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.

Howdy, Stranger!

Quick Links

Categories

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

Comments