solar panel not putting out amps

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  • grumpybear
    Junior Member
    • Nov 2013
    • 12

    #1

    solar panel not putting out amps

    new here so please be nice
    i have three 144 watt {made myself } panels 130 watts actual output
    6x6 cells rated at 4.1 watts and .5 volts 36 cells in each panel 12 volt output
    30 amp pvm charge controller
    4 deep cycle marine 12 volt batteries
    i wanted to monitor the in coming amps so i bought a panel mount 30 amp amp gauge and installed it inline from the positive side coming in from the solar panels (to make sure i dont over amp the controller }
    well today was a cloudy day so im only getting 12.55 volts from the panels but only 1 amp
    i have a 2000 watt inverter and i had all my garage lights on and a ban saw ,drill press running but still only 1 amp from the panels
    so what am i missing here
    thanks for the responses and understanding of a new member just diving into the solar world
    still learning about solar
  • inetdog
    Super Moderator
    • May 2012
    • 9909

    #2
    Originally posted by grumpybear
    new here so please be nice
    i have three 144 watt {made myself } panels 130 watts actual output
    6x6 cells rated at 4.1 watts and .5 volts 36 cells in each panel 12 volt output
    30 amp pvm charge controller
    4 deep cycle marine 12 volt batteries
    i wanted to monitor the in coming amps so i bought a panel mount 30 amp amp gauge and installed it inline from the positive side coming in from the solar panels (to make sure i dont over amp the controller }
    well today was a cloudy day so im only getting 12.55 volts from the panels but only 1 amp
    i have a 2000 watt inverter and i had all my garage lights on and a ban saw ,drill press running but still only 1 amp from the panels
    so what am i missing here
    thanks for the responses and understanding of a new member just diving into the solar world
    Several things for you to consider:
    1. 4.1 watts and .5 volts per cell does not mean that you will get 4.1 watts at .5V. The Vmp may be lower than that.
    2. If you are getting 18V Vmp from the panels, then the current available, somewhere between Isc and Imp, will only be 7.2 amps for each 130 watt panel.
    3. With a PWM controller, the panel voltage will be pulled down to just above the battery voltage, reducing the amount of power you get.
    4. If the battery is charged, the CC will only put out what the battery can accept, not all that the panels can provide.

    If you disconnect the CC from panels and batteries, cover the panels, connect the gauge directly between panel + and panel - and then uncover the panels, you will read the Isc from the panels, without the CC limiting it to confuse things.
    If that number is too low, check out one panel at at time. (You can do this by just uncovering one at a time without changing the wiring.

    BTW, I hope that you have the panels connected in parallel! And with three panels you should have an individual fuse for each panel for safety.

    Looking back at the details of your post, I see that you only got 1 amp even with a load on the battery. I would chalk the low current up to the clouds in that case. And remember that with only 4-6 volts per panel to spare, any weak cell or any partial shading will kill the output from that panel. (Are you using one or two bypass diodes in each panel?)
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

    Comment

    • grumpybear
      Junior Member
      • Nov 2013
      • 12

      #3
      ok ill start with i have a volt meter on the panel output before it goes into the charge controller for the output voltage of the panels
      no diodes on the panels
      i do have a 30 amp inline fuse on the positive side before it goes into the cc still need to install the same on the output side to the batteries
      sorry don't know all the abbreviations yet
      are you talking about an inline fuse for each panel ?
      if so any suggestions ?

      all i am seeking to do at the moment is run everything in my garage/workshop from solar this winter
      heater 24/7 an mostly lights mabey 4 to 6 hours daily so i am trying to build a system to obtain this goal
      added a pic to show setup
      thanks for the reply

      20131101_150840.jpg
      still learning about solar

      Comment

      • Naptown
        Solar Fanatic
        • Feb 2011
        • 6880

        #4
        Originally posted by grumpybear
        ok ill start with i have a volt meter on the panel output before it goes into the charge controller for the output voltage of the panels
        no diodes on the panels
        i do have a 30 amp inline fuse on the positive side before it goes into the cc still need to install the same on the output side to the batteries
        sorry don't know all the abbreviations yet
        are you talking about an inline fuse for each panel ?
        if so any suggestions ?

