Solar combiner box questions

[johnm1]

I'm looking for a solar panel combiner box for the RV's roof.

I'm going to start with 2 panels with the option to add 2 more if needed. I've seen some that are stupid expensive and some that aren't even remotely weather resistant (and still really pricey). Some people say to use waterproof junction boxes (like from the home stores) and some say they don't last very long.

Also, do I need to add fuses/circuit breakers in the combiner box of do I add them down nearer the charge controller? Seems in the combiner box is "better"?

What are my options here?

[hedge]

I also used a grey electrical box and painted it with uv protection paint. I didn't want to cut off the mc4 connectors so I made my box so the panels plug in to them.

It is my understanding that you don't need to fuse the individual legs of the panels until you have enough panels that the amp rating could be above 'max series fuse rating'. On mine this is 15A so 3 panels is fine (5a each) but if I go to 4 then I need to fuse the individual legs. I'm not an expert on this so maybe someone will come along and correct me.

below is the box I came up with. Of course if you wire them in series you don't need a box at all.

[Colo_Native]

Here's what I did painted it white hopefully to keep to sun from trashing it used Gorilla glue to hold the bus bars and divider.

[azrving]

I ran my panel wires into a Home depot gray plastic junction box with two terminal strips screwed to the bottom of the box. I then ran my number 2 wire down the frig vent using plastic strain reliefs on all the cables at the frig and junction box. Mine has been up there for 3 years. The cover gasket did leak a little so I used easy to remove silicone to seal it.

I installed a fancier low profile black plastic solar junction box for a friend but it was about $60.00 and it still needed to be drilled for strain reliefs. Gray plastic electrical pvc seems to be used outdoors on service panels and plug boxes all the time.

[brulaz]

I use MC4 Y connectors.

Did also use a grey PVC box like RoyB mentions, but painted it with white plastic paint for UV protection.

[gatorcq]

LINKbox

[RoyB]

Using the PVC boxes and tubing on the roof will be getting alot of the SUN UV rays... The PVC Electrical lines and products sure don't do well over time having to be sitting in the high sun like that... I still however like the LOWES/HOME DEPOT PVC Electrical Boxes idea with weather tight lids and PVC tubing. On the edge of the trailer roof line you can drill out a large hole in the center of the PVC Electrical box and route your solar lines into the trailer coming inside on the ceiling mounted cabinets we all have... Then you go from there using the PVC lines to where the cables need to go to... This allows all of your solar cabling be inside PVC boxes and tubing...

I am referring to these type of PVC ELECTRICAL Boxes with tubing connections on their sides. These come in all sizes and multiple number of tubing connections to suit your needs...






This is the way I am going to install my solar install on my off-road POPUP trailer roof. No drilling on the roof line at all... I can only drill into the wood side portion of the roof and will want to do that on the side of the trailer - not on the top...

I think I would want my electric components inside my trailer near the tie-in point for the batteries with meters and controls etc... Mainly so I can easily see what is going on. The combiner boxes will up near the roof and all feeding a solar panel inside the trailer near the battery install area.... Just my thoughts...

Roy Ken