Solar port wiring

[AJMike]

I have been looking into adding at least 100 watts of additional solar to the 3 100 watt SunPower panels on the roof of our Winnie Fuse, and perhaps 200 watts. Since most tools more complex than a hammer are a mystery to me I checked with a solar installer in this area and he asked me if I knew what the gauge of the wiring between the roof port and the solar controller was. Of course I did not.

He said he could check easily enough by looking but I thought I would ask if anyone with a newer Winnebago Class C RV with the standard 2 100 watt SunPower flexible solar panels knew what the wiring gauge was.

[Winterbagoal]

Is there any info on the Solar stuff in the black info kit bag that came with the Fuse? Might be in there. I could climb up top of my Navion and see if the wiring is labeled, but it's almost dark here.

[imnprsd]

Here's a couple suggestions:

When it comes to "efficiency" you want to keep your "amps" as low as possible; and your wire gauge as thick as possible -- if you have a long wire length.

2-Solar Panels: When it comes to hooking your solar panels up in series or parallel... go with series so your solar panel out put is 36V. This will keep your solar current in the wires low... and the 6-gauge wires that come with your solar panel will work out fine.

4-Solar Panels: Connect 2 in series to create Bank #1; then hook the other two solar panels series to create Bank #2. Then connect Bank #1 in parallel to Bank #2. This will result in 36V and twice the current.... and again, the 6-gauge wires that come with your solar panel will work out fine for less than a 30' wire to to your solar controller.

==> If this sounds confusing, just remember to connect all your solar (+) wires together; and all your solar (-) wires together. (See picture.)

Solar Controller: MPPT controller cost a bit more, but not much more, and they are more efficient than PWM solar controllers. Just be sure your solar controller can handle 36V.

Also, if it's not clear, the output of a 12V solar controller (MPPT or PWM) will be fluctuate current and voltage depending on the sun, but will not exceed the maximum charging capacity of your FLA or FLA-AGM or Lithium battery.

Also, if you only have 2 solar panels, I understand some PWM solar controllers are much cheaper and are very close to the same efficiency as MPPT solar controllers. So if you want to save $50-100 then this maybe another option for you.

Note: Prices for lithium are coming down! And lithium weighs 40% less than lead acid. So if you have a smaller RV you really want to look into lithium compatible solar controllers. ...This has as much to do with if your lithium box will fit in your lead acid battery tray so you will need to measure and compare footprints.

* I also am a fan of Victron products because they often integrate a bluetooth cell phone App that will give me useful charge information. This includes their solar controller, and a separate 17A or 25A battery maintainer.

Note: If you go lithium you need to educate yourself on how to charge it manually; or I understand there are some programmable BIS products you can add for more $$$, but I'm not experienced with these.

Lithium prices have come down and are definitely preferred over lead acid, but they cost more. Other than this big difference, all the other issues are minor (IMO) when it comes to lithium. (But this is just a guess on my part, because I have not yet made this jump!)

Optional: I highly recommend you use a easy "on-off" fuse as close to your battery as possible.

[AJMike]

Originally Posted by Winterbagoal

Is there any info on the Solar stuff in the black info kit bag that came with the Fuse? Might be in there. I could climb up top of my Navion and see if the wiring is labeled, but it's almost dark here.

The installation guy is concerned that the wiring that Winnebago put up there might be enough for only the 2 (or possibly 3) solar panels, but not enough for 500 watts of solar, so he asked me if I knew the gauge.

Of course I don't, and he suggested that I might want to remove the front of the solar controller so I could see the gauge of the wiring used. He said it is not a big issue to replace the wiring if needed, but I thought it would be best to check and since I don't have access to the Fuse right now I wanted to know what others found. He also questioned the type of port Winnebago used with those Zamp connectors.

[AJMike]

Originally Posted by imnprsd

Here's a couple suggestions:

When it comes to "efficiency" you want to keep your "amps" as low as possible; and your wire gauge as thick as possible -- if you have a long wire length.

2-Solar Panels: When it comes to hooking your solar panels up in series or parallel... go with series so your solar panel out put is 36V. This will keep your solar current in the wires low... and the 6-gauge wires that come with your solar panel will work out fine.

4-Solar Panels: Connect 2 in series to create Bank #1; then hook the other two solar panels series to create Bank #2. Then connect Bank #1 in parallel to Bank #2. This will result in 36V and twice the current.... and again, the 6-gauge wires that come with your solar panel will work out fine for less than a 30' wire to to your solar controller.

==> If this sounds confusing, just remember to connect all your solar (+) wires together; and all your solar (-) wires together. (See picture.)

Solar Controller: MPPT controller cost a bit more, but not much more, and they are more efficient than PWM solar controllers. Just be sure your solar controller can handle 36V.

