CHOICE membership

Solar storage batteries: Tesla Powerwall and 17 others put to the test


Great article but during reading it, I saw a link to another great article by Tim Peacock.


I won’t. It was a bit tongue in cheek, but I can’t find a suitable emoji to make that clearer!

‘Let me count the ways’, however some might think that irreverent? Unfortunately perhaps the new Aussie wheel owes much to the kangaroo. More an uneven jarring motion than one of even continuous movement. SA has done a fine job of repackaging, given the need for global ISO accreditation?

It remains a fine line between a shared solution that promotes a common outcome and individualism that enshrines difference!

Whether a repackaged DIN or BS adds value in adapted form or simply serves self interest, it is a great question?

SNELL RX-7 comes immediately to mind (historically of course), but has little to do with solar or batteries?


I’ve posted the link to Finn’s blog already, look back up the page!


DR2 AS/NZS 5139:2018 (SA project no 103207)

Electrical Installations – Safety of battery systems for use with power conversion equipment

The horse Is long out of the starting gates on this one, for now? Public comment closed on the second draft of the standard 03/04/2019.

It is still listed at the public review stage which includes subsequent to the closing date an internal resolution process for all comments. Generally the detailed discussions within the review committee are not published. It will be up to the committee to decide if it can be passed onto the next stage, or further amended?


WorkSafe/WorkCover Qld encouraged public comment for the first draft released in 2017. (Apologies to all if this is a little one state minded. Researching every state independently, I’ve assumed all have similar outlooks.)

Acceptance and ratification of the second draft of the standard awaits? There appears to be substantial state level interest in the subject matter.

For one example WorkSafe/WorkCover Qld has issued the following advice to installers.

It further references the following non mandatory guide supported by the CEC, CSIRO and others.

Discussion of the proposed standard in general raises some interesting points concerning development of standards that apply directly or indirectly to the consumer environment? To what extent does Choice as an organisation have interfaces with Standards Australia, and to the extent the wider Choice community may be kept informed of opportunities to comment or become involved?

The draft AS5139 is no longer available for public access. In many aspects this is a highly technical topic. For it to become mandatory once approved and issued, will be up to each state government to clarify. Not withstanding any views household insurers may also adopt, or risk adverse battery installers?

Background to the standard and committee can be found here.

One of the committee members presented to Engineers Australia last year on the topic. The registration invite makes a revealing comparison.

A 200kWh energy storage device stores approximately the equivalent energy in 20 litres of petrol and there are regulations about how much petrol can be stored in the home. Safety is paramount, irrespective of whether the setting is residential or commercial

Hopefully the final version of the standard reflects the much lower energy potential and risk factors for a more typical residential 10-20kW storage system. I’ll note our local Solar PV & Battery Supplier eyed off our all colourbond steel garage when I enquired about an offgrid storage option.

Does anyone have pics of a Tesla Powerwall installed directly on a timber framed Queenslander?

There is a genuine concern looking for a practical outcome?


So park a 50 cc scooter in your driveway close to the house, on it’s centre stand of course, empty the tank and bolt your battery to it - if we are suggesting this is a real comparison - should be fine! :rofl::rofl: - if we are looking to stored energy for a comparison, there are plenty of houses with 90 kg or more LPG held there with little more than a ‘terrier lead’ and piped all through the house … I also remember the day when sizable oil tanks for heaters were mounted on outside walls - I understand volatility is a factor here, so not all stored energy is the same (and lets not dwell on those people who store gunpowder in various forms ‘in kilos’ …)

Seriously though, I think these people understand what we peasants call science and theory and newfangled equations, but they don’t understand ‘reality’ (risk, common sense, etc) - they seem to have to protect everyone from every thing with zero tolerance because we can’t be accountable for a single failure - of course in the process becoming the catalyst for significant spin, employment, revenue and sometimes one might suggest even protection of ‘interested parties’ … or am I being cynical?


