Setting up my solar system

[GravelRider]

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

[CA_Traveler]

I used this on the CC output. https://www.waytekwire.com/item/46691/80A-Bussmann-Circuit-Breaker/

Be aware that generally panels should be connected/disconnected with the CC on. So you would need to pull/insert fuses.

[GravelRider]

By the way, thank you everyone for all of your help. I'm definitely learning as I go.

[GravelRider]

Okay, so now that I'm thinking about it, if I just use a solar parallel connector rated for 30 amps, I could put a waterproof inline fuse on each of the positive leads, then only run one set of wires down, and if I use about ten feet of 10 AWG wire from the parallel connection (48 V, 20 amp), I'll get a 0.87% drop in voltage, which sounds okay to me.

In other words:

Solar panels --> 10 AWG 48 V, 10 amp (maybe 5 feet?) --> parallel connection --> 10 AWG 48 V, 20 amp (10 feet) --> controller --> 2 AWG 14 V, 50ish amps, likely less due to real world numbers (5-7 feet)

This calculator from Renogy recommends 10 AWG if 12 feet or less in the 20 amp run of wire. I think this is very doable and would make my life a lot easier.

https://www.renogy.com/calculators#tab_solar-cable

[GravelRider]

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.

Okay, good to know. I wasn't sure how close the current got to that. Thanks. I'll use 15 amp fuses. I wanted to do breakers, but I couldn't find anything rated for 48 volts that wasn't for a breaker box, so I'll just use two inline blade type fuses.

I'm not actually going to use a combiner box. I am planning on using a stud junction block for the negative wires and then I am going to just mount both 10 AWG wires coming from the panels directly to the 30 amp circuit breaker (rather than 20 amps, as per your post above). I'm assuming this won't be an issue, right?

And I'm going to do the parallel junction in my forward basement storage area where the controller will be. I'll have to run more wires down, which will be a pain, but I figure this will maximize wire length in the lower current wires and minimize it as the current increases.

[CA_Traveler]

BTW MPPT controllers usually switch to PWM mode (uses Isc - I short circuit) for lower charge rates which is another reason for a larger fuse, might even reach full amps under the right conditions, probably for a limited time.

I have a switch, no fuses on my 3x serial panels. And a 60A switchable CB, Blue Seas I think - but independent unit that isn't installed in a breaker box. No need for a breaker box. PLUS DC switching under load is much more intense on contact arcing than AC. DC breaker boxes and CBs are expensive and not found in hardware stores.

[CA_Traveler]

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.

[GravelRider]

And by the way, these panels have a short circuit current of 10.19 amps. I'm assuming a 10 amp breaker for each panel before the parallel connection would be appropriate, and then a 20 amp after the parallel connection to the controller, and then a 60 amp from the controller to the battery. Or will I run into issues with the breaker tripping because of that additional 0.19 amps (and 0.38 amps after the parallel connection). To be honest, I don't know how close the current ever gets to the short circuit current with regular use. However, I would assume it does not get close, as normal optimal operating current would be around 8 amps (400/48).

[GravelRider]

CA Traveler wrote:
Aluminum angle, HD etc sell it.

Oh okay! So obvious now. Lol. Thanks for the recommendation.

[GravelRider]

MrWizard wrote:
Those are 48v panels, what are you using for a charge controller ?

GravelRider wrote:
I called a local solar installation business, and they will sell me two 400 watt panels for $500 total out-the-door for both panels. Sounds like a great deal to me and I won't have to deal with shipping.

These panels:
https://www.solarelectricsupply.com/q-cells-q-peak-duo-l-g7-2-400w-solar-panel

I'll be using a 60 amp MPPT controller. I haven't picked a specific brand yet.

[StirCrazy]

CA Traveler wrote:
If those mounts are Z mounts pitch them. Instead use 2x al angle connected with a bolt like a Z and the panels are much easier to remove when needed.

A number of posters have used only 3M VHB tape to secure panels. I used VHB tape, screws and sealed with Dicor.

I like that idea, I just picked up a 325 watt 120 split cell panel to put on my truck caper with an alumium roof. only thing left to arive is the mounting brackets.

did you put the alumin angle on the inside of the panel skirt and tap it for the bolt or the out side and use a nut and bolt?

Steve

[CA_Traveler]

Aluminum angle, HD etc sell it.

[GravelRider]

CA Traveler wrote:
If those mounts are Z mounts pitch them. Instead use 2x al angle connected with a bolt like a Z and the panels are much easier to remove when needed.

A number of posters have used only 3M VHB tape to secure panels. I used VHB tape, screws and sealed with Dicor.

I don't know what you mean by al angle.

[MrWizard]

Those are 48v panels, what are you using for a charge controller ?

GravelRider wrote:
I called a local solar installation business, and they will sell me two 400 watt panels for $500 total out-the-door for both panels. Sounds like a great deal to me and I won't have to deal with shipping.

These panels:
https://www.solarelectricsupply.com/q-cells-q-peak-duo-l-g7-2-400w-solar-panel

[CA_Traveler]

If those mounts are Z mounts pitch them. Instead use 2x al angle connected with a bolt like a Z and the panels are much easier to remove when needed.

A number of posters have used only 3M VHB tape to secure panels. I used VHB tape, screws and sealed with Dicor.

[GravelRider]

CA Traveler wrote:
Panel size didn't line up with the beams and I didn't use the 4' beams initially.

The roof is peaked and the beams are flat on 4' centers. Removing some ceiling items like lights determined one location. I drilled a small hole next to one from inside to determine it's exact center location from the roof. From the roof for other beams I drilled a small hole and used a small wire to confirm. I used 3" screws to secure the al angle.

Good to know. I'm hoping my install goes a bit easier. This is making me consider those glue-down no-drill mounts... But I don't know that I'd ever be comfortable driving down the road with glue-on mounts...