Interview: Finn Peacock talks solar battery storage in Australia (and more)

finn peacock

Finn Peacock talks shop with Rich Bowden

It’s been a big year for news on solar battery storage in Australia. With the imminent release of Tesla’s Powerwall onto the market and influential reports predicting a new way of accessing energy, the trend has not been “if” but “when” renewables will end up dominating new energy takeup in the country.

But how much of this is kosher and how much wishful thinking? Are we on the cusp of a solar battery storage revolution? Can we start tearing up our electricity bills? To find out the answers we asked Finn Peacock, SolarQuotes founder (and professional cutter through bullshit), his opinion on exactly what has made 2015 so important in solar power and what his predictions are for the near future.

His frank analysis is fascinating, sometimes controversial and may surprise some.

SQ: Has 2015 been a gamechanger for solar power storage? If so why?

Finn: Yes because of Tesla’s innovation.

Let me be clear – there is nothing innovative in the battery chemistry they are using or the price per kWh of the actual cells. Anyone can go to Panasonic and buy similar cells for a similar price, if they order enough of them.

The stepchange is the 10 year guarantee and the package they have put around the batteries. i.e. the thermal control system which lets you keep the batteries safely indoors, and the power electronics and software that make installing a Powerwall into an existing solar system cost a few hundred bucks in extra hardware and installation labour instead of many, many thousands:

[NB: For more, check out Finn’s “The cheap, cheerful way to add a powerwall to your existing solar system“.]

Tesla have explicitly said that the software + power electronics in the DC-DC converter will allow it to be charged directly from the panel array. No charger required. They have also said that the powerwall can use the existing solar inverter (as long as it can talk to the Tesla BMS). No battery inverter required. Whether a spare input is required is yet to be confirmed. There are rumors that Tesla have worked out a way to put the powerwall between the array and the inverter without compromising the MPPT. But a spare input is probably prudent.

The final BOS (Balance of System) hardware required is a meter so the BMS knows when to charge/discharge. This can be achieved with a $20 CT (Current Transformer).

And the major point in all this is that the daily cycling 7kWh powerwall is intended to be installed without backup functionality. This is a complete change of paradigm. Adding batteries without outage protection!

This concept is crazy in many installers and consumers’ minds, but that is what many people looking at hybrid are asking for. They want the battery so they can use 7kWh of their solar power through the night. As simple as that. To do this they want a solar system that is going to be as Powerwall compatible as possible. e.g. they want a Fronius or SolarEdge inverter and a nice big panel array.

SolarEdge have already released details of their solution.

The Australian SolarEdge office won’t tell me the pricing, but as an electrical engineer, I know what those boxes have to do (they appear to be a Modbus interface) and it is very cheap and simple electronics. I’m expecting the extra hardware to integrate the Powerwall to be hundreds of dollars not thousands. 

SQ: In your estimation, how long before off grid solar power and storage is viable for Australian households?

Finn: I get into a lot of trouble for saying this. But let me be as clear as I can be. Going off grid if you have a grid connection at your doorstep is financial lunacy.

By all means get enough batteries to bring your grid imports down to almost nothing, but don’t disconnect from the grid. You will always have surplus solar and you should use the grid to share it (offsetting coal fired electricity and supporting the grid through peak periods). The Reposit Power software that will be added to many battery packs in the near future can even make the grid a profit centre for you.

The grid has been built and all the embodied energy has been spent, so it you have a grid connection use it to share your power and support people without solar. Getting 3 times the amount of batteries so you can go off grid (instead of a moderate amount of batteries to go hybrid) and wasting all your excess solar, and having a diesel generator as a backup is really fricking bad for the environment and your hip pocket.

In terms of grid connected storage, in 3 years it will be as popular as solar panels are now.

SQ: A number of reports are hinting at a change in the way we access energy. Are traditional fossil fuel utilities dying? How do they need to adapt to survive?

Finn: No new coal plants will be built in Australia. It will go to gas in the medium term. But there will be so much locally produced energy that electricity retailers will soon move to become brokers, not retailers. They’ll buy and sell electricity for individual homes and businesses directly on the wholesale market and take a small percentage, like a stockbroker does buying and selling shares for you. Software innovation will enable this.

So there you go, Finn’s full and frank thoughts on the way energy will be sourced in the very near future. What do you think of Finn’s views on solar battery storage in Australia? Will utilities become more like energy brokers as Finn says? Will Tesla’s Powerwall prove to be the gamechanger? Please feel free to add your comments below.


  1. Love reading about solar battery storage. Way to go, cant wait for it to happen
    D Nalli

  2. It’s just a matter of time, and not so long to wait. The ISEM department at University of Wollongong is having success with research which will change the status quo and make solar/battery storage as common as the kitchen fridge.

