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Old 04-01-2020, 12:22 PM   #1
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2014 Tour solar wiring

My coach came with a prewired 100w solar panel. I want to add more panels and need to find out what size wire is used for the factory install. I want as many panels as the wiring will support.
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Old 04-01-2020, 12:30 PM   #2
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I can't help you with the wire size, but you can wire two 12V nominal panels in series and feed them to a MPPT controller. The current will be the same as with one panel so the wire size shouldn't be a limitation.

You will lose output on both if one panel is shaded, unlike if they are wired in parallel where only the shaded panel will lose output.

Some controllers can take up to 100 volts input voltage which would let you wire four in series or two 24V nominal panels in series. The Victron 100/30 can do this.

David
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Old 04-01-2020, 01:07 PM   #3
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If I am not going to increase amperage to charge my batteries then why bother adding another panel?
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Old 04-01-2020, 01:44 PM   #4
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Ok, I need to explain how solar controllers work. This discussion is based on a MPPT controller which lets the solar panel operate at its most efficient point, usually about 17 volts for a nominal 12V panel and converts that voltage down to about 13V while charging the battery and increasing the amperage so as to get as much power as possible out of the panel.

12V nominal panels operate at 17 volts at maximum power and 21 V or so with no load on the panel, ie in an open circuit situation. A 100 watt 12V panel hooked up to a MPPT controller will supply about 7 amps to the battery at 13V while producing 6 amps at the panels at 17 volts.

Most MPPT controllers can operate at up to 50V input so they can work with 24V nominal panels. Some like the Victron 100/30 go up to 100V.

When you hook two 12V nominal 100 watt panels in series you are effectively creating a 24V nominal panel that the MPPT controller can deal with. The two 12V panels in series produce about 34V at the controller input at the same 6 amps as a single panel would produce. But the amperage to the batteries at the output of the controller is doubled to 14 amps at the 13 volts that the battery needs.

That is how you can wire two nominal 12V panels in series and feed it to a MPPT controller and have the same current in as a single panel but double the current out.

David
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Old 04-01-2020, 01:59 PM   #5
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Very interesting and thank you.
If I could run 48 volts to a MPPT controller then the wire size would definitely not be an issue as the higher voltage does not require as large a wire as 12v does.
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Old 04-01-2020, 04:41 PM   #6
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I can't tell you what is on your 2014, but on my 2017 they used a Zamp 100w panel and a 30-amp Zamp PWM solar charge controller. On the roof there is a 3-port Zamp combiner box that can host up to 3 SAE connectors from solar panels.

If you have that configuration... I don't know if you do... They used 10g wire from the roof to the solar controller and 10g wire from the solar controller to the battery bank.

Again IF you have that it's easy to attach two more panels. Zamp panels are unique in that they use SAE connectors not the standard MC4 connectors. You can buy Zamp panels and they'll come with SAE connectors - or - you can buy less expensive panels that come with MC4 connectors and then buy adapters to convert MC4 to SAE.

I added 2 additional Renergy 100w panels and it was super easy. Here's a photo. Zamp panels were 4X the price of Renergy when I did this a couple of years ago.

They should be easy to find. Just make sure that the Positive wire goes to the Female SAE side of the connectors not to the male side. They are available both ways and Zamp always wires the positive to the female side that's sheathed.
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Old 04-01-2020, 05:17 PM   #7
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That is good info. I will look for the combiner box and if it is there I am sure it is the same configuration as your 2017. Why wouldn't it be. I do have a 20 fuse for the solar circuit. Is your fuse 20 amp also?
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Old 04-01-2020, 05:19 PM   #8
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I believe it's 30 amp, since the controller is a 30-amp. RV is in storage and I don't remember.

Also, inside the 3 port combiner box on the roof is a 30-amp self resetting fuse.
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Old 04-08-2020, 09:45 PM   #9
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Call the Winnebago service number at 800-537-1885. The first time you call them, they'll get the VIN number of your rig and your contact info. From then on, they recognize your phone number when you call and have your rig pulled up on the screen. They can usually tell you exactly which components were used on your particular coach. I bought a used Itasca last year and have made numerous calls to them and they've been very helpful.
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Old 04-09-2020, 09:05 AM   #10
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Thanks a lot. I called this morning and was told it is a 12awg so very limited as to the idea of adding panels. Too bad they went cheap on an all elec. coach.
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Old 04-09-2020, 09:38 AM   #11
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Quote:
Originally Posted by trower View Post
Thanks a lot. I called this morning and was told it is a 12awg so very limited as to the idea of adding panels. Too bad they went cheap on an all elec. coach.
They must have changed at some point... my 2017 (not all electric) Gas coach with OEM solar uses 10ga wire from the roof to the solar controller.
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Old 04-09-2020, 10:56 AM   #12
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Like I said in an earlier post, with an MPPT controller you can wire a second 100 watt panel in series and the 12 gauge wire will be fine as the amps will be the same as a single panel.

