Solar panel appears dead on 2024 Tab 400 Boondock - appreciate some input

Trudy · February 11

Tomorrow I am due to get with the seller and take delivery of the 2025 tab 400 HB. He has allowed me to see the Cerbo Gx readout remotely for the last 2 months and the solar panel's output seems very diminished to me. During the height of the sun on a sunny day the output is only in the 30s 40s and maybe 50watts. For two 310W panels totaling 620 W that seems too poor to be acceptable, what should I do? Will I be caught with seriously underperforming panels and nucamp telling me that's normal, just live with it?
Thanks for your opinions and feedback, I appreciate it.

pthomas745 · February 11

Unless you know exactly the position of the trailer in relation to the very low sun angle during the winter, this will be difficult to sort out. There can be many variables in solar input for roof panels.

You would need to match the Victron readouts from the solar controller while you are looking at the panels, if that is possible.

andytabrv · February 11

It would be helpful to know if that value is related to how full the batteries are. If the batteries are just doing their daily top-off (as they are full) and the value you are seeing is how much wattage they are pushing into the battery you may naturally see a limited amount. With the Victron Solar Controller app, the default view (at least on my 2024 Tab) defaults to how much wattage the panel is pushing into the batteries. So, if they are full you may even have the occasional day (particularly a warm one when the battery heaters haven't used any juice) that no solar gets used at all.

A good way to get a general read is (1) ensuring the camper is positioned "relatively" well to receive sunlight, (2) Turn on lots of juice hungry things in the camper like fridge, fans, lights, and the inverter, and (3) take a look at the what the shunt is reporting being pulled from the batteries. Then you can see what the controller is being reported as being supplied and get an idea of how well the solar panels are keeping up supplying the load.

Remember the solar panels on the 400 are curved. So, it's really hard to get the full wattage, even with the sun directly overhead.

vttj · February 14

Hello everyone. I am glad to report after starting this thread in August of 2025 my solar panel is now replaced. Nucamp did warranty the panel. I have a few questions though if others could support and also a point to be aware of.

First item. I have yet to see if my solar panel can output 310W. On the VictronConnect app I am actually getting very little watts. I tried to show more wattage by running lights and fridge but could only get to 100W on a sunny day but camper was not aligned properly to sun and at full charge. My question is if the battery is fully charged will it reduce the drain of wattage hours and also the wattage that the VictronConnect app reads. Has others confirmed they get 300W out of the new panel? Is the only way for me to do this is drain battery down a decent amount?

Second item. I was impressed and surprised how quickly the panel was replaced. Dealer had it done in a couple hours. I expected the panel was glued on but it is taped on. I was also surprised that the top of the camper has a very large hole bigger than your hand, in the shell for the controller on the back of the panel. This I could see being a problem in the future if the seal is not done correctly as it is hidden by the the panel. The fan you can inspect if seal breaks down around it. With that said one camper serviced by the dealer ahead of mine, the tape did not hold and panel came up. On mine it appears to be holding as suspect they took more care. There is one spot where it seems to not as flush to camper shell as other spots but I don't think it risks the water seal as it seems intact. Does make me a bit nervous of the item blowing off the camper while going down the road. Has anyone else noticed the tape not holding the panel flush?

Again like to thank Nucamp for taking care of this panel as this unit was just on the outside of warranty. They knew they had an issue and didn't dodge it. Makes for a good customer and glad I stuck with the brand going from 320 to the 400.

Appreciate the support on confirming panel is can preform at 300W or if I am approaching this wrong.

pthomas745 · February 14

Solar panel "wattage" ratings are based on test conditions that are not really applicable to "real world" conditions. You will "probably" never see 300 watts being directed to the controller. On probably the best possible day I ever saw on my older 100 watt panels, I might have seen 70 watts, or about 6 amps going into the battery. Generally, the idea is that solar panel "ratings" are only realistic under those "tested in a lab" conditions.

You should be thinking of what the charging the panel/controller is capable of sending to the battery. "Generally", under good conditions, each 100 watts of solar panel might be able to provide 8 amps of charging to the battery. In theory, your 310 watts of solar might be able to provide 24 amp hours to the battery under good solar conditions. There is a downside to having panels on a curved roof: part of the panel may not be in a position to gather as much sunlight as other parts of the panel more aligned to the sun.

My 200 watt solar setup "maybe" has sent 10-12 amps to my battery on a decent day.

The state of charge of the battery also has a lot to do with hot much power is going to the battery. When a battery is in "bulk" or the "absorption" stage of charging, the battery can charge at a higher rate. As the battery voltage increases, even on that perfect solar day, the amps that the battery can safely take is reduced considerably. So, yes, what you are seeing for slower charging rates might be limited by the status of the battery.

There are several threads about removal of solar panels on the first generation of installed panels, or removal of panels installed by owners. Using "glue" to attach the panels became a nightmare when the panels needed to be removed, and "double sided tape" became the norm.

