Do i need a 3 phase solar inverter with 3 phase power ?

[vjsaggi]

Hi, 

My home has a 3 phase power and i am going for 6.6 kw solar connection with 5 kw three phase inverter. 

The solar company is advising me that i can go with single phase inverter as the new solar smart meters are programmed in such a way that it records the consumption across all there phases. 

See attached info shared with me. 

Is this how the solar smart meter of AGL works ?

Would you recommend that i can go with single phase inverter?

Thanks,

Vijay

[jayden_AGL · Accepted solution]

Hi vijaychauhan,

Welcome to the AGL Community!

I can confirm that the information you've been provided is correct and that a single phase inverter will meet your requirements based on the above.

Kind regards,

Jayden

[Schander · Accepted solution]

Hi Vijay,

The article you are quoting is spot-on. Your house should be fine on a single-phase inverter because your inverter is rated at a max of 5 kW.  If you have three phases, then the assumption is that you have a three-phase smart meter (You can cross-check this with AGL). When you get solar installed, you will need to contact AGL to make sure they reprogram your smart-meter for bi-directional energy (i.e. Drawn versus Delivered energy). It should record the consumption across all three phases and reconcile it with excess solar power.

The main issue with not getting a 3 phase inverter is Voltage Rise. As many people are now putting solar on their home, each house then begins to contribute to the voltage rise. I am not exactly privy to how fast solar panel systems are being installed, but I assume it is still part of the "boom" phase.  Eventually, if there is significant voltage rise, then this would make an inverter turn off and generate less power.  The way to minimise this effect on a 3-phase home is to install a 3 phase inverter. 

I also note, as a different issue altogether, that with a 5 kW inverter, that's the maximum benefit you are going to get even though you have a 6.6 kW solar panel system.  That's because of the loss in efficiency which takes place to convert the Direct Current (DC) to Alternating Current (AC), the inverter doing the conversion, the cabling, etc.  So assuming you had a 100% sunny day (maximum sunlight) and assuming the angle of the panels are positioned in the northerly direction, you may get between 50% and 75% efficiency. I would mention that the 6.X kW solar panel is the limit (you won't be able to add more solar panels without jeopardizing the inverter). You don't have that limitation on a 3-phase inverter.

Regards,

Schander

[ocsclan]

How can they cancel each other out when you are paying a 8 cent feed in tariff and you are charging 25 cents. I'm not sure about your maths but in my cancel out that does not equate

[Schander]

Hi Ocslan,

The cancelling out effect that the original poster was referring to was at the Meter level, not at the Tariff level (after the concluding meter reading is read by the energy retailer).

So, it is all based on the amount of kWh produced by the Solar system versus how many kWh were consumed by the household.  In a 30 minute interval, say you kicked on a Dryer which consumed 2 kWh and your solar was generating at the same time around 4 kWh, the netting effect would be 2 kWh.  Since the solar generated more than the household consumed, using the rates you mentioned in your response, that would be the 8 cent FiT per kWh. Hence, since the net gain was 2 kWh fed to the grid, it would be 2 x 8 cent FiT per kWh = 16 cents.

The energy retailer is always higher when drawing from the grid than what solar can be sold back to the grid for (that's currently the way it works).

The idea is to use as much of your power during the day when solar is generating so that it barely has to draw from the grid (to keep your expenses down).  Exception to this is if you had a Solar Battery being charged.

Regards,

Schander

[Thad19]

Yes, a single phase will suffice, but surely a 3 phase system would be better because the cost of purchasing power from grid is more expensive than receiving feed-in credit. For the example given, you would only utilise 1kW of solar out of the 4kW being generated with 3kW being fed into grid for credit. But you would need to purchase 2kW from the grid. Whereas with a 3 phase system, the solar would cover your entire 3kW of usage plus you get 1kW feed-in credit. 

[Schander]

Hi Thad19,

I think you may have misunderstood.  If you have a three phase grid connected to the house, but only a single phase inverter for solar, the electricity meter is configured to manage a "Netting" effect.  Say your inverter was on Phase 1 of the 3 phases connected to your house.  It's a bright sunny day and your solar is generating a lot of electricity.  Your house has minimal electricity appliances on phase 1.  But, Phase 2 and Phase 3 has appliances drawing electricity.  All three phases first go through the electricity meter.  The meter looks at the Solar Feed-In and compares it against what is being drawn on Phase 2 and Phase 3, and then nets the results.  If the results means that Solar Feed-In can't completely service the other two phases, then only the excess that is drawn goes to the electricity provider to draw from the grid.  You aren't losing the benefit that solar provides just because it is a Single Phase.  The Smart meter's job is exactly that, it has to look at all three phases and net the results before it draws from the grid or sends to the grid.  The inverter's job is simply to convert the DC to AC and send it to the meter.

Nothing should go to the electricity retailer (i.e. Grid) until the smart meter has done its job of netting the three phases first.

Regards,

Schander

[Thad19]

Thanks for clarifying.

[GeorgeB]

Hi Jayden,

How about a larger solar system - say 8.8kw or larger? We're looking at swapping to AGL with our new solar system but are planning a larger array - and potential to grow - so we can handle pool and future electric vehicle.

Thanks, George

[-Nam- · Accepted solution]

Hi GeorgeB! 

Welcome to AGL Community! 

You'll want to speak with our Solar team and they'll be able to assist you there. You can contact them directly on 1300 377 118 Mon-Fri 8:30am - 5:30pm. 

Kind regards, 

-Nam-