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Why Australian households are desperate for battery storage

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So, who wants to be an energy pro-sumer? In some states in Australia, around one in four houses already boast rooftop solar PV systems, and it’s having a big impact on the operation and the optics of the National Electricity Market, with big implications for the traditional business models of generators, retailers and network operators alike.

The next big question is by how much this penetration will increase, and to what extent will it be accompanied by battery storage? The anecdotal evidence suggests there is a lot of inquiry about storage from consumers and grid operators. But where will the the best value proposition lie – in the household, or in the grid? And who is going to deliver this service?

First of all, however, let’s understand the reasons why Australian households might want battery storage in the first place.

Mostly, it is due to the fact that households are not getting paid for exports of solar electricity back into the grid. In NSW and parts of Queensland, any payments are voluntary. Even where retailers are offering 5.1c/kWw, they are then selling those same electrons to the solar household’s neighbour for as much as 48c/kWh if that household in on peak rates. Someone is making money, and it’s not the solar households.

Gordon Weiss, a solar and storage expert from Sydney-based Energetics, produced some interesting graphs and observations at the Clean Energy Week event last week.

He said that to limit a solar system to have no exports – based on average daily household consumption of 19kWh, the array would have to be sized at just 600 watts – just two or three panels. It would look something like this.

weiss solar not export

A larger system of around 2.5kW (see graph below) – of about 8-10 modules – results in a huge amount of exports during the middle of the day. Some things can be done to address that – timing appliances to operate during that period, for instance – but the most effective option is to find a way to store the energy, to put it in a box for use later in the day or the evening.

weiss solar export

Let’s also remember that the average system size installed in NSW when those generous gross feed-in tariffs of 66c/kWh were on offer was 3kW. Since then, the average system has increased to nearly 4kW. When those NSW systems come off those tariffs at the end of 2016, there will be some 160,000 households wondering how best to leverage the value of their output.

Here are a few simple rules that Weiss has on the attraction of rooftop solar and battery storage.

Rooftop solar: When the levellised cost of solar PV falls below the sum of the wholesale price and retail margins, then it doesn’t matter what happens to network tariffs – even if they went negative! This is similar to what we said a few weeks ago when we pointed out that even if the cost of coal fired generation was free, it could not compete with solar. The price of wholesale and retail margins is 13c/kWh. In the sunniest states, rooftop solar is not so far from that.

Battery storage: Weiss says that when the levelised cost of solar PV plus battery storage falls below the evening peak price, then batteries will appear in garages and basements.

Off-grid: And when the levellised cost of solar PV and batteries falls below the average cost of power to the consumer, then consumers will go off-grid. Of course, networks will have ways of repackaging tariffs and moving away from volumetric rates, adding in fixed components and capacity tariffs, but it seems unlikely that they will be able to bring the average bill down below $2,000 a year. That is the key benchmark for solar and storage (and back-up – which is another problematic issue if this happens en masse).

Of course, it’s not quite as simple as that – but that is the basic maths that households are facing. Once again, we are brought back to the fact that it is up to the utilities – be they network providers or retailers – to tailor their product to match the cost options being presented by the new technologies. It is not good enough to simply repackage tariffs to make solar and storage more expensive, as networks are inclined to do, and as we reported yesterday.

It seems inevitable that regional communities will look to evolve in some form of micro-grid arrangement, using locally generated energy and local storage. Network operators in South Australia, Western Australia and Queensland accept this as inevitable. The NSW government is promoting the search for the first town in that state that could do the same and become the first zero net energy town.

The difficulty comes in how to manage the issue in the cities.

On Weiss’ rough numbers, to take an average household off grid would need a 7kW solar system, around 35kWh of storage, plus a generator of some sort. That is not what you want to see happen in huge numbers in the suburbs.

As Weiss says: “Do we want, as a society, lots of 35kwh battery storage systems in the suburbs and lots of backup generators? Maybe a better solution is centralised storage – a big battery pack next to sub stations.”

But that requires the network operators to get cracking, and to do this at a competitive price.

“Right now, the pricing signals that are going out to consumers may result in people going off grid in metro areas in large numbers. That wont be environmentally or economically desirable,” says Weiss.