    • Probably right, Colin. And I can remember when a new Kelvinator cost nearly as much as your house ~ even with the missus and three kids thrown in!

      Unfortunately we had to stick with the bi-weekly ice delivery because we lived so remotely the nearest grid-power supply was miles away.
      We lived in Bayswater: about 20 Klicks from Central Melbourne. 🙂

      ….but on the upside the swamp over the (dirt) road was full of tadpoles and frogs and snakes……

  3. Bruce Nicholson says

    Any word on the Enphase solution for battery storage yet?

  4. “I know what those boxes have to do (they appear to be a Modbus interface)”

    I suspect SMA opening up the modbus interface this year on their inverters might not be coincidentally timed to around the Tesla battery announcement.

  5. I asked elsewhere what you’d been smoking, Finn. Now I’m beginning to wonder whether it’s rotting your brain.
    Your broad and sweeping assertions are way off the mark, and I can post the arithmetic if you want me to…..(Unless you’ve got a swag of shares in the ‘new grid-connect technology’ of course.)

    ” Getting 3 times the amount of batteries so you can go off grid (instead of a moderate amount of batteries to go hybrid) and wasting all your excess solar, and having a diesel generator as a backup is really fricking bad for the environment and your hip pocket.”

    1…..”three times the number of batteries so you can go off-grid” is a nonsense. All you need to do is adjust the way ~ and times ~ you use your various loads. And, of course, reduce wastage. Origin has it the ‘average’ house uses around 25kwh per day; I use ONE-TENTH of that, and don’t go without anything I need. (Admittedly a 1-person household, but so is a large and growing proportion of the population.) Happy to send you a copy of my last bill if you’ll tell me how.

    2…….The …(“moderate amount of batteries to go hybrid) are not “moderate” in price. Your own projections of price makes a ‘power-wall’ 5 to 15 times more expensive than reasonable-quality deep-cycle batteries available anywhere today. And technology being what it is the Tesla power-pack is as liable to destruction as any other system.
    More so in fact, given the added complications of the ‘system’ both coming and going, since you’re connected to the grid. (eg. What happens when a lightning-bolt ~ up to say 5MILLION volts, 200,000 amps and several terawatts [Google] ~ hits the local substation a mile down the road?)…And don’t think it can’t happen: one substation was hit THREE TIMES in a fortnight in Coburg years ago!

    3……The point has been made before that only a dill with more money than brains installs a system that produces much more than he needs. And that includes ‘back-up’ diesel generators, which are only of any value if you needs huge amounts of consistent power have NO other means of generating it.

    4……. And as for being “fricking bad for the environment and your hip pocket.” you apparently haven’t factored in the enormous environmental costs (in cash and kind ~ including massive periodic bushfires and/or coal-mine fires that burn for months!) in maintaining the grid (even after it’s been built) ~ or the huge waste in energy which needs to be produced (coal-burners!) just to keep the environment warm whilst pushing the energy through the network before it gets to your house.
    ….And let’s not forget the detrimental (and/or lethal) effects on any living thing within reach of the emf.

    In order to waste all that energy my ‘hip-pocket’ is currently being lightened by about $600 a year (or 300ah of storage!) ~ and growing exponentially.

    5……. This:- “so if you have a grid connection use it to share your power and support people without solar.” is the sort of furphy that makes me a bit sus about your motives. Solar feed-in ‘export’ in NO WAY ‘supports people without solar”: and in fact, selecting “green power” costs them MORE than the standard coal-generated stuff.

    I’m happy to send you details demonstrating every one of the claims above. You ~ or anyone else ~ can reach me at: [email protected] (note the THREE b’s)

    ‘Ave a good day anyway! 🙂

    • Gurkha Black Dragons mostly.

      If you use 2.5kWh per day then it makes total sense to go off grid. Unfortunately, as you point out, the average is more like 10x that. And that changes the equation completely. Also electric car charging is coming very soon, which will at least double the current average usage.

      • Just a comment in contrasts:-
        I’d suggest the 25kwh per day used commonly is downright wasteful and unnecessary.
        That the ‘Tesla-wall’ apparently provides 7 kwh back-up for night-time use and when when the grid goes down/etc. the suggestion is that figure represents a more ‘appropriate’ usage for energy-conscious people.

        eg. Put up enough (cheap today) panels to run your fridge, freezer ~even air-conditioner ~ and so on at full-bore all day and not at all overnight……and charge your battery-bank up as well. Say, 2000-or-3000-watt panels at $1 per watt. Even a 5kw array can be justified.
        That way battery-storage need only run lights, TV, computer etc. overnight.
        And there are low-energy-use products available for all those purposes.
        A small demand-start generator to run intermittent heavy-users like microwaves, etc. is a small-low-cost incidental and feeds a separate circuit.

