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!

aditto · July 16

https://tab-rv.vanillacommunity.com/discussion/comment/222224#Comment_222224

I am having the exact same issue. I don't know how long it's been going on but I just discovered that my panels are going down to zero sometime between 11am through 3-4 pm regularly. The app says mppt is in off state since solar voltage needs to be 5V above battery voltage. I can't tell if this is a shadow related issue or panel issues. I'm going to take my camper on a trip this weekend to see what happens on the highway so I can isolate any shade issues from my drive way.

However when I copy pasted your issue in Gemini I got the following information suggesting this might be a loose soldering getting affected by thermal expansion. Aka panel failure needing replacement. Lets stay connected.

Pasting the Gemini response here -----

It is incredibly frustrating when a premium solar setup decides to take a nap during peak sun—the exact time it should be working the hardest.

The symptoms GordoB described on the T@B Forum point to a very specific, physical culprit.

### The Likely Culprit: Thermal Expansion

When GordoB measured the incoming PV voltage during a failure and saw only **0.6V to 0.7V**, it confirmed that the MPPT controller isn't the problem—the panels simply stopped sending power.

Because this happens specifically during the hottest, brightest part of the day and recovers when it cools down, it is highly likely a **thermal open circuit**:

* **The Heat Expansion Effect:** As the flexible Sunflare panels sit in direct midday sun, they absorb massive amounts of heat, causing the materials to expand.

* **The Broken Connection:** This thermal expansion pulls apart a weak solder joint or a failing connection inside the panel's internal cell matrix, the bypass diodes, or the junction box on the roof.

* **The Cool Down Recovery:** As the sun goes down and temperatures drop, the materials contract, the physical connection re-establishes, and the panels suddenly "wake up" and start working again.

### What This Means for You

1. **It’s Likely a Hardware Failure, Not Settings:** You can tweak your Victron MPPT settings all day, but if heat is physically breaking the connection inside the panel, the only fix is replacing the physical panel.

2. **Warranty Support:** Other members in the thread, like SavvyNurseCamper, mentioned that nuCamp has been replacing these panels under warranty. NuCamp is well aware of the issues with certain batches of these flexible roof panels.

3. **Confirming Your Issue:** If you want to prove this is your exact issue to your dealer or nuCamp:

* Open your **VictronConnect App** when the system goes "OFF" in midday heat.

* Check the **PV Voltage (V)**. If the battery is depleted but the PV voltage is sitting near 0V while the sun is blazing, you've caught the thermal break in action.

SavvyNurseCamper · July 16

@aditto take it back to the dealership where you purchased it. Have them pull the refrigerator and behind that are the wires coming from the roof where your solar panels are. They can hook up a solar watt meter and measure the watts directly coming from the panels. One of mine was 0 and the other was producing 64.4 watts till it heated up and then stopped producing any power at all.

aditto · July 16

https://tab-rv.vanillacommunity.com/discussion/comment/222360#Comment_222360

Not driving it back to Blue Compass Las Vegas from San Francisco for this (they were nice to me when I bought it but it's just too far). I need to find a different solution/dealer nearer. I replied to your other thread.

Looks like it's a thermal expansion issue.

GordoB · July 16

@aditto I initiated a service ticket with Nucamp. They need to approve a warranty replacement in conjunction with a Nucamp dealer. I can send you my info package ( built with ChatGPT assistance ) which detailed all of the symptoms, Victron screen shots, as well as photos of blemishes on the panels…which I believe these are the most indicative symptom the failed Sunflare panel issue.

aditto · July 16

https://tab-rv.vanillacommunity.com/discussion/comment/222368#Comment_222368

I'll try to send you my email address via private message. Thank u sir

RockyRichard · July 16

We have a 2024 TAB 400 on which both panels failed in June 2025 (0V output). After reading warranty info (nüCamp 1 yr, SunFlare Panel 2yr) and numerous calls to nüCamp and WindishRV (Denver dealer), it was decided that I needed to drop the trailer for 4 weeks at Windish for "testing and diagnosis." We had numerous camping season reservations, so we elected to wait to end of season (October), and I installed a temporary system (pix below some DIY wiring involved). It worked exceedingly well (maxed at 200W from 2 100W Suitcase Renogy panels).

I delivered the trailer for diagnosis on October 6. By mid October WindishRV and nüCamp determined the panels had indeed failed and that the SunFlare warranty would be honored at least for cost of panels (~$800; labor to replace would be ~$1000). Panels were ordered and trailer came home to wait. nüCamp finally delivered replacement panels to Windish about February 1. Windish had them installed by February 6, and checkbook in hand I retrieved our trailer. Amazingly, Windish had convinced nüCamp that labor should be covered also. So, out the door ($0). They have worked well (400W max so far).

My story and sticking to it.

