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How connect 2 solar panels in parallel ?

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  • #16
    Dear All;

    I hope I am not wrong as for being quite a newbie in the field.

    What I have studied in the past few weeks on the web, as the amps goes up you have to take care of the wire, fuse and most importantly a charge controller that could support that amount of amps.

    So the question is; does your charge controller support that amps.

    Naeem

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    • #17
      Originally posted by Mike90250 View Post
      2 diodes are not enough to be bypass diodes, and "blocking" is so 60's, because all modern charge controllers provide the blocking function. Best ask the seller of the kit, what they are intended for, and maybe you can get a schematic of where they go.


      I use rectifying diodes on each one of my panels no voltage nor amp loss plus no power will return to my cells. they also work well with grid tie inverters so i got to say bye bye smelly batteries.

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      • #18
        Originally posted by boatdog357 View Post
        I use rectifying diodes on each one of my panels no voltage nor amp loss plus no power will return to my cells. they also work well with grid tie inverters so i got to say bye bye smelly batteries.
        Even if you use Schottky diodes for your blocking diodes, the voltage drop while carrying full current will probably be at least .6 or .7 volts. This may not be much, but it is not zero, and amounts to a 5% or more power loss on a 12 volt Vmp panel.

        They are not needed with grid-tie inverters either.
        SunnyBoy 3000 US, 18 BP Solar 175B panels.

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        • #19
          Originally posted by inetdog View Post
          Even if you use Schottky diodes for your blocking diodes, the voltage drop while carrying full current will probably be at least .6 or .7 volts.
          FWIW a Schotty Diode has an average forward VD of .3 volts. However it comes with a price.
          MSEE, PE

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          • #20
            Originally posted by Sunking View Post
            FWIW a Schotty Diode has an average forward VD of .3 volts. However it comes with a price.
            I was referring to the fact that although the forward conduction voltage is .2 to .3 volts, if you look at the volts versus amps curves in the specifications, then unless you use a greatly oversized, more expensive, diode, the forward voltage at rated current still ends up being around .6 volts.

            For a standard silicon diode with a forward conduction voltage of .7 volts, the actual drop near full rated current will be about 1.0 volts.
            There is internal resistance in the diode which is reduced primarily by increasing the size of the diode.

            Like most things, it comes down to what you are willing to pay for the extra power. And that will vary with the application.

            People who cannot tolerate even the .3 volt drop will do their reverse-voltage protection with a circuit involving a FET instead of just using a diode -- costing even more and introducing one more potential point of failure.
            SunnyBoy 3000 US, 18 BP Solar 175B panels.

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            • #21
              Originally posted by inetdog View Post
              Even if you use Schottky diodes for your blocking diodes, the voltage drop while carrying full current will probably be at least .6 or .7 volts. This may not be much, but it is not zero, and amounts to a 5% or more power loss on a 12 volt Vmp panel.

              They are not needed with grid-tie inverters either.
              ya but i hook my panels up parrell and if one panel cuts short of its voltage for any reason due to clouds or my batterie banks take over.
              it will drain my amps, or that panels cells will short out. I would rather deal with my 3% loss than fry one of my panels.

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              • #22
                Originally posted by boatdog357 View Post
                ya but i hook my panels up parrell and if one panel cuts short of its voltage for any reason due to clouds or my batterie banks take over.
                it will drain my amps, or that panels cells will short out. I would rather deal with my 3% loss than fry one of my panels.
                If in parallel and one becomes partially shaded the voltage will still remain constant. The AMPS will drop off however.
                Solar panels will produce full voltage on even a heavily overcast day or shadowed. It is the amps that they produce which are severely diminished.
                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]

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                • #23
                  Originally posted by Naptown View Post
                  If in parallel and one becomes partially shaded the voltage will still remain constant. The AMPS will drop off however.
                  Solar panels will produce full voltage on even a heavily overcast day or shadowed. It is the amps that they produce which are severely diminished.
                  So in your experience problems come up only when dealing with a damaged panel or string (bypass diodes shorted, etc.) or when the light actually goes to zero and you are getting into the reverse bias part of the cell characteristic curve? Even in the latter case, will it damage the cells or just drain the battery (if you have batteries)?
                  The first scenario is a reason for using a fused combiner, which does not drop much voltage under normal conditions compared to diodes, yes?
                  SunnyBoy 3000 US, 18 BP Solar 175B panels.

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                  • #24
                    Originally posted by rdlrn19 View Post
                    Hi

                    I want to connect 2 solar panels in parallel, I know that I need to connect the "positive with positive" and "negative with negative", but my question is about how do I connect them together?

                    I'm attaching an image to clarify my problem.

                    Do I need to wire with soldier? or how I connect together?

                    Thanks in advance
                    replying so i can see picture

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                    • #25
                      posting so i can view pic

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                      • #26
                        Originally posted by excursionist View Post
                        posting so i can view pic
                        Ditto with a newbier{{HARRUMMPH!!}}

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                        • #27
                          Originally posted by spektator View Post
                          Ditto with a newbier{{HARRUMMPH!!}}
                          Ditto ditto

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                          • #28
                            Yup me too, no Jpg.
                            Pete

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                            • #29
                              Originally posted by excursionist View Post
                              posting so i can view pic
                              Me too!

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                              • #30
                                me too

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