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Solar charge controller question

Discussion in 'Power Electronics' started by Alan1018, Jul 12, 2019.

  1. Alan1018

    Alan1018

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    Jul 12, 2019
    I am looking at a solar panel installation with a 24 volt battery bank. My question is when the charge controller shunts the excess power can it supply a 48 volt dc water heater element?
     
  2. Externet

    Externet

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    Aug 24, 2009
    What do you mean by 'shunts' ?
     
  3. Alan1018

    Alan1018

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    Jul 12, 2019
    Some charge controllers advertise they shunt power when the batteries are fully charged to another load. I understand this to mean the transfer the extra power.
     
  4. Martaine2005

    Martaine2005

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    May 12, 2015
    If that's what they advertise, then yes.
    But it will depend on your solar panels and charger.
    I would imagine the company would supply some kind of interface boards with switching on board.
    You might also need boost converters. But again, depends on the panels and charger.
    You need to have a GOOD read about the system you intend to use.

    Martin
     
  5. Martaine2005

    Martaine2005

    2,394
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    May 12, 2015
    Youtube has hundreds of videos about charge controllers. Do some research there too.

    Martin
     
    Last edited: Jul 12, 2019
  6. Externet

    Externet

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    Aug 24, 2009
    If the 24V charger controller diverts the panels energy to your 48V water heater, do not expect full heating.
     
  7. dave9

    dave9

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    Mar 5, 2017
    You'll have to look at the charge controller specs to see what it is capable of, for example the current.

    You may need to have its output to the heater, open a normally closed relay to disconnect the regular 48V supply to it.

    You may find it takes a terribly long time to heat the water with it, that you end up disconnecting it to let the heater run from the intended 48VDC supply while in recovery mode. You might be able to develop some circuit that overrides the relay opening based on the tank water temperature so it only switches to 24V solar panel input for temperature maintenance.

    Are you certain you're really going to have enough excess solar power to bother? If so you may be overpaying for a larger solar array than needed, or could get another battery to have more reserve capacity and not discharge the batteries as low, as well as gain the capability of powering higher current loads (given a suitably sized inverter).

    Frankly I would wait and see what the charging duty cycle is. Many panels have nice lofty ratings that are just "best case" and won't be achieved.
     
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