        all i am seeking to do at the moment is run everything in my garage/workshop from solar this winter
        heater 24/7 an mostly lights mabey 4 to 6 hours daily so i am trying to build a system to obtain this goal
        added a pic to show setup
        thanks for the reply

        [ATTACH=CONFIG]3391[/ATTACH]
        And what kind of heater is this that you are running.
        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

        • grumpybear
          Junior Member
          • Nov 2013
          • 12

          #5
          heater

          it will be one from lowes electric just enough to keep the chill off
          also need to note that the panels are not mounted outside yet due to i have to run 80 ft wire to charge controller from the panel to have them at the optimal spot for maximum sunlight
          also in a rental so roof mounting is not an option

          the specs of the heater

          Type Electric stove
          Maximum BTUs 5200.0
          Max Supplemental Heating Area (Sq. Feet) 1000.0
          Warranty 1-year limited
          Remote Control Included Yes
          Thermostat Yes
          Flame Operates with and without Heat Yes
          Adjustable Flame Yes
          Number of Heat Settings Variable
          Maximum Wattage 1500.0
          still learning about solar

          Comment

          • Naptown
            Solar Fanatic
            • Feb 2011
            • 6880

            #6
            1500 watts is going to be a deal killer
            That will kill your batteries in very short order leaving you in the cold.
            Run the off grid battery design calculator in my sig line.
            This could be an eye opening experience for you.
            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

            • PNjunction
              Solar Fanatic
              • Jul 2012
              • 2179

              #7
              With a 40 foot run from the panels to the controller, you are going to want to pay attention to the wire gauge or you'll have excessive voltage drop. This is one of the perils about 12v systems, and you'll want to consult an online solar dc voltage drop calculator. Generally, you don't want to exceed a 3% drop for serious installations, or perhaps 5% for goofing around.

              I'm assuming you are paralleling nominal 12v panels (18-22 v OCV), for a grand total of 390 watts, or about 21 amps on the best of conditions.

              With a 40 foot run (one way) from panel to controller, I'd be looking at #2 (#two) gauge cable. For a single panel of only about 7A, then perhaps 6-8GA cable would be called for.

              You've got the meters, so try measuring at the panel, and then later at the end of your run and see if you are exceeding 5% voltage drop.

              You may want to reconfigure for 24V as this will lower the voltage drop, or allow you to run longer lengths of transmission line. See the online dc voltage drop calculators before spending any more money on what appears to be 10GA wiring.

              Be especially mindful of the fact that some calculators may show the result in a "one way" configuration, or a "two way" configuration, the two-way counting the length of a single wire from your panel to the controller AND back to the panel instead of just a simple point-a to point-b one-way result.

              Comment

              • grumpybear
                Junior Member
                • Nov 2013
                • 12

                #8
                well the wire i currently have is 8 coming from the panels to the charge controller 30 foot run right at the moment
                i have done tests as you suggested now at the panel i get 12.54 and at the controller i get the same reading { keep in mind this is an inside test with three 100 watt bulbs on the panels )
                but what seems odd to me is that before i hook up the panel to the charge controller my meter reads 15.34 volts but drops to 12.54 when hooked up
                i have tested all three panels witch give same results . is this normal ?
                i have rethought the location of putting the panels and will now only be approx. 18 feet from the charge controller and battery bank
                i will change the wire from the panel to charge controller to 6 awg wire which comes out as a 1.25 % voltage drop
                now on to more newbie questions
                as far as switching to 24 volt that wont be a problem charge controller can handle 12/24 volt
                now does the battery bank also have to be setup as 24 volt ?
                my power inverter will only handle 12 volt input so i would have to put regulator to step it down to 12 volts to the inverter correct ?
                i really appreciate all the advice i can get
                i do want this setup right and safe
                still learning about solar

                Comment

                • Mike90250
                  Moderator
                  • May 2009
                  • 16020

                  #9
                  A PWM charge controller will pull down panel voltage to the battery voltage. That's just the way it works. You loose 10-40% of the panels wattage, depending on the state of the batteries, the lower they are, the less efficient the controller is.

