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Thread: Storing off peak power

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    Default Storing off peak power

    Just wondering of the feasibility of storing off peak power?

    My power is by smart meter and is billed like this


    Weekdays


    Weekends




    I'm wondering if it's economical to charge batteries off peak and use a timer to switch to inverter power at shoulder and peak times?

    I guess I would need about 60A at 240V peak, by the time the stove etc is added up. So some kick ass inverters would be needed as well as batteries.... Also a smooth power switch over.. I guess some cheap UPS's would smooth out the changeover so PC's don't reboot & clocks loose time.

    I though a bit about solar, but I just don't think the technology is quiet there yet

    Thoughts?
    Anyone seen similar or have one.

    I'm thinking it would pay for it's self over time because off peak is only 8c compared to 36c for peak
    Reality is an invention of my imagination.
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    Solar will be quite a bit cheaper than the batteries you'll need to make this viable.

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    I use a fair bit of power. About $700 a quarter / $3k a year

    I want power when I want it... Not just when the sun is shining.
    I'm hearing you about the batteries though. You would think in the 21st century we would have had a cheap solution
    As for solar panels, I think solar will become viable when output rises x5 and cost drops x5.
    That's promised with printable cells, but there not here yet.
    Reality is an invention of my imagination.
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    Good thinking.

    Every remote station in he outback has batteries and inverter UPS with diesel and /or solar as the battery charger. Mate runs a shearing shed and workshop with a couple of welders off his.



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    Last edited by Farmsky; 25-08-10 at 09:35 PM.

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    What's a ball park guestimate for 'not cheap' ? (I couldn't see a price on the web site you linked to, just 'contact us')
    Reality is an invention of my imagination.
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    $300 to $500 /kw
    go solar 60c kw feed in
    with a battery bank charge at night at 8c pump back at 60c

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    I have numbers like $20k in my head for my mates system out Woomera way using existing diesel alternators.

    Probably a little larger than you need, its fully programmable to kick in and out, on time, load, etc, etc.

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    Hi Fernbay ,

    This is subject I have researched and have quite a bit of experience with so will give you some accurate answers.

    Firstly to Mickc's comments , no energy provider in Australia allows grid feeding via storage batteries , mainly because people would be charging them off peak for 14.9 cents and selling the power back on peak at 60cents.
    Having said that there is nothing stopping you from charging batteries off peak and using it during peak to supply your loads , well nothing except quite a bit of money to set something like this up.

    A generator seems like a logical solution , but not very practical in a residential area , the noise and pollution will attract some unwanted attention not to mention the cost of generation / generator plus fuel there won't be much of a saving.

    Now to look at charging batteries and using an inverter , , to do what you want to be able to do will require a special type of inverter , nothing like a UPS that will explode if you want to boil the kettle or switch on the Air Con.

    There is basically only one inverter on the market that will do everything automatically and capable of supplying all type of inductive and resistive loads , the unit is made by SMA Germany and is an SBU5000 , it will supply 5000W continuous and even up to 8400W for 30 mins. and even larger transient start up currents needed to start Air Cons etc.
    It's uses a 48V Battery bank of whatever size you choose depending on how much reserve you want , keeping in mind the battery bank needs to be at least twice the size you require to prevent taking the batteries below 50% charge.
    The Inverter + Automatic switch box controller ( cannot be used without each other ) is around $12,500 .
    Lets assume you wanted to be able to draw 4000W for 6 hours , or 2000W for 12 hours , = 24Kwh .
    The current from the batteries will be between 80 and 120amp , transients up to 200amps @ 48v

    4 car batteries suitable for a V8 would last about 14 minutes , 4 big tractor batteries could give you up to 38 minutes , the discharging gas and heat would be a concern during this cycle , actually regardless of the size of the battery bank if you wanted to use Lead acid batteries they would need to be a long way from the inverter , due to the explosive , corrosive and poisonous gasses.
    So in reality you would need Pure Gel or AGM batteries so you don't need to be concerned with the above.
    At very least for 24Kwh you would need about 720AH Storage at 48 Volts , so if using readily available 240AH 12v batteries in series and parallel you would need 12 of them and they are big and heavy! 72KG's each , costing between $800 and $1300 each battery.
    so allow at least another 10K. , cabling etc will set you back another 2K at least so not far from your 20K guesstimate .

