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When will it make sense to buy solar battery storage... in Perth?

Almost certainly, the answer to that question lies in when we will see some state and/or federal government subsides on battery storage.

The Labor Goverment has proposed that they will deliver a $2,000 solar battery subsidy for anyone with a taxable income under $180,000.

In South Australia 45,000 households are eligible for up to a further $6,000 subsidy, and Queensland and Victoria also have some battery subsidy schemes running.

Let's look at the economics as they stand at the moment in WA, with zero subsidies.

If you have bought a hybrid solar installation and its smart meter already, then all you need to buy on top is the battery itself.

The LG Chem 10kW high voltage battery, is $8,800 including installation.

If we assume that you manage to drain the battery fully, every day then at current prices that is worth $0.2833 x 10 = $2.833 a day or $1,034 a year.

However, if you didn't have a battery then those 10kWh of solar power would have been exported to the grid and you would have been paid 0.7135 x 10 = $0.7135 a day or $260 a year.

Therefore the value of the battery to you is $1034 less $260 = $774 the first year and a little more each year thereafter as power prices rise.

So,allowing for power price rises, we can say that it's likely to take 9- 10 years before you start making a profit on your battery.

If there was the promised $2,000 subsidy then the battery cost is $6,600 and the payback time 6-7 years.

If we got something like South Australia has by way of subsidy, then it's only about a year to get your money back.

Case Study
The Goanna Battery limited time offer
Several of our long time clients alerted us to a 66% discounted, limited time blah blah blah offer they received from a Melbourne company.
Not $15,000, but just $5,000 for the Goanna 3kW AC coupled inverter and battery. Let's just say that isn't a bad product (made by AlphaESS) and it's a pretty good price too.

The trouble is that the battery is too small. With 2.4kWh of usable power to meet their 10 year warranty rules it can only provide a return of $200 a year.
$5,000 sounds pretty cheap to many, but 25 years before you have paid it off ???

Battery prices may fall. It appears likely that they will over time, but the real cataylyst will be subsidies.

The question is ...Why would the want to incentivise us to get batteries?

The first answer is cynical. It is a vote winner. The Liberal Party appears pro coal and anti-renewables, and the Labor party goes the other way.

The second answer is practical. There is a huge amount of solar already installed that is pumping a lot of surplus power back into the grid in the middle of the day, and there aren't enough buyers for it. It's also raising street voltages to levels that often exceed allowed limits.

That second point leads us to another important thing...

People who already have solar, and didn't get a hybrid can't just plug in a battery into their inverter.

They need to either replace the inverter with a hybrid and smart meter at a cost of at least $2,150, or else buy a battery that has an inverter already built into it.

The Tesla Powerwall 2 is a good example of one of these, but there are several others, although most are more expensive than the Powerwall.

It costs $12,000 installed, which rather changes the economics described above, where we based it all on a $8,800 battery plugging into a hybrid.