Also, if it's not clear, the output of a 12V solar controller (MPPT or PWM) will be fluctuate current and voltage depending on the sun, but will not exceed the maximum charging capacity of your FLA or FLA-AGM or Lithium battery.

Also, if you only have 2 solar panels, I understand some PWM solar controllers are much cheaper and are very close to the same efficiency as MPPT solar controllers. So if you want to save $50-100 then this maybe another option for you.

Note: Prices for lithium are coming down! And lithium weighs 40% less than lead acid. So if you have a smaller RV you really want to look into lithium compatible solar controllers. ...This has as much to do with if your lithium box will fit in your lead acid battery tray so you will need to measure and compare footprints.

* I also am a fan of Victron products because they often integrate a bluetooth cell phone App that will give me useful charge information. This includes their solar controller, and a separate 17A or 25A battery maintainer.

Note: If you go lithium you need to educate yourself on how to charge it manually; or I understand there are some programmable BIS products you can add for more $$$, but I'm not experienced with these.

Solar prices have come down and are definitely preferred over lead acid, but they cost more.

Optional: I highly recommend you use a easy "on-off" fuse as close to your battery as possible.

Thanks for the suggestion, but the solar controller that the Fuse came with is rated at 12 volts and 30 amps. Connecting the panels would produce far too much voltage.

I suppose your idea would be useful if I replaced the solar controller, but I am trying to keep the cost down and would rather keep what I have.

[Morich]

Some info to file under, "I think this is right?"
I'm not a solar user so don't follow that thinking much but is this helpful?
Seems to show a number 8 (gauge) pair coming from the solar panels. #8 grn with yellow stripe and 8 black with yellow stripe and a pair of number 8 going out to the controller?
Better/more sure way is to look at the wire size stamped into the insulation of each wire --but that's on the roof, huh? Or is this a point which you can get to and look?

[Winterbagoal]

Originally Posted by AJMike

The installation guy is concerned that the wiring that Winnebago put up there might be enough for only the 2 (or possibly 3) solar panels, but not enough for 500 watts of solar, so he asked me if I knew the gauge.

Of course I don't, and he suggested that I might want to remove the front of the solar controller so I could see the gauge of the wiring used. He said it is not a big issue to replace the wiring if needed, but I thought it would be best to check and since I don't have access to the Fuse right now I wanted to know what others found. He also questioned the type of port Winnebago used with those Zamp connectors.

OK, from the 2018 Navion OM, the max input of the Zamp ZS-30A controller is 510W, and the indivdual ports in the rooftop combiner is 150W per port. If you wanted to go to 450W up top, you could do that by swapping the 100W panels for 3 X 150W panels. So, whatever the wire gauges are, they can handle up to 150W each. As far as the wire gaues go, I'm thinking Zamp Solar supplies all the parts for their solar systems, including the combiner and wiring harnesses, so maybe they could give you the wire gauge, if the other limitations aren't show stoppers. I honestly believe Winnebago bought the systems as kits and installed them using Zamp parts. Here's what they use, but no specific wiring gauges are listed. You could try sending them an email and ask.
https://www.zampsolar.com/ports-wires

[AJMike]

Originally Posted by Winterbagoal

OK, from the 2018 Navion OM, the max input of the Zamp ZS-30A controller is 510W, and the indivdual ports in the rooftop combiner is 150W per port. If you wanted to go to 450W up top, you could do that by swapping the 100W panels for 3 X 150W panels. So, whatever the wire gauges are, they can handle up to 150W each. As far as the wire gaues go, I'm thinking Zamp Solar supplies all the parts for their solar systems, including the combiner and wiring harnesses, so maybe they could give you the wire gauge, if the other limitations aren't show stoppers. I honestly believe Winnebago bought the systems as kits and installed them using Zamp parts. Here's what they use, but no specific wiring gauges are listed. You could try sending them an email and ask.
https://www.zampsolar.com/ports-wires

Thanks.

OK. So that is really interesting. It means that I can not do what I was planning to do, combine 2 100 watt panel outputs into one port, and I can also not connect a 200 watt panel to a single port if the max wattage per port is 150 watts. I can't even connect 1 170 watt panel to one of the ports.

The installer said that he might have to remove the entire roof port system and install MC4 connectors instead, and perhaps that is what needs to be done.

Why is everything so complicated? What is it? One of the basic laws of the universe?

[DavidM]

Wiring solar panels in series is a good idea, but not if they are feeding a pulse width modulation (PWM) controller which is what Zamp uses.

If you feed it the higher voltage (36 as noted above) resulting from series wiring, the PWM chops that voltage into a bunch of short pulses that averages out to what the batteries need for charging- 13 to 14 volts typically. The difference between 13-14 and 36 is lost. So the efficiency is horribly low- 30-40%.

