 2, the meter should be smart enough to figure out that I am consuming only 2kW NET and NOT exporting the 2kW (as shown in the negative number) + consuming further 4kW on the grid on the other phases?

    It seem to worry me sometimes as I noticed I export a lot of power to the grid while I still seem to consume a lot too from the grid concurrently even on a bright sunny day.

    GM, Brisbane, QLD

    1. I’d say it wasn’t connected properly. Did anything ever result from this?

      or you were just using power when little solar was being generated, and using less when more power was being generated.

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