Our council had a virtual 100% turnover at the last election mainly because while the previous membership were well intentioned, they had no concept of risk management. The lawyers always told them about ‘the risks’ and they naively felt they had to protect rate payers by accepting the lawyers’ positions and make those risks disappear. One example was concrete instead of gravel paved trails in case someone might trip and sue, another being no tree could be close enough to a rural property to have a fire jump from it to the dwelling; and on it went.


Hi Chris,

Many thanks for the update and it’s encouraging to know that were considered but even more encouraging that they were able to identify technical issues which would not have made them a viable option for their intended purpose.


How do you know what my house looks like? :sunglasses: Google earth is not yet that good!
The big gas bottles are actually connected via a 1/4” copper tube, with the relief plugs pointing away from the wooden house walls. The instantaneous gas HW is bolted to another external timber clad wall, cause you can’t have that inside. They all comply to code and regulation.

If there is a risk it is the two big fat DC isolator switches on the roof for the two PV strings. That is in addition to the two big fat DC isolators next to the inverter. The ones you should never operate under load because they are not designed for that duty. Scary!

I do however keep the petrol for the farm implements and ride on and diesel for the tractor elsewhere. Probably very close to where a big fat battery might go if they ever become cheap and longer lasting. Safety always, I’ll need to rethink that one!

Oh, now little they understand?


The is Nillumbik Shire where Black Saturday hit big time and Marysville is just up the road.


The latest 6 monthly (or should that be 9 monthly?) report is now out from the Battery Test Centre here:

Ronald Brakels’ blog on Solar Quotes has some discussion about the report here:

The main conclusion appears to be that a lot of the batteries did not fare very well.

Meanwhile, my CALB battery is 6.5years old, and still operating reasonably well, although I don’t think all the cells will last 10 years with my energy demands. However, it is called on to deliver much more power than any of the test batteries, and is subject to very high summer temps, not being in a temperature controlled environment.
Oh, and it did cost a lot less per kWh than any of the commercial batteries!


It is interesting to read about the pros, cons and reliability of domestic battery systems. I question, why do we need a domestic battery , when I have survived without one for many years. Why should I spend $10-15k, on a 10 kwhrs battery to store $3.00 of DC power. I can use up to 50,000 kwhrs of AC power, directly off the grid, for the same out lay. At night I use off peak power @ 16 cent/kwhr to heat my water. I have solar panels which net 22 cents/ kwhr feed in tariff. Domestic batterys are so inefficient at storing power, for blackouts I have a standby generator. Transgrid have a backup 50 Mwatt gas turbine, at our local substation, which they used for 7 days when the 220kv transmission line went down. A battery system would never cope.


It’s a good question to ask.

This topic is looking at how well current battery technology performs, across a number of samples currently under test.

There are Choice members who live off grid.
Not all households can access generous feedin tariffs.
Some owners with Solar PV choose to go green, and accept the longer term payback.
The value proposition is very different depending on needs.

For most users perhaps there is no immediate need or benefit. It might be just a personal choice.

An alternate question to ask could be, at what cost for a battery and at what rates for mains power does a residential battery become a cost saving when compared to not having one?

Does Choice’s update assist others in making the best decision?


I’m not sure what your source for that claim is, but I run comprehensive data logging on my system and the overall (panel output to inverter input) factor I’m currently using in my daily system operating graphs is 0.975, ie 97.5% efficiency. This includes direct power from PV to inverter, which is close enough to 100% efficiency, and overnight plus daytime cloudy period discharging. At this time of year, due to living in a valley, battery discharging time is about 16.5 hours per day in sunny weather, delivering the majority of energy usage per day.
I’m quite confident that the battery, despite its age, is still operating at better than 95% charge-discharge efficiency, which IMO, definitely could not be called inefficient. It is a little down on the efficiency when it was new, but I consider that it is still quite satisfactory, and a lot better than any Lead-acid batteries I have used over previous decades.
Here are a couple of graphs from Tuesday, which had some cloud around. I had an electric heater running, and also the oven baking a couple of loaves of bread. All the load spike triplets are due to the oven when set to 40C for proving the loaves. When not running a heater or baking bread, a significant part of our daily energy usage is due to various pumps in the aquaponics systems, the house generally using <10kWh/day for fridges, freezers, computers, induction, cooktop etc.