Always use a maximum power point (MPPT) controller for series wired panels. These controllers convert the high 36 V power to 13-14V with very little losses, typically 3 per cent.

It isn't too difficult to replace a Zamp controller with a good PWM. Victron makes nice ones.

There are two specs you need to stay within for any solar controller: maximum voltage input and maximum current output. Victron controllers have a maximum voltage input of 50 or 100 volts both of which work fine with series wired panels. Two nominal 12V panels can produce as much as 42 volts (2 x Voc). A rough approximation of current output is to divide the total panel wattage by 12. Victron has a controller selection calculator that is a bit more liberal than that and lets you go to 400 watts for a 30 amp rated controller.

David

[Winterbagoal]

Originally Posted by AJMike

Thanks.

OK. So that is really interesting. It means that I can not do what I was planning to do, combine 2 100 watt panel outputs into one port, and I can also not connect a 200 watt panel to a single port if the max wattage per port is 150 watts. I can't even connect 1 170 watt panel to one of the ports.

The installer said that he might have to remove the entire roof port system and install MC4 connectors instead, and perhaps that is what needs to be done.

Why is everything so complicated? What is it? One of the basic laws of the universe?

Yes, I believe so. Annoying Basic Laws of the Universe, 101.

Seriously, if you want to up the overall wattage/solar power output, you'll probably have to remove the Zamp stuff and replace it with a more robust system. 450 max up top, and the 60W remote portable panel connection in the water/electrical bay, if you have one. In some vehicles, Winnebago didn't fuse that 60W auxilliary port properly, there was a recall a while back.
The Zamp factory installed sytem was designed for low to moderate off grid use. I think at max output, it could keep a few hundred amp hours charged up in decent sun, depending on all the other usage and depletion factors.
If you do upgrade, and go to hard panels up top, watch your weight. Some of the bigger panels are heavy. Remember the OCCC.

[Winterbagoal]

Originally Posted by DavidM

Wiring solar panels in series is a good idea, but not if they are feeding a pulse width modulation (PWM) controller which is what Zamp uses.

If you feed it the higher voltage (36 as noted above) resulting from series wiring, the PWM chops that voltage into a bunch of short pulses that averages out to what the batteries need for charging- 13 to 14 volts typically. The difference between 13-14 and 36 is lost. So the efficiency is horribly low- 30-40%.

Always use a maximum power point (MPPT) controller for series wired panels. These controllers convert the high 36 V power to 13-14V with very little losses, typically 3 per cent.

It isn't too difficult to replace a Zamp controller with a good PWM. Victron makes nice ones.

There are two specs you need to stay within for any solar controller: maximum voltage input and maximum current output. Victron controllers have a maximum voltage input of 50 or 100 volts both of which work fine with series wired panels. Two nominal 12V panels can produce as much as 42 volts (2 x Voc). A rough approximation of current output is to divide the total panel wattage by 12. Victron has a controller selection calculator that is a bit more liberal than that and lets you go to 400 watts for a 30 amp rated controller.

David

I thought the amps out was equal to the panel's max wattage divided by the panel's average voltage? In my case, one of my 100W Zamp panels averages (is rated at) around 18V which equals around 5.5A in good sun.
Not an expert observation. I am a noob at this stuff, too.

[powercat_ras]

You will be fine putting 200 watts into one of the Zamp solar ports. 200 watts will max out at less than 12 amps at the aproximate 17-18 volts max MPPT power point. The Zamp 2 pin connectors can handle up to 15 amps each safely. You should be able to get some Zamp "Y" splitters and not even have to cut and splice the existing solar panel cables.

[Old Navy]

Sticking with the Zamp 30A PWM charge controller, your only real choice is to add panels in parallel to the old panels. When connecting panels in parallel, the array voltage will be determined by the lowest voltage panel, so find a panel that has similar voltage specs to your existing Sunpower panels.

I've heard from numerous people that flex panels have a pretty short service life. Note that Sunpower has a 2 year product warranty vs 25 years on their fixed panels. I can see why they recommend fixed panels...

[creativepart]

I have the Zamp 3-port combiner on my roof and now have 3-100w panels. I have not checked the wiring jacket for gauge info but I was told previously by someone on irv2 that it was 8ga wire. If it’s 6ga that would be great. I’ve seen and handled the wire. It’s solid green colored on my rig. I’m lousy at knowing the gauge of a wire by looking at it.

You can find Zamp 2-into-1 wiring pigtails on Amazon And according to those sellers the total amperage is fine with the portal.

