Problem with solar system in RV

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  • evafla
    Junior Member
    • May 2012
    • 6

    #1

    Problem with solar system in RV

    Hello all, please educate us !

    We RV/ live in Mexico . Our solar (exactly batteries, quit long time ago)
    and we were without own electricity for long time .
    After long time of saving , we bought very
    expensive , two, 24 v each, gel batteries, and two more panels .

    We have right now 4 panels, 75W each and above two batteries .
    The name of batteries brand is Cecasa, and they are from Spain .

    We also bought new controller (Steca), which does all possible
    readings .
    For few days everything was great .

    Now already we have problems . ( three weeks)

    Problem number one is with computer .

    If I use computer without access to electricity, and battery goes lower, let say to 70%, later connected in RV does not charge,
    and connection of computer to electricity jumps literally every second on/off .

    When I start to use computer with battery 100% charged,it remains this way,
    and connection is constant on .

    Let me add ; with our old three 12v "add water" batteries and two
    panels
    I did not have above problem at all , and I was using computer a lot,
    because I take many pictures and work on them .

    Second problem; few days were not very sunny, and possibly we abused
    consumption, and our gel batteries went down to 59% charge .
    Now for two full days, better weather, and we almost do not touch anything, and charge is only 84% .

    Questions, can be first problem related to our inverter which is only 750 W , will buying stronger solve the problem ? How strong should we have ?
    Second problem, are our panels to week to charge this batteries
    faster ? Will adding one more panel help/solve the problem .
    We have room only for one more .

    Or maybe everything together is something else , we are not aware off ?

    And we have one more question .

    Please be patient with us !

    We want to buy solar refrigerator, cooler rather, 2 cubic food size,
    consumption 60W (we do not know what it means).
    This is also very expensive item for us, so we would be very thankful,
    for advise, is it going to perform right with our settings, or
    do we need to upgrade, and what batteries ? panels ?
    People who sell this stuff here in Oaxaca, are telling us that everything is and going to be perfect . We lost our trust a little bit .

    Please help, yes, we are pretty close to ignorant level .
    We really try very hard to educate ourselves , but seems like our problems are sort of unique .

    thank you very much eva
  • Naptown
    Solar Fanatic
    • Feb 2011
    • 6880

    #2
    can you provide spec's or links to all the specific components.
    I can tell you right off the bat that gel batteries are not a great choice for RE
    NABCEP certified Technical Sales Professional

    [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

    [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

    [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

    Comment

    • evafla
      Junior Member
      • May 2012
      • 6

      #3
      Originally posted by Naptown
      can you provide spec's or links to all the specific components.
      I can tell you right off the bat that gel batteries are not a great choice for RE
      uff, it does not make me feel so very well...

      I made mistake in my post, batteries are 12v .
      Link, the only I found



      I will include link to the fridge below, can not manage 2 links in one post , sorrry, eva

      Comment

      • evafla
        Junior Member
        • May 2012
        • 6

        #4
        refrigerator




        and thanks for adwise
        eva

        Comment

        • Sunking
          Solar Fanatic
          • Feb 2010
          • 23301

          #5
          I will try to help you but I need exact information on your equipment.

          Panel Manufacture and model number.
          What model Steca Charge controller
          What manufacture and model of inverter.

          How are you powering the laptop? Are you using a the laptop power brick plugged into the inverter?

          Last comment is forget the refrigerator. You do not have enough panel wattage or batteries to power it up.
          MSEE, PE

          Comment

          • inetdog
            Super Moderator
            • May 2012
            • 9909

            #6
            Originally posted by evafla
            Hello all, please educate us !

            Problem number one is with computer .

            If I use computer without access to electricity, and battery goes lower, let say to 70%, later connected in RV does not charge,
            and connection of computer to electricity jumps literally every second on/off .

            When I start to use computer with battery 100% charged,it remains this way,
            and connection is constant on .

            Let me add ; with our old three 12v "add water" batteries and two
            panels
            I did not have above problem at all , and I was using computer a lot,
            because I take many pictures and work on them .

            Questions, can be first problem related to our inverter which is only 750 W , will buying stronger solve the problem ? How strong should we have ?
            Second problem, are our panels to week to charge this batteries
            faster ? Will adding one more panel help/solve the problem .
            We have room only for one more .

            Or maybe everything together is something else , we are not aware off ?

            The sort of problems you describe with the computer power supply sound like what would be expected from a non-sine wave (MSW) inverter with too low a peak output current.
            The computer supply will draw large pulses of current at the transitions of the jagged MSW waveform. When running on your low resistance flooded cell batteries the inverter can handle the surge current and the computer supply is happy.
            But with your new gel batteries feeding the inverter and an attempt to fast charge the computer battery, the current pulses are more than your inverter can handle. If this is the case, you may be able to get some advice on a filter circuit which could allow the computer charger to work properly. Perhaps as small a change as a series resistor would do the trick, but that would depend a lot on the details of your inverter and your computer power supply. And i would not try to build it on my own without good knowledge of electronics and safe wiring.

            A pure sine wave (PSW) inverter would cost more than the one you have, but would also probably help. Different batteries, because the gel cells may not be suitable for this RE use are also a possibility. I would spend money there rather than on more panels if it were my decision.
            SunnyBoy 3000 US, 18 BP Solar 175B panels.

