portable solar panel with no controller

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NEWYORKHILLBILLY

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The other solar thread got me thinking of a portable solar panel and remembering I had one in basement from my casita days.
My question is if I connect to the roof top controller and the roof is shaded but the portable is in full sun will the shaded panel bring down the sunny panel? Attached labels from both panels
 

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Just curious, and maybe the implicit reason for your question, but do you no longer have the 30A Adventurer PWM Charge Controller that came with that kit?
IMG20251102130839.jpg

Wiring that directly to your battery would avoid any question of adverse interaction between the two arrays. The portable and the rooftop would be completely independent, each delivering the best charge it could.
 
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As long as the voltage of all solar panels are near the same why not just run them all through the same charge controller. I did that for my fixed and portable panels. Easy to do and works great. My two types of panels are all near 18V.
 
Jim Bennett said:
As long as the voltage of all solar panels are near the same .....
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I'll welcome some education. Even if the panels are rated for near-same voltage, will that be the actuality when the rooftop is shaded and the portable is not (the OP's scenario)?

In that particular scenario, if all are routed through one controller, will either of the panels actually deliver the charge that they would deliver through separate controllers (close to the OP's original question)?
 
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I may be wrong, but my understanding is they will all be diminished even if bypass diodes are present. I’m not sure why ETI routes the input from the portable into the coach controller. I’d much rather my portable have its own onboard controller and be connected directly to the battery bank.
 
Centex said:
Just curious, and maybe the implicit reason for your question, but do you no longer have the 30A Adventurer PWM Charge Controller that came with that kit?View attachment 1949579
Wiring that directly to your battery would avoid any question of adverse interaction between the two arrays. The portable and the rooftop would be completely independent, each delivering the best charge it could.
Click to expand...
I no longer have that controller. I believe my last install with this on my casita all the panels where the same voltage so I bypassed it.
 
GinoandLinda said:
I may be wrong, but my understanding is they will all be diminished even if bypass diodes are present. I’m not sure why ETI routes the input from the portable into the coach controller. I’d much rather my portable have its own onboard controller and be connected directly to the battery bank.
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Any modern solar panel will come with at least a blocking diode (different from bypass diodes). The blocking diode prevents a low (shaded) voltage panel from "pulling down" the higher panel in a parallel configuration.

I will on occasions use 2 portable panels in addition to the ETI-provided roof panel. They all have different voltages at different times and are all connected in parallel to the single ETI-provided controller. If all 3 have sun then I get the full amperage going into the batteries. If 1 or 2 are shaded then I get the amperage provided by the sunny panel(s). Nothing is lost and there are no harmful interactions.

But... (Always a "but"). In a mixed panel situation - be it due to panel design or shading - a MPPT controller attached to individual panels can provide more power than the simpler design that I am using. This is because MPPT can adjust the load on the panel to match the peak power Volt-Amp combination (Vmp, Imp) that is unique to each panel. But the trade-off is more complexity and more expense. Personally, I don't loose sleep over the additional 5-15% power that I could have gained.
 
alanmalk said:
Personally, I don't loose sleep over the additional 5-15% power that I could have gained.
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That's where I'm at. Going on three years with the ETI setup of two 180watt panels on the roof through a single controller and my 130watt portable with it's dedicated, onboard 10amp controller connected directly to the 400ah battery bank. We've camped all four seasons and all kinds of conditions and have never even come close to being concerned about power.
 
Centex said:
I'll welcome some education. Even if the panels are rated for near-same voltage, will that be the actuality when the rooftop is shaded and the portable is not (the OP's scenario)?

In that particular scenario, if all are routed through one controller, will either of the panels actually deliver the charge that they would deliver through separate controllers (close to the OP's original question)?
Click to expand...
The voltage will change a bit with the change in light available but this is a small amount. Amperage of course will vary a lot. It was told to me by a solar tech sales guy I confided with, and learned from, when I wired up my trailer solar system in 2017 that though varying voltages would work, the controller will operate at the lowest voltage of all the panels connected in parallel causing power losses in the larger voltages.

He had also said that when wired in series if you have two different amperage output panels the output would be reduced.

I think I am remembering correctly. :rolleyes: :cool:

I have been looking into solar for my house and garage and the three companies I talked to insisted it would be best and they would only install identical panels in both wattage and voltage. I never got into reasoning as to why as the guys I had talked to were sales guys and I only talked to their engineering guys once we worked on the setup.



