Solar Panel Output Regulation

Discussion in 'General Electronics Chat' started by Gbatts, Aug 7, 2008.

  1. Gbatts

    Thread Starter New Member

    Aug 7, 2008
    2
    0
    Hi All - I am new to this site so my apologies in advance if i mess up. So the problem> I have solar panel that puts out about 0 to 22 volts in full sunlight. I would like to limit the upper range to 12-13volts. The device I am connecting this solar pannel to cannot take more than 13.x volts.

    Would the "Potentiometer as a rheostat" http://www.allaboutcircuits.com/vol_6/chpt_3/7.html work for what I am trying to achieve? What do you suggest?

    Thank you kindly for your help
     
  2. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    Hi,

    You actually need a buck/boost switching converter. You probably will not find one much below 1.5V, so you can consider that power a loss. The converter will accept the wide range of voltage and fight to keep a preset voltage output.

    I am actually doing something very similar to you ,but my range requirements are a bit different. I calculated about 6-18V of useable power from the panel. I am operating at about 4A max current. I don't really know of any commercially available product, but there are probably many available. I'm designing a large system, so I am doing my own custom PCB. I was last checking out some of maxim's buck/boost converter ICs with external FET.

    Steve

    Oh, and your rheostat idea isn't a good idea. This is because sunlight can vary quite quickly, so the setting will need to be constantly changed. Secondly, different loads on the rheostat/pot will cause huge voltage fluctuations, which your load will not appreciate.
     
  3. Gbatts

    Thread Starter New Member

    Aug 7, 2008
    2
    0
    Thank you Steve,

    Yes! that is what I am looking for something that will "fight to keep a preset voltage". And thank you for confirming my suspicion about the rheostat idea - it was not clear from the e-book whether the output would remain constant with different input... Where can I learn more about "buck/boost converters"?
     
  4. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    You're Welcome :)

    Just about any switching regulator book will give you more than enough information on the subject. Or, you can do what just about every engineer does and copy an evaluation schematic / PCB layout from the manufacturer.

    intro to dc/dc : http://pdfserv.maxim-ic.com/en/an/AN4087.pdf

    Maxim has some battery charger ICs that integrate switching converters within, but I am not sure if they're simple buck or full out buck/boost converters. This way you could potentially charge your batteries directly through the circuit. Otherwise, you'd probably want to have some control over the charging process. Do you have a charger already that runs off of 12V ?

    Steve
     
  5. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
    1,438
    368
    Depending on your requirements, you might be able to use a simple shunt regulator.

    Although a switching converter has the advantage of being able to provide some current to the battery even when the output of the panel is below the battery voltage.
     
Loading...