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  • Backpacking PV: looking for MPPT with energy buffer build-in?

    Ola,

    I use some Suaoki 40W Solar paddle with SunPower mono-crystalline panels since quite some time, and like many other panels it has a raw output of up to 24V.
    In the past my only device connected to it was my battery charger which by surprise was able to run with it: For this I simply connected the PV raw output to the 12V input of the charger. Seems like the charger did not take any damage from this until now, but to skip using it it that out of spec and run it more efficient I researched a bit and found other threads in that board and the web suggesting to use a Power Tracking Module.

    Because I am not into electric modulation I wanted to find a "more or less" plug and play product: In a case - with warranty - from a commercial brand ...
    Couldn't find any. Like it is non existing for backpacking applications.
    Seems like it needs to be some spare MPPT Module which comes pre-assembled but needs to get wired for In and Out, which is a basic "mechanical" (not really electrical) task I can do.


    Now it was about to find some great Module, the rest like a housing and the connectors I was sure about to be able to find by my own.
    [B]Q:[/B] So may I ask if you got any experience and want to suggest your solution to get from Raw 24V to finished modulated 12V for max. 50W, and maybe with a buffer between to store energy?


    Off course I tried answering that question by my own and found many MPPT modules just by hitting it into the web/ebay/aliexpress, and it seems like there are a ton based on BUCK Converters that might work already, but as far as me as a newbie have read up, BUCK Converters only step down, so every input less than the target 12V would be dropped.
    This is something I like to come around with a another Converter principal (a more expensive one I guess) which should have great efficiency - like stepping up also?

    Another idea I wanted to have include is some kind of "buffer" - but that seems like a rare idea at the market, because I could only find very few informations of others doing this. One of the few instructions/self-assemble kits I could find used Super Capacitors for this:
    https://www.instructables.com/id/The...er-Capacitor-/

    LTC3625/LT1784 Solar Powered Super Capacitor Charger with MPPT
    https://www.analog.com/en/design-cen...ml#cc-overview

    Super Capacitor Battery:
    https://www.watelectrical.com/rechar...citor-battery/

    I like this idea alot, but the comments below the thread already have stated opinions that the solution is not constructed very great, because some components where used out of spec.
    Anyways: A capacitor and LiIon Battery mix to have a small buffer sounds "genius".


    Well, and here I ended up for now and am not able to decide for the next step.
    I would like a solution that combines the benefits I stumbled over while researching:
    - capable of running up to 24V/50W Input for my case, up to 24V/100W would be maybe acceptable as well - I just do not want to get too big because of the weight and size.
    - as efficient as possible (step down, step up, MPPT)
    - for a perfect "gapless" use of the connected devices I would like to store 10-30Wh by capacitors or batterys, depending on the weight again
    - no fancy controls with Touchscreen needed, as long as I can set it with a potentiometer and LC Display readout to my target Output I would be happy:
    But it looks like the road goes deeper into the topic and need you to gain enhanced knowledge about this to build your own product - which is a path I would like to skip as far as possibly?
    - I will only run a 12V device to charge battery's with it - no USB or other outputs needed!

    [B]Q: [/B]Can someone help me out of this mace and knows where I can simply order a device like this,
    or if there is some instructions I could trust to assemble by myself?


    Thanks

    Ps.: Please excuse my brevity or non-sens - your language is not native to me, but I try to play with it to get better.
    Last edited by letmefreak; 07-11-2019, 08:13 AM.

  • #2
    PV modules are a current ( amps ) source, nearly all electronics are designed around a Voltage Source (like a battery)

    Most dc-dc converters do not allow for MPPT of PV modules.

    The closest [I]off the shelf[/I] thing I can think of is a Linear Current Booster, designed to run a motor off a PV panel. It stores energy till it has enough to run the pump momentarily.

    Only one controller (Gensun) has step-up, step-down capability, all others I have seen are step-down.

