Solar panel hook up to a power bank

Discussion in 'General Electronics Chat' started by telerian, Mar 8, 2016.

  1. telerian

    Thread Starter Active Member

    Jul 19, 2010
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    Hi,

    I have a 5000 mAh power bank that I need to charge using solar panel. The power bank is standard USB one, with micro USB charging port and I have 2 6V solar panels. Can I connect the 2 panels in parallel and connect them directly to the USB charging port or do I need charge controller ?
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,969
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    Most solar panels are connected all in parallel then fed into the charger, you can use diodes in series with each panel this prevents back feeding due to shadowing.
     
  3. telerian

    Thread Starter Active Member

    Jul 19, 2010
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    What about the 6V, would that be ok on the 5V USB charging port ?
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Whats the spec on the usb charger say, if you want to drop some voltage put a diode in series with the solar panels.
     
  5. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,281
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    Do you have specs on the solar panels you could post?
     
  6. telerian

    Thread Starter Active Member

    Jul 19, 2010
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    This is the power bank (I assume you meant that), standard USB.
     
  7. telerian

    Thread Starter Active Member

    Jul 19, 2010
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    This is the solar panel, I have 2.
     
  8. Roderick Young

    Member

    Feb 22, 2015
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    A few thoughts.

    When a small panel like that is advertised as 1 watt, it probably has far less output. It might be 1/10 watt.

    If this was my experiment, I would put both panels in parallel, and also put a 100 uF capacitor in parallel. The capacitor is to supply surge currents, in the likely event that your power bank uses some sort of switching converter on its charger. Then I would hook it up. There are no guarantees when hooking something that is 6 volts to device designed to accept USB power, but my guess is that when the panels are hooked up, the voltage will drop, possibly to an unusably low voltage. If that happens, then you know that you need more or stronger panels.
     
  9. telerian

    Thread Starter Active Member

    Jul 19, 2010
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    What about this one ?
     
  10. Roderick Young

    Member

    Feb 22, 2015
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    I have never ordered from AliExpress, but have a distrust of claims made by Chinese vendors. It says monocrystalline, but that's indistinguishable from a cheap amorphous panel in a picture. I use a 10 watts per square foot as a guideline to true power, but unfortunately, there is no dimension given. The hand in the picture gives an idea of scale, I suppose. When I look at a panel, I'm always suspicious when only a wattage is given - no open circuit voltage, no short circuit current, no CEC or PTC rating. The vendor can make up whatever number they like for the power.

    Only way to know with such a thing is to get one and try it.
     
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