5GW battery storage: How households can stabilise the grid

5GW battery storage: How households can stabilise the grid

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Reposit Power says home battery storage the key to Australia’s energy security puzzle, not grid-scale applications.

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Canberra-based software company Reposit Power says the best guarantee of energy security is battery storage systems installed behind the meter, in Australia’s homes and businesses, and not grid-scale applications.

Speaking at a Special Parliamentary Briefing on Energy Storage on Wednesday, Reposit director Luke Osborne said that Australia’s energy sector was rapidly decentralising, with new technology allowing consumers to be much more active in the management of the grid – while also giving energy market operators access to thousands of megawatts of back-up power capacity.

The energy storage briefing, hosted by Greens MP Adam Bandt and independent MPs Cathy McGowan and Andrew Wilkie, with support from the Australian Solar Council, was attended by a smattering of politicians, including former Nationals MP Bob Katter, and Liberal MPs Tim Wilson and Craig Kelly.

It is part of a broader industry effort to bring politicians up to speed on Australia’s rapidly changing energy landscape, as fossil fuel generators exit the market and increasing amounts of cheap renewable energy generation is brought online.

It may also be an effort to shift the policy focus away from grid-scale energy storage, after a month of ambitious state and federal policy announcements – and provocative billionaire Tweets – put big batteries and pumped hydro in the spotlight.

Two weeks ago, the South Australian government surprised the market with plans to install what would be Australia’s biggest battery storage installation, of at least 100MW, to be built through a tender process.

That announcement was followed swiftly by more surprising news, this time from the federal government, of plans to spend $2 billion on a 2GW pumped hydro scheme in the Snowy Mountains.

Reposit, meanwhile, has been busy working on a number of game-changing projects, via its pioneering solar and storage monitoring and trading system that earns consumers “grid credits” when their solar energy is sold back to the National Electricity Market (NEM) or network utilities.


It is also working on virtual power plant technology, as is California-based Sunverge, which is involved in the AGL Energy-led South Australian VPP – officially launched earlier this month – that is combining the stored solar power from 1000 homes across Adelaide to effectively create a total of 7MWh of storage capacity and 5MW peaking capacity.

Impressive, but just the tip of the iceberg, according to Reposit, which told an Energy Storage Council conference in Brisbane last week that the projected one million home and business battery systems of 2020 Australia could provide 5GW of “virtual power plant” capacity.

“Australia’s leading position in smart home energy systems has been seriously undervalued in the energy debate,” Osborne told the Parliamentary briefing on Wednesday.

“Homeowners can solve the crisis more cost effectively than any other option on the table.

“With the advent of cost effective battery storage combined with solar, homeowners can address their rising energy costs and at the same time address the balancing problem we are experiencing in the wholesale market.

“A smart way to solve the energy crisis is a wide-reaching network of smart and inter-connected solar batteries in thousands of homes across Australia.

“And we already have it. With Reposit, hundreds of households are already using home solar batteries to keep the system balanced – many of them in South Australia.

“This (solar energy) trading system not only benefits customers, but it can benefit retailers and networks who can save money by having to build new power stations or power lines.

“Moving to a distributed energy system saves everyone money,” Osborne said.

“Opening the retail market to households gives consumers lower energy costs, more control, and long term price stability.”

Note: This story has been corrected to make clear that Sunverge, not Reposit, is involved with the AGL VPP in Adelaide.

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  1. Greg Hudson 4 years ago

    ”who can save money by having to build new power stations or power lines.”
    should be:
    who can save money by NOT having to build new power stations or power lines.

  2. Andrew Woodroffe 4 years ago

    So are we to understand that any report on storage quoted in MW not MWh is for grid stability which requires responses in milliseconds and duration, at worst, for seconds only – time enough for the rapid response gas gensets to start ramping up/down? That the MW refers to invertor size and capacity banks and flywheels (wind turbine rotor blades?)? Thinking of some UK articles, here, too. It is of a period of time where the variability from winds gusting and clouds passing appear flat – unlike tripping transmission lines and substations and big generators.