            Comment

            • Mike90250
              Moderator
              • May 2009
              • 16020

              #7
              Batteries, your best bet is go to a golf course, and get 4, 6V 200ah flooded cell (caps come off, you add distilled water every month) batteries. That would create a 400ah, 12V battery bank. You are a bit low on PV wattage to charge that much battery.

              And be sure to wire the parallel batteries properly - on the diagonal:
              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

              • evafla
                Junior Member
                • May 2012
                • 6

                #8
                Originally posted by Sunking
                I will try to help you but I need exact information on your equipment.

                Panel Manufacture and model number.
                What model Steca Charge controller
                What manufacture and model of inverter.

                How are you powering the laptop? Are you using a the laptop power brick plugged into the inverter?

                Last comment is forget the refrigerator. You do not have enough panel wattage or batteries to power it up.
                Thank you;
                I can only identify two last panels, 90 Watts


                about two another ones, installed earlier, everything what I know, one is 90 Watts (instaled in USA), and second one
                85 Watts, installed in Mexico already, but by another company, not the one I am dealing right now, it was in Gualdalajara .

                Controller, Steca PR2020, 12-24 V, 20 A

                Inverter, Duralast, 750 Watts Inverter

                and answer to your question about powering laptop; is yes, this is the way how it is done .

                thanks
                eva

                Comment

                • inetdog
                  Super Moderator
                  • May 2012
                  • 9909

                  #9
                  Originally posted by evafla

                  and answer to your question about powering laptop; is yes, this is the way how it is done .
                  It might make more sense to get a computer power supply which is designed to run directly from 12v DC. You should be able to find a "universal" model with the right optional connector to plug directly into your laptop. Two benefits from that:
                  1. No need to worry about the way the output of the inverter interacts with your standard power brick and
                  2. You could charge your computer without having to run the inverter, if you do not need other 120v loads at the same time.

                  Disadvantages:
                  1. You would have to run DC wiring to where you use and charge the computer.
                  2. No protection against draining the battery too far, if your PV system battery drops to the point where the inverter cuts out.
                  SunnyBoy 3000 US, 18 BP Solar 175B panels.

                  Comment

                  • Sunking
                    Solar Fanatic
                    • Feb 2010
                    • 23301

                    #10
                    My bet is your inverter is new right? I also bet your inverter is Modified Sine Wave and your laptop power brick cannot operate from an inexpensive MSW inverter. Get a 12 VDC power brick and loose the inverter.
                    MSEE, PE

                    Comment

                    • evafla
                      Junior Member
                      • May 2012
                      • 6

                      #11
                      Originally posted by Sunking
                      My bet is your inverter is new right? I also bet your inverter is Modified Sine Wave and your laptop power brick cannot operate from an inexpensive MSW inverter. Get a 12 VDC power brick and loose the inverter.
                      No , my inverter is 2 years old, and yes probably was cheap, I will buy the new one . Thanks .
                      About this another option, I simply at the moment do not understand, how can I connect anything
                      with loosing inverter .

                      However, one more time to all good people reading my post of desperation .

                      Please explain to me, why I can not operate this fridge . How much of storage ( batteries ) this fridge required
                      and how many more panels and why ?
                      Please , explain it to me, and this is not asked because I doubt in your opinion,
                      I just want to try to get my high down back, money which I paid so they can order fgridge,
                      after I was told everything with it will be fantastic .


                      thank you very much
                      eva

                      Comment

                      • Sunking
                        Solar Fanatic
                        • Feb 2010
                        • 23301

                        #12
                        Originally posted by evafla
                        No , my inverter is 2 years old, and yes probably was cheap, I will buy the new one . Thanks .
                        About this another option, I simply at the moment do not understand, how can I connect anything
                        with loosing inverter .
                        Well if the laptop worked before with the same inverter, then you have a problem with your solar system.

                        Most all laptop manufactures offer a 12 volt DC power brick for their laptops. They are made for the mobile markets and come with a plug that fits the cigar lighter in all vehicles. You simply cut the plug off and wire it to the battery

                        Originally posted by evafla
                        Please explain to me, why I can not operate this fridge . How much of storage ( batteries ) this fridge required and how many more panels and why ?
                        Very simple the power demand from the fridge exceeds what your system can produce in a day. If you tried it would drain the battery down to 0.

                        The fridge consumes 60 watts. What is unknown is the on/off run cycle. If 100% the fridge uses 60 watts x 24 hours = 1440 watt hours per day. That would mean in your area 750 watt panel, 60 amp MPPT charge controller, and a 12 volt 600 AH battery just to run the fridge. You only have 300 watt pane, 20 amp PWM controller, and a 12 volt 240 AH battery. You are not even remotely close to what you need to have. .
                        MSEE, PE

                        Comment

                        • inetdog
                          Super Moderator
                          • May 2012
                          • 9909

                          #13
                          Originally posted by Sunking
                          ... and come with a plug that fits the cigar lighter in all vehicles. You simply cut the plug off and wire it to the battery.
                          Being VERY sure to get the polarity right!
                          SunnyBoy 3000 US, 18 BP Solar 175B panels.

                          Comment

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