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Storing Power

Discussion in 'Renewable Energy' started by Matt L, May 17, 2012.

  1. Matt L

    Matt L New Member

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    In Australia, probably as in many countries, our power is charged at different rates depending on the time of day (peak, shoulder, off peak).

    The peak rate is substantially higher than shoulder and off peak, and the peak rate runs 6 hours per day.

    I have a 1.5Kw solar system, that due to government incentives pays me a higher rate than even the peak cost, yet I still have to pay the balance each quarter.

    My question is simply this: Why cant I draw power down from the grid during off peak times, store it in batteries and then use it during peak times?

    I am not overly familiar with electrical theory etc, but I assume I would need to convert 240VAC to DC (12 or 24V?) to be able to store it. My problem is how do I work out how much I need to store to get me through the peak time of 6 hours? I do know that I use @ 5Kwh each day during the peak. Is this enough information to work out how much, or do I need more detail?

    Matt
     
  2. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    You can, but it's probably not cost effective - the costs would be pretty high, for relatively little gain.

    Far better to put the money towards more solar panels and increase your payments from that.
     
  3. magnatro

    magnatro New Member

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    considering the initial costs , the maintenance costs of the batteries and the losses due to batteries, nah, it wont work (unless you have super current eating monsters in home.. nah.. still wont work..lol)
     
  4. dave

    Dave New Member

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  5. Jules_Theone

    Jules_Theone Member

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    I had the same idea - store energy from the solar panels that would otherwise feed onto the grid and then use that energy later at night etc. I had a couple of ideas to achieve that -

    1. Ensure everything on mains will operate OK on DC. Put a diode in series with live and put the 20 or so lead acid batteries in series and loads after that. When the batteries are fully charged, the house runs only on batteries, when they are flat they will charge from mains (assuming the solar array is supplying). At night if the batteries are flat AND there's no solar, everything can run on mains through the diode with the batteries disconnected.

    2. High current battery charger connected to mains charges a 10kWh battery bank during daytime, 500w GTI powered from the batteries runs during the night to make sure the small loads never use paid electricity. Problem is that it's the fridge / freezer which is on at night and that uses high power for short periods of time.

    Jules
     
  6. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    It's still a silly idea :D

    Simply sell the excess power to the electricity company, and then buy some back when you need it - essentially using THEM to store your excess power, and making money as well.

    Nothing to buy, nothing to maintain, and nothing to take up space.

    If you're completely grid free, then that's a different matter, it's essential to store power, regardless of the extra costs and limitations.
     
  7. stevez

    stevez Active Member

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    Matt - this may or may not apply to your situation but you can store power in other ways. You can make ice off peak then use it for cooling later - they do it in some commercial buildings but it's probably too complicated for residential use. You can heat up a mass of some sort - rocks, earth, water, etc off peak then use the heat on peak. I offer this just in case there is a way to employ this strategy in a cost effective manner. Pumping water from a well up to an elevated storage tank off peak - then letting gravity be the on-peak pump is another one.
     
  8. RichTheDude

    RichTheDude Active Member

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