    There will be a lot more advantages than you think , The SBU5000 is a full blown home substation ! It is totally automatic and most importantly is Australian approved to be connected to the Grid , meaning it can charge the batteries from the grid off peak and disconnect from the grid during peak and become it's own power station , It will also detect blackouts and take control within 20ms (max) , It has a generator input that can be totally controlled to switch a generator on or off depending on the charge state of the batteries or call it online if your loads are greater than it can produce.
    It is also the only unit in the world that can control an SMA PV inverter so that you can use your solar power during a blackout allowing it to charge the batteries or supply house loads , but when the gird is online it will feed into the grid selling back excess the batteries or loads don't need.

    A lot of people think a home PV system is a back system when the power fails but unfortunately this is not the case , PV systems switch off when the power goes off.
    Another very common misconception is that you can use a PV inverter like a normal inverter to supply loads ,, I can explain in more detail if people want to know why it's not possible.

    Anyway Fernbay , I have the above system integrated with a 4.2Kw PV system so we can basically switch off from the grid but we don't because we make more power than we use so all the excess is sold back.
    During the last major storm when our area was without power for 4 days we went on as normal , the only house in the suburb with power and no need to watch what we were using.

    Like your thinking

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    Wow Joey, you have done your homework.............
    You can learn alot using Google, and the search button.....

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    Quote Originally Posted by Fernbay View Post
    Just wondering of the feasibility of storing off peak power?
    Been done since the dark ages...

    Electrics Hot water services / Slab Heating / Heat Banks etc etc

    I just reconnected some slab heating a month ago, 90Kw of floor heater, all running with no thermostat, just on flat chat... Meter is spinning like a top.
    Ironically its a holiday home and no one is there most of the time.

    Do the Maths, its no cheap to store electricity.
    Last edited by oceanboy; 26-08-10 at 02:35 PM.

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    In an Australian first, the rural town of Scone will have batteries fitted to up to 20 homes, creating its own "micro-grid".

    Fridge-size 5kW zinc-bromine batteries will be installed outside houses to store energy as part of a three-year trial that would not only power neighbourhoods during blackouts but also allow relief from soaring power prices.

    As part of the experiment, up to 40 households in the Newcastle suburb of Elermore Vale will use the batteries to store power from the grid in cheap times and then use the battery storage to run the house during peak times.

    "We're testing whether energy storage technology can make the electricity supply more reliable and give customers greater control over their household energy use," Ausgrid energy efficiency expert Paul Myors said.


    "We will create a micro-grid in Scone, making part of the area self-sufficient during outage trials and any unplanned interruptions caused by storms or other events."

    Cattle farmer Charles Cooke, among the first householders to be fitted with the technology, said the batteries would be useful in storms when the power goes out.

    "I see this as an insurance if you like, we all need that," Mr Cooke said.

    "I have been a great one for grabbing on to new technology. I can go back to the days of the old home generators when houses were wired to a 32-volt battery. Wind turbines charged a battery system that ran the house."

    Mr Myors said reducing the demand for power during peak could prevent the need to build costly infrastructure and would make the electricity network more efficient.

    Contracts were signed last night allowing Ausgrid (formerly Energy Australia) to roll out the mini-power stations to 60 homes, including 40 in Elermore Vale. The trial, funded as part of the $100 million Smart Grid Smart City project, hopes to transform the way energy is used.

    Reality is an invention of my imagination.
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    Fridge-size 5kW zinc-bromine batteries will be installed outside houses to store energy as part of a three-year trial that would not only power neighbourhoods during blackouts but also allow relief from soaring power prices.
    interesting battery -

    The zinc-bromine flow battery is a type of hybrid flow battery. A solution of zinc bromide is stored in two tanks. When the battery is charged or discharged the solutions (electrolytes) are pumped through a reactor stack and back into the tanks. One tank is used to store the electrolyte for the positive electrode reactions and the other for the negative.

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