Solar and 3 phase power



The Quick Answer

About 20% of Perth homes have 3 phase power.
For solar installations 3kW or less, it makes no difference
Over 3kW then there are Western Power rules about what inverters you

are allowed to use. For a typical 5kW installation we would normally

recommend either a 3 phase inverter or 2 x 2.5kW single phase inverters.

Three phase inverters

The best 5kW three phase inverters are the Fronius Symo ($2190) or the SMA Tripower ($2310)
followed by Goodwe ($1620).

2 x single phase inverters

You can save about $300 by buying 2 x 2.5kW single phase inverters (of a good brand like Goodwe)
All solar power goes to the meter and then the meter decides what phase in

your home needs it, so it actually makes no difference at all if you choose to

go with the often cheaper option of 2 x 2.5kW inverters instead of a 5kW

3 phase inverter. Two boxes and their associated breakers on the wall instead of one is the only drawback.
You also only need to have space for two single pole breakers in your switchboard, not three.

How can I use a single phase inverter on three phase?
It's all about how the meter works...see below

The Western Power Rules

This is how Western Power officially describes it...

"The 3 phase meter measures the combined consumption and

generation across all three phases continuously - it does not distinguish

between phases and then takes the net after a set period (of 10 minutes).

If there is excess generation on one phase, and a load on another phase,

then the excess generation will supply that load. If there is still more power

required, then the customer will receive electricity from the network and it

will be recorded in the meter as purchased/imported electricity. But if

there is still excess generation after supplying all of the household load,

it will be sent out onto the network and recorded as sent out (or exported

onto the network), which is where the customer receives REBS and/or FiT

(or neither if they aren't eligible)."

The above explained
Whilst the Western Power explanation is 100% correct, it is just a tad hard to follow.

What they are saying is that ALL the solar power goes to the meter first and the meter
decides whether to send it to the house if required, or sent back out into the grid if not.
It therefore makes no difference whether the solar is connected to a single phase or to
two or all three phases as everthing goes to the meter first no matter what.

3 Phase Meter

If you have 3 phase power you should see either above or below the meter 3 cigarette packet sized black boxes (shown below the meter in this picture)


News & updates

Barnett backflip 12-08-2013
The WA State Government took on WA solar customers and lost. In a very hasty backflip the hugely unpopular decision to remove the feed-in tariff from customers was reversed by Premier Colin Barnett today. is the web site for Good Day Mate Pty Ltd trading as SOLAR4EVER Company registered in WA on 26th October 2008 (A.C.N.133884938)

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