    Is it when storage size is reported in MWh that we are addressing peak loads and peak generation, shifting energy to another time of day? And not grid stability at all. Though, also, avoiding the risk of brownouts and blackouts.

    Is this understanding correct?

    • Giles 4 years ago

      Nope. It’s when we quote people. So if Reposit quote GW, we not going to make GWh up for them. Maybe Reposit know nothing about storage, but i doubt it, they writing the software for it. Ditto with governments. We reported when S.A. announced they wanted 100MW of storage, reported it when they decided they wanted 1 hour storage so 100MWh, and when they changed their mind and said they were open to suggested configurations. Why people insist on RE making up MWh and GWh numbers is beyond me and I not going to bother arguing it anymore.

      • Steve 4 years ago

        On the plus side some of us learned the difference between power and energy on this site, so the frustration you feel did some good at least!!!

        • Ian 4 years ago

          Giles, we feel for you, trying to report on the information given to you . You may need to add some sort of disclaimer such as ‘sic’ or ‘apparently’ or ‘MWH capacity information not supplied’ when quoting storage as MW instead of the MWH capacity. Why let others apparent ignorance of the difference between power and energy make you look silly.

        • stalga 4 years ago


      • Andrew Woodroffe 4 years ago

        But are there not two distinct roles, one with a duration in seconds, tops, and the other, in hours?

        If Reposit is playing with behind the meter batteries for grid stability, surely the GWs refer to the size of the inverters tied to the batteries, the duration of these systems, hours, being way, way in excess of the seconds actually required to fix this particular issue?

        To be fair, it sounds like the SA government is also trying to work this out, too. 100MW even for just 1hour is not necessary for frequency control. Or even to get peak gas turbines to respond – as much as Elon is selling (and, my, what brilliant recognition of an opportunity, real or perceived) – it maybe that 1MWh of flywheel (Beacon Power?) behind 100MW of invertor is sufficient.

        The ability of behind the meter batteries (or in front, whatever) to flattern the load peaks and fill in the valleys, will help in other ways. But as I understand it, not with grid stability.

        • Karl Edmondson 4 years ago

          Andrew I work for Reposit so I can help clarify your last point. Our control system is designed specifically to deal with grid stability, through voltage, frequency and energy. So it allows any Reposit integrated battery to play a local grid support role where needed and the homeowner then gets paid for the service their battery has performed. The process is also completely automated for the homeowner doesn’t need to organise anything.

          • solarguy 4 years ago

            Sure I can see your point Karl, but whatever amount of kwh are needed you have to have a critical mass of home owners with enough battery capacity to spare, to make this work. It will happen in the future perhaps, but when bad weather hangs around for days and home owners need every thing they have stored it won’t be enough. Bring in big solar and wind and utility scale storage.

          • Karl Edmondson 4 years ago

            Hi solarguy, the system is already working and being invested in by most of the electricity distributors around the country. I agree a range of renewable solutions are needed in Australia, but smart distributed storage is certainly one of them.

          • solarguy 4 years ago

            I agree Karl, that distributed solar energy and storage will be one of the solutions. But like I said it won’t and can’t be the only one.
            The utilities will need to work with this technology or face extinction, the system owners will need control of when their storage is taken and when they don’t want to sell.
            When a critical mass of these systems are installed, I’m sure it will help the grid dynamics tremendously. Investors of utility scale RE already have a vested interest and how this will all balance out in the future will be interesting, to say the least.

          • Greg Hudson 4 years ago

            From what little info is on the Reposit website, the battery owner also has no idea how much a peak event (of up to $140/kWh) on the NEM will earn them in ‘Grid Credits’. I’ve looked, and can find nothing…

          • Andrew Woodroffe 4 years ago

            My mistake, what I meant, is that you do not put in batteries sorely for a grid stability service (‘measured’ in MW, not MWh), it is a side benefit.