Gross graph

Net + State of Charge graph


Which admittedly is itself a non-trivial cost if it is good one, capable of generating enough power for a whole house, capable of long periods of continuous use, has autostart function - and it’s rather noisier than a battery.

As mark_m commented, Choice was looking at reliability and performance, rather than the economics or any other decision factors.


I guess from the discussion here that it would be timely for us to write an update on the current economics of solar and batteries. The short answer is that for most Australian homes, solar panels make economic sense but batteries don’t. But it will certainly depend on personal circumstances, location, available feed-in tariffs and so on.


@gordon 95+% efficiency for your battery is impressive! What model is it, can I ask? (I’m sure you’ve described your system at some point but I can’t remember where.)


Hi Chris, it was originally 16 X 400AH CALB cells. I replaced one weak one a few years ago with a Winston 400AH cell, as the CALBs were no longer available in Oz in that capacity. Since then I’ve paralleled the removed weak cell with another weak cell- the sort of thing you just can’t do with commercial battery in a box product.


hi nickh64,
re -1. there wasn’t any problem that I was aware of - apart, from the “waiting” for it to hit our shores…
re -2. yes, runs off what is stored in the Battery which is a max of 14kWh …. IF there is 14kWh stored, the only time it would use all of it is when the air con was on bcoz of the high temps……… and, yes Tesla 2 runs if total blackout… which was a ‘choice-consideration’ (bcoz of the blackouts in SA and VIC in the last few years)

18 months since I looked at Battery choices - Sonnen were pushing hard at the market at the time … Bradford were pushing LG… I looked at the non-lithium (I liked Redflow (QLD based)… but…)
. I used the COMPARISON Table that can be found at - — it was "Last Updated: 19th Jun 2019 "

would I pay $11,790 again for the Tesla Battery? - I don’t know, payback years is a long time
. I think that the ‘more panels’ you get, the better… but, IF there is any chance of ‘grid failure’, then yes…
…on the $22,470 total cost of my system, I have saved about 4k over 15 months …
… however, I haven’t done a cost-benefit-analysis of ‘More panels/ no Battery’ vs ‘Panels/ Battery’
Tesla Battery Price has risen slightly (bcoz of the AUDollar)

  • and, Battery Prices have not decreased even tho there is even more competition out there

Enphase Battery, I noticed on the table, is still at 1.2kWh @ $2,000 installed - therefore, to get 14kWh, you would need 12 units @ 2k = $24,000 cost - this was OBVIOUSLY a deterrent for me - bcoz it is double the Tesla Battery cost…



Many thanks for taking the time to put such a comprehensive response to my questions. This is so greatly appreciated.

The information you have provided is more than I would have hoped for but it has got me thinking that Enphase is not really the way to go as the costs far outweigh the benefits. You have saved me an enormous amount of time on research and for that I am eternally greatful.

I can see however why you made the decisions that you did as the power situation in SA is all over the shop and if it means anything, I believe you made the right decision and based on the no.'s you have provided buy-back will come quicker than you think.

Thanks again,
Nick (Armidale NSW):smiley:


I think you have come to the right conclusion Nick :slight_smile:
The Enphase batteries really do not stack up against the alternatives, the cost is one factor I’ve mentioned earlier in this thread, and the very low usable/allowable discharge rate is a major negative. You really have to spend a fortune to be able to run simple loads such as an electric jug, and I suspect they would probably fail at starting moderate sized pumps due to high start-up current and poor power factor, unless you had a huge stack of them covering your walls.