You could even add three for a total of 400 watts and use the same wire. Wire them in series/parallel. The total voltage drop at maximum output will be a bit less than a volt. That uses up a bit of your power but will still work fine. You will almost certainly have to upgrade your controller though.

The Victron 100/30 has a 30 amp output limit and is a good one. 400/12=33 amps. But you should be able to live with that as I suspect that your panels will never hit their maximum rated output. See- https://www.amazon.com/dp/B076N5PTBN...ding=UTF8&th=1

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Old 04-09-2020, 05:15 PM   #13
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Are you saying that if I run 24v into the controller I can get 12v out to the batteries? I would love to do that. 400w would be great.
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Old 04-09-2020, 05:29 PM   #14
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Quote:
Originally Posted by trower View Post
Are you saying that if I run 24v into the controller I can get 12v out to the batteries? I would love to do that. 400w would be great.
Just like batteries you can wire solar panels in series or parallel. In parallel the amps are combined just like with batteries. In series the voltage is doubled just like with batteries. And you can wire a combination of 2 pair in series and connect them in parallel.

Higher voltages output has less voltage loss on smaller gauge wire.

Your panels put out between 18v and 22v each. So, wiring a pair in series you get about 40v.

Many MPPT controllers can take a higher voltage and tailor it for your 12v battery bank.

So, doing this you don't need the lower gauge wire from the roof to your controller.

The example of the Victron 100/30 charge controller is a good one. The 100 is volts and the 30 is amps. So, you could put all your panels in series and get 80+volts which the controller will reduce to your charging profile.

There's a small catch. When you wire your panels in series you create one large panel out of the two - just like batteries - but if you block the sun on one panel you knock out the entire panel's output. Again, just like batteries. One bad battery in a series wired pair will knock out the entire pair.
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Old 04-09-2020, 05:45 PM   #15
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Originally Posted by trower View Post
Are you saying that if I run 24v into the controller I can get 12v out to the batteries? I would love to do that. 400w would be great.
Yes, that is exactly what I have been saying for my last three posts on this thread!!! This is what MPPT controllers do but PWM controllers do not.

And to creativepart's example of wiring 4 panels in series to get 80V or so. That will work but 80V will shock you and requires different wiring techniques. I would keep it to two panels wired in series so the voltage stays below 50V, the general low voltage DC wiring limit or two wired in series in parallel with two others wired in series.

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Old 04-09-2020, 11:09 PM   #16
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I recently installed four 250 watt panels on our Itasca 27N. I wired them in two parallel pairs and used 10 gauge wire, as recommended by the place I bought my panels. I have two Epever 40 amp MPPT controllers. Two 40's are cheaper than one 80 amp controller. I got rid of the two lead acid coach batteries and replaced them with three 100 ah Battle Born lithiums. I also put in a Victron 3000/120 inverter/charger and put the whole set-up (except the solar panels, of course), in the compartment next to the entry door.

I'm all ready for Quartzsite. Works great, sitting right here at my house, unfortunately!

"All dressed up and nowhere to go!"

Be safe,

Jon F.
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Old 04-10-2020, 08:56 AM   #17
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DavidM thank you. I have been reading and researching and asking this question on several sites and no has ever explicitly answered this question. Every time my answer was how great a 24v system was but not tell me I could use it in a 12v battery pack.
Thank you again. I can proceed with my project with confidence.
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Old 04-10-2020, 08:59 AM   #18
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Your project looks great. How did you get the 4 10awg wires from the roof to the compartment?
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Old 04-10-2020, 09:22 AM   #19
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No matter what the voltage is coming from the solar panels, the controller converts it to 12v. My panels put out about 48 volts each.

Rather than drill another hole through the roof, I ran the wires down the vent pipe for the gray water tank. That vent pipe just happens to run next to all the wiring for my control panels and monitors, so Winnebago made a chase for it all, accessed by removing the air return grill on the wall next to the floor. I then cut a 1 1/8" hole in the vent pipe by the floor and fished the wires through the hole and then fished them across the top of the gray water tank which is in that same compartment. (You can kind of see the tank behind the plywood on which the inverter is mounted.) It wasn't easy, but it worked. The four 10 gauge wires just fit through the hole, which I then sealed off by wrapping it with Gorilla tape. Should be OK on the gray vent, but probably would not do it using the black water vent. I guess it depends on how sensitive your wife's nose is! ;-)

Jon
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