Setting up my solar system

I'm in the planning stages of adding solar to my travel trailer.

I currently have a battery bank of two 6V flooded lead acid GC batteries in series that is 215 Ah 12 volts. I am planning on adding two more of the same batteries in series-parallel for a 430 Ah 12 volts (215 Ah usable) battery bank. I then plan to add 800 watts of solar. Right now I'm leaning toward using four of the Renogy 200 watt panels.

I plan to wire in parallel, as from what I've read, if I'll be camping in shaded/partial shaded spots, which I usually do, parallel gives better output in these conditions. However, if the panels have internal diodes, does this make this line of reasoning not applicable?

I'll then combine these at a combiner box. Is a combiner box necessary? Or can I just do a T-branch coupler, assuming the amp rating is high enough? And when run in parallel, am I correct in assuming I'll need a fuse/breaker at each positive cable from each individual panel? And if so, is there a combiner box that also has breakers?

From the combiner box, I believe I also need to have a properly rated breaker/fuse to the charge controller, right? And I am planning on a 60 amp MPPT charge controller, that should be correct for 800 watts panels, right?

From the charge controller, I'd need a final breaker/fuse between the controller and the battery, right?

And I'd be using proper gauged wire, based on run length and amperage at each station, probably 10 ga --> 4 ga --> 6 ga. I'd have to measure distances and consult an ampacity chart.

I'm planning on putting the charge controller in the front underneath storage compartment of my Grey Wolf 22MKSE, as this is the closest covered compartment to the batteries. I'm thinking actual line length would be about 5-7 feet from the charge controller to the battery. I don't know where the best place to put the combiner box. I'm thinking having it right next to the controller would be best, in order to cut down line length.

I'm pretty comfortable with electrical in general, but this will be my first go at solar, so please critique my plans and add any advice, it will be appreciated.

Thanks!

EDIT: I should add that the trailer came with a factory installed 50 watt panel with a piddly charge controller. I'll be completely removing this from the system entirely.

EDIT AGAIN: Oh, and what do I do about the AC-DC converter. Will the solar charge controller work seamlessly with this?

And I don't need an inverter at this time. The only thing I really need that is AC when I'm not plugged in is the air conditioning, which I would only use if I had shore or a generator

GravelRider
Explorer II
Aug 19, 2020
I got the rest of the wiring done and the MT50 remote sensor mounted and wired.

So far so good. I towed my trailer to work so I can keep an eye on how it is producing, as I didn't want to leave it on and unattended after getting it first set up. At 7 am this morning, and it's a very cloudy dark morning, the panels were putting out 2 amps at 35ish volts.

I also need to weld up some battery mounts and get the other two GC2 batteries mounted in series-parallel. I should be able to get to this over the weekend, but I wanted to test out the solar setup first.
GravelRider
Explorer II
Aug 18, 2020
I got more work done last night on my solar project. Dicor is now on both panels at the mounts.

and I wired the panels to the controller.

I still need to weld up some battery mounts for the additional two 6 V GC2 batteries, run them in series-parallel with the other two, then run wires from the controller to the battery bank. I also have to run wires and mount the MT50 remote, the grounding cable, and the temperature sensor, and I'll be done.
GravelRider
Explorer II
Aug 17, 2020
bpounds wrote:
Looks great. I'm a bit jealous of how much space you've got to work with. But I do like having my roof vents too.

I used the same Renogy Zee clips. They seemed fine to me, but the one downside I saw was that it is pretty much impossible to remove a panel from the clips. Can't get to the bolts. Or, you have to pull them up from the roof and tear through the Dicor. If I do have to remove a panel, I won't do either of those. I will just saw through the clips, leaving the lower 'L' portion at the roof, and improvise a different upper portion. Assuming the new panel was the exact same width. It's enough of a long shot idea that I didn't put too much worry on it.

I do definitely wish I had an extra roof vent up front... But at least I've got the extra space for panels!

These weren't Renogy brackets; they were some offbrand off of Amazon. But I'm sure it's all the same, just branded differently. I drilled the holes in the panel in such a way that the bolt heads are against the side of the aluminum frame, so that you only need one wrench to remove the bolt and reattach it. I'm quite certain it will still be a giant pain in the ass, but it will be doable without having to remove the bracket from the roof itself.
bpounds
Nomad
Aug 17, 2020
Looks great. I'm a bit jealous of how much space you've got to work with. But I do like having my roof vents too.

I used the same Renogy Zee clips. They seemed fine to me, but the one downside I saw was that it is pretty much impossible to remove a panel from the clips. Can't get to the bolts. Or, you have to pull them up from the roof and tear through the Dicor. If I do have to remove a panel, I won't do either of those. I will just saw through the clips, leaving the lower 'L' portion at the roof, and improvise a different upper portion. Assuming the new panel was the exact same width. It's enough of a long shot idea that I didn't put too much worry on it.
GravelRider
Explorer II
Aug 17, 2020
I got started on the installation. I got both panels installed, but only got Dicor on one before I lost light for the day. And ran out of light for pictures of both installed too.

I also got started on fishing the wires... Easily the worst part of any electrical job!
CA_Traveler
Explorer III
Aug 14, 2020
I don't agree with the link. A shorted panel in 3 or more parallel panels can be back biased by the other panels, overheat and catch fire. That is the main concern. For 15A panels I'd use a 20A fuse which would also protect the wiring.

Panels are designed to work with Isc which is the only mode for PWM CCs. Therefore a serial shorted panel will not cause a problem. There actually was a discussion about apparent lower voltage by a RVer with serial panels. I suggested he had a shorted panel and he did and repaced the panel.
GravelRider
Explorer II
Aug 14, 2020
CA Traveler wrote:
You'll have a nice setup.

Thanks. I'll post updates as I get things mounted.
GravelRider
Explorer II
Aug 14, 2020
JKJavelin wrote:
I like your periodic table.
Oh, nice panels!

LOL. Thanks. My garage brewery is off to the left of the picture.
GravelRider
Explorer II
Aug 14, 2020
CA Traveler wrote:
For 2 parallel panels no breaker required. For 3 it's a good idea. Usually fuses are used in the combiner box on the roof, not likely they will ever blow. Use 15A as 10A is to close to the panel or whatever the panel specs say. There are effects such as cloud edge that can cause max current.

I was doing some more reading and came across this article: https://www.windynation.com/jzv/inf/how-properly-fuse-solar-pv-system#:~:text=Commercially%20made%20solar%20panels%20over,30%20amps%20of%20current%20flow.&text=In%20the%20case%20of%20panels,20%20amp%20fuses%20are%20required.

"Commercially made solar panels over 50 watts have 10 gauge wires capable of handling up to 30 amps of current flow. If you connect these panels in series, there will be no increase in current flow so fusing is not required for this string. This is not the case when you have panels connected in parallel, as when connected in parallel the system current is additive. For instance if you have 4 panels each capable of up to 15 amps, then a short in one panel can draw all 60 amps towards that short-circuited panel. This will cause the wires leading to that panel to far exceed 30 amps causing that wire-pair to potentially catch fire. In the case of panels in parallel, a 30-amp fuse is required for each panel. If your panels are smaller than 50 watts, and use only 12 gauge wires, and 20 amp fuses are required."

So really I probably don't need fuses at all, since if all the current flowed through just one wire, I'd still be fine. But, after reading this, I think I'll just go with 20 amp fuses.
CA_Traveler
Explorer III
Aug 14, 2020
You'll have a nice setup.