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Battery ready solar inverters in Australia

The purpose of solar battery storage is simple enough.

Most people's 6kW solar install produces 30 kWh per day on average across the year.


The house uses 10 kWh of it during the day
The battery stores 10 kWh for night time use
The other 10 kWh gets exported back to the grid for some payment.

 

In other places in Australia the difference between the cost of a unit (kWh) of power and what you get paid for surplus power is greater than it is in WA, but here it's 19 cents.

So 10 kWh of daily battery storage simply can't be worth more than 10 x 19 cents or $1.90 a day or $693 a year if used to the max every single day (which is highly unlikely).

 

However, what with politicians offering subsidies on batteries at state level over East and now the first tranche of pre-election promises at a Federal level with Labor offering $2,000 off solar battery costs, in all likelihood the economics of battery storage going forward will be more to do with buying votes than lithium prices dropping.

 

There are a veritable plethora of solar batteries on the market all with an average price per kW of unsubsidised storage of about $1,000. You don't have to have a Fields Medal in mathematics to work out that $10,000 worth of battery with $693 a year return is not a fantastic investment just yet.

 

For the last year at least, more than 75% of the sales we have made have been with hybrid inverters...inverters that can connect batteries. We are simply meeting demand. People are asking for hybrids more and more. They aren't asking for batteries so much, they just want to be ready when batteries make sense financially.

 

Whilst there are a few die hard sales reps still out there desperately trying to persuade people into believing that the regular inverter they are selling can connect batteries, the reality is that most people now know better.

 

Pictured below are two inverters. On the left, Austrian made Fronius Primo . One of the best single phase inverters but reaching the end of it's life now, because it is NOT a hybrid. On the right, Huawei's single phase inverter which is a hybrid. The red arrow marks where the battery plugs into. Not very surprisingly, Fronius will be introducing a NEW Primo that IS a hybrid sometime around mid 2019.

 

If you already have solar, or if you have your heart set on a non-hybrid Fronius/SMA inverter now, then fear not, there is a battery solution which is typically called 'AC Coupling'. It works just fine but it will cost you a couple of thousand dollars more than buying a hybrid.The solution is another inverter that connects to your switchboard. There are products available today from SMA (Sunny Boy Storage), Tesla Powerwall 2, Goodwe, Sonnen and others provide 'AC Coupling' and no doubt more are on the way...there are 2 million existing solar homes in Australia alone that may soon want these retro-fit products.

 

The maths works out like this...(AC Coupling)

Fronius Primo Inverter  $2,200
Goodwe 5kW AC coupled battery inverter and smart meter $2,200
Installation of both inverters and the Goodwe smart meter $600

Total $5,000

Now just add batteries.

 

As against buying a hybrid (DC Coupling)

Huawei 5kW hybrid and Huawei smart meter $2,050
Installation of inverter and smart meter $300
Total $2,350
Now just add batteries.

 

There are plenty of other hybrids available to throw into the mix from Sungrow, Goodwe, Delta, SolaX, SolarEdge with more coming with some that would make the case for hybrids even more attractive than the example above, although Huawei is an exceptionally well made product and is our current recommendation.

 

You can bet your bottom dollar (where did THAT phrase come from??) that when the Fronius Primo hybrid eventually arrives, all those who have been strongly arguing against hybrids, will change their tune overnight. We have nothing against Fronius. In fact prior to the past year they were our top seller. It's just that we don't play favorites with products. We have been here long enough to understand that inverters have a shelf life of a few years before being replaced with something better. If Fronius have been a bit slow with a hybrid range, then that's just temporary.

 

Read on if you want more detail...

 

Hybrid inverters manage both the solar panels AND the battery.
They all have their own smart meter installed in the switchboard that monitors loads in your house and notifies the inverter so that battery power can be released to power those loads.
Many people install the hybrid smart meter even though they aren't connecting batteries yet in order to view reports on their home power consumption.

 

There are 2 million solar installations in Australia and whilst a very large percentage of current NEW installations install a hybrid inverter in readiness for batteries, the older installations were not hybrids. Whilst the solution isn't as cheap or efficient as a hybrid, the good news is that any of those earlier installations CAN have battery storage too. All that is needed is to have two inverters instead of one. The second inverter connects to the batteries only, not the solar panels, and like the hybrids, has a smart meter in the switchboard to manage the store and release of battery power. It's main role is to intercept any surplus solar power heading out to the street for export, and store it in the battery instead.

 

Inverter manufacturers are all moving towards hybrids. The Fronius Primo pictured above for example will be released in hybrid form by mid 2019. Huawei, Goodwe, Sungrow, Sonnen, SolaX, Growatt, SolarEdge, Delta have all released single phase hybrids in Australia.

Three phase hybrids are a rarer beast. Fronius have a hybrid version of their three phase Symo inverter albeit $1,400 more expensive, SolaX have some in their range and Huawei and Goodwe are releasing their 3 phase hybrids early 2019.

 

If you have purchased a non hybrid inverter and want to connect batteries then the second inverter is going to cost over $2,500. Goodwe 5kW SBP product is $2,100, SMA Sunny Boy storage is about the same price for their 2.5kW product and another $500 for the 5kW version...amd then you have the smart meter and all the materials and labour to install the second inverter. The Tesla Powerwall 2 includes the inverter in the same big white box as the batteries so its hard to say exactly what the inverter costs.

 

If you are deciding now on whether to buy a non hybrid but top quality inverter like SMA or Fronius or an equally good quality hybrid like Huawei, then the good news is that it will cost you nothing more to get the Huawei hybrid. Huawei don't make non hybrids so its hard to compare prices with them as easily as it is with manufacturers like Goodwe who make both. With Goodwe the 5kW single phase non hybrid is $1,200 and the hybid version is $2,200 although when 'specials' are being offered the gap can be as low as $500.

 

Power cuts
Whilst the primary attraction of battery storage is "load shifting" ...taking the surplus solar power and storing it in batteries for use when the sun has stopped powering the solar panels, there is also the attraction of having power available when there is a power cut. We are fortunate in Perth to have a very stable power supply but of course, power cuts do happen, usually just after the big Christmas shopping trip has been put put away in the fridge and freezer.

It's unrealistic to expert a relatively small solar battery to power your entire home during a power cut, but it can provide enough power to run the fridge and some lights for a while. To do this an electrician would need to wire up an emergency circuit of your critical loads, and then connect that to the inverter.