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Using generated power rather than selling it...

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  1. #1
    Weekend Warrior
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    Default Using generated power rather than selling it...

    Hi All,

    My mum has recently moved into a new build house in Northern NSW with an 1.8KW solar system using a Samil Power SR2K8TLA1 "Solar River" inverter. It's grid connected and gets a massive 8c/kw rebate, which is really only averaging $8-10 off each bill. I was wondering, it is possible (feasible) to use the solar to power the 1000w pool pump rather than sending it out to the grid? Seems like the savings you'd gain would be more than the income it generates.

    I'm not sure if this would require battery storage, or just some sort of load balancing device so it can take some from the mains and some from the solar? The inverter is right next to the switchboard, and the pool pump is on its own circuit.

    Dave

  2. #2
    Senior Stinkologist Sir Stinkalot's Avatar
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    You can get pool pumps that run directly off solar panels - but you would need to weigh up the cost of the new pump. Perhaps its easiest to have your pump run on a timer which matches the peak output of your solar system (ie 12pm or 1pm depending on orientation). That way your pool pump will be using what is being generated before it gets sent to the grid.
    Licence to drill!

  3. #3
    4K Club Member Marc's Avatar
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    How about having a timer and using the pump between 11pm and 6am hooked on off peak.
    Cost you 6c.
    Whenever you find yourself on the side of the majority, it is time to pause and reflect
    Mark Twain

  4. #4
    Resigned SilentButDeadly's Avatar
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    Have your mum talk to the lads from Solar Power | Solar Lighting | Solar PumpingĀ@| Rainbow Power Company as they are local to the area and well experienced

    I'd be inclined to think that unless your mum is the tiniest of power users then there won't be much to export regardless
    Joined RF in 2006...Resigned in 2020.

  5. #5
    Weekend Warrior
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    My understanding was (from the electrician that installed it) that everything produced by the solar is sent to the grid at 8c/kwh, not consumed locally first with the remainder exported? Is that not correct?

    As for running it off-peak, local council laws forbid any mechanical noise from 10pm-7am - as we found out the first week the pool was installed and the neighbours complained (rightly so, it's pretty close to the fence line, even if it is in an insulated shed). Luckily the council were understanding that during the first week it needed to be run 24/7.

  6. #6
    Community Moderator phild01's Avatar
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    Quote Originally Posted by Sir Stinkalot View Post
    Perhaps its easiest to have your pump run on a timer which matches the peak output of your solar system (ie 12pm or 1pm depending on orientation). That way your pool pump will be using what is being generated before it gets sent to the grid.
    +1

  7. #7
    1K Club Member UseByDate's Avatar
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    Quote Originally Posted by Boeing777 View Post
    My understanding was (from the electrician that installed it) that everything produced by the solar is sent to the grid at 8c/kwh, not consumed locally first with the remainder exported? Is that not correct?
    .
    In South Australia (and probably in Queensland) only instantaneous excess power is sold to the grid. As others have said. If you install a timer so that the pump is running when the solar system is generating power, then it will be used by the pump, more generally the house, first. Any power generated by the solar system in excess of the house load will be sold to the grid. Selling all solar power generated to the grid at 8c per kWh would make the system uneconomic.

  8. #8
    Weekend Warrior
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    The pump runs 6 hours/day in winter and 8 hours/day in summer starting from 9am so it would seem there's not much else I can do to help, thanks for the clarification.

  9. #9
    Senior Stinkologist Sir Stinkalot's Avatar
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    Quote Originally Posted by Boeing777 View Post
    The pump runs 6 hours/day in winter and 8 hours/day in summer starting from 9am so it would seem there's not much else I can do to help, thanks for the clarification.
    If that is the case then in general terms the pool pump will be consuming as much of your generated power as it can when operating and then the excess is then being sold off to the grid. If there is excess being sold off then the next step is to move your other power requirements to when you are generating your own power. This can be as simple as using delayed start on the dishwasher or washing machine to operate during your peak solar generation period. You mention your credit on the bill is around $10 or so ..... it would be more interesting to see how much you are saving by not having to purchase the additional power that you are generating.

    If you need to buy power from the grid more than you sell it back to the grid (which is often the case) it makes sense to try and use as much of your own generated power as possible to avoid having to buy it at a higher rate. Its not always going to be perfect but I always delay start the dishwasher until about 1pm when my solar is at its highest - my wife just puts it on when its full (even at night). Nothings going to help if its cloudy at 1pm but you just take your chances!

    When the prices of battery storage drop (or become more competitive) which they are already starting to do then its a new ballgame and more power to the homeowner!
    Licence to drill!

  10. #10
    1K Club Member UseByDate's Avatar
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    Quote Originally Posted by Sir Stinkalot View Post

    When the prices of battery storage drop (or become more competitive) which they are already starting to do then its a new ballgame and more power to the homeowner!
    If the rebate is only $8 - $10 there is not much saving to be made.
    $8 “rebate” at 8c/kWh is 100 kWh /quarter. Assume buy back cost of energy is 30c/kWh then the saving would be 22c/kWh if all energy was used locally (no export).
    100 times 4 times 22c = $88 /year
    Assume that a battery would have a useful life of 10 years then the battery would need to cost A$880 to break even and to make it worthwhile would need to be priced at under A$500.
    A$500 is 1/10 the present predicted price of the latest technology. (7kWh Power Wall).

  11. #11
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    1.8kW system in Northern NSW should be producing around 3000 kWh a year. If you're only exporting 400 kWh a quarter, $8 at 8 cents / kWh, then you are already about 650 kWh of the 750 kWh (average, will vary seasonally) produced so there's not much more to be saved. The 650 kWh already being used will be saving somewhere around $160 a quarter depending on what you pay for electricity from the grid. So there's not much more to be saved really, most of the power produced is already being used within the household based on those figures.

  12. #12
    1K Club Member UseByDate's Avatar
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    Quote Originally Posted by Smurf View Post
    1.8kW system in Northern NSW should be producing around 3000 kWh a year. If you're only exporting 400 kWh a quarter, $8 at 8 cents / kWh, then you are already about 650 kWh of the 750 kWh (average, will vary seasonally) produced so there's not much more to be saved. The 650 kWh already being used will be saving somewhere around $160 a quarter depending on what you pay for electricity from the grid. So there's not much more to be saved really, most of the power produced is already being used within the household based on those figures.
    A slip of the keyboard.
    It is 100 kWh per quarter. 400 kWh per year.

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