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Thread: Excess power production - what to do with?

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    Default Excess power production - what to do with?

    Quote Originally Posted by admin View Post
    I havent been keeping much of a record, but can tell you what has been officially generated via my supplier, United Energy's "Energy easy" portal.

    488 Aug 14
    671 Sep 14
    806 Oct 14
    990 Nov 14
    926 Dec 14
    908 Jan 15
    692 Feb 15
    791 Mar 15
    518 Apr 15
    361 May 15
    297 Jun 15
    322 Jul 15
    355 Aug 15

    8125
    Not particularly relevant to my location but still gives the basis for my question.

    Given our consumption, the above figures, and an assumed 3.5kW panel system we will have a deficit in power production for 5 months of the year.

    If I install a sufficient number of panels to cover those 5 months there will be a massive over production during the other 7 months.

    I cannot see the logic in simply "giving" the excess to the power company so what are my alternatives if any?

    My ultimate goal is to go completely off-grid.
    If Australia is a democracy why, then, is voting compulsory?

    "What has changed between the arrival of the First Fleet and today?"
    "Wearing leg irons is now not required."



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    Buy a Tesla Powerwall ?

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    The idea was that whatever you produced was balanced against what you used and 'In the Beginning' you got paid more than what they charged for doing so.
    As you will NEVER be able to accurately forecast how much you will generate because of the vagaries of the Weather so one season you could have surplus but a year later it could be marginal, but myself I would prefer to be 'In the Black' so the extra panels would be worth considering.
    It wouldnt hurt to check with your provider (and others) and ask if they give 'Credits' if you should generate more power than you use and that its taken off your account during those periods when its not in surplus.

    I think each State has a different way of dealing with Solar Power so you need to have all the details before making any choices.
    Last edited by gordon_s1942; 19-04-16 at 02:37 PM.
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    If you are really keen, buy an older electric/hybrid car (like a Camry or whatever crap we have thats now obsolete) and use it as a powerbank.

    Someone on Whirlpool actually did it a while ago Parked it next to house and connected it.

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    Do the maths
    It might not be worth trying to keep all the power.
    Is your goal ideological or economic ?

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    Quote Originally Posted by admin View Post
    Buy a Tesla Powerwall ?
    I propose to have some battery capacity to cover the hours that the panels are not producing.

    Quote Originally Posted by Dishtrackted View Post
    Do the maths
    It might not be worth trying to keep all the power.
    Is your goal ideological or economic ?
    Ideological in as much as I would like to say goodbye to the power company.

    Economic in as much as spending the money on extra panels to provide the 5 months power and then having them sitting there during summer effectively doing nothing.
    If Australia is a democracy why, then, is voting compulsory?

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    Install enough panels so that you generate enough in credits to give you a zero bill ?

    Realistically, I would say its your best option.

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    Cheers, Tiny
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    The information is out there; you just have to let it in."

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    Quote Originally Posted by admin View Post
    Buy a Tesla Powerwall ?
    You are kidding, right?

    I asked Origin and they say they will be delivering the power wall for (hold your breath) AU$8000 in May.
    I found sites in the USA that had offerings about US$3000-3500. Preeeeetty sure our customs will have a big say when you try to import them here to AU.

    AGM or any other Lead acid batteries are out of the question, calculated many times and at the current electricity prices will never reach ROI before they die.

    Unless you are pensioner or stay at home parent solar is only useful for businesses with constant power demand which is also near impossible in a normal home.
    So unless you have a plugin electric car, 3.5kW of panels is useless and you are giving away your energy most of the time to your neighbourhood while the Energy retailer charges them full price.

