Good Sam Club Open Roads Forum: Remove Stock 40w Panel Before adding?
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 > Remove Stock 40w Panel Before adding?

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TriBeard

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Posted: 08/23/20 10:58pm Link  |  Quote  |  Print  |  Notify Moderator

So I just got an Arctic Fox 811, and I'm adding 2 x 100 solar panels to the unit to help us with boondocking. The camper came with a zamp solar 40w panel already on the roof, and a zamp solar 30a pwm controller already installed.

On the roof, there are two SAE plugs (inverted wires because of being "zamp ready") and my plan was to wire my two panels together in parallel on one of the plugs, leaving the 40w factory panel plugged into the other one as it came originally. Then I got to thinking, I'm not sure if that's the best plan. Will having that one other panel, presumably also wired in parallel with the larger panels (not sure how they wire it up from the factory) cut down my output? Should I just disconnect it and use the 2 100w panels?

TriBeard

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Posted: 08/23/20 11:10pm Link  |  Quote  |  Print  |  Notify Moderator

Some additional info - these are the panels in question:

https://www.amazon.com/Richsolar-Polycrystalline-Efficiency-Module-Marine/dp/B07DNP14JY/ref=sr_1_4?dchild=1&keywords=100w+solar+panels&qid=1597084597&sr=8-4

https://plugandplaysolarkits.com/products/obsidian-45-watt-solar-panel-kit?variant=31384666538097

corvettekent

Marysville, WA

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Posted: 08/23/20 11:35pm Link  |  Quote  |  Print  |  Notify Moderator

I would add another controller or remove the 40 watt panel.


2007.5 GMC Dually EC/LB, LMM. Banks IQ, Speed Brake, Six Gun. B&W Turnover Ball, Companion Hitch, Amp power steps. Hadley Air horns.

2004 32' Carriage 5th wheel. 860 watts of solar MPPT and four 6 volt batteries. Samlex 2,000 watt Pure Sine Wave Inverter.


naturist

Lynchburg, VA

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Posted: 08/24/20 06:43am Link  |  Quote  |  Print  |  Notify Moderator

Assuming all panels are the same voltage, a 30 amp controller should be able to handle all 240 watts of panels. Put them all in parallel, and it should be fine. 240 watts at 12 volts is 20 amps, well within the controller’s capacity.

But that does require all panels to be the same voltage. If the existing 40 watt panel is 24 volts, your extra 200 watts being 12 volts, you would have to put the new one in series to combine with the existing 40 watt panel.

Of course, upgrades are always possible. But the simplest is just adding the 200 watts.

* This post was edited 08/24/20 06:56am by naturist *





TriBeard

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Posted: 08/24/20 06:56am Link  |  Quote  |  Print  |  Notify Moderator

naturist wrote:

Assuming all panels are the same voltage, a 30 amp controller should be able to handle all 240 watts of panels. Put them all in parallel, and it should be fine. 240 watts at 12 volts is 20 amps, well within the controller’s capacity.

Of course, upgrades are always possible. But the simplest is just adding the 200 watts.


Judging by the spec sheets I was able to find, the voltages are within a volt or two of each other, but they're not identical.

naturist

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Posted: 08/24/20 07:46am Link  |  Quote  |  Print  |  Notify Moderator

TriBeard wrote:

naturist wrote:

Assuming all panels are the same voltage, a 30 amp controller should be able to handle all 240 watts of panels. Put them all in parallel, and it should be fine. 240 watts at 12 volts is 20 amps, well within the controller’s capacity.

Of course, upgrades are always possible. But the simplest is just adding the 200 watts.


Judging by the spec sheets I was able to find, the voltages are within a volt or two of each other, but they're not identical.


Volt or two isn’t important. Raw voltage from a 12 volt panel is going to range from about 8 volts to about 19 volts depending on sun. What matters is spec voltage, thus a 12 volt panel can’t be parallel with a 24 volt panel, which will put out between 16 and 38 volts. The panels will adjust their own output to cover a volt or two.

Same thing happens if one panel is in sun, other in shade. Two panels of same nominal voltage will be fine, the shaded one just won’t contribute.

Lwiddis

near Jawbone Canyon, CA

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Posted: 08/24/20 10:41am Link  |  Quote  |  Print  |  Notify Moderator

I agree. Same voltage, keep it. Different voltage, remove or disabled and save.


Winnebago 2101DS TT & 2020 Chevy Silverado 1500 LTZ Z71, 300 watts solar-parallel & MPPT, Trojan T-125s. TALL pole for flags. Prefer USFS, COE, BLM, NPS, TVA, USF&WS, state & county camps. Bicyclist! 14 year Army vet - 11B40 then 11A - (MOS 1542 & 1560)


3 tons

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Posted: 08/24/20 11:21am Link  |  Quote  |  Print  |  Notify Moderator

It’s important to avoid conflating 12 and 24 voltage terms...

Your existing panel is a ‘12v panel’, as are the 100w panels you are considering...

What ‘12v panel’ refers to is merely a shorthand jargon for ‘nominal’ battery voltage (not actual), nor does it refer to ‘actual’ panel output...

The typical 12v ‘any-brand’ panel has 36 cells, each cell output is at approx 0.5v - 0.6v x 36 = approx 18’ish volts which is an ideal amount to overcome inherent wire run, connector and controller-heat loses and still provide the battery the 14 + (or so) volts needed to overcome internal chemical resistance (chem soup sluggishness)...

https://en.wikipedia.org/wiki/Solar_cell

As a ‘practical matter’ the efficiency advantages of mono vs poly have more to do with per sq inch roof-top footprint...(a photon yield thingy).

No real need to overthink matters - I would simply utilize the extra OEM connecter (by adding a duplex splitter), parallel connect the additional two panels, then call it a day...JMO

3 tons

TriBeard

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Posted: 08/24/20 11:50am Link  |  Quote  |  Print  |  Notify Moderator

I did wind up just going ahead and adding the two additional panels to the OEM connector with a splitter, and everything seems to be working normally. It is hard to tell how much power the panels are pulling because I think the charge controller I have only shows me the current amps that are going into the battery, not the amps the panels are producing/capable of producing. I've never had the batteries run low yet, but the highest I've seen (I've actually had these installed for about a week but started second guessing my install) is about 6-7amps. I know I won't get 240w in reality, but on a sunny day I figured I'd get 180ish or so, which would be more like 12-15A right?

3 tons

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Posted: 08/24/20 02:12pm Link  |  Quote  |  Print  |  Notify Moderator

Agreed, but if theres and shadowing over a panel, its harvest will be drastically reduced...Make sure your in full sun...For a bit of troubleshooting and a good place to start, you can disconnect each panel (say one panel at a time) to confirm a possible output reduction at the controller - no reduction in amps means that that panel(s) or wiring is not functional...

Good Luck,

3 tons

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