“We have to acknowledge the reality of new technologies. We have to begin to think of he grid as fundamentally different thing. It’s no longer here to deliver centralized energy to consumers, but to ciruculate energy. Solar PV with storage is now part of the landscape. The challenge is to use it efficiently.”

And just how far away are the economics of solar and storage?

Weiss pointed us to these fascinating graphs, produced by the University of Sydney this month as part of a report being prepared with the CSIRO.

They might give you a bit of a headache at first glance, but allow me to explain.

In the first graph, the purple line is zero NPV (net present value) – and to the right is a rising grey colour, illustrating that smaller to medium size solar PV systems, with no storage, offer some positive returns in the current market. Those figures are based on $3,000/kW solar PV and $1,000/kWh battery storage costs.

Hop to the second graph, which is based on $1,600/kW solar PV – some say that already exists, but be careful about the quality – and $400/kWh battery storage.

On that basis, it is a bit of a no-brainer. The NPV increases sharply, and does so by the same margin when large battery storage systems are installed. That is more than $10,000 of savings over 10 years with large solar and storage systems.

Hence, Weiss’ conclusion that we could see homes with very large arrays and very large battery storage systems in the suburbs. Hence the need for utilities to get on the front foot – and not just by twisting tariffs. This is going to be one of the big social equity issues of the day.

weiss solar NPV

weiss storage npv

 

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  • Sean

    600w, not 600Kw

  • Rob G

    I called my solar installer yesterday and asked about when storage would be affordable. He said the progress on battery storage was on a parallel path to electric car batteries and it was probably 2-3 years off. He thought the most likely source for the batteries would be Elon Musk’s Tesla’s company in the US. Really, utilities ought to be looking at local storage before they miss the boat and consumers do it themselves.

  • WR

    19kWh per day from a 2.5 kW system doesn’t look realistic. The graph shown above suggests that 8-10kWh would be a better estimate.

    Also, the annual consumption value of 8544.4 kWh might be the current average if you include electrical hot water, but if someone is going for battery storage you would expect them to look to improving energy efficiency first. They should be able to easily reduce that total consumption to something between 4000-5000 kWh.

    • Ronald Bruce Jones

      I have a 3kw system and during summer it will generate 25 +kw per day 12 kw during winter on a bad day. My daily average consumption is about 11 kw, my service provider gives me 8 cents but charges up to 36.883 cents peak power and 14.487 cents controlled load and the service fee just keeps climbing up at an unbelievable rate to compensate for lost revenue from power sales.
      Also I live in a rural area and you only have to get a thunderstorm and your left in the dark for hours.

      • RobS

        sounds like you will be in one of the earliest groups for whom going off grid will make economic sense.

        • Ronald Bruce Jones

          That depends on the price of batteries they are still quite a sizeable investment,  but the price will probably drop within the next few years or if they keep pushing up the cost of being on the grid this could help me make the jump. Ron

          Sent from Samsung tablet

          ——– Original message ——–
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          Date: 30/07/2014 16:15 (GMT+10:00)
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          RobS
          sounds like you will be in one of the earliest groups for whom going off grid will make economic sense. 2:15 a.m., Wednesday July 30

          Reply to RobS

          RobS’s comment is in reply to Ronald Bruce Jones:

          I have a 3kw system and during summer it will generate 25 +kw per day 12 kw during winter on a bad day. My daily … Read more
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          • juxx0r

            Ron, want to remove your email address via the edit function?

          • RobS

            Yeh cut that email address before the web spambots find it

      • WR

        From your description , your panels are probably close to horizontal. You should be aiming to match generation with use. If you are using twice as much electricity on a summer’s day compared to a winter’s day, then the orientation of your panels is okay. However, If you are using a similar amount of electricity year-round, then you should be aiming for similar amounts of generation year-round. This basically comes down to the orientation of the panels, although seasonal variations in cloud cover will also affect generation.
        The 8-10 kWh value I quoted is just the area under the graph in that 2.5 kW diagram. Generally speaking, for mainland Australia, I believe the average AC energy output from the inverter in kWh is between 3.5-5 times the DC kW rating on the panels for north facing panels that have a reasonable inclination from the horizontal. This takes into account cloud cover, rain, and variations in day length. So a 3 kW system will generally average about 12-15 kwH per day for the year. If you live somewhere very dry, you will probably average a bit more that that.

