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Help needed designing a microcontroller based solar charge controller/MPPT

Discussion in 'Renewable Energy' started by mjohnson12, Nov 12, 2012.

  1. mjohnson12

    mjohnson12 New Member

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    For a solar project I'm doing for school I was interested in building an MPPT in order to save some money. Basically I want to construct an off grid solar generator for adverse weather conditions for temporary relief. I was going to use two 12V 100Ah (not sure if series or parallel would be better). I planned on using a 250W panel which would likely have similar characteristics to this one

    http://www.solar-electric.com/sosu250wamo.html

    I've been researching MPPT design and most of them seem to be for 12V panels and lower power panels. I particularly liked this design

    http://www.electro-tech-online.com/custompdfs/2012/11/Solar20Charger.pdf

    but it's only for 10-40W panels. It says modifications could be made for higher wattage panels, but I imagine this goes deeper than changing the resistor values for the voltage divider.

    I also read that PIC controllers might be better suited for this purpose due to an internal ADC converter and an internal clock. Another design I saw on this forum was based on an Arduino board, which is fine for programming, but I'm not allowed to use the board in the final design. Here it is:
    http://www.timnolan.com/index.php?page=arduino-ppt-solar-charger
    Basically I'm wondering if the protoshield is really necessary? And where could I learn to display the output onto an LCD screen?

    http://www.scribd.com/doc/51163743/Solar-Battery-Charger-With-MPPT-Using-Microcontroller

    The above design seems geared towards a high voltage panel, which is useful, but doesn't provide the microcontroller code. Does anyone know a good resource/tutorial for learning this stuff?

    Any help would greatly be appreciated.
     
  2. bryan1

    bryan1 Well-Known Member

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    Hello M Johnson,
    Now first as you have said this is a school project I will expect you show the work you are doing in this thread, myself and other members may help but remember as you will be graded for this project most of the work should be done BY YOU.

    Now as you have mentioned you want to use a pic micro have you sorted out which one you want to use and what type of code are you/we going to program in. Personally I use Oshonsoft Basic which has an easy learning curve and a simulator so the code can fully tested on a computer before building the hardware. But it isn't free and the trial software can be used by you.

    As a custom circuit will need to be designed you will have to learn circuit design too .

    From the links you provided which does show how a MPPT works, they use a buck converter and a micro to pwm depending on the solar input and step the voltage down to the batterybank voltage.

    Ok I'm going to stop here and wait for your input mate.

    Regards Bryan
     
  3. mjohnson12

    mjohnson12 New Member

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    Thanks for the reply Bryan. I'm ready to put in the work, I just have no exposure to microcontrollers at all. My only programming experience is with fortran and that was about two years ago. Chip wise I'm not really sure what I need. I had a friend suggest just sticking with buying an Arduino board and using the chip that comes with that. He says it's fairly easy to program, and I can just go to Radioshack and buy one. I know some basic design stuff, I'm mostly worried about the programming.
     
  4. dave

    Dave New Member

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  5. Mr RB

    Mr RB Well-Known Member

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    I suggest you check ebay first, there is a ton of cheap solar regulator stuff for sale, for peanuts, many of which claim to have MPPT capability.

    You can probably buy what you need as a finished product cheaper than the cost of the parts...
     

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