Solar Panels not working

pilot1each
pilot1each Member Posts: 11
in Battery/Electrical & Solar

I have a TAB 400 BDBC purchased in 12/2025. It has Two 100 AH Battleborn batteries. All Victron products firmware is up to date.


I just finished dry camping in the Redwoods at Jedidiah Smith SP. There was little sun.  The batteries SOC when we departed the campground was 23%.  It is a cloudless day.

We arrived at or next destination SOC was 20%.  The solar controller never attempted to charge the batteries.

We have been on a 5 week trip mostly plugged in to shore power.  During our transits in good solar conditions I have noticed the solar output has been diminishing. September 8-10 cloudless skies with few obstructions.

How can I troubleshoot to ascertain if the panels are bad or the Victron MPPT has failed. Is it possible to reset the MPPT?

Here is a screenshot of the MPPT history 

image.png

Comments

  • Horigan
    Horigan Member Posts: 915

    On a sunny day I would use a voltmeter to confirm the solar panel voltage reading from the Victron app matches what you get when you probe the solar input terminals at the controller. If they match and it shows very low voltage, as shown above, I would check the fuse on solar power line and also check the voltage on the input side of the fuse holder. If those all read low, then that would point to the panels being bad.

    If the measured solar input voltage is different from what the Victron app shows, then the controller is bad.

    Rich
    2019 T@b 400
    2025 Toyota Highlander 2.4L Turbo
    Bellingham WA
  • aditto
    aditto Member Posts: 13

    Our 2025tab 400 bd solar panels went bad and are currently being replaced by the dealer. Could you show the app screenshot where it shows hourly solar generation chart from a clear day? We found that our panels won't charge in the middle of the day between 12-3pm. In California also. Fell free to message me

  • pilot1each
    pilot1each Member Posts: 11

    Here is a screenshot of the last 30 days

    IMG_0512.png
  • lyrawinslow
    lyrawinslow Member Posts: 2

    That screenshot actually helps narrow this down quite a bit. The MPPT is showing only 0.04V PV and 0.00A, while the battery is at 13.74V, so the battery side appears to be connected but the controller is basically not seeing the solar array.

    Since you mentioned the solar output had been gradually declining even during clear days, I’d troubleshoot the PV side before assuming the MPPT has failed. I’d start with the PV disconnect/breaker, fuses, MC4 connectors, and the roof wiring. If you have a multimeter, check the PV voltage directly at the MPPT while the panels are in full sun. If there’s no meaningful voltage there, work backward toward the panels and wiring. If you have proper PV voltage at the controller but it still reads around 0.04V, then I’d start looking more closely at the MPPT.

    I’d also check the Victron history/logs to see when it last detected PV and whether the output was progressively dropping. Since the system was producing around 26kWh previously, it clearly has worked, so I’d look for a failed connection, fuse, disconnect, or other PV-side issue before replacing the controller.

    I’ve also been looking into solar panel kits from Off Grid Stores for a separate setup, and one thing I’ve learned is that checking the actual PV voltage at the controller is one of the quickest ways to separate a panel/wiring problem from a controller problem. I definitely wouldn’t replace the MPPT until that voltage check is done.

  • andytabrv
    andytabrv Member Posts: 51

    Some things to check in addition to what is mentioned here.

    1. Be sure the MPPT is setup correctly for the batteries. Mine was not setup correctly from the factory. There are a few topics on this forum with the correct setup. Here is a link with the settings directly from BattleBorn's website. This discrepancy could cause the controller to stop charging the battery if it is detecting the wrong voltage levels.

    2. My 2024 T@B was one of those that had the batch of bad panels (not nuCamp's fault). nuCamp replaced them under warranty even after my year period had expired. I saw odd behavior like you were describing they would sometimes appear to work then not. I used a voltmeter to verify they were not producing the necessary voltage at the MPPT controller input.

    Hope this helps and good luck!! Report back here what you figure out as that will help the hive mind 😁.

    2024 T@b 400 BD  "Tabba the Hut" 
    2022 Nissan Pathfinder
    Cary, North Carolina

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