Home battery storage (solar systems)

It looks like the blogger I linked above wasn’t as well informed as he might have been, as Tesla have announced that the Powerwall 2 AC will be available in Australia next month. An article covering the Oz launch by Elon Musk’s cousin appeared on RenewEconomy today here: http://reneweconomy.com.au/tesla-launches-powerwall-2-says-all-solar-homes-will-have-storage-53696/


Found this from Canstar Blue whilst “browsing” around . Lists the different makes of home storage batteries available .



Thanks for your ideas, @gordon. I understand we are in the messy transition period right now and so it would be difficult to use such a system tomorrow. Your last comment is what I was thinking about in the long-term.

When everyone has finally converted to clean energies, you could charge anywhere and discharge anywhere. I’m glad this is being heaviuly discussed in other forums; I barely have time to keep up with this one let alone to start delving into others!


Things are not looking for good for Aquion: https://www.pv-magazine.com/2017/03/09/aquion-files-for-chapter-11-bankruptcy/

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Cost less than a regular roof? I’ve always found that very hard to believe… maybe they meant less than the most expensive alternative they can think of! Less than Gold plated Colorbond perhaps? :wink:

Bloomberg New Energy Finance reckon they will cost ~20X as much as regular asphalt tiles (common in the US)


Hi @gordon

Just added a link on another discussion about the pricing and warranty on the Solar roof tiles, link is here:

Solar and Grid Connections


Solar battery installs are surging.


The AC version is available in 2018. And it’s control system (Backup Gateway 2 for PowerWall 2) handles three phase as well as single phase.


We’ve had solar panels since 2009 and I keep the quarterly figures for daily averages of - kWh we make in total, kWh we export to grid, kWh we import from grid, kWh we consume in total.

Winter is our low useage time of year (averaging between 12 and 14 kWh per day). If we had a battery system we would still have a net export to the grid in this season from our little solar system.
Only in summer would we still need to import a little, average 2 to 8 kWh per day depending on how hot the summer is.

To store enough kWh to handle one day in summer entirely from battery I reckon we’d need battery with capacity to discharge 25 kWh.

Question: to allow for a period of consecutive cloudy days, what is the recommended multiplcation factor?


25kWh is a big investment.

I ran our house through the calculator on the solarchoice web site.
There is no one size fits all.

Choice has a very basic guide most of us may have seen before.

For a hybrid system if you need to cover 1, 2 or 3 cloudy days in summer have you considered that you will need enough surplus solar when the sun comes back to run your house and fully recharge your battery at the same time?

You also loose feed in credits when charging so perhaps also need to consider the difference between your feedin tariff vs purchased power price. The smaller the difference the longer the payback on the battery.

I used the BOM web resource for my nearest weather station to obtain solar data to assess what was statistically relevant to our location.



Another relevant link from my ‘go to’ source.


How much energy do you use per day? I use up to 50kWh with a 21kWh battery.

You are generally better off putting in more panels to better cover cloudy weather, PV panels are much less expensive than batteries. Lots more panels and not so much more battery.


Looking for a better option for the next gen home storage battery?

Enough room for a container in the backyard?

Will your council give planning approval to keep a container in your back yard, permanently?

For early adopters there is an alternative to lithium battery technology. With a great cycle life and high peak discharge capacity, oh and it will not catch fire. There’s are a few draw backs including low trip efficiency. Read on to see if you agree.

Or a more in depth practical assessment by a recognised expert.

There remains some possibility of another break through which could scale the technology to the average home. Although it has taken nearly 40years to develop lithium technology.


May I request Choice start surveying members about home storage batteries.
I live in an off grid community. In our region, there would be several hundred households, mainly part time residents living in battery powered homes. Almost every house has a different system to the neighbour. Some systems are approaching 20 years old. Some are putting in the latest and greatest Li chemistry. The cheapest systems use little petrol generators.
That’s an enormous wealth of experience, untapped. There must be many similar communities.
It’s just that I find the results of the Canberra Battery Testing Centre depressing, and unrepresentative of our collective experience.


Hi @Pjrpd, I am a Customer of AGL and I telephoned the Customer Service phone line and asked them about a home storage battery. The gentleman informed me that for the small sum of $100 AGL would install a battery at my home and connect it up with my Solar Panels! (I have 25 on my roof) Subsequently, I took down all of the details and then did some feverish searching about the battery, offer, reliability and feasibility of this on DuckDuckGo (my search engine). Cutting a long story short, I took them up on the offer, the battery has been installed and now I am saving huge amounts of money on my Electricity bill… :slight_smile: and it only cost me $100 to take AGL up on the offer. So ring your electric company and ask about their batteries - you may just get a profitable and pleasing reply, as I did. Hope this helps you @Pjrpd, and dont just ring AGL, ring them all! You wont know if you dont ask. :slight_smile: Cheers NatNat :wink:


Supplying a backup reduces their revenue and the solar backing batteries on the market are generally in the $1,000s not $100s as you probably expected.

Would you post the details of your battery? Are there any trailing payments, eg such that it is actually an instalment purchase bundled into a solar plan?


Just wondering what experiences people have had re batteries for home solar?

We have panels & save a decent amount on bills - we produce more than we use, but still use at midnight, for example whilst excess goes to grid at midday.

Wondering what people have paid & what time frame expected break even is?



I’m off-grid with batteries for nearly 30 years, but from the comprehensive studies I’ve read, in most cases households will be unlikely to benefit from the commercial offerings of grid-connected batteries.

For an outright purchase at full retail price the most likely outcome is a gradual decline in storage capacity, and the gradually reducing savings never actually getting to covering the cost of the battery before it expires.
Studies show in most cases that the battery will be well out of warranty before it has paid for itself, and in most cases, it never will. If, however, you can score one as part of a virtual power plant or similar subsidised scheme at a greatly reduced price, then the economics changes substantially, and it may be worthwhile economically.
Of course pure electricity economics is not the only important factor, something which many studies do not cover. If you are in a zone of frequent extended blackouts- what is a freezer or 5 full of food worth?
Of course you may be able to cover that with a generator, but setting that up to operate automatically in case you aren’t home can be expensive too.

If blackouts are not an issue for you, going with a PV array significantly larger than your daytime requirements can mean you earn enough FiT credits to cover night time use. PV is much better at producing savings than grid connected batteries for the near-term future at least.


There has been mixed reports about the payback period, Some are very optimistic while others indicate that the battery will not pay for itself over its life.Choice has produced a buying guide in relation to home solar battery systems:

This buying guide states:

For most homes, we think a battery doesn’t make complete economic sense yet. Batteries are still relatively expensive and the payback time will often be longer than the warranty period of the battery.

There are also a number of threads in the forum where other members have provided their own thoughts on solar battery systems. These threads include:

One thing which is very concerning about batteries systems is that they are relatively new technologies and current available models are not reliable. It is worth reading this report:

Personally I would be waiting a few years until the battery industry can prove that their batteries are reliable, and there is sufficient evidence indicating that for most (rather than a few) consumers a battery system is economically viable proposition.

What do you use at midnight? Pool, electric hot water storage system, air conditioning?

If it is the pool and hot water, it may be possible (subject confirming with your local utility) to change the times that these devices operate. For example, to run water heating or pool cleaning during the day when your would otherwise be exporting. Shifting their use to when solar is being generated may increase the value of the solar being generated. Calculations need to be considering difference in FiT, cost of midnight/offpeak use and whether one also draws additional electricity from the grid when the devices are used during the day (as usually this is peak times compared to night time electricity prices)


Thanks for the link to the CBTC report above - I enjoyed the reporting!!