  • Leigh Ryan

    One of the major points being missed here, is this if i buy Tesla Batteries for my Solar Storage, clearly i might very well also be considering using the same battery in my car, i believe the Tesla battery to be dual purpose like this, since i for one will be happy to go off grid i am also happy to opt for a new electric car rather than a fuel guzzler, so i am saving around $5500 pa on fuel as well, right now the Tesla electric car and dual purpose battery is already looking the cheaper option by far.

    • MrMauricio

      The Tesla S itself can act as your storage with up to 85kw battery capacity-it could feed your house at night (at least the hump) then be topped up at off peak hours.Teslas are already being used for this purpose in the car parks at office buildings in the U.S linked to chargers in the basement feeding the building during peaks and being charged at low points in building power use.A home owner with solar could do much the same thing.

      • RobS

        Do you have a reference for Tesla’s already being used for that purpose? I was under the impression Tesla had been quite stubborn in not enabling this sort of technology up until now for unknown reasons.

        • MrMauricio

          Hi Rob,Saw a picture of this in an under office car park somewhere-perhaps in Green Car Reports.will have to search for it-will let you know

          • Pied

            You are all dreaming. The cost of storage wether it is 5kWH or 50kWH currently is not even close to being viable, it is still cheaper to buy expensive peak power. Also the complexity of using Lipo cells rule it out at the moment, of course some good marketing and sales techniques would certainly get some early adopters who want to throw their money away, I can remember 1kW solar systems selling for $20K. Some were still sold.

          • RobS

            Im most certainly not dreaming and you are about 5 yeears behind. Whilst true in the suburban setting storage can not yet be justified on a cost basis just as solar went through a phased lifecycle where its cost effectiveness was initially only in satellites and spacecraft where the cost of each kWh of fuel for a generator or fuel cell was measured in the millions of dollars, then extending to remote installations like communications towers and remote cabins where diesel fuel had to be trucked in and generators had to be bought and maintained until now finally grid parity in the suburbs is or is about to be reached worldwide. Storage is and will continue to go through a similar process, initially only justified to decrease reliance on fuel in remote settings, then in situations where connection to the grid is possible but at a steep cost until finally if trends continue in suburban on grid situations too.

            I have a friend who lives in a semi rural setting on 40 acres, when building his house a few years ago the distance to the nearest power lines was about 3 km, the quote to run power lines to the house? $15,000 per km or $45,000. The cost for a storage system and backup generator to render that connection unnecessary AND allow him to use solar power far cheaper than the 40c/kwh grid rate? $42,000. SO now he quite happy generates his own power, runs his generator about once a month in summer and about twice a week in winter for a few hours each time, has saved himself $3,000 upfront and somewhere on the order of $1,000 per year or so when comparing the cost of grid power he would be paying vs the small amount of biodiesel he uses.

  • RobS

    The article ignores efficiency and shifting time of use. If you want to maximise solar self consumption you are much better off slashing consumption and shifting as much consumption as you can to daytime. Only then should one consider storage because by doing so the simple if the storage bank and therefore it’s cost is minimised.

  • Kevin Brown

    Couldn’t domestic hot water system thermostats be increased from 60C and then be timed for used during midday to store solar PV energy instead of exporting to the grid for free?

    • RobS

      This is just one example of many types of demand shifting which can occur to avoid the need to store power for later use by shifting the demand to match the supply. Other examples are running dishwashers and washing machines during the day on timer functions. Using slow cookers to cook meals during the day. Running heating and cooling systems harder during the day to pre cool or warm the house by using its thermal mass to maintain temperature late into the evening with less energy used. All these type of things significantly reduce the amount of storage needed to supply after hours power needs.

      • patb2009

        i suspect soon enough people will have little DC electric freezers which will make ice, during the day and then provide chilled water for cooling at night.

        • TechinBris

          Just heat ammonia and water. Works a treat.

    • Pied

      Its a bit more complicated than that, what if the water is already hot? So you need something that is predictive of the weather, so if it is overcast you want it to heat from the mains but not if it is sunny. I believe a product will be released soon for this exact application.

