Solar Panel use with out battery ????

Discussion in 'The Projects Forum' started by bergybob, Dec 21, 2012.

  1. bergybob

    Thread Starter New Member

    Dec 28, 2011
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    I have bought a 50 w solar panel and a 12v 1amp pump for a fountain and would like to run it without a battery.I have a regulator but it seems to require a battery.When I connect a battery it runs continuously including throughout the night.What I would like to achieve is day light hours only with no need for a battery.
    Any ideas ?????
    Brian
     
  2. DickCappels

    Moderator

    Aug 21, 2008
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    Most motors can operate over a wide range of voltages without damage, check the maximum output of your panel under load (perhaps by actually connecting it to the pump while it pumps the fountain and measuring it. Maybe you can omit the regulator?

    If it turns out that you need to use a regulator, then you can photo detector to switch the thing off at night.
     
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  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
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  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    The other problem is that a 50W solar panel will make up to 22v with light loads (if the motor is not consuming enough current).

    The OP needs to state what current the motor uses, and then needs a solution if the motor uses less than 50W of how to reduce the excess panel voltage down to 12v.
     
  5. bergybob

    Thread Starter New Member

    Dec 28, 2011
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    How would I go if I blanked off half of the 50 watt panel.The open circuit voltage is around 22 volts.Would that reduce the open circuit voltage ??
    Brian
     
  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Nah... don't do that. A partially covered panel may give you zero useful power.
     
  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Do you have the motor specs? Ie running current at 12v, startup voltage or current needed etc. It might be easy enough to build a simple 12v regulator if the motor is not too large.
     
  8. bergybob

    Thread Starter New Member

    Dec 28, 2011
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    The only info I have about the pump motor is draw 1 amp .I bought it from ebay (China) and no specs are supplied.A 12 v regulator would be good.Are they easily built ?? Can I get a diagram ??
     
  9. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    A simple control would be to dump excess power via NPN transistor,12V to 15V zener diode & resistor to limit base current.
     
  10. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Yeah a shunt regulator would be simple to make and would work, although with a 50W panel and 12W motor the shunt regulator could be dissipating 30+ watts of waste heat.

    A buck regulator with 12v DC output is probably the best system? And maybe a circuit to disable it at low light/power levels to avoid motor brownout.
     
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