        Extrapolating my 2.5 kwh per day consumption, a 7kw battery-storage should easily accommodate a three-or-four-person household.
        And to quote your expert self:- “4kWh of electricity storage will get an efficient house through the night.”
        I’m no engineer (and think there’s some sort of constant that needs consideration?/whatever) , but in round figures that requires 165 AH of stored power @ 24 volts……No?

        To achieve a 50% DOD double that 165AH to 330 AH, which (@24volts) can be bought new for under $1500 and can be expected to last 3 years or more. (Get a strong warranty!)

        What’s the point, then, of remaining grid-connected ~ when the connection alone will cost you more than the properly-sized battery-bank?
        …….and keep you dependent on the industry/political-finangling and ever increasing prices. In three years expect the cost of serviceable batteries to reduce by, say, 25% ~ and the service-to-property charge to double at least, and maybe quadruple.

        I was impressed by a ride in a hybrid car recently, but would NEVER depend on one ~ particularly in a life-and-death situation. And not only does the multi-step process of feeding them waste a huge amount of energy before you even get on the road, but if something goes ‘wrong’ one wouldn’t even begin to know where to start looking for the fault.

        I can already see the roadside-rescue and tow-truck services smiling in delight and cranking up their super-sized cash-registers!

  6. Kate Gunn says

    We are off grid, having had a system installed 6 years ago. The 650Ah batteries have deteriorated to the point now that they need replacing, and we do not know what the best replacement would be since these were meant to last 10 years!! Help please.

    • What brand are the existing batteries?

    • I’d be interested in details (including price) on what batteries you’ve been using Kate…..and how you’ve been using them

      Were you actually told they would last ten years, or was that the inference from a claim that they had a ’10-year design life’.?

      I’ve had a good run from 2nd-hand (standby UPS) Vision AGM 200 ah batteries which also had a 10-year design life originally. They’d been in that standby role for 3 years ( when I bought them for $1 per ah.
      I only use then to a DOD of about 15% when the weather is suitable, and they’ve been connected to a 340-watt solar array for 8 years.
      Two died recently and the other 6 are wearing thin.

      But good value for my money, and I sought to replace them with the same product. Vision warned me that they were NOT specifically deep-cycle and shouldn’t be used as such.
      That the prices for new ones had also risen substantially over the period decided me to explore the options.
      As with anything, you can spend as much as you’ve got, but from what I see some of the ‘generic’ brands available new at about $2 per AH will be a good buy. I think the key lies in the warranty ~ how long and how strong. Some of them come with a 3-year warranty, and if you can get that on paper would be a useful buy. eg. Over three years they’d save you about 65%/75% of what the ‘service to property charge’ for a grid-connection would be. (I’d question Finn’s arithmetic about the value of grid-connection.)

      And you can be surprised. We used to buy 2nd-hand batteries from the SEC depot (Back when nobody had any use for them 2-volt 1340 AH batteries could be had for $9 each ~ probably about $50 in today’s money. A friend of mine finally threw hers out a couple of years ago ~ after 30 years in a stand-alone situation. (I’d also question the need for some people to use 25kwh per day ~ and suspect you’d agree!)

      All the best

      • Jason,
        Thanks for the advice. The batteries are Sungel 2SG650. I can’t tell you what the cost of the batteries themselves were as it was a package with all the rest of the gear. They came with a 10 year “warranty” and from all the costings I ran through with the sales people they were certainly selling them on the basis they would last 10 years (silly me!)
        I had one fail completely a few years ago, which put the whole system out of whack as they weren’t charging properly for this period of time, and I think this may not have helped the longevity of the rest.
        After that one was replaced I was ok living on my own but I got married earlier this year and my husband has moved in, meaning twice the showers and toilet flushes (an 800W water pump) in the dark and we are struggling in the short days!
        I will definitely look into those options you suggested. I would be happy to spend money if something would definitely last 10years, but am a little wise and weary now so want to explore all my options and make sure I either spend less or get more.

        • Thanks for the feedback Kate.
          And certainly, things ain’t what they used to be. I’m a great fan of modern technology (but not at ANY price!) for the independence-choices it provides.

          Y’can’t get the SEC batteries (and LOTS of other great stuff dirt cheap) since Kennett’s gang sold the SEC; but the point was that it’s always well worth checking around because you never know what you’ll find ~ or discover alternatives.

          eg. I also, way back, used to get used big truck/bulldozer batteries for free, and finished up with a huge stack of dead ones. Nuisance?? Fill ’em with with water and use them to build walls/pave floors for things like glass-houses. Brilliant heat-banks!

          As for the ‘warranty’ stuff you were fed, when you were probably too green to know better, I’d be inclined to go back to the seller and make a few noises ~ and veiled threats about using Facebook, Ebay Feedback,
 dent his income. May not get far, but it’ll cost you nothing and you never know…..

