Partial shade — no power from solar?

benpc · May 16

I’m sitting in partial shade (see photo) my charger says it’s off, generating 0W. Is this expected behavior? I would have thought (having solar on my roof at home) that even sitting in full shade I’d see a little generation. 2024 BD, 310W solar on roof.

I’ve seen some posts on the forum about a known issue with failing panels on this model year, but everything I’ve read seems to suggest that once the panel fails, it’s done and cooked. Thing is, looking back in the history my panel does generate power sometimes

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Grumpy_G · May 17

Generally that amount of shade affects the solar panel output significantly. For verification that it's not the panel that is the problem just check the charge controller when the panel is in full sun.

Marceline · May 18

The voltage from the solar panels must be at least 5V higher than the voltage of the battery for the solar controller to start sending power to the battery. Your battery is at 13.05v so the panels will need to show 18.05v for the controller to start charging.
However, according to your screenshot, the voltage from your panel is only 0.01v, which seems very low indeed, even under the trees. I was camping under giant redwoods a couple of weeks ago with a 200w panel and the output was measly, but they did produce some power.

I think that you'll need to get the trailer into full sunlight to confirm whether the panels are actually dead/defective. You might also want to check the connection between the panels and the controller.

benpc · May 18

Yeah, the previous evening in similar lighting conditions I was seeing ~17-18v, and a couple watts of generation. Will check in full sun sometime, crossing my fingers it’s just a loose connection!

elbolillo · May 18

The problem with the Sunflare panels that Nucamp is now using (Flex-SI) compared to prior years (Flex CIGS) is that they do not have bypass diodes on every cell and thus their output is affected more by shading.

SavvyNurseCamper · May 20

@elbolillo Why did they do that? That makes no sense ! On perfect sunny days it's fine but that can be rare. Having partial sun thru the trees is what many of us can expect. I have a Tab 400 Boondock- black canyon with the 620 watts of power but if they don't have the bypass diodes it will mean little to no power generation . I will have to bring a generator or find camping with a power pole. 😢

SavvyNurseCamper · May 20

PS that's a 2025 model!

rfuss928 · May 20

It seemed to me to be unlikely any quality solar panel design would not include the very common "bypass diodes".

A quick search results:

AI Overview

Sunflare (creators of XPLOR and Sunflair Flex) bypass diodes are integrated at the individual cell level, eliminating traditional, localized hot spots. Unlike standard modules, if one cell is shaded, only that single cell is bypassed, meaning output scales proportionally to the unshaded area

elbolillo · May 20

https://tab-rv.vanillacommunity.com/discussion/comment/221454#Comment_221454

The CIGS panels have bypass diodes on every cell. That is why they are more expensive. Most other panels, including the FLEX-SI series come with only two bypass diodes that string multiple solar cells.

SavvyNurseCamper · May 20

Well having 2 is better then none but would have preferred the bypass diodes integrated onto every individual cells (CIGS panels). I prefer to camp in the trees with partial sunlight and I am not a fair-weather camper. I can camp in any weather. 😉 Thank you both for responding . I learn a little more each time.

rfuss928 · May 20

https://tab-rv.vanillacommunity.com/discussion/comment/221455#Comment_221455

AI Overview

The Sunflare XPLOR FLEX-Si series are lightweight, flexible silicon solar panels tailored for RVs, overlanding, and marine applications. Designed to conform to curved surfaces, they feature bypass diodes on every individual solar cell rather than at the string level. [1, 2, 3]Bypass Diode Details & Shading Performance Unlike traditional rigid panels that group dozens of cells per diode (meaning a single shaded cell drops the output of an entire section), the FLEX-Si has a dedicated bypass diode on every cell. [1, 2]

Active Protection: When a single cell is shaded, only that specific cell is bypassed and goes inactive.
Proportional Output: The module’s power output scales exactly with the amount of shading. If 50% of the panel is covered, you will still get roughly 50% of the rated power.
Hotspot Prevention: The diodes prevent the shaded, high-resistance cell from experiencing reverse-bias heating (hotspots), extending the module's lifespan. [1, 2, 3]

elbolillo · May 21

https://tab-rv.vanillacommunity.com/discussion/comment/221460#Comment_221460

Unfortunately, your use of AI is combining different pages to come up with an answer that is flawed. If you actually look at the page for the FLEX-SI you will not find any references to bypass diodes on each cell nor is it referenced in any of their materials for this specific panel.

Direct from them:

XPLOR FLEX+

FLEX+ is XPLOR’s flagship product. The FLEX+ is the standard solar in the Overland space for power generation and durability for off-grid adventures. Known for its Bypass diodes on every cell to combat shading, this solar panel is the world’s most durable solar panel that can take a beating. Literally!

XPLOR FLEX-SI

Our newly introduced FLEX-Si solar modules are an exceptionally high-quality yet cost-effective solar solution for typical camping and off-grid needs. Made with A-grade silicon cells, the modules are strong yet flexible, allowing them to fit perfectly on almost any smooth, flat, or curved surface.

SavvyNurseCamper · May 21

@elbolillo the new charge controler by Vitron somewhat takes care of the issues if the solar panels don't have the individual diodes to each cell. The smart solar controller 150/35 vs 100/35 has a better grasp on that and improves the rate on absorbing power better. If I don't have this I will buy and install this as well.

rfuss928 · May 21

I was a bit concerned about the AI solution That's why I included that qualifier.

I have 2 CGIS panels on the UT that have surprised me by hitting rated output in northeast full sun several times. I've been very impressed with the quality, durability, and performance of the CIGS Sunflare product. I think with modern processes individual cell diodes would be an insignificant expense to alleviate such a significant compromise.

The zero watts and zero solar volts seems too low for even the shading in OPs pictures but my experience is biased.

elbolillo · May 22

@rfuss928 In talking with a supplier of Sunflare panels, they confirmed for me that the Flex-SI does not have bypass diodes on each cell. But I do agree with you that the zero watts the OP is experiencing is too low. I think there is something either not set up correctly in the controller or wiring issues.

Partial shade — no power from solar?

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