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The very very good Single axis tracker

Discussion in 'Renewable Energy' started by umer27, Mar 1, 2009.

  1. umer27

    umer27 New Member

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    Read this INTRO first please ..


    Dear All !

    Hi, Im new to this forum...

    Im designing a single axis solar tracker as an engineering project. Im doing this for a manufacturer , and its going to compete with a commercially available tracker,

    IF my tracker is viable, we go into mass production.After a lot of testing off course.. So, I'd like to discuss lots of things with you guys because I think there are a few very bright people here.

    A little introduction about my tracker,

    --> Single axis (90 degree east -west)
    --> Uses a 10W solar panel as a sensor and its not connected to the other big panels..

    --> Im using a linear actuator with a reed sensor , amazingly takes ~2A current at 12V for moving this mammoth 300kg load (coz of the ball screw.. :) )

    --> The Circuit has an on-board 12V, 4.5 Ah battery that im supposed to charge the battery with as well.
    --> Im using an AVR Microcontroller, ATmega8. It has 6 ADCs , an analog comparitor, PWM pins, and lots of other goodies..
    The system has a 8 x 250W panels as you can see. Its hooked up to a sunny boy 1700E grid tie inverter.
    --> The tracker will also have a learning capability , ie it will log data and will become more efficient as time passes by.

    IF IM MISSING A TRICK SOMEWHERE , PLEASE POINT IT OUT.
    The questions:

    1. im measuring the 10W solar panel voltage and current, for this im using a simple shunt, the INA128 instrumentation amplifier and reading the ADC value.any bright ideas on improving this setup are most welcome ...

    2. Please tell me about Solar tracking algorithms that you are aware of.. I have this idea of MPPT, i know its in the regulators.. but I think if I measure the current and voltage of the 10W panel .. and position the panels so I can get the Max power on the IV curves (ie max current and voltage value ).. That would be great.. I have also looked into other algorithms .. as well..

    3. I plan to use the LMD 18200 motor driver , since my actuator's reqs are so small.. anyone know of any protective circuitry in addition with the thermal and current flags on the LMD 18200 , Plz let me know..

    4. Was getting problems with counting the pulses of the reed sensor, but now I think using a Schmitt trigger OR RC filter with ADC monitoring would work..

    Please remember , I dont want any hardware that I dont really want.. The circuit has to be super efficient..

    5. For the battery, I want two charging stages. A simple charge.. and a float charge that I can apply with PWM. to protect the battery from overcharging, I will use a switch .. (in the high or low side, haven't decided yet.. ) . I need Ideas for the switch. The switch will remain closed for extended periods of time, I also want to apply float charge via PWM , so I think I have to use a high side P-channel MOSFET.. help needed with this one..


    Thanks for reading and answering .. sorry if i missed a imp detail ..

    Cheers ..
     

    Attached Files:

  2. Mike_2545

    Mike_2545 Super Moderator

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    Looks pretty cool, though I would go with a dual axis tracker to make it worth the extra cost. Otherwise you'd have to adjust the azimuth a minimum of 4 time a year to optimize efficiency.

    Take into account cloudy days, and all of the normal weather, a dual tracker is that much better than a single axis tracker.

    But...a single axis is better than stationary...
     
  3. umer27

    umer27 New Member

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    dude, I have made provisions for making this design Dual axis.. so, far my algo also supports the dual axis thing..

    :)
     
  4. dave

    Dave New Member

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  5. umer27

    umer27 New Member

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    dont worry , If this works .. making it dual axis is a matter of 15 days..
     
  6. duffy

    duffy New Member

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    I don't see anything that works as a gnomon. Got to have something casting a shadow between a pair of sensors.
     
  7. umer27

    umer27 New Member

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    sweetheart .. Im using a solar panel as a sensor .. :) actually Im positioning the small panel so its at its MPP ...

    If the 10W panel is tracking at its MPP , then the array would also be reasonable close ..
     
  8. umer27

    umer27 New Member

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    reasonably *
     
  9. Mike_2545

    Mike_2545 Super Moderator

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    Duffy, he called you sweetheart and me dude, in the same thread, that's hilarious!
     
  10. duffy

    duffy New Member

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    You need to have a pair of sensors with something casting a shadow between them.
     
  11. duffy

    duffy New Member

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    If he's cute he can call me sweetheart as much as he wants. The funny part is where he asks for advice and when he gets it he throws it out.
     
  12. Mike_2545

    Mike_2545 Super Moderator

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    Well he's got a pair of something:)
     
  13. umer27

    umer27 New Member

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    @ duffy .. Sorry mate, I didnt mean to offend ya .. this is facebook lingo .. again .. my apologies .. :)
     
  14. kchriste

    kchriste New Member Forum Supporter

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    Without a gnomon and two sensors, how is your system going to differentiate between clouds slowly covering the sun versus the sun moving west? ie: without a gnomon, your system will do a lot of unnecessary hunting as clouds block and unblock the sun.
     
    Last edited: Mar 1, 2009
  15. umer27

    umer27 New Member

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    hmm.. whats gnomon .. ?

    goto the internet , and search for lorentz ETA track .. its a solar tracking system .. DOES NOT use sensors .. rather it uses a solar panel , like im using .. for tracking..
     
  16. duffy

    duffy New Member

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    No, it uses a clock and a calendar for tracking. The solar panel output is used to synchronize the clock and calendar.

    That's a fine way of doing it, but you don't need your separate "10W solar panel as a sensor", and should probably mention you are using a clock and calendar approach somewhere in your posts.
     
  17. Mike_2545

    Mike_2545 Super Moderator

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    The wattsun dual axis tracker uses 5 sensors to find the fire ball in the sky.
     
  18. Mike_2545

    Mike_2545 Super Moderator

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    Well solar dude, A Gnomon is the part of a sundial that casts the shadow.

    but you knew that didn't you sweetheart?
     
  19. umer27

    umer27 New Member

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    Please goto the Lorentz website and look at the tracker , before making any assumptions that I am using a clock ..

    When you first turn on the whole thing, It goes to the extereme east position and jogs to the extreme right position .. finds the palce (angle) at which the 10W got its max power and BAM .. tracking !


    Please read the questions that I have posted , Id like help with that .. :)

    PS you can only call me sweetheart, if yr a grl and smoking hot !
     
  20. duffy

    duffy New Member

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    Please goto the Lorentz website and look at the tracker, before making any assumptions that you don't need a clock.
     
  21. umer27

    umer27 New Member

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    Ive asked a few questions .. and your suggestions are most welcome ..

    Discussing the details of the project which are out of the scope of this forum is not relevant .. It would take me days to make you understand how It works out.
     

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