            If they already exist, sure (but how do you get paid for such services?). But if it is a greenfield proposal, UK and SA, then maybe flywheels and capacitor banks are a better bet.

            Grid stability/frequency control is supposed to be done in seconds, flattening fluctuations from wind and clouds passing is minutes if not hours and existing rapid response gas turbines can ramp up and down over these times, right?

            In addition, all new invertor technology, all PV and Wind turbines (Enercon, 100%, and the others to a lessor degree) has an ability to inject or absorb VARS regardless of weather or daylight, very quickly.

            Perhaps it is rule changes rather than new equipment that AEMO need to focus on. See also Katie Summers brilliant article . . .http://reneweconomy.com.au/fast-frequency-service-treating-the-symptom-not-the-cause-79573/

            As for dealing with the duck curve (and the Enroning), well, that is another story, a different task. And for even more fun, we can start to add EVs to the mix, next year?

        • Charles Hunter 4 years ago

          I don’t think that is true. See http://spectrum.ieee.org/energy/renewables/can-smarter-solar-inverters-save-the-grid and http://www.nrel.gov/docs/fy16osti/66547.pdf . If a PV-only VOC-enabled inverter behind the meter can help stabilise the grid then it can’t be a great leap to do the same thing with battery energy.

    • Antony Day 4 years ago

      Have attempted to point this out before – it’s bizarre that in the same article the unit used for storage capacity is MW and MWh interchangeably – it’s no wonder the media uses the wrong units when specialist publications and companies also do – and don’t try to educate those who are using the incorrect units. I guess we’ll just have to assume that the writer meant something else.

      • Andrew Woodroffe 4 years ago

        ” it’s no wonder the media uses the wrong units when specialist publications and companies also do”

        Yes, absolutely.

  3. Finn Peacock 4 years ago

    Hi Sophie,

    Love your work.

    I’m fairly sure the AGL VPP software is Sunverge, not Reposit as your article implies.


    • FeFiFoFum 4 years ago

      Reposit is doing the trial for SAPN, and Sunverge is the supplier for the AGL trial.
      There are two separate VPP trials underway in S Australia.

  4. trackdaze 4 years ago

    With 6Gw of behind the meter solar already installed a good portion of this will be retrofitted with battery storage.

    • stucrmnx120fshwf 4 years ago

      Very true, I’ve heard 30,000 household battery installations ​last year, 100,000 likely this year, 200,000 next year, if the price of storage, keeps going down faster, than the price of solar power. Then the low installation costs, compared to rooftop solar, means rapid uptake, installation is at least as much cost, as the solar power panels. Home installation costs, are much higher, than utility installation costs, but grid transmission costs, are avoided in the home, with the feed in tariff, sometimes scandalously low, householders, are looking to harvest their own energy. The worse the feed in tariff, the greater the take up of battery storage, the poor prices being offered by the utilities, encourages retaining as much of your own power, as possible. So the utilities are breaking their own business model, the only way they can compete, is cheaper installation cost desert solar farms, with say sea water hydro power storage.

      They’re up against grid costs, the household is up against installation costs, once again, with installation costs low, for household batteries and battery prices going down faster, than solar power prices, it’s a big market.

      • trackdaze 4 years ago

        I think it was about 7000, 52Mwh installs last year but growth will be through the roof this year and next, possibly to the point supply is the limiting factor and wait times extend many months.

        the biggest impediment to retrofit may be battery cost, install cost or inverter compatability. all of them are travelling in the right direction.

        • stucrmnx120fshwf 4 years ago

          Me thinks your figures, May be wrong, 52 MWh per installation, did you perhaps mean 52 kWh, 52,000 X a kW bar heater, for an hour, is a lot of power storage. That would cost over a million dollars and 7,000 possible, but out of 1.6 million households, only one in 200, bought a household battery. My figure was 30,000, or one in 50, also possible.