      • Kevin Brown

        My proposal to bank solar PV output in domestic hot water
        most advantages electricity consumers on low tariff off-peak water heating arrangements. My five person household has been on off-peak water heating for many years. We have experienced occasional lukewarm showers but never suffered serious inconvenience from a shortage of hot water. My off-peak electricity water heating rate is 16c/kWh. My solar PV export rate is 4c/kwh. It isn’t hard to work out that I would be better off storing my solar PV output in my hot water system. It is likely that super-heating my hot water system to 75C would likely eliminate any need for even off-peak mains water heating.

        If this regime was widely adopted then the midday spike in
        solar PV exports to the grid would be reduced which gentailers claim is causing grid management difficulties and the late afternoon/evening peak load would be reduced by removing water heating from the peak load period.

        • TechinBris

          {start sarcasm} What!? Think about all those poor Energy Corporations. Do you think it is that cheap to bribe a Politician to change the Law so you can make a better profit? Someone has to pay and if you start utilising your energy instead of only being able to export it to Energy Corporations, how will we be able to continue to work such a efficient scam as other Corporations doing. Please spare a thought for the Shareholders! Please {end sarcasm}

  • Nick Loeve

    This is also other energy storage options (ie hydrogen storage: http://www.merlin.unsw.edu.au/) with much better energy density than a battery. These materials are not consumer ready, but are ready for pilot scale storage from renewables. Its impossible to compare on cost of ownership at the moment, but the demand is certainly there! Australian Made!

    • Miles Harding

      Hydrogen has a fundamental problem of efficiency. At best, the hydrogen cycle is about 30% efficient, compared to an all-electric system at about 80% wind to wheel (or toaster) efficiency. Somewhere near 3 times the input energy is needed to run a hydrogen based system over an all electric alternative. This fact alone is sufficient to render the “hydrogen economy” a curiosity, then there are the handling and distribution issues of such an intractable gas.

      BAU oil companies have seized on the hydrogen concept to perpetuate their supply and distribution business models, but the reality is that they are dead unless they get out of that business entirely.

      • Nick Loeve

        I would argue that the availability of renewables sources of electricity, like solar, are enabling more work to be done on the efficiency of electrolysis and there are research and development groups that are already beating that figure.

        Regardless of efficiency, new generation hydrogen storage materials solve most of the safety and distribution issues, and enable energy density on par with fossil fuels. Not only is this good for transport applications, but also energy export.

        As I said, the technology is not a serious contender at the moment, but the idea that hydrogen should be ruled out of the clean energy equation is silly. Expecting hydrogen to obsolete every other energy storage materials completely is also silly. I think people would be very interested in generating their own high density, clean fuels. Especially as solar feed-in tariffs drop and people realise they are all going to need large battery packs to be more independent energy producers.

  • howardpatr

    Down the track smart electrical engineers and IT experts will develop the hardware and software for all PV energy to be used, with minimal fuss, for hot water and our EV. That will see the fossil fuel interests pushing for huge connection to the grid fees but the sporadic spiral is only down for them.

  • MrMauricio

    There is another option in the interim-mass movement of solar system owners to green retailers-sell your power free/cheap to a green retailer who’s business will profit rather than a dirty coal electricity retailer.This will eventually hurt the dirty producer’s business model even more and perhaps enable the green retailers to pay more for your power and move to stored distribution options as progressive businesses.Retailers like Diamond,Powershop and Momentum deserve your excess green electricity-not the big and dirty 3!

  • Zvyozdochka

    If we base any of this around the current standard Australia house design we will fail, wasting huge amounts of money in the process. I agree with GP’s earlier concern efficient use of capital in that regard.

    Moving to extremely efficient, low/zero energy housing should be our first investment nationally. Our obsession with air-conditioners will have to be a casualty.

    • RobS

      Extremely efficient houses can have an air conditioner or heating, they just need a far smaller unit and it has to run far less as rather than recycling the entire air mass of the house several times an hour a well sealed house keeps the conditioned air inside and heat exchange ventilation recovers the warmth or coolness of the air which is cycled for hygiene reasons.. Passive heating and cooling further reduces the workload on any A/C unit.

      • nakedChimp

        Yup, they have this tech in Germany since the 90s for big buildings like hospitals etc.

  • Simon_Strauss

    I wonder if someone cleverer than me could give a detailed explanation of what the two charts above actually mean. I also wonder how many people saw today’s AFR article (http://www.afr.com/Page/Uuid/41f41e60-16b3-11e4-a530-595918d51630) comparing the costs of wind, solar, nuclear and gas and if they agree with the conclusions reached.

