Wiring a Watts Up Meter

The Only Sarge
The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
in General Solar Power Topics #1
I have the Watts Up meter "Source" on the Morningstar 20 am controller's solar panel input.
I have the "Load" on the battery terminals output from the controller.
It is reading volts from the batteries that jive with my meter.....but....only showing amps being drawn from the batteries.
I want to read the volts/amps from the panels....I have googled until my eyeballs fell out and rolled across the floor on how to wire a watts up to read input from the panels. Any help would be appreciated very much.
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #2
    Re: Wiring a Watts Up Meter

    I am wondering if I should connect the Source side to the connectors off the solar panel (at the combiner box) and not at the controller solar panel input. I dunno...may be (hopefully) somebody has already skinned this critter.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Wiring a Watts Up Meter

    Wired between the charge controller's output and the batteries it will show the Amps flow from the controller to the batteries, not out of the batteries. This is the number that matters as it is the charging the batteries are receiving. As for wiring it between panels and controller, I doubt it's designed for that. Not much advantage in that number as it would only differ from the other by the loss in the controller.

    I could be wrong, as I don't have one of these. The big, expensive MPPT controllers meter both incoming and outgoing current, but then there can be a marked difference using them.
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #4
    Re: Wiring a Watts Up Meter

    Thank you for your reply.
    But are we saying the input from the panels is not reflected at all?
    Just the output of the controller to the batteries? Which is what I am seeing.
    I see all these youtube videos showing watts up meters reading solar panel input....but of course no wiring on how they did it :)
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Wiring a Watts Up Meter

    It can only read one or the other, that's for sure, and what goes into the batteries is the important one.

    In theory:

    "12 Volt" panel -> source WATTSUP load -> charge controller -> batteries

    Would read output from panels. But why do it? In the case of a PWM charge controller the difference would be Watts from panels - controller loss = Watts to batteries. Since there is no downconverting as with MPPT the difference would be minimal. And if you do have the MPPT controller you get the meter and read both (with a few exceptions - the smaller capacity units skip this).

    You could buy two Watts Up meters and put one on the in and one on the out, see a difference of 2%, and realize you just wasted your money on a second meter. :roll:

    Not aimed at you, but some people are obsessed with measuring system function at every stage. And they like to post videos about it on Youtube. :p
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #6
    Re: Wiring a Watts Up Meter

    I think I have it now. Yes...I am in the curious George stage with this solar stuff.
    Thank you again for your reply. I appreciate it.
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #7
    Re: Wiring a Watts Up Meter

    I just put the watts up meter with the panels into the source side of the meter and then connected the load side of the meter to the solar panels input of the controller.
    It is telling me the input from the solar panels now.
    I have a battery meter and I can already tell what is happening with the battery bank....I just wanted to see what these Kyocera panels are putting out compared to the other panels that are paralleled via a Morningstar controller that has a display.

    I know I know :)
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #8
    Re: Wiring a Watts Up Meter

    OK...I am reading less than 1.3 amps and 17.93 volts coming from the Kyocera 130 watt panel....my batteries are at 14.1V according to the Monringstar controller. Again....I am reading directly from the panels in full sunlight. When the batteries were charging this morning (not full sun or direct sun should I say) the panels read 5.6 amps and 17.XX volts.

    This is one of the things I wanted to see.....so if I understand this correctly the charge controller is "shorting" the panel?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: Wiring a Watts Up Meter

    The batteries are at 14.1 Volts: they don't need any charge current. They don't need any charge current, the panels don't produce any charge current.

    Turn a load on and see what happens.
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #10
    Re: Wiring a Watts Up Meter

    I'm learning now.....so the charge controller does/can "short" the panels then?
    I wanted to see it....I assumed (we know the first three letters of that word) that a controller would just "regulate down" the input voltage to a trickle or altogether shut it off....but it appears it can actually manipulate the output voltage back at the panels? Correct?
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #11
    Re: Wiring a Watts Up Meter

    Yup...cranked on/up the surround sound system in the shop @140 watts and voila....she shot up to 5.9 amps and the voltage went from 17.XX to 13.XX....

    I am slowly "getting it"...sorta like learning cam grinds :)
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #12
    Re: Wiring a Watts Up Meter
    The Only Sarge wrote: »
    I'm learning now.....so the charge controller does/can "short" the panels then?
    I wanted to see it....I assumed (we know the first three letters of that word) that a controller would just "regulate down" the input voltage to a trickle or altogether shut it off....but it appears it can actually manipulate the output voltage back at the panels? Correct?