          The power your pump uses can be reduced to zero if you put up a water tank. Even just a couple of 44s (the black plastic ones even pre-warm the water quite usefully) on a bit of an embankment or a simple stand (attached to a tree!) will do the job. And if it means running your fire-fighting pump (presumably you’ve got one) or other alternative option for a few minutes every other day it’s still the most efficient ~ and reliable ~ way to go. (if you heat water with an instantaneous gas heater (Junkers or such) you tanks will need to be 12 ft. above the heater in order to provide enough pressure.
          …and if you have access to a small creek I can send you instructions for building a basic hydraulic ram pump for very little. (Such rams might be my favourite mechanical invention of all times! Super-efficient and foolproof.)

          Gotta go, but would be interested to hear how you go.

          ps….keep in mind too that you can easily adapt most petrol/diesel engines (including generators, pumps, etc.) to run on lpg (cheaper and no shelf-life concerns) or ~ if you want to put in a bit more effort ~ set up a wood-gas producer….which will also heat your water as it produces the gas to run your stationary engines..

  7. William Sharpe says

    I don’t think the Powerwall itself will change much, simply because Tesla can not produce enough of them to make a big impact. Don’t bank on getting one for yourself, that will probably never happen.

    What the powerwall really is, like most of Musk’s ventures, is a high-tech stick to bludgeon the market with. It shows customers what is possible and raises their expectations of the industry, forcing other companies to develop products that are just as compelling.

    Customers who want a Powerwall should instead call Enphase or another company and demand something that is just as good. Post them a link to Tesla’s open-sourced patients if they can’t comply.

    • Tesla has a huge investment in electric cars, which make residential solar energy even more economical. However, that requires energy storage to allow recharging at night, if one isn’t using the grid’s off-peak tariff.

      I’d say Musk has a pretty strong financial incentive to get integrated home energy storage off the ground in high volumes.

    • William, your suggestion that “Tesla can not produce enough of them…” is arguable. Tesla’s whole purpose in announcing the Powerwall “gamechanger” was to get pre-orders. An how immensely successful that’s turned out to be with millions of pre-orders received. Now your assertion seems sustainable but for a lack of understanding Tesla’s (Musk’s) “book to bill” strategy, and the fact that the Gigafactories currently proposed, and one well progressed in construction (Reno), present him with a mammoth challenge: how to absorb the massive increase (resulting in unit cost savings of 30-50%) in Li-ion battery production into the vehicle manufacture cycle: fact is, it’s going to prove impossible to build the Tesla’s quickly enough in the foreseeable future to do that. SO, he’s stirred up the next emerging market that he alluded to about three years ago: home battery storage, and voila, every electricity retailer in the country is on “high alert” and even rolling out “virtual products” just to stay in touch with this new threat to their traditional business model.
      Your assertion that Tesla “(It) shows customers what is possible and raises their expectations of the industry, forcing other companies to develop products that are just as compelling” is spot on, but it plays right into Tesla’s battery (supply) plan, as, once the Gigafactories come “on-line”, “other companies” will be buying their (cheaper) batteries en masse. This is a good thing for all those who recognise the benefit of battery storage for RTS, and arguably, for split tariff customers as well. Whether they purchase a Powerwall or other brand, it’s my guess in 18 months every cell in any of them will have the Telsa(/Panasonic) $tamp on them. The only risk in all of this remains with the electricity suppliers and how savage they have to get with their pricing structures to protect their profit from the savings consumers with storage will accomplish.

  8. ….another good reason for going nowhere near electric-powered/controlled cars:- hackers! (see this morning’s news.)

  9. I have moved into a new home with ideal roof for up to 15Kw solar panels and have prepared the garage walls for energy storage unit(s) and charging dock for a future EV.

    My personal dilemma is when should I do this. I keep reading about improving solar panel efficiency, (PERL type for one), and improved battery density, (Oxis, is developing lithium/sulfur technology.

    There is no answer really but it is fascinating watching the evolving technology – shame someone in the LNP Government could not inform Abbott and his fellow dinosaurs.

    • Your decision has absolutely nothing to do with Prime Minister Abbott. If you need his encouragement to invest in this amazing technology, perhaps you should wait a bit, to see if your confidence improves.

      Most of us know that solar energy is not terrible cost effective when all things are considered. Particularly if you decide to sell your home after installing one of those marvellous systems. It really hurts to hand it all on to someone else, knowing that you have not recovered even a small part of its cost.

      I fitted a 10 kw system on my place two years ago, and I am moving out at the end of the year. I just wish these systems could be portable, but they are not. However, I will still install a state of the art system next time I set up in a new home. It may not be a good investment, but it certainly is a great obsession and I look forward to seeing the next one installed.

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