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  • Testing panel output

    Hi. I have a single solar panel which is rated at 250 Watts and 36V.

    I want to test the maximum watts output on a clear sunny day and most info suggests that I simply attach a 10A Multimeter to the + and - output cables coming from the panel however each time I try this it simply blows the Multimeter 10A fuse.
    Can anyone suggest a safer way to test the panels output.

    Also I need some advice on running a 24V5A water circulation pump direct from the panel without using a battery.
    I hope to use a Capacitor to overcome the extra current draw on start up and my idea is the pump would continue to run only when there is sufficient output from the panel.

    Appreciate any help offered

    Thanks

    Farticus123

  • #2
    Look at the label on the back of the panel, what are the number for these 2 values
    Isc _______ (short circuit amp)
    Imp _______ (max power amps)
    Then we will know if you can use a 10a meter to measure it.
    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
      Thank you

      ISC 9.58A

      IMP 8.33A

      Comment


      • #4
        If you measure a single 9.58A panel at a time, it should not blow a 10A fuse So try getting a slow blow 10A fuse and use it for this test only. Just one panel at a time. Maybe, if you feel adventurous, try a 12A or 15A fuse. I don't see how a 9.58A panel can blow that, but again, I'm not there to verify you are setting this all up properly.

        BE sure to re-configure meter after measuring amps, or you can mistakenly leave the leads in the amps jack and get a real flash bang surprise when you measure battery voltage.
        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


        • #5
          Thanks for the info, Problem wss I must have previously blown up the Amps testing innards of both Multimeter.

          Tried out a borrowed one and it worked just fine 9.7 A.

          Any answers on the second part of my question about running the 5A water pump direct from the solar panel without a battery in the circuit.

          I am using a buck boost converter to maintain the volts at 24V as much as possible and using a Capacitor to help with the Motor Start.

          Comment


          • #6
            Originally posted by farticus123 View Post
            ......

            Any answers on the second part of my question about running the 5A water pump direct from the solar panel without a battery in the circuit.

            I am using a buck boost converter to maintain the volts at 24V as much as possible and using a Capacitor to help with the Motor Start.
            a simple buck-boost will not work, unless it's solar aware and works with a current source (PV panels are current sources, not voltage sources)

            What you want is a LCB ( Linear Current Booster ) most large / good solar gear vendors carry them, they are rated for the motor load they power, they have their own storage capacitor, do not use an external cap with them.

            Google solar LCB

            http://ieeexplore.ieee.org/document/...6/?reload=true abstract of longer article
            Last edited by Mike90250; 02-06-2018, 02:10 AM.
            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


            • #7
              Thanks Mike for your help.

              I have one more question but I will start a new thread as it differs from this discussion.

              Comment


              • #8
                Originally posted by carmelinasweeney
                Find the voltage and current ratings of the panel by checking the back of the device.To obtain the rated output that is mentioned on the panel, there should be optimum sunlight.Understand how a multimetre works.Then set it for the appropriate requirements...
                Sanity check yes, but that isn't enough to do the job. A load is needed to see if the approximate MPPT
                voltage will result in expected current. I have more than one panel set aside which passed sanity but
                could not pass the load test. it happens because a section may go into bypass under full load.

                I am not a fan of connecting multimeters as ammeters in solar circuits. Connecting-disconnecting may
                result in dangerous arcs, and an error can easily blow the meter. I wire a shunt into the circuit when
                inactive (at night) and observe its voltage output operationally. A clamp on DC meter also works.
                Bruce Roe

                Comment


                • #9
                  After reading carmelinasweeney's posts this morning I have to question his/her motivation. Something not quite right in all the simplified replies. I guess time will tell .
                  2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                  Comment


                  • #10
                    Originally posted by littleharbor View Post
                    After reading carmelinasweeney's posts this morning I have to question his/her motivation. Something not quite right in all the simplified replies. I guess time will tell .
                    BIG +1 on that one.


                    Carmelita: Further to what Butch & Littleharbor write: I'd respectfully suggest you read old threads and get the lay of the land before you comment. So far, a lot of your stuff looks like a repeat of the popular fiction pollyanna reality of treehuggers and the treehugger press who are short on experience and education and long on ill- or non-informed half truth/half wishful thinking.

                    Welcome to the neighborhood and the forum of few(er) illusions.

                    Comment


                    • #11
                      Originally posted by farticus123
                      Any answers on the second part of my question about running the 5A water pump direct from the solar panel
                      without a battery in the circuit. I am using a buck boost converter to maintain the volts at 24V as much as
                      possible and using a Capacitor to help with the Motor Start.
                      A buck boost is a poor solution, when the motor voltage drops off (lack of panel output) the boost will try to
                      bring it up, which will just flatten the panel output. A linear current booster might be the ultimate solution,
                      but perhaps you are worried about over voltage on the motor. If you use a simple buck converter, it will
                      very efficiently limit the motor voltage when power is available. When panel output can't maintain voltage,
                      a typical buck will just switch on continuously, in effect connecting the panel directly to the motor. This will
                      allow the motor to run at reduced power. Bruce Roe

                      Comment


                      • #12
                        Originally posted by carmelinasweeney
                        Find the voltage and current ratings of the panel by checking the back of the device.To obtain the rated output that is mentioned on the panel, there should be optimum sunlight.Understand how a multimetre works.Then set it for the appropriate requirements...
                        carmelinasweeney - re-posting previous data is not improving the quality of this forum, and just raises the noise level.

                        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

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