  • Ronald Bruce Jones

    Yes remo ve it, I didn’t realise it would be posted

  • Ronald Bruce Jones

    WR
    My panels are mounted at an angle and face north although they didn’t mount them so that they would be parallel, they follow the pitch of the roof the hip has a north/ south orientation which to me is annoying but woudn’t make that much difference to the output as the roof doesn’t have that much slope on it. The reason for 3kw? I wanted the excess to help cut my bill down, the excess cutting out the night time consumption, but the service fee keeps rising and defeats you.

    • patb2009

      cheaper panels may allow you to add panels on the west side.

      • Ronald Bruce Jones

        My panels are positioned on either side of hip the hip runs north/south and the panels are tilted to maximise winter sun

  • The Off Grid Solar House

    Hi everyone, thought I’d add my two cents. Off grid energy storage is expensive but viable. I wrote about this in last week’s Sunday Age (http://www.theage.com.au/comment/living-off-the-power-grid-gives-me-a-buzz-20140725-zwnyw.html) and have a blog on the subject at http://www.theoffgridsolarhouse.com

  • John Silvester

    To get the most out of a pv system requires a holistic approach.

    Reducing demand should be highest priority. Break down demand into energy services, space heating/cooling, hot water, refrigeration, lighting, entertainment, cooking and cleaning.

    As space heating/cooling for many households is a large energy user so would be a good place to start.
    Passive technology is best. Things like insulate and draft proof building envelope, have some thermal mass within the building envelope, exclude direct sunlight in summer and allow during winter. They don’t consume energy, don’t wear out, require little or no maintenance. This can greatly reduce the need for active heating/cooling, allowing the installation of a smaller heating/cooling system, reducing up front cost.

    Work through the list of energy services and use cost effective energy efficient appliances to further reduce your demand.

    Move as much demand as possible to daylight hours.

    This greatly decreases the size of the pv system required to meet daily demand. Also reducing the size of any energy storage needed to match night time demand with day time generation.

    Staying connected to the grid greatly reduces size of the energy storage required. The daily charge imposed by utilities could be thought of as fee for backup for when demand exceeds the systems ability to supply.

    As utilities increase fixed charges, are unwilling to pay a fair price for exported generation and storage cost declines, larger storage systems become cost competitive. At some point grid defection will become cost competitive.

    As energy storage is still too expensive, cost effective efficiency measures are probably better investments right now.

    • RobS

      The number of efficiency measures which beat solar on a return on investment basis is dwindling as solar costs plummet. There are some big ones like swapping halogen downlights for LEDs, but many of the more expensive options don’t match the ROI of solar, in which case simply going with a larger solar system is more sensible.

      One example is adding extra insulation. Say your’e considering adding underfloor insulation and you have a quote of $2,800 to lay it, the insulation is going to save 5kwh a day of A/C demand. To generate 5kwh a day with solar requires about 1.5kW of solar capacity, this used to cost ~$10,000 which is why the mantra of “efficiency at all costs then size the solar” arose. Now those same 1.5kW can be installed for ~$2,000 and generate those 5kwh a day for 25 years+ suddenly it turns out that it is actually more expensive to try and save that power with added insulation than it is to generate the power with a larger solar array.

      Obviously if you are talking about off grid situations then higher consumption means you also have to have a larger storage capacity and the cost of storage needs to be taken into account, this significantly increases the number of efficiency measures which are cost effective.

      The moral of the story is avoid blind “efficiency at any cost” approaches and actually look at the comparative cost of each efficiency measure per kWh saved vs the cost per kWh produced with a solar array.

      • John Silvester

        Thanks Rob, you are absolutely correct, efficiency at any cost is not what I am advicating.

        What I am saying is a majority of peoples homes will have a wide range of cost effective efficiency measures across all energy services that can be implemented. I mentioned passive approaches because they can lead to meaningful reductions in the amount of energy required to maintain a comfortable living environment. They are often overlooked because they are so long lasting that their savings will last for the remaining life of the building, but the payback period is longer than many would care to consider.

