Idea for Higher Amp Solar Wiring

[CoreyTrevor]

First post, so hello to all WTWers! I will confess to lurking off and on for years.

I want to put 2 of the Renogy 160 amp flexible panels on my 2012 Eagle roof. I've read lots of threads with differing opinions on whether the 12g existing solar wiring is adequate, and also how running the panels in series will allow more current with smaller wires. I don't really want to rehash those old topics.

I had an idea that I haven't looked into details on the actual work needed to do it, but was hoping for some input on the concept itself.

The thinking is to use the roof structure and camper frame structure as the ground from the panels to the controller, and then use both 12g existing wires, hot and ground, for the hot side. I would run a good sized ground wire from the roof frame to the camper frame, behind one of the lift panels, then ground the panels to the roof frame and ground the controller to the camper frame.

All that aluminum should be able to carry lots of amps with no real voltage drop. I would just have to come up with a really good way to make the connections so they don't degrade over time. Dielectric grease would help to prevent corrosion.

I don't see any reason the ground side wouldn't work fine, but is there any reason that the 2 hot wires running side by side would be any problem? I just see this as an easy way to get more amps from the roof to controller without ripping half the camper apart to run larger wires.

I'm pretty good with vehicle electrics, but I'm sure there are people here that have more in-depth electrical and FWC knowledge than I!

Thanks!

 

[Vic Harder]

You don't want to use the frame to pass current. Galvanic corrosion horror stories exist on this forum.

Also, there is no need. I have almost 400W of solar on the roof (single glass panel) and a good MPPT controller (wire your two panels in series) makes this a moot point.

 

[pvstoy]

I would run those two panels in SERIES with a good MPPT controller as Vic mentioned and just use what factory wiring is there.

I have factory wiring with 480 watts of solar, Victron smart MPPT, panels in parallel.

You will be fine.

 

[CoreyTrevor]

I was aware of the corrosion issue, but hadn't looked into a good way to prevent it, if there is one.

Do you have any specs on your max solar amps/watts and voltage drop to your controller at max? You are a long way North of me, so your max at 400w might be about the same as mine at 320w.

Thanks.

 

[CoreyTrevor]

I would run those two panels in SERIES with a good MPPT controller as Vic mentioned and just use what factory wiring is there.

I have factory wiring with 480 watts of solar, Victron smart MPPT, panels in parallel.

You will be fine.

That sounds promising. Thanks.

 

[rando]

You definitely don't want to do this. Firstly because you don't need to (there is no issue with running 320W of solar through the 10 AWG wire, in series or parallel) and secondly because is can cause issues with your charge controller. ATC wired their campers this way for a while, and there are a bunch of threads here from people who have issues with it. Some charge controllers disconnect the negative side of the panel when the battery is full, but if the current can travel through the frame to the battery, you can't disconnect when the battery is full. Secondly, many MPPT charge controllers measure the current on the negative, and if the current is running through the frame, they can't measure it, and therefore they can't find the maximum power point.

 

[Vic Harder]

I was aware of the corrosion issue, but hadn't looked into a good way to prevent it, if there is one.

Do you have any specs on your max solar amps/watts and voltage drop to your controller at max? You are a long way North of me, so your max at 400w might be about the same as mine at 320w.

Thanks.

rando has commented on this here and elsewhere... the voltage drop is a non-issue running in parallel as long as their is more voltage available than needed. A PWM style controller throws away any voltage in excess of about 0.5V over the batteries present voltage. 14V and 10A will result in the same charge rate as 28V and 10A with a PWM. So, if a few volts drop from your panels that are outputting 18-20V, no big deal.

The 160W Solar Overland panel puts out 19.1v at optimum, so you should be fine there.

That said, MPPT controllers work differently and in series you would harvest more power than in parallel.

In either case, as rando says, don't do it for other reasons.

 

[CoreyTrevor]

I guess what I needed was firsthand experience of running a lot of solar with the 12g wiring, and that's what you guys have given me.

I have been planning on an MPPT controller and panels in series for the reasons stated, and I expect to rarely have partial shading issues where running in parallel would help.

I tend toward overkill on projects, and I will usually spend more to try to do things right the first time.

Thanks for the help and advice!

 

[Vic Harder]

cool. Planning is good. We will want to see pictures of your results!

