The aim of solar system owners in Australia should be to use as much solar energy as possible indoors at the time of generation. Electricity costs have skyrocketed in recent years, with most households on usage-based billing now paying an average of over 30 cents per kWh.
So why are you getting a quote for a single phase inverter when you have three phase power? Won’t you still pay to power the other two phases? let’s find out
A single phase inverter on a three phase supply
After completion of your solar system, your existing meter must be exchanged for a new bidirectional solar meter by your energy dealer. If you have three-phase power, this meter is a three-phase digital meter and will replace your existing meter (or meters if you have three old analog meters). Typically your new meter will be the Atlas EDMI Polyphase meter or similar.
This meter is programmed to count consumption across all three phases before considering solar power as excess. The meter balances the three phases and records your total consumption as a grand total before recording excess solar energy.
As an an example:
- You use 1kW of power in each of your three phases for a total of 3kW
- You have a 5kW solar array with a single phase inverter putting out 4kW of power.
What technically actually happens is that 4 kW of power is injected into one phase. You use 1kW of the solar power and 3kW are fed into the grid. Your other two phases consume electricity from the grid, in this case 2 kW in total. So you have 3kW going to the grid and 2kW being used by the grid.
However, what is recorded in your meter in this example is initially the sum of your consumption over the three phases: 3 kW. It then records the excess solar power, in this case 1kW. You don’t pay for the 2kW you took from the grid as it’s covered by the 2kW you fed into the grid – one explanation for this is that the phases cancel each other out.
To clarify, you have not drawn any power from the grid and you receive a feed-in tariff from your dealer for the excess 1kW fed into the grid.
This means that in most cases, Solaray will install a single-phase inverter for any system smaller than 10kW, including our SolarEdge and Enphase systems. It’s a waste of money to buy an expensive three-phase inverter because it simply doesn’t add any value.
If you are considering a 10kW or larger system please contact us for more information on a 3 phase system. In some cases you will need three phase power to install a larger system and therefore we need to install a three phase inverter, but this varies.
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