                  MPPT controllers run about 95% efficient under nearly all conditions.
                  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

                  • Sunking
                    Solar Fanatic
                    • Feb 2010
                    • 23301

                    #10
                    Well let's see. You have roughly 450 watts of panels trying to run a 1500 watt heater. What does not add up?
                    MSEE, PE

                    Comment

                    • SunEagle
                      Super Moderator
                      • Oct 2012
                      • 15169

                      #11
                      Regardless of the issue with the heater that may drain his batteries in minutes his bigger issue is how he is testing his panels.

                      He is using 300 watts of incandescent lighting inside. He needs to be testing outside with the sun on a clear day around Noon time to understand if his panels are working properly.

                      Once he has sunlight as part of the equation we can dissect his system concerning the true panel Volt/amp output, PWM charge controller limitation, 12 volt battery system AH size and of course the very large 1500 watt heater.

                      His lack of any measured amps from the panels can be from any number of issues from the light source to the battery state to the wire size.

                      Comment

                      • inetdog
                        Super Moderator
                        • May 2012
                        • 9909

                        #12
                        Originally posted by SunEagle
                        His lack of any measured amps from the panels can be from any number of issues from the light source to the battery state to the wire size.
                        The lack of any measured amps from the panels would be something more serious than just light or wire size.
                        The presence of measured amps which are lower than what he expected, on the other hand, could well be any of the things that you mention.
                        Among other things that you did not mention: a single bad (low current but not open) cell combined with bypass diodes can cause both the Voc and the Isc to look normal but reduce the available working current at battery charging voltages (near what would be Vmp/Imp if not for the bad cell.)
                        And on the poor light side, if he shines his strong 300 () watt light at the center of the panel, the corner cells could be getting enough less light to seriously cut the panel output.
                        SunnyBoy 3000 US, 18 BP Solar 175B panels.

                        Comment

                        • SunEagle
                          Super Moderator
                          • Oct 2012
                          • 15169

                          #13
                          Originally posted by inetdog
                          The lack of any measured amps from the panels would be something more serious than just light or wire size.
                          The presence of measured amps which are lower than what he expected, on the other hand, could well be any of the things that you mention.
                          Among other things that you did not mention: a single bad (low current but not open) cell combined with bypass diodes can cause both the Voc and the Isc to look normal but reduce the available working current at battery charging voltages (near what would be Vmp/Imp if not for the bad cell.)
                          And on the poor light side, if he shines his strong 300 () watt light at the center of the panel, the corner cells could be getting enough less light to seriously cut the panel output.
                          300 watts of incandescent lighting is no where near equal in wavelength and intensity to true sunlight. Now if he had used Xenon lamps then he would have gotten much closer to real sunlight and at a pretty high intensity.

                          Comment

                          • inetdog
                            Super Moderator
                            • May 2012
                            • 9909

                            #14
                            Originally posted by SunEagle
                            300 watts of incandescent lighting is no where near equal in wavelength and intensity to true sunlight. Now if he had used Xenon lamps then he would have gotten much closer to real sunlight and at a pretty high intensity.
                            Absolutely right. If you figure that his 300 watt bulb has perfect efficiency in producing visible light (only off by a factor or 10 or so in that assumption) and all of the light goes directly toward the panels and spreads its energy uniformly over the panel surface, it would still be difficult to get 1000 watts per square meter of panel that way.
                            It should produce a measurable current just the same, assuming nothing else is wrong.
                            SunnyBoy 3000 US, 18 BP Solar 175B panels.

                            Comment

                            • SunEagle
                              Super Moderator
                              • Oct 2012
                              • 15169

                              #15
                              Originally posted by inetdog
                              Absolutely right. If you figure that his 300 watt bulb has perfect efficiency in producing visible light (only off by a factor or 10 or so in that assumption) and all of the light goes directly toward the panels and spreads its energy uniformly over the panel surface, it would still be difficult to get 1000 watts per square meter of panel that way.
                              It should produce a measurable current just the same, assuming nothing else is wrong.
                              Agreed. He should be getting more than the 1 amp output even with just using the 300 watts. Issue is somewhere else.

                              Comment

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