    Maybe check trucker/big-rig catalogs for 24v battery chargers, most big rigs use a 24v system, and there are many 24v appliances for them

    Also, maybe Maha makes a 24v charger https://www.thomasdistributing.com/B...-Chargers.html

    The other alternative is to use a simple zener diode voltage regulator to limit the panel voltage. That could be a DIY project

    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

    Comment


    • #3
      It sounds like an MPPT charge controller into an adequate 12V battery would work. Bruce Roe

      Comment


      • #4
        Hello,

        thanks for the quick reply:
        @Mike90250: Well - there are a TON of Step Up/Step Down Controllers on the market based on different technologys. I saw some SEPIC, I saw controllers like the LTC3780 which is a Buck/Boost Chipset and so on.
        For example:
        https://www.ebay.co.uk/itm/DC-5V-32V...kAAOSwQwRbzZAM
        Can be used with MPPT like:

        Here another SEPIC with MPPT, sadly SEPIC is only ~90% efficiency compared to 98% StepUp/93-95% Step Down)
        https://www.ebay.co.uk/itm/PM-6009M-...cAAOSwldxbVw9p
        Here some idea how to compine this SEPIC with Batterys:
        http://www.rroij.com/open-access/pdf....php?aid=43881

        Here a YouTuber testing different components, and in the list are few MPPTs aswell as StepUp and Downer:
        https://www.youtube.com/channel/UCKs...BQsERZhpZHU_7Q

        Here Texas Instrument even offers with the C2000 something, but for way to big for me:
        https://www.ti.com/tool/tidm-solar-dcdc

        PDF Implementation of DC-DC Converter for MPPT by Direct Control Method
        https://www.ijert.org/research/imple...V3IS091056.pdf

        another PDF AN MPPT CHARGE CONTROLLER FOR SOLAR POWERED PORTABLE DEVICES
        https://web.wpi.edu/Pubs/E-project/A..._Charger_1.pdf

        ... just what was still open from yesterday, I had a bunch more integrating MPPTs or Capacitors or Batterys.


        I guess the question is way more complex: it is about to find a PERFECT solution, not just "some crap"!
        Stated already: Needs to be stepping up and down, needs to have MPPT, needs maybe to have some Current Regulation, needs to have some kind of buffer!
        Nothing less than this.
        To give you an idea what my mind is spinning around: The LTC3780 for example has an Input Range of 5-35V - getting the best alternative is more the question I am concerned: For example finding some chipset that starts already from 3V, to have less dropped energy!

        So it is not only about the few Gensun products (which, by the way have sometimes bad reputations on YouTube Vids...) - it is an intransparent mess of hundreds of components on the market.

        The link you qouted seems like just some random store - How does this comes into play with my case?

        Like I sayed: This is a backpacking scenario! Every gram counts!
        I am not looking into getting some workaround solution - that is not why I registred here and am willed to spend hundreds of Dollars into that device.


        @bcroe
        "It sounds like an MPPT charge controller into an adequate 12V battery would work. Bruce Roe"

        I considered this solution aswell, but I dislike this:
        If I charge from the PV -> MPPT -> 12V Battery Pack, I got to charge all of my devices from this 12V Battery Pack.
        I do not want this extended wear on the pack, to charge everything.
        I do not want this extra weight of carrying the same Wh in the "12V Pack" as I carry in all my single cells.

        I want this "buffer" only integrated for a stable current: If I run my 12V Device (Battery Charger), I want this charger to charge without interruption.
        If the PV generates nothing, the battery should jump in like an uninterruptable power supply, but as soon as the PV produces some amount of energy I want this to charge my 12V Device and not to charge the 12V Battery Pack.

        This is why I considered ~20Wh for the "internal Battery", to only work as buffer,
        and not a 100Wh Pack to charge entirly from that one.

        This is why something that easy like an Genasun GV5-Li-12.5V would not fit.


        Further: No, MOST MPPT Controllers are NOT stepping up and have way to big dimensions for me,
        so after my initial post both of you should see bevor that my question is not solved easy like that.

        Please consider to reply in an adequate manner of details next time, like with a specific product - because replying like "yeah anything on the market will fit your needs" is just a waste of your time, because if it would be that easy I would have found it in the past 50hours of research!

        Thanks
        Last edited by letmefreak; 07-12-2019, 09:54 AM.

        Comment


        • #5
          You said start with 24V panel down to 12V, I do not see why you are talking about Buck/Boost.

          You wanted to store energy, but you did not say how much. That is a battery. Bruce Roe

          Comment


          • #6
            Sorry Bruce but if you lack to read this entire first post and I reply to you that you missed something, dont argue and claim things I never saided.
            It is CLEARLY saying that I want Boost - and it should be CLEAR to you with 3789 posts in a solarpanel forum that a Panel not always has 24V!

            So if I have a target of 12V output, and my Input is less - guess what I need?

            All this thread was about nothing else than getting EVERY SINGLE BIT OF JUICE out of the PV because, again: Backpacking!

            Thanks.

