The new voltage and current sensors on the battery side mean that Watts in and Watts out can be measured and an efficiency percentage calculated. High efficiency values (96% - 97%) are achievable when the buck converter is stepping down from 18v to 12v. With a 72-cell panel and the converter stepping 35v down to 12v, the efficiency drops to around 88%.
Code for this project is now available on my website:
http://www.256.co.uk/?p=1104 and
http://www.256.co.uk/?p=1107

By Julian

Youtuber, shed dweller, solar charge controller aficionado

12 thoughts on “Arduino mppt solar charge controller #17 – buck converter efficiency”
  1. Avataaar/Circle Created with python_avatars lary angel says:

    Oo

  2. Avataaar/Circle Created with python_avatars Ibnul Sahgianto says:

    nice explanation, nice channel btw very educate, btw the links are down. thanks

  3. Avataaar/Circle Created with python_avatars Psalmuel Yvan says:

    what if I like a 100khz PWM is it possible? how?

  4. Avataaar/Circle Created with python_avatars dadaderk says:

    Website is not working? Neither is Tim Nolan's. Must be the the MPPT mafia again!

  5. Avataaar/Circle Created with python_avatars Enverex says:

    Something in this video is giving off a really nasty high pitched whine (17500Hz or so at a guess) normally when you're playing about with the dial. May be worth looking into if you can't hear it because others will be able to.

  6. Avataaar/Circle Created with python_avatars José Diniz Neto says:

    What the Frequency of PWM in arduino to switch?

    What Method of MPPT you uses?

  7. Avataaar/Circle Created with python_avatars Julian Ilett says:

    I guess so – I've never tried it. But a solar charge controller will be more efficient, will do a better job (with it's multiple charge stages) and lose less power overnight.

  8. Avataaar/Circle Created with python_avatars DOM THE SAUSAGE says:

    can i use a LM2596 dc dc converter as a solar panel regulator to charge a car battery

  9. Avataaar/Circle Created with python_avatars quaxk says:

    damn, 101% efficient! screw you thermodynamics! 🙂

  10. Avataaar/Circle Created with python_avatars Julian Ilett says:

    That's a really good little article – thanks. I really don't know much about inductors – something I need to learn.

  11. Avataaar/Circle Created with python_avatars krazatchu says:

    Julian, check out this project on ferrite by Elm-chan.
    The explanation and graphs are fantastic:
    elm-chan.org/works/lchk/report.html

  12. Avataaar/Circle Created with python_avatars xanataph says:

    Yes, made the inductance bigger I could lower the frequency. In my application it's not too important because I just want it to operate at a fixed duty cycle rather than being controllable, and I can get that from a single 555. Interestingly, the circuit works better with a straight 555 rather than the cmos one. But inductors..arrrghhh…! hehe All I know is that the powdered iron is normally used in suppression chokes where as the ferrite is used in transformers…usually.

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