    That all said I will be attempting to make my own experiments with a mini self built Powerwall using these batteries:
    Their price goes down the more you buy.
    That is about 12W/h for about $4. So $2300 gives you as much storage as the Tesla Powerwall and I am thinking AU$ for such a bulk order.
    Life expectancy should be 3 x that of AGM so ROI should be possible.
    Big soldering job but plenty of Youtube videos to show you how.
    Last edited by Uncle Fester; 19-04-16 at 07:45 PM.
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    Quote Originally Posted by nomeat View Post
    That all said I will be attempting to make my own experiments with a mini self built Powerwall using these batteries:
    Their price goes down the more you buy.
    That is about 12W/h for about $4. So $2300 gives you as much storage as the Tesla Powerwall and I am thinking AU$ for such a bulk order.
    Life expectancy should be 3 x that of AGM so ROI should be possible.
    Big soldering job but plenty of Youtube videos to show you how.
    Looked at some of the videos but:

    (a) not in the mood to go through all the hassle of connecting the cells
    (b) not in the mood to go through all the hassle of trying to manage charge/discharge cycles i.e keep the cell voltages equal
    (c) not in the mood to clean up the mess if just one cell decides to go pop.

    If Australia is a democracy why, then, is voting compulsory?

    "What has changed between the arrival of the First Fleet and today?"
    "Wearing leg irons is now not required."

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    Like an idiot I forgot in my previous post about over generating that unless you have a Battery Pack or sit in the dark and use no power over night, there is no way you can ever generate more than you can use unless you have Solar Farm and if you have that many, then you can go 'Off Grid' completely.

    As I only use between $1200 and $1500 a year of electricity, I have a hard time justifying the cost of the Solar panels and now that 'Powerwall' at a reputed cost of $8000 just doesnt add up for me.
    Then at some time in the future, this will all need to be replaced particularly the batteries and their contents disposed of safely and who know what that may cost to be done?
    I stand unequivicably behind everything I say , I just dont ever remember saying it !!

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    Quote Originally Posted by gordon_s1942 View Post
    I forgot in my previous post about over generating that unless you have a Battery Pack or sit in the dark and use no power over night, there is no way you can ever generate more than you can use
    Even with my hypothetical 3.5kW system with battery back-up during 7 months of the year the system will produce enough power to run everything overnight - from the battery bank - then next day produce enough to run everything plus recharge the battery bank and then some.

    Hence the question in my OP, What to do with the excess power generated after the battery bank is fully charged?

    Even without a battery bank you can easily produce more than you can use. I'm sure admin will confirm this.
    Last edited by Guiseppe; 20-04-16 at 06:03 PM. Reason: typsos
    If Australia is a democracy why, then, is voting compulsory?

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    Quote Originally Posted by Guiseppe View Post

    Even without a battery bank you can easily produce more than you can use. I'm sure admin will confirm this.
    This will always be the problem with net metering. You will never use exactly what you are generating at that moment and most of the time you will be giving it away to the power retailer when the sun shines. So if you are intending to use batteries then just install more batteries to be sure nothing gets wasted, even when off-grid. More batteries means less DOD per cycle and significantly longer life, no matter what chemistry.

    ... or if you have too much left over in summer get an (extra) airconditioner.
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    Quote Originally Posted by Guiseppe View Post
    Hence the question in my OP, What to do with the excess power generated after the battery bank is fully charged?
    There really is only 3 choices.

    1: Store the power in more battery banks or as extra hot water.

    2: Use the power. Use it for cooling, heating, hot water generation. Build a huge flashing light display at the front of your house that reads; "I've got the power & I wont give it away!"

    3: Lose the power. If grid connected - give it away to the power co.
    If stand alone system, regulate it. (when the batteries are full, the regulator shuts off the incoming power generated; usually by Pulse Width Modulation or by shunting to a dump load).
    Cheers, Tiny
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    As Tiny says, 25 years ago when we did Solar on remote properties, any extra power was shunted into a HWS element.
    So that means the Batteries were full, and there was no where for the excess to go..... So into Hot Water Storage it went.

    It's called "Diversion Loads".... Storage Heat Banks or Hot Water Service or Batteries
    I see some people are shunting 40-50% of their daily usage into Diversion Loads nowadays
    BTW, the elements are DC, so there is no Inverter load and loss, its just straight ecxess DC energy as directed by the controller.

