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Rbertalotto's avatar
Rbertalotto
Explorer
May 20, 2014

Solar Panel Problem?

Last year I installed a 120w solar panel and a SunSaver 20L controller to my Truck Camper.

To monitor the system I installed a TRIMETRIC TM2025-RV / TM2025-A BATTERY MONITOR.

And to read the voltage and current directly from the solar panel I installed a simple panel mount meter and shunt.

Here is the SunSaver install:


And here is the Trimetric and the small V/A Meter:


The Solar Panel's neg lead goes through the panel meter shunt before it is connected to the SunSaver

The SunSavers neg output is run through the Trimetric's shunt before it is connected to the battery.

My problem is I'm not seeing any current from the solar panel. Even if I bypass the panel meters shunt I still see no current on the Trimetric.

When I substitute my battery charger for the solar panel, the trimetric reads positive amps flowing into the battery. With just the solar panel on a bright sunny day I'm seeing 21-24 volts, but no amps.

I'm starting to think the solar panel is defective.

Any ideas?

37 Replies

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  • BFL13's avatar
    BFL13
    Explorer II
    May 20, 2014
    The panel has its own voltage and amps ratings. It will be on its label on the back. A 120w panel will be about 7.6a Isc and 22v Voc.

    You can only measure these by shorting the panel with your meter across the panel pos and neg. When you put your meter across these with the controller /battery still connected you get no amps to the controller/battery because the panel has been shorted. (no harm to panel doing that BTW)

    To see the amps to the battery just use the Trimetric. With PWM controllers you will get close to Isc of the panel to the battery anyway, so no need to measure Isc as such unless doing a panel test of some sort.
  • 2oldman's avatar
    2oldman
    Explorer II
    May 20, 2014
    Rbertalotto wrote:
    I have no idea what Isc is. Could you explain?
    Isc= current.
  • time2roll's avatar
    time2roll
    Nomad
    May 20, 2014
    Isc = panel short circuit amps. s/b listed in the panel specs.

    You had verified Voc (open circuit voltage) so verify amps and you can know the panel is good.
  • MrWizard's avatar
    MrWizard
    Moderator
    May 20, 2014
    That looks "incorrect" to me

    You need a battery negative connected to the trimetric power input negative

    Power positive and negative for meter must come from battery
    In your drawing I only see two positives to the meter
    Meter power must be from battery, not solar panel positive
    Both wires from battery pods and neg for meter operational power
  • Rbertalotto's avatar
    Rbertalotto
    Explorer
    May 20, 2014
    I believe you need to have the shunt in line with battery ground (-) and frame rather than the controller's ground to the shunt.


    There is no "frame" so to speak. A wood framed camper. I believe I have the shunt connected properly

    Do you have a meter to verify the panel Isc?


    I have no idea what Isc is. Could you explain?

    Here is how I have the V/A meter wired with the panel as the "6a Charger" and the SunSaver inputs as the "Battery"

  • westend's avatar
    westend
    Explorer
    May 20, 2014
    I believe you need to have the shunt in line with battery ground (-) and frame rather than the controller's ground to the shunt.

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