 

[CoreyTrevor]

No problem on the photos, but don't hold your breath. I still have to figure out how to get the Eagle on the full size Dodge! Shouldn't be too tough, but the solar is a few slots down on the project list.

I'll post something when I have some progress to show. Or when I ruin something.

 

[pvstoy]

"......

The 160W Solar Overland panel puts out 19.1v at optimum, so you should be fine there.

That said, MPPT controllers work differently and in series you would harvest more power than in parallel.

...."

Vic He is looking at 2 of the Renogy 160 amp flexible panels.. And they are at 19.1 V. Don't mix that up with Overland Solar where they put out a higher voltage at optimum. A miss-type of the fingers as that might confuse a person down the road reading this.

I went with the Overland Solar panels wired in Parallel to take advantage or cumulative AMPS since the panels have a higher Voltage. If I was looking at the Renolgy at 19.1 V that is low end and would wire in SERIAL to increase voltage as that is helpful in getting charge in less desirable light conditions. Of course use a good Victron MPPT smart controller to get max out of the panels either way they are wired.

Cheers....

 

[CoreyTrevor]

I missed the Overland panels somehow in my research. Are they worth the higher price vs the Renogy? From what I have read and learned, the 2 Renogy 160w panels will be overkill for me as it is.

I do like knowing all the options, since I waste endless amounts of time researching everything to death before buying anything.

 

[rando]

My suggestion (learned the hard way) is that if you are using semi-flexible panels (any brand) don't bond them to the roof. I have now had two sets of semi-flexibles fail in the past 6 years. The first was VHB'd to the roof of the camper and it was a major pain to remove them. The second set were attached with studs through the grommets and bolts, so they should have been easy to replace, but the manufacturer changed the shape slightly so the replacement panels no longer line up with the studs.

I am back to a rigid panel. The weight savings of the semi-flexible is attractive, but the tradeoff is durability.

 

[pvstoy]

No worries, Get what your budget allows. Overland Solar is a different option, FWC is installing them on lots of campers.

As you said "...the 2 Renogy 160w panels will be overkill for me as it is." then you can save money and put it elsewhere for your needs.

How about a nice Victron battery monitor to keep track of your system health?????

 

[Helmut]

There has been a interesting suggestion about using the largest common household panel combined with a mppt controler. Sounds very smart to me if you dont have any hardware yet.

 

[CoreyTrevor]

It's not so much that I couldn't afford the Overland option, but I might as well try to keep costs under control.

I do need to put in more time researching controllers and monitors. I'm kind of an information junkie, so I know I will want to see what is doing what and going where.

Using one fullsize panel would probably work too, but the weight and aerodynamic advantages are a high priority for me. I've always tried to keep weight off my vehicles as much as possible. Probably a bit silly with a truck/camper that will weigh around 8k pounds, but I definitely don't want weight up high where it will raise center of gravity and mess with handling. I may have to learn the hard way too if the panels don't hold up. At least the Renogy panels have a great warranty.

Thanks again for all the help and suggestions!

 

[ckent323]

Corey,

You wrote that you are using 12 ga wire. Are you sure? I thought the factory wiring is typically 10 ga.

Standard solar cable is 10 ga. The cables coming out of the solar panels and the outdoor rated cables available to consumers are typically 10 ga. However, some connector adapters use 12 ga (e.g. Renogy SAE to MC-4 adapter).

I looked at the spec sheet for the Renogy RNG-160DB-H 160W Flexible Monocrystalline Solar Panel and it comes with 10 awg MC-4 connectors.

Regards,

Craig

 

[ntsqd]

My friend in the power generating business tells me that PV's operate on a thermal differential and that getting cooling air to the backside of the PV's is a requirement for best performance. I've never been interested in the flexible PV's for this reason. It is also why our old camper's PV panel was mounted at a slight slope (.25"/30") and the rear of it's frame (high end) had several large holes drilled in it. The goal was a passive air exchange driven by the hot backside of the panel.

 

[CoreyTrevor]

Sorry, missed your post.

I was referring to the FWC installed wiring for the solar. I have read at least a few times here that it is 12g. Maybe(hopefully) it is really 10g in there. I can't check mine right now because it is in my garage and packed with crap I don't have anywhere else to store.

Thanks

Hey, Solvang! I lived most of my life in the Santa Maria area before moving up here 5 years ago. Got too crowded for me and now I can be 4 wheeling 5 minutes from my driveway!