            Comment


            • #7
              The Thomas Distributing link was for battery chargers, they carry many models. sort of one stop shopping and I have bought AA chargers from them. the Maha C401 charges single AA, most chargers need 2 AA cells and of course, if they are not perfectly matched, they are not properly charged.

              When you are referencing chips, those are bare bones chips, not a complete charger/controller. Beware stuff from flea bay, some may actually be engineered, most likely isn't.
              The way solar PV works, when there is any light, the panel quickly produces full voltage. No need to try to harvest any power below 50% of Vmp, there is nothing there worth going after. The intensity of light, produces more amps, that's the goal of the MPPT, to seek that balance point without collapsing the PV output.

              And sorry if my responses don't meet your engineering standards. If you'd shown your prior research up front, I'd not have wasted my time on your goose chase.
              Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
              || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
              || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

              solar: http://tinyurl.com/LMR-Solar
              gen: http://tinyurl.com/LMR-Lister

              Comment


              • #8
                What you do not understand, is that the output voltage of a best operated solar panel
                varies little, only the available current varies widely. That is why an MPPT controller
                is used. Try to understand the facts, lay down more specific need numbers, and not
                waste time with accusations. Bruce Roe

                Comment


                • #9
                  Hey,
                  [USER="1076"]Mike90250[/USER]
                  "The Thomas Distributing link was for battery chargers,"
                  Where did I asked for AA chargers - sorry I completly do not get what you are referring for?
                  I do not want to get unpolite but how can it be that Bruce and you are talking complete off-topic to me?
                  Sorry if my english was that miserable to get the story, but if I read just the "spec list" of the end of my first post, everything is cristal clear to me what the Question was.

                  "When you are referencing chips, those are bare bones chips, not a complete charger/controller. Beware stuff from flea bay, some may actually be engineered, most likely isn't."
                  Yes, I am referencing for single parts because like I sayed in the first post, it does not look like there is ANY commercial product that got what I need,
                  this is by the way the same reason I am not looking for a battery charger.
                  Thanks for the hint with the fake stuff from eBay/China, thankfully I was aware of it and it was more to hint for product specs that exists.


                  "The way solar PV works, when there is any light, the panel quickly produces full voltage. No need to try to harvest any power below 50% of Vmp, there is nothing there worth going after."
                  I see that this is how to work in a static environment: But you guys are looking for USD per Watt and criterias.
                  This is why I sayed that this is a complete different envoirement!
                  I am backpacking - every single bit of energy collected matters - every single gram matters.
                  If I could I would buy GaAs Panels.
                  You get it?


                  "And sorry if my responses don't meet your engineering standards"
                  No need to get passive agressive.
                  I made clear what I am looking for, this has nothing to do with a chase for a magic Unicorn.

                  I just expected to receive replies that either a) contain products links I was asking for or b) talking about the concept I asked and how to get there - like creating some own device - or suggestions how this concept could be simplified.
                  I did not expected to get links for AA battery chargers (I do not even have NiCd/NiMh chemistrys...) or some MPPT, even if that has nothing to do with my Qs.

                  [USER="9197"]bcroe[/USER]

                  "What you do not understand, is that the output voltage of a best operated solar panel
                  varies little, only the available current varies widely."
                  Wow Bruce, now you totally go non-sens, mh?
                  No - the output voltage of a PV variies not just "a little"!
                  Just because your standards think its okay, does not makes it universal to the one guy who asks how to get everything out of it because he uses a 40W panel and even considers to go for a smaller panel if the efficiency increase!

                  What is this - I have to argue why it is a good idea to not waste any energy?
                  With this attitude:
                  Would you please downgrade to an older generation of PV and please use the worst inverters you can find, so you loose more energy also please?

                  Please try to explain ANY backpacker that he please needs to carry more weight for the same features,
                  they will think you are nuts.


                  "Try to understand the facts, lay down more specific need numbers, and not
                  waste time with accusations"
                  Maybe I try to read minds or see for the future aswell, mh?
                  Ask what "more specific numbers" you need to give me some proper reply, and I would be happy to answer them in the first hand. Instead, I get 3 useless replies from you.
                  So:
                  I can not see what specs you ever could miss if you would have read my first post entirely, so ... ?


                  Bevor you reply something again:
                  I do not want that this topic develops into a discussion how legit my wish is or not. I only want conceptional input. Like: Your Idea sucks BECAUSE you better should do X Y Z.