          • stucrmnx120fshwf 4 years ago

            I began to realize, that 52 MWh was the total installed, nationwide, if you’ve got a reference, I’ll trust you, disappointing though, so small a number. Still at 300% growth a year, 17/21,000, 18/63,000, 19/189,000, 20/517,000, that’s 800,000 units, total before even, the roaring twenties begin. We must remember, that general projections for solar, were 100 times lower than the actual outcomes, that steam’s peak decade, 1860’s wasn’t untill​ the efficient steam engine happened. That the internal combustion engine, had been around for decades, before Mass production and electricity had been around for decades too, before Edison, benefited from it’s mass implementation. Giving us the roaring twenties, solar, storage, electric vehicle, LH2 air transportation​, high rise agriculture, do seem to be getting us closer, to a repeat of the roaring twenties.

  5. Les Johnston 4 years ago

    If there was a large number of plug in hybrids in the transport industry, the size of battery storage potentially available would grow even further. With few plug in hybrid vehicles, the availability of mobile source battery storage is restricted. With a large battery storage system available (and owners paid for their storage availability) the peak gets shaved and we can then look for average energy charges instead of the current system which enables fossil generators to rip into consumers at peak demand times.

  6. humanitarian solar 4 years ago

    “Storage aggregators” use complex costly hardware and software to create an income stream for them. There’s many reasons it’s not needed. When storage is sized sufficiently, it will carry individual properties through the evening peak reducing said peak. Introducing demand tariffs would incentivise this. Additionally, when fossil fuel generators leave the grid, the need for demand management will be allot less. Inverters ramp in milliseconds and I’v read by another commenter that the ramp of hydro is 30 seconds to 90 seconds, so the need for demand management isn’t the big issue that “storage aggregators” make it out to be. Inverters automatically match the supply with the load. The only role I know of for demand management in renewable energy, is not exceeding the power rating of the local inverters, in households, city councils, regional areas etc.

  7. humanitarian solar 4 years ago

    The only reason this cultural fascination with demand management and storage aggregators is happening, is because we still have so many people with grid-tie inverters in their households and they are accustomed to seeing kWs constantly flying backwards and forwards between them and the grid. Once we get storage, this constant “traffic” reduces to relatively less periods of grid access. In terms of managing that remaining access, battery inverters have software with “grid interaction profiles” and we have this programmed based upon our requirements. Additionally, there is already provision for all system data to be viewed on a phone or computer. Apparently some companies have to keep adapting and crafting existing technologies, so these technologies are centrally located and they get a cut.

  8. Chris 4 years ago

    How does behind the meter storage help the grid stabilise more so over grid scale storage? It makes no sense! Behind the meter storage is limited to the capacity of the LV network and distribution transformer if the storage power was to be exported. Grid scale storage injects straight into the HV network and is much less limited…

  9. Kay Schieren 4 years ago

    The grid is irrelevant in rural areas, apart from the fact that it exist in Australia. I have been off grid with solar, some gas and firewood for thirty years. My power is never off, my lights never go out. I do not have to go off the block for energy, except for a little gas and about 20l of petrol a month. And I live 100km from the supermarket. I have installed and managed my own systems for the last ten years on a single pension with a 8.5k credit card. I manage some acres with fire and old machinery. I weld, cook, fabricate , etc., with solar and a little petrol (although soon I won’t need that, either). When I see the fortune in labour and foreign debt spent on the renewal of rural power poles, I shudder at the short-sighted idiocy of it. What is wrong with this country’s leadership? Is it so corrupt and moronically stupid, it can’t organise itself better than an old amateur in the bush? Are the corruption and blindness so deeply entrenched? Yes, I’m afraid so – and unless a little string of miracles pops up, and the biggest fools and knaves suddenly leave this mortal coil, or have a revelation of some sort, nothing much is going to change, unless we get rid of them asap and find some less vain, stupid and corrupt leadership who know what’s what. Good values are needed, good ethics to make them the basis of good organisation, and flexibility to enable the variety of available resources, and local people’s ingenuity to be used effectively. Different locations require different local solutions. One garment does not fit all – but tell that to a bureaucrat driven to near despair by an idiot politician who actually thinks that politics is a science!

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