An aside here. I had originally wired my four 80W rooftop panels as two parallel sets of two panels in series. I wired up my two portable in series too. My trailer was broken into and the portable stolen and when I decided once again to get portable I rewired the rooftop panels to be all in parallel. With the short length of cable I used any loses with the no doubled amperage would have been minimal, though I never calculated it. Now I can easily add one or two portable panels to my trailer.
 
the problem with parallel, say one panel is in 100% sun and is outputting 18 volts at load, while the other is partially shaded and only outputting 16V. that panel with the lower voltage won't contribute any current to the parallel stack. with separate controllers, each panel would contribute what it could to the battery charging.
 
I have a Zamp port on my E19 but don't use it. I have an external panel with it's own controller. It connects directly to the 7-Pin connector that normally plugs into my truck when traveling. It has it's own controller and connects directly to the batteries. No fuss, no muss and a 15' cord that came with it plus a 30' extension cord. All Anderson connectors so simple setup and use.
 
I installed a trolling motor 2 pin connector on the side of my trailer where the original battery vent was, because this is a decently waterproof connector. its fused for 40 amp, and goes directly to my battery main bus bars. I took the trolling motor plug, and put it on a 6' length of marine 10/2 wire with a Anderson PP45. then I have an assortment of stuff on Anderson PP connectors including a 1:4 splitter, a car stereo in a small wooden box, a 3 cigar socket + multiple USB charger thing, etc. This has served us quite well. oh, my old Renogy 100W solar panel has a PP on the end of its output cable, too. My Viair 88p tire inflator also has a PP30 on it, so I can use this to inflate the trailer tires (since the cable isn't long enough to reach the truck battery when hitched)
 
John in Santa Cruz said:
the problem with parallel, say one panel is in 100% sun and is outputting 18 volts at load, while the other is partially shaded and only outputting 16V. that panel with the lower voltage won't contribute any current to the parallel stack.
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Hmmm, are you sure about that? Two thoughts just for consideration ....
  1. All other things being equal, partial shading seems to have a much greater effect on panel current-output than panel voltage-output (see this article)
  2. All other things being equal, it seems that in a parallel-wired array a partially shaded panel does contribute to the current the string presents to the controller, albeit less current than the unshaded panels, with a net positive power result (source of diagrams here)
Parallel vs Series panels in partial shade.png
 
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Thrak said:
I have a Zamp port on my E19 but don't use it. I have an external panel with it's own controller. It connects directly to the 7-Pin connector that normally plugs into my truck when traveling. It has it's own controller and connects directly to the batteries. No fuss, no muss and a 15' cord that came with it plus a 30' extension cord. All Anderson connectors so simple setup and use.
Click to expand...
I didn't even know such a thing existed. I have always been hesitant to use the Zamp with all the talk of reverse polarity, equal power, parallel, in series, etc. I'm still trying to wrap my brain around solar and learning about it. We have only had solar on our trailer for 2y. We currently have 1 x 190w panel on the roof and haven't needed more as of yet.

So if I hook up a portable panel to the 7pin connector and the portable panel has a controller, I don't have to worry about any of the above concerns and can run both my rooftop solar and the portable?
 
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this is a partially assembled Andersen PowerPole PP30 .... PP15, PP30, and PP45 can be plugged into each other, they only differ in wire gauge (different pins for different size wires).

i-7FNV24B-X3.jpg


and here it is on a piece of marine 12/2 wire
i-XgNmFV8-X3.jpg



this is a pigtail I made for my Casita, the ring terminals connected directly to the battery, and the PP30 end could be stuck out the battery compartment vent and I plugged my solar panel into it. While this doesn't show a fuse, I redid it with a 10A fuse holder on the red wire for safety's sake.

i-b2CZWLQ-X3.jpg


As long as you assemble these with the red and black the right way, there's no way to plug these in wrong, + will always go to +, and - will always go to -.
 
Ron in BC said:
You have it so it'd be handy to check it and observe the polarity. It is handy to use on occasion.

Ron
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I'll have a look and revisit it in the spring. It will give me some time to research (and ask questions)

I noticed this on my build sheet (red text)

1762290572117.png
 
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