        We are talking here about the desire to add energy storage to PV systems to maximize self consumption of PV generation because utilities are not prepared to pay fair compensation for exported generation. So the cost of storage should be included in any calculations.

        Using your example, a saving of 5kwh a day of A/C demand with insulation costing $2,800 with an operating life of the remaining life of the building V additional generation cost $2,000 with operating life of 25 years.

        Let’s assume it were possible to install energy storage at a marginal cost of $400 kWh with an operating life of 10 years. If we assume we maximize the direct consumption of the AC by running it in the afternoon to minimize A/C load after the sun has gone down. A proportion of that additional A/C load would be consumed after dark. If 2kWh of the 5kWh are consumed after dark, 2kWh of that additional generation will need to be stored. After 10 years you find your replacement battery costs half as much and lasts 50% longer, $200/kWh lasting 15 years.

        In that same 25 years you will probably have to replace the A/C twice. Had the insulation option been taken with the reduced load, a smaller replacement A/C system would be required. So we have a lost benefit of let’s say $100 on the replacement on the A/C because of the need for a larger system, per replacement.

        Over 25 years.

        $2,800 Insulation
        V
        $2,000 Extra PV
        $1,200 additional storage 2x2kWh @ $400/kWh + 2x2kWh @ $200/kWh
        $200 lost benefit on A/C upgrades 2x$100
        ——
        $3,400 total
        ——

        Given that all these numbers are ment to be illistrative rather than predictive it would suggest that over 25 years there may be little difference in cost between the two options, over the life of the building saving from insulation will continue long after those extra few panels have been replaced.

        That 5kWh per day saved with insulation will continue for the remaining life of the building. The additional accumulated marginal cost of needing to run larger generating and A/C equipment, will continue to accrue for the life of the building. Which will in all likelihood see a number of generation and A/C upgrades/replacments over the life of the building.

        It is impossible to know what generation and HVAC systems will be available in 25 30 50 years, but it is likely that bigger systems will still be more expensive than smaller ones.

        To compare apples with apples the full life savings need to be accounted for even if those savings accrue over an inconveniently long and possibility uncertain length of time.

        Genuine long term savings are being over looked because some short term savings are cheaper. And while 25 years might be not sound short term, compared to savings that continue for 2, 3 or more times longer, it is.

        • Motorshack

          John, I agree with your longer-term analysis, and, in fact, had a similar long conversation with Rob many months ago.

          In addition, what I note about choices like insulation versus more panels is that insulation is both passive and technically simpler in other ways. So, it is more likely to work long term without expensive failures, or indeed any active management at all.

          I’m a retired software designer, and you might think I would have a taste for fancy, high-tech solutions, but, in fact, my experience leaves me painfully suspicious of complex technology. It never works as well as the designers might hope, and that is triply so when the system must be managed by amateurs with little or no technical background.

          The key design principle here should be K.I.S.S. – namely, keep it simple, stupid.

          In my own case, I live alone, and I don’t have to argue with anyone else about lifestyle, so my approach is the simplest of all – very small total floorspace.

          My office/apartment has a total of a bit under 400 square feet, but in the winter I only heat one 9′ x 12′ room. The rest can be heated if necessary, but normally is not.

          So, my total energy costs come to about a dollar a day on average, with no loss of comfort or functionality at all.

          Also, as a retiree I don’t have to commute to work anymore, so I ditched the car years ago. Thus, my electricity cost is also my entire energy cost.

          I realize that not everyone is in a position to be as aggressive as I have been, but there are other approaches that get similar efficiencies.

          For example, my landlord lives in a nice, large, suburban house in an upscale neighborhood, but he and his wife share the house with a daughter, son-in-law, and three grandchildren, so the per capita floor space and operating costs are in the same range as what I manage. His recently widowed mother-in-law may soon join them, as well.

          The point here is that the fundamental inefficiency these days is grossly excessive floorspace per capita. So, if you get a few more people into the house, the overall efficiency will double or triple, with no capital investment at all.

          As I say, keep it simple.

          • CrankyFranky

            good motoring – even simpler and more economical if you like – is to live in a medium-density unit complex – with concrete and brick floors and ceiling, neighbours two sides, above and below (insignificant thermal difference/loss), and only exposed walls/windows north and south for cross-ventilation, we have excellent thermal mass/heat storage/balancing, our heating/air-con bills are minimal, in fact the main problem for us in summer or winter is walking out in the wrong clothes when we were perfectly comfortable inside – only after we step out we find the temperature outside is uncomfortable.

