Use of Combiner Box with Solar

[Grodyman]

Hi all,

I am researching solar for a 5th wheel I have on order. I am interested in battery charging only and will probably go with 2 6v batteries or 2-3 12v grp 29 @125 amp hrs ea. for a total of 250-375 amp hours.

I am looking at Sunelec. and they seem to have good prices on Sun solar panels either 100W or 120W (2).

So, with 200W or 240W of solar panel (2 panels only) is it necessary to use a combiner box? I want to make the install as simple as possible and use a non mppt controller. Thank you.

I had an Arctic Fox truck camper with 100W panel installed from factory and 2 grp 27 batts, and it seemed ok, but I have no idea what charge controller it had. It did have a Intellipower converter with charge wizard. I would like a little more than the 100W but don't want to get fancy, I really don't know how I am going to route the wire.

Would it be better to go with a larger single panel and MPPT?

What are the basic components I would need for simple battery charging and approx cost?

This is the model 5th wheel:
http://www.cheyennecampingcenter.com/SBS320FQDS

The front compartment is below the bathroom, and the refrigerator is pretty far away to use the refer vent.

Gman

[John Hilley]

Quote:

Originally Posted by Grodyman Hi all, I am researching solar for a 5th wheel I have on order. I am interested in battery charging only and will probably go with 2 6v batteries or 2-3 12v grp 29 @125 amp hrs ea. for a total of 250-375 amp hours. I am looking at Sunelec. and they seem to have good prices on Sun solar panels either 100W or 120W (2). So, with 200W or 240W of solar panel (2 panels only) is it necessary to use a combiner box? I want to make the install as simple as possible and use a non mppt controller. Thank you. I had an Arctic Fox truck camper with 100W panel installed from factory and 2 grp 27 batts, and it seemed ok, but I have no idea what charge controller it had. It did have a Intellipower converter with charge wizard. I would like a little more than the 100W but don't want to get fancy, I really don't know how I am going to route the wire. Would it be better to go with a larger single panel and MPPT? What are the basic components I would need for simple battery charging and approx cost? This is the model 5th wheel: Sabre Silhouette 320FQDS Fifth Wheel Bunkhouse Travel Trailer by Palomino The front compartment is below the bathroom, and the refrigerator is pretty far away to use the refer vent. Gman

You should use a combiner with 10 gauge wire from panel to combiner and 4 gauge from combiner to charge controller. 200 watts should be minimum and 400 watts would be about right. You could start with 200 watts though and see if it is sufficient for your needs. You will probably use more power in the 5th wheel then you did in the camper. I think 200 watts is about right for a pickup camper.

[Grodyman]

Ok, two solar panels with #10 to combiner box...#4 welding wire down to charge controller in main storage bay...#2 welding wire through barrier to battery?

I lose it when I try to think about adding monitor and/or fuse boxes, temp sensors......etc...I don't live in the rig, just plan to dry camp for 3-4 days at a time...

Gman

[JeffinTD]

#2 to the battery bank I would think would be plenty, assuming the length of run is reasonable.

I would consider adding fuses. From suggestions here I spent like $15 for an outdoor rated fused AC disconnect. Simple to install, pretty much no voltage drop, and priced right. Even if you only use the rig occasionally, safety is still important.

The trimetric monitor isn't absolutely necessary, but I find it very helpful. It is something you could always add later if you want.

Are you using panels with MC4 connectors? If not, I used a couple buss bars in a waterproof junction box on mine, which worked well.

Some of the Sun Electronics panels have solarlok connectors, which can be hard to find mating leads for.

[Grodyman]

I'm not sure how the solar panels are configured, but want to figure out what is easiest to install before I order. I think the combiner boxes from AM Solar come with bus bars. So I want a panel without MC4? How do you attach MC4 to #4 welding wire? Obviously I'm not an electrician...I might have to find someone to do this. I just need to see a sytem to understand it, reading about them just doesn't give me the details I need.

Gman

[JeffinTD]

Panels will either come with a junction box to which you attach your own wire, or with leads with MC4 or more rarely Solarlok connectors on the ends.

If they are MC4 (or solarlok) you can buy male and female ends with a length of 10 ga UV proof wire, or you can buy an extension lead that would have male on one end and female on the other in a variety of wire length. You can just cut that in the middle.

Then to connect to #4 cable you can just use a buss bar, but you will want one that has holes large enough to accept the #4 wire, and holes small enough to secure the 10 ga wire.

About 5 minutes into this video, I show the junction box I used, if that helps.

[ralper]

Use a combiner box so it will be easier to add more panels later. Use #4 wire down to the controler and it too will handle more panels. With 200 watts of panels #4 wire will have esentially no voltage drop and you will get the full power from your panels into the batteries.

MPPT used with panels putting out 16 volts to 18 volts is not necessary and adds cost, more to go bad and very little benefit. I know what the MPPT control manufacturers claim. They claim the extra is "UP TO" but not guaranteed "TO BE".

Use a Morningstar controler as they are the best and most cost effective.

[Grodyman]

Thanks guys, I am leaning away from MPPT, the higher watt panels don't seem to put out much more amps, but really it is cost. I think I am figuring it out with your help.

Gman

[JeffinTD]

In my case two 220 watt panels at 30v were enough cheaper than similar 17v panels that would have been appropriate for a pulse modulated charge controller that it made the mppt controller worth while.

Absent a situation like that, I think the route to best performance per $ would likely be pwm controller and spending the money saved compared to mppt on more panel.

I'm no expert, but the rest of my install is on u-tube and it performs well.