    No. A PWM type charge controller connects/disconnects the panel output to the batteries. When the batteries come up in Voltage it does this rapidly: pulsing (the 'P' in PWM).

    The "magic" here is the panels themselves, which are a current source rather than a Voltage source. Put just a little light on them and the Voc will shoot right up. Apply a load and the Voltage drops like a rock until enough light gets on them to produce enough current to overcome that load and push the Voltage back up. A discharged battery is low resistance: draws a lot of current. A charge battery is low resistance: draws little current. The sweet spot is where Vmp meets Imp and the output becomes maximum Watts.
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #13
    Re: Wiring a Watts Up Meter

    I got it. Thank you. Now I understand.......a light just went off.....
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #14
    Re: Wiring a Watts Up Meter

    When I got my MorningStar SunSaver charge controller, the manual was very specific that it does not 'short' pv panels, but it did imply that other types of pwm controllers do.
    The Only Sarge wrote: »
    I'm learning now.....so the charge controller does/can "short" the panels then?
    I wanted to see it....I assumed (we know the first three letters of that word) that a controller would just "regulate down" the input voltage to a trickle or altogether shut it off....but it appears it can actually manipulate the output voltage back at the panels? Correct?
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #15
    Re: Wiring a Watts Up Meter
    bmet wrote: »
    When I got my MorningStar SunSaver charge controller, the manual was very specific that it does not 'short' pv panels, but it did imply that other types of pwm controllers do.
    I am talking about that exact controller. I have the watts up meter reading just the PV panel. When the batteries are fully charged the power coming from the panels is significantly reduced. How they do it ...I dunno....
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  • bluewickedburner
    bluewickedburner Solar Expert Posts: 78 ✭✭✭✭
    #16
    Re: Wiring a Watts Up Meter
    Cariboocoot wrote: »
    The batteries are at 14.1 Volts: they don't need any charge current. They don't need any charge current, the panels don't produce any charge current.

    Turn a load on and see what happens.

    That you for that, I was wondering about that myself. To be real clear then, when the battery doesn't need charge the charge controller doesn't send any even though the panel are producing. That current stops at the charge controller right?

    Then say you wanted to see if a panel was producing independent of the charge controller or if the batteries didn't need current, measure at the panel correct? I ask because on a motorhome, the engine alternator usually charges the batteries while traveling point to point. Sometimes things can and do go wrong because everything moves around, maybe you caught a rock that got thrown up (happens). At station you would read the current between the panel and the controller and in good sunlight that reading would confirm they were more or less ok?
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #17
    Re: Wiring a Watts Up Meter

    That is what I thought. That the current still was being produced by the PV panel and being "stopped" at the controller. Nope. I am monitoring from the panel. When the battery bank is full the panels output is reduced at the panel.

    When I put a load on the system the panel instantly starts sending power.

    I am not measuring anything at the controller.
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #18
    Re: Wiring a Watts Up Meter

    Or maybe I am really measuring what the controller is pulling from the panels.
    Oh heck.....now I am confused again :)
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #19
    Re: Wiring a Watts Up Meter

    Panels don't actually produce anything without a load attached. They sit there full of current potential and do nothing with it. No circuit, no current can flow. The completed circuit is panel to battery and back, through the charge controller. The charge controller senses the battery Voltage and disconnects the panel; current stops flowing. During Bulk charging the PWM controller will allow everything the panel(s) can put out to flow through the batteries. When Absorb is reached the controller switches on and off to maintain the Voltage level, effectively reducing the current. If you could take a snapshot of the current when it's flowing it would still be full Amps, but for a fraction of a second. Meters can't see this; they see an average of zero Amps plus full Amps weighted according to how often it is on and off and for how long.

    The difference in current on the input side of the PWM controller and its output is how much power is lost within the controller (circuitry requires power; it will use some). This is not the same as the cheap controllers that clamp the Voltage to a certain level, draining surplus current potential to ground.

    This is not an easy thing to understand. Nor, I regret, is it easy to explain.
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #20
    Re: Wiring a Watts Up Meter

    Of course....no circuit= no nothing.
    Thank you for explaining to a 2nd grade level for me.
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