    It will be a shame when the Buy Back stops, so many Holiday Homes here have Solar and they currently Off-Set the owners main home power usage by a huge amount
    (Generally covering the Holiday Home completely and paying for 50% of the Main Homes power bill)

    When these introductory buy back rates stop, there will be a lot of wasted potential for these people.
    Unless..... Energy Retailers allow grouping of Homes owned or Rented under the same name.
    (I wonder if that will ever happen?)

    EDIT: If you have any Batteries on charge or constant float charge, configure them to only operate on your excess power
    Might not be much of a saving, but every little bit helps.

    Maybe you could buy one of those Zip Boil under bench Hot Water units and divert the extra power to it?
    Then do away with the kettle

    Your last statement says you want to go completely off-grid, so that means one thing.... Batteries!
    It shouldn't be long before "PowerWall" copies are pouring out of China from 1000's of competing manufacturers.
    It is going to be hell for local regulators, just wait for the first house fire where the Power Supply can't be isolated easily.
    Although, currently the Chinese can't keep up with Tesla's orders, let alone have excess stock to sell on the open market.
    Last edited by ol' boy; 21-04-16 at 12:49 PM.
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    Re; Diversion loads
    My mate who is off grid solar does a load of washing clothes/ dishwasher at night with lots of lights on as required.
    Sometimes even clothes dryers are involved.
    Everything has to be planned.
    Its all a mathematical planning manoeuvre o He has solar hot water too so no relief there.

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    I've often wondered, in the case of Excess Solar Generation.....
    And with out going to the extremes of a "Power Wall" type arrangement for the whole house.
    If just setting up say the Fridge to run from its own Battery and Inverter as a stand alone product would be viable?

    Cost of Inverter, cost of Battery, Cost of Charger, loses in the conversion
    It probably isn't cost effective, but it would give you a Fridge that operated even when the Grid went down
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

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    Thats a major plus.
    I went away for a few months last year and came home to a rotting chest freezer when the power went off and tripped the safety switch.

    In a SHTF scenario you can go to bed when the sun goes down but it would be nice to have stuff in the freezer so you didnt have to go hunter gatherer every day.

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    Quote Originally Posted by oceanboy View Post
    It shouldn't be long before "PowerWall" copies are pouring out of China from 1000's of competing manufacturers.
    Yes that will be fun. Your average Chinese 18650 cell has 300mA/h capacity (very lucky if you get 500mA/h and that would be the capacity of an AA NiCad from the 1970's)
    I really ordered a few from different sources for shits&giggles and tested them myself, not getting these claims from the net.

    So a Chinese copy of a Tesla power wall would give you at least enough to watch a Plasma telly for 90 minutes until it's DOD has reached 100% , providing you don't have a fridge or use any lights

    Ther are at least two other US companies and one German one who are working on a competitive alternative to Tesla's Powerwall so that could eventually help drop prices but here we will always have a hefty 'Australia tax'.
    Last edited by Uncle Fester; 22-04-16 at 12:59 PM.
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    Quote Originally Posted by oceanboy View Post
    If just setting up say the Fridge to run from its own Battery and Inverter as a stand alone product would be viable?

    Cost of Inverter, cost of Battery, Cost of Charger, loses in the conversion
    It probably isn't cost effective, but it would give you a Fridge that operated even when the Grid went down
    Running a family sized fridge the whole day would require about 2kW/h per day from the bat. incl. losses.
    So for decent battery life you need at least 6kW/h battery, almost a powerwall just for that which also has it's own panels that can charge the battery and run the fridge at the same time.
    The cost of this REALLY isn't effective, but a much smaller(where you don't have to worry about DOD) backup system for power failures that would require automated switching would work and is in the back of my mind for my mini powerwall system, including powering my router/voice modem directly from the 12V.
    You don't know how fidgety I can get when I don't have internet when we have several hours of power failure and I have to pay 5c/MB from tethering my phone and then having to eat sloppy ice cream doesn't comfort me either
    Last edited by Uncle Fester; 22-04-16 at 01:34 PM.
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