This was a "dealer installed" panel that was glued on.

https://tab-rv.vanillacommunity.com/discussion/11493/flexible-solar-panel-removal

The hole in the roof is designed to position the small "junction box" on the back of the panel where the wiring for the panels drops into the trailer.

You are correct to be concerned about the panel "lifting" where the tape might not be close to the edge of the panel, and I would keep a close eye on that.

GordoB · July 5

I'm hoping to tap into the experience of other 2024 TAB 400 Black Canyon owners with the factory-installed Victron solar system.

I've been working directly with nuCamp Technical Support for the past couple of weeks, and they've been very responsive, but we haven't yet identified the root cause. I'm hoping other owners may have seen something similar.

My trailer

Factory-installed flexible roof solar panels (nuCamp advised mine are Sunflare Flex SI310 310 W panels)
Two roof panels
Victron SmartSolar MPPT 100/50 controller
Victron SmartShunt

Symptoms

The solar system behaves very strangely:

Solar charging works normally during parts of the day.
During the brightest / warmest part of the day, the Victron controller frequently changes to State = OFF and charging stops.
Later in the afternoon or evening, the controller often wakes up on its own and resumes charging.
This pattern has repeated over multiple days.

Diagnostics completed

With the help of an electrical engineer (and a lot of patience!), we've completed quite a bit of troubleshooting:

Battery side of the MPPT is normal.
Inline PV fuse tested good and was replaced as a precaution.
MPPT communicates normally via Bluetooth.
We disconnected the incoming PV wiring from the MPPT and measured the incoming panel voltage directly.
During one failure event, the incoming PV wiring measured only 0.6–0.7 V, suggesting the controller was not receiving usable voltage from the solar array at that time.

I've also discovered what appear to be concealed factory wiring connections behind the cabinetry, but they are not accessible without disassembly.

I'm hoping to learn from other owners

Has anyone experienced similar symptoms, especially charging that fails during the hottest part of the day and later recovers?
Has anyone had the factory roof panels replaced under warranty? If so:
- What was the actual failure?
- How did nuCamp diagnose it?
- Was it the panel itself, wiring, junction box, connector, or something else?
Can anyone confirm where the factory roof panel wiring is connected on a 2024 TAB 400?
- Behind the radio?
- MC4 connectors?
- WAGO connectors?
- Another hidden junction?
Has anyone removed the interior panels and taken photos of the factory solar wiring? Those would be incredibly helpful.
If you have the same system, what PV voltages do you normally see on your Victron controller during a sunny day?

I'm communicating with nuCamp and they've been trying to help throughout this process and I'm trying to determine whether this is an isolated issue or something that other owners have already solved. If I get to the bottom of this with nuCamp, I'll gladly post the solution here so future owners can benefit.

Thanks very much!

Gord

SavvyNurseCamper · July 11

@B0atguy Will be interesting to see the new panels I get to replace my current panels from my 2025 Tab 400 BC. BD. I had the DC to DC charge controller installed as well so I can get a full 50 amps coming to my Trailer while driving In addition to having a single 460 amp hour battery installed that is lighter than the 4 100 amp batteries I had previously .

Horigan · July 11

To get 50 amps safely from the TV alternator to the trailer battery through a DC DC charger you need at least 6 AWG wire for the whole run. Is that what you installed?

SavvyNurseCamper · July 12

@Horigan Yes , While they were at it upgraded the off switch which was too small for the Inverter and put in bigger breaker for the whole system. I had MEL hinge the door for the battery compartment and put a strap on the Alde compartment cover to make it easier to access when flushing the system . Someday want to see a better way to keep that cover secure without using the screws. MEL will now just use 2 screws for the Alde compartment.

Horigan · July 13

@SavvyNurseCamper My concern is the wire diameter from the TV alternator or battery to the trailer. The standard wire run through the trailer connector and trailer wiring is 10AWG, which has a 2.5mm diameter conductor and supports 30 amps. If you try to drive 50 amps through that wire it will overheat and have excessive voltage drop, thus being a hazard and defeating the function the charging. If you're going to drive 50 amps to the trailer, you need a dedicated 6AWG (4.1 mm diameter conductor) wire all the way back from the TV battery to the DC DC charger, including through a dedicated electrical connection across the tow hitch.

SavvyNurseCamper · July 13

@Horigan Thank you for your concern. I checked with MEL Trailer and yes indeed it is 6AWG throughout the truck and the trailer. They did excellent work installing it. MEL will become the west coast NuCamp repair shop besides the one in San Diego. While I was there I met the director for Airstream that was extremely happy with the work happening at MEL trailer. If you ever need work done on your tailer let me know and will send you their contact information . 😉

SavvyNurseCamper · July 13

Plug used to pass the power to the trailer.

Hitch I am using to tow my trailer . It is fantastic.

Horigan · July 14

Excellent!

Solar panel appears dead on 2024 Tab 400 Boondock - appreciate some input

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My trailer

Symptoms

Diagnostics completed

I'm hoping to learn from other owners

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