Portable Solar System Cost (All from Amazon)	$460.17
Renogy 100W Portable Lightweight Solar Suitcase (x2)	$268.67
Victron 75\|15 Controller	$71.50
Wires Fuses Adapters	$120.00
SAE to MC4 Adapter (Battery to Controller)		$13.37
Controller MC4 Pigtails (x4)		$13.37
Fuse 1000V 20A MC4 Fuse Holder (x2)		$26.46
MC4 Y-adapters (x2-Connect Panels)		$10.00
3ft MC4 Solar Cable-Connect Panels		$13.42
20ft MC4 Solar Cable-Y-adapter to Controller		$26.48
MC4 Connector Wrenches (x2)		$6.82
Solar Connectors (x8 w/ 2 Wrenches)		$10.08

2024 TAB 400 BC 2024 Subaru Ascent Premium Denver and CO Rocky Mtns and CO Plateau

Horigan · July 17

I'm surprised they didn't install fuses at the positive wires coming out of the controller. I would add 30A fuses there.

Marceline · July 17

https://tab-rv.vanillacommunity.com/discussion/comment/222362#Comment_222362

If you're in Northern California I would recommend calling the people at Vogel's RV in Ukiah. They are a NuCamp dealer and have a very strong reputation in this area.

https://www.vogelsrvs.com/parts-and-service

aditto · July 17

https://tab-rv.vanillacommunity.com/discussion/comment/222386#Comment_222386

Thank you. Yes on my radar! I met with them at Oct@berfest last year and probably the most likely option we will go with.

SavvyNurseCamper · July 18

@RockyRichard So the solar port where you tied into in the Nautalis well is suppose to go straight the the Solar Charge controller inside the camper. Was the one inside not working ?

RockyRichard · July 19

@SavvyNurseCamper Sorry if you (or anyone else) are getting double msgs. I'm not real savvy on posting protocols in a forum setting.

When decided to use temp solar after the panels on the roof bellied up, I spoke with nüCamp rep (probably Jordan Brown) about the external solar connection plug in the Nautilus box (mainly I wanted to know polarities). He explained that it connects directly to the battery, not the solar controller installed by nüCamp for the trailer's roof solar panel(s). You must have a separate controller that feeds to the solar connection plug in the Nautilus box if you are going to use external solar panels. (He sent me the pic below that I annotated.) The Victron 100/50 Controller for the roof panels works splendidly (when the roof panels are working).

SavvyNurseCamper · July 19

@RockyRichard that is interesting. Mine was hooked to the charge controller . It sits right next to the Alde 3030+. Originally when I was given the trailer from Blue Compass I was told it was disconnected . It was not!

RockyRichard · July 19

@SavvyNurseCamper

I'm in a 2024 TAB 400 Black Canyon. I guess they rerouted the wiring for 2025 models, which may deserve an email to tech@nucamprv.com asking whether there are any limits/restrictions on the external solar panels plugged into the solar port. Response times to my queries have varied from an hour to a week. In the email, I suggest briefly explaining the wiring differences between the 2024 and your 2025 (I have found a couple of instances on my TAB where things were not where they were supposed to be).

SavvyNurseCamper · July 20

@RockyRichard they can't even provide a Manuel . For 50 grand plus you would think that were possible. I have had to print my Manuel and ask for each thing which as you pointed out takes time. They want you to pay to learn about your tailer. I refuse to do that. 😉

Marceline · July 20

https://tab-rv.vanillacommunity.com/discussion/comment/222429#Comment_222429

The Victron SmartSolar MPT 100 | 50 has only one terminal for battery connection. Are you saying that both the roof panel and the SAE port were wired to the same solar controller? That doesn't sound right and that doesn't sound like something that would've been done at the NuCamp factory.
Manual

B0atguy · July 30

Just some more observations on the 310w solar panels that were installed on the 400's .

We had nuCamp install a 2nd 310w solar panel (on the front) on our 2024 400 (have a non - Black Canyon 400) in the fall of 2025 while at the factory for some warranty work . We did notice that the original rear 310w panel , and the new front 310w panel were definitely different . The new front panel was working better than the original rear panel , but NuCamp tested the original rear panel and said it was good. Fast forward to this spring/summer , and the original rear panel slowly started to diminish output an had finally failed. NuCamp agreed to replace the original rear panel at the factory , and they installed the updated 310w panel on the rear like the one they installed in the front last fall .

Happy to say that both new style 310w panel are working fantastic .

Also, Tim at NuCamp (service center) , said that they have seen NO problems with the new updated 310w panels that they have been installing on new builds and as warranty replacements for the old original defective 310w panels , that NuCamp was installing in 24/25 .

Just some good news on the new 310w solar panels for everyone !

AnOldUR · July 30

@B0atguy can you share a photo of the old panel and new one for comparison?

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