            Your landlord’s higher bills may thus also have something to do with four exposed external walls and roof space and large temperature gradients between inside and outside leading to significant heat loss/gain, a problem we simply don’t have in our unit.

            I know – we used to live in a brick-veneer free-standing house in Canberra – in winter we had two powerful gas furnace radiators going full blast to stay comfortable in living and/or bedrooms – and we still froze/dreaded going to the unheated toilet – ooh !

  • John Silvester

    To get the most out of a pv system requires a holistic approach.

    Reducing demand should be highest priority. Break down demand into energy services, space heating/cooling, hot water, refrigeration, lighting, entertainment, cooking and cleaning.

    As space heating/cooling for many households is a large energy user so would be a good place to start.
    Passive technology is best. Things like insulate and draft proof building envelope, have some thermal mass within the building envelope, exclude direct sunlight in summer and allow during winter. They don’t consume energy, don’t wear out, require little or no maintenance. This can greatly reduce the need for active heating/cooling, allowing the installation of a smaller heating/cooling system, reducing up front cost.

    Work through the list of energy services and use cost effective energy efficient appliances to further reduce your demand.

    Move as much demand as possible to daylight hours.

    This greatly decreases the size of the pv system required to meet daily demand. Also reducing the size of any energy storage needed to match night time demand with day time generation.

    Staying connected to the grid greatly reduces size of the energy storage required. The daily charge imposed by utilities could be thought of as fee for backup for when demand exceeds the systems ability to supply.

    As utilities increase fixed charges, are unwilling to pay a fair price for exported generation and storage cost declines, larger storage systems become cost competitive. At some point grid defection will become cost competitive.

    As energy storage is still too expensive, cost effective efficiency measures are probably better investments right now.

  • Wombat

    Hi, Can you please provide the analysis for the 35KW storage requirement? My back-of-the-neuron calculations make it more like 12KW, assuming 3 days’ storage.
    Cheers.

  • CrankyFranky

    ‘bit of a headache’ – I should have taken that as a warning – for how I’d feel after reading your description – that you didn’t really understand it either …

    if you can’t explain a graph in simple terms for average readers, it’s probably not useful to include it (BTW I’m up on all these terms – it’s just your explanation I didn’t understand) !

  • Alistair

    Why can’t we just have a 1:1 FiT? I don’t see how this isn’t the ideal solution for both households and electricity providers?

  • TechinBris

    When it comes to storage of energy, we can save energy as heat far more efficiently as heat than Electricity. Micro CHP/ORC isn’t there yet to help in this. As such, Battery is the go. The trouble is that we are still locking into a world of consumption which is killing us and the most efficient batteries are going to require replacement every few years. $$$$$$$$$$$$$$$$$$$
    Whilst only 75% efficient, the old fashioned Nickel-Iron (NIFE) Batteries last a lifetime (if you keep the simple maintenance up). Yeah, the tech is as old as electricity generation is, but Tesla’s original batteries are still working today over 100 years later. So do we generate 25% more than we require in order to go around the inefficiencies of the Battery, but without the cost of a 5 years cycle of battery replacement? No hydrogen issue either. Worth thinking about.
    Here in QLD, “Can Do Ripoffs” has made it so non-worthwhile to do grid connect we have held off, at least till I can find a Grid Gonnect System tha allows to save my power, for my use, and use Grid as a backup. It is just not worth exporting that energy to keep a Greedy Corporation, who just bribes my Representatives (why do we vote for these Jerks) with the money that is raised by my giving them my excess energy to them to onsell at grossly inflated prices to pay for that bribe, which then gives them the permission to screw me blind. Sorry, I am not going to pay for THAT privilege!
    Grid Connect just is becoming a dead horse under the Energy Retailer’s current extortionate behaviour. The Grid is only cost effective as a backup under their current model of doing business for an ordinary solar panelled house in the burbs, unless to like to pay for the privilege of them doing you over with their feed-in Tarrifs they are offering.
    When I make my exit from using a Company that has screwed me ruthlessly, it is extremly rare I ever return to experience their “joy” again.