photovoltaic panel load problem

Discussion in 'The Projects Forum' started by mah, Oct 31, 2013.

  1. mah

    Thread Starter Active Member

    Mar 15, 2010
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    i have photovoltaic panel max 150 watt , i want to put a potentiometer around 20 ohm to be its load . could you propose a solution .
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Get out your credit card. They're not cheap.

    There are better ways to make a dummy load. What are you trying to do?
     
  3. MrChips

    Moderator

    Oct 2, 2009
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    Why do you want to do this?

    Is the 20-ohm pot rated to handle 150W ?
     
  4. mah

    Thread Starter Active Member

    Mar 15, 2010
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    i want to measure current and volt at maximum power by changing the load resistance using potentiometer.
     
  5. strantor

    AAC Fanatic!

    Oct 3, 2010
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    how about parallel a few mosfets on an extruded aluminum heat sink and operate them in linear mode?
     
  6. mah

    Thread Starter Active Member

    Mar 15, 2010
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  7. strantor

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  8. mah

    Thread Starter Active Member

    Mar 15, 2010
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    will that give me a control in resistance around 20 ohm ?
    .
     
  9. mah

    Thread Starter Active Member

    Mar 15, 2010
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    why won't it work ?
     
  10. strantor

    AAC Fanatic!

    Oct 3, 2010
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    you want to dissipate 150W. your pot is rated 1W. you will need a pot with 15,000% higher power rating than the one you have.
     
  11. MrChips

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  12. MrChips

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    Or get a whole bunch of 12V automotive headlight lamps and wire them in series/parallel combination.
     
  13. mah

    Thread Starter Active Member

    Mar 15, 2010
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    so what to do ? isn't there resistors with high power ratings , i will also need another one when connecting dc-dc converter.
     
  14. strantor

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  15. #12

    Expert

    Nov 30, 2010
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    I'm getting similar answers at Mouser. $180
    Headlights are a lot cheaper, especially at automotive dismantling and recycling emporiums.
     
  16. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Get a bunch of 10W to 50W wire-wound power resistors. Fill a plastic bucket with water. Immerse the resistors in the water. As long as the resistors are submerged in water, they can dissipate about 10X to 20X their rated power. Even if the water boils the resistors will be no hotter than ~100deg C....

    Automotive engine oil in the bucket can also be used. Dont burn yourself with the hot oil...

    When I started, we used to mount metal-jacket 6L6s upside down in water or oil and get 100W of RF on 40meters out of them.
     
  17. mah

    Thread Starter Active Member

    Mar 15, 2010
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  18. #12

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    Nov 30, 2010
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    Light bulbs.
    Incandescent light bulbs are just resistors designed to operate at very high temperatures.
     
  19. mah

    Thread Starter Active Member

    Mar 15, 2010
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    will i get the required resistance around 20 ohm ? i need to change it by 1 ohm .
     
  20. strantor

    AAC Fanatic!

    Oct 3, 2010
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    how about parallel a few mosfets in a bucket of oil and operate them in linear mode?
     
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