                  If you do not need a device like this, and you will only post doubts - Ciao.
                  If you do not agree that it is smart to Boost also - Ciao
                  If you do not agree that it is smart to have some kind of buffer/temporary storage, so a stable current is guaranteed - Ciao. If you think I could simply use any MPPT and charge some Battery with it, and use the Battery to charge my devices - Ciao.

                  It has a reason why students of Universities world wide publish papers with concepts of Boost/Buck MPPTs combinations -
                  so I do not feel like I am that wrong with that need.

                  That easy.
                  Last edited by letmefreak; 07-12-2019, 12:06 PM.

                  Comment


                  • #10
                    Originally posted by letmefreak View Post
                    Ola,

                    I use some Suaoki 40W Solar paddle with SunPower mono-crystalline panels since quite some time, and like many other panels it has a raw output of up to 24V.
                    In the past my only device connected to it was my[COLOR=#FF0000] battery charger [/COLOR]which by surprise was able to run with it: For this I simply connected the PV raw output to the 12V input of the charger. Seems like the charger did not take any damage from this until now, but to skip using it it that out of spec and run it more efficient I researched a bit and found other threads in that board and the web suggesting to use a Power Tracking Module


                    ..........
                    - I will only run a 12V device to[COLOR=#FF0000] charge battery's[/COLOR] with it - no USB or other outputs needed!

                    ..........

                    Ps.: Please excuse my brevity or non-sens - your language is not native to me, but I try to play with it to get better.

                    I'd thought you were looking to charge batteries and you did not specify anything, so i gave you the best data I had.

                    And your grasp of english is commendable .

                    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                    solar: http://tinyurl.com/LMR-Solar
                    gen: http://tinyurl.com/LMR-Lister

                    Comment


                    • #11
                      I'd thought you were looking to charge batteries and you did not specify anything, so i gave you the best data I had.
                      Just because you see the term "battery charger" you want to suggest me some... Yeah...
                      Whatever:
                      For sure you already understood that all I was saying is that THE ONLY CONNECTED DEVICE IS A 12V DEVICE - THIS IS WHY I ONLY NEED 12V OUTPUT.

                      And your grasp of english is commendable .
                      I can text you in spanish or french if you prefer this!
                      The first post already stated that I my language skill may suck: Feel free to ask me or correct the text.

                      May both of you two with 3800 and 13000 posts see that with all your and my replies this whole topic already crashed, because everyone else who may read this will already see that its just lame discussion of the author against 2 "Forum Gods". No one will see that I have a legit question with more or less importance (because no one bevor asked it) anymore.

                      So please just stop - lean back - and have a look if I am maybe lucky and someone replies to me who can actually help me finding a off-the-shelf product or designing some layout for what I need!
                      But I guess that train is gone already...


                      Thanks

                      Comment


                      • #12
                        Originally posted by letmefreak View Post
                        I get 3 useless replies from you.
                        They are definitely useless, if nobody is listening. Bruce Roe

                        Comment


                        • #13
                          Originally posted by letmefreak View Post
                          No - the output voltage of a PV variies not just "a little"!
                          It varies just a little. Temperature changes output voltage slightly; if you make the panel 20C hotter voltage might drop by 5%.. Current draw changes a little more; you might see a 20% drop from open circuit to maximum power point. (If you drop the voltage more than that you are doing something wrong.)

                          That's why people use MPPT buck controllers, so they don't have to match battery voltage and panel voltage exactly.

                          Choose a panel or a range of panels. Decide if you want the PV voltage to be higher than or lower than the battery voltage. Choose a controller accordingly.
                          If you do not agree that it is smart to have some kind of buffer/temporary storage, so a stable current is guaranteed - Ciao.
                          Temporary storage = battery or capacitor. If you are a backpacker you are going to want a battery.

                          Comment


                          • #14
                            Letmefreak - I suggest you inquire at https://forum.solar-electric.com/discussions A different pool of users, you may get some answers there.
                            Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                            || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                            || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                            solar: http://tinyurl.com/LMR-Solar
                            gen: http://tinyurl.com/LMR-Lister

                            Comment


                            • #15
                              I have to laugh any time I see these MPPT schematics. It isn't only ebay that plays with the truth. That first link is to a MPPC controller. That is what happens when marketing takes over. MPPC is quite effective and I use it a lot in solar. Any cheap buck converter can be turned into a MPPC controller with only a couple parts. You are splitting hairs on efficiency. Again much of what you see posted is made to deceive, it is not a fixed number.

                              Comment

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