I did replace the Zamp Controller with a Victron MPPT but I stayed with 30-amp. However, my Zamp Controller was in a basement compartment not mounted on an interior wall like most WBGO Class C’s and B’s. I made this switch for the increased efficiency of the MPPT and greater info with Victron’s Bluetooth app. It cost a little over $200, took 20-mins to DIY install. Easy-Peasy. But I just did a direct replacement. Took off the Zamp and installed the slightly larger Victron In its place. Just moving the wires from one device to the other

But it’s not as attractive as the Zamp Controller so be aware you might not want it mounted inside. Plus, the Zamp hides the wires on the back of the controller while the larger Victron has all four wires exiting the bottom of the device.

The Zamp roof portal is convenient and all, but I wouldn’t hesitate to replace it with a better combiner box and have looked at doing so myself. I’m not a huge fan of the flimsy SAE connectors Zamp uses. I’d much prefer MC-4 connectors, or better yet direct wiring to a bus bar inside a combiner box.

I have been planning on adding a 4th panel and using a two into one pigtail. But haven’t moved forward on that project yet.

[Elkman]

4 panels putting out 48 volts DC is not a problem for any wiring that is already installed. No reason not to run all 4 panels in series which is what is commonly done with non-RV solar installations.

The gauge wire from the MPPT controller to the battery bank is what matters as it will be carrying 12 VDC and the longer the run the greater the current loss. But the loss is trivial, as whether it takes 5 hours or 6 hours to fully recharge the house batteries is seldom of any consequence in actual use.

[DavidM]

I respectfully disagree with both of your assertions above.

Four panels wired in series will be producing 68 volts (the Vmp x 4) not 48 and will produce 84 volts (Voc x 4) when the batteries are full. That is more than typical DC wiring practices can handle safely.

It does matter whether it takes 5 or 6 hours to recharge due to voltage drop. A charge controller can only adjust the charging voltage based on what it sees at its terminals. If there is a large voltage drop the battery will see much less and not be charged as efficiently because the controller is seeing the wrong value. I like to keep the voltage drop in the controller to battery circuit down to 1/4 volt or less at full output.

Maybe it doesn't matter that the system charges slower but for a few bucks more for larger wire, your whole system will perform better.

David

[AJMike]

I went to the RV this morning to do some checking. First, the solar port device on the roof is marked as 500 watts max, which differs from the spec for the ports and device in the Operator's Manual, which is 510 watts and 150 watts respectively. Don't know why Winnebago can not be consistent, but that is what is written in the manual and what is labeled on the port device.

I also removed the solar controller from the wall to check the wiring and it is 8 gauge, or at least that is what it is marked. 8 gauge for about 3 feet seems like it should be reasonable.

The installer wants to remove the existing port device and replace it with MC4 connectors because he says that the existing ports are insufficient for 200 watt connections, which would be needed for either 400 watts or 500 watts of solar. My main concerns are two - first, that it might cause a roof leak and second that doing that might void the warranty.

Any comments?

[Old Navy]

If he is just replacing the existing Zamp roof port, I would think that is pretty minimal risk, especially on a one piece fiberglass roof. Add in that he's probably done it a few times. As long as his price is reasonable and you trust him, I would go for it. As far as warranty, I would think that unless his work caused the problem, you would be fine. But then I've not been through a claim with WGO.

[AJMike]

Originally Posted by powercat_ras

You will be fine putting 200 watts into one of the Zamp solar ports. 200 watts will max out at less than 12 amps at the aproximate 17-18 volts max MPPT power point. The Zamp 2 pin connectors can handle up to 15 amps each safely. You should be able to get some Zamp "Y" splitters and not even have to cut and splice the existing solar panel cables.

I don't have the expertise to know, one way or the other, but the Operator's Manual for the Fuse specifies that the max power rating for each port is 150 watts, not 200 watts. And the manual further says that the 150 watt max for each port is for all solar ports, both the 3 on the roof and the one that may be in the cabinet housing the 30 amp plugin.

[AJMike]

Originally Posted by Old Navy

If he is just replacing the existing Zamp roof port, I would think that is pretty minimal risk, especially on a one piece fiberglass roof. Add in that he's probably done it a few times. As long as his price is reasonable and you trust him, I would go for it. As far as warranty, I would think that unless his work caused the problem, you would be fine. But then I've not been through a claim with WGO.

He is the solar installer for one of the solar supply stores near where I live, and tells me that he has been doing these solar installs for 4 or 5 years so I assume he knows what he is doing. At least that is what I hope.

He does not think much of the Zamp ports, saying that he thinks that they should only be used for temporary solar panel connections like those on some of Winnebago's RV. That is, the single port used to plug in an extra solar panel rather than those are are permanently installed.

Mostly the Winnebago warranty has expired on our coach since it is now 2 years old and we have about 32,000 miles on it, so it really is a question about the extended warranty company, and I don't know if they can be trusted at all. I did find a mixture of sawdust and thin metal shavings on the floor of the RV where the slide opens and closes so I think I will be finding out about that extended warranty fairly soon ...