Solar Wiring Basics

[mello mike]

I just purchased two 95 watt Sunwize solar panels and a Xantrex C35 PMW Charge Controller. I have a few basic questions about wiring these panels and controller. What wiring should I use? I'd like to go with a simple two-wire romex. I'm curious what others have used for their wiring and if they're happy with their choice. Also, I'm torn on wire guage. Should I go 10 or 8 awg?

And what about a positive lead cutoff switch on the panel and/or battery side? And what about a fuse, overkill or needed?

Is protecting the wires on the roof with conduit needed?

[bangzoom]

Mike:

Funny you should ask. I just finished installing two Sunwise 80W panels on my AS.....putting the finishing touches on the project today. Actually, it was a re-install. Found out that they were incorrectly mounted and incorectly wired after I bought the trailer(not a factory install). Did lots of reading and wound up mating the panels to mounting brackets, wires, junction box and charge controller offered by AMSolar. Check out www.amsolar.com, in particular, the "education" section. They are RV solar specialists offering competant technical support. I needed a charge controller that offered temperature compensation as my battery box is on the outside of the trailer. Their website explains all of this, including the benefits of an MPPT charge controller. Your questions about fuses and wire types will be answered as well. They can explain it better than I can. Check it out and let me know what you think. I'll be happy to share anything I've done with you.

[mello mike]

Thanks Bangzoom. I didn't see anything on their site about wiring (unless I just missed it). What size wirng did you use? Did you use the two-wire romex?

[Inland RV Center, In]

Originally Posted by mello mike

I just purchased two 95 watt Sunwize solar panels and a Xantrex C35 PMW Charge Controller. I have a few basic questions about wiring these panels and controller. What wiring should I use? I'd like to go with a simple two-wire romex. I'm curious what others have used for their wiring and if they're happy with their choice. Also, I'm torn on wire guage. Should I go 10 or 8 awg?

And what about a positive lead cutoff switch on the panel and/or battery side? And what about a fuse, overkill or needed?

Is protecting the wires on the roof with conduit needed?

Mike.

Use stranded wire only.

The wire size depends also on the distance the current must travel. The longer the run, the larger the wire.

A fuse would add another margin of safety.

A kill switch should be a part of the regulator. If not, add one.

Using an over sized wire, causes no harm. Undersized wire, will have a voltage drop under higher current loads, that you may not want.

Since your dealing with low voltage DC, I would suggest the #8 wire for optimum performance.

Andy

[bangzoom]

Mike:

I used 10ga shipboard cable from the panel to the roof junction box----it's round and a perfect match to to the weathertight strain relief on the panel junction box and combiner box. I then ran 8ga from the combiner box through the rooftop refrigerator vent to the charge controller mounted nearby, and finally 8ga from the charge controller to the battery box. The positive lead is fused(30a) at the battery. All of this stuff came from AMSOLAR. On their home page, click products, scroll down to mounts and tilt bars, wire harnesses, and combiner boxes. You'll see some pictures there.

[elfirebob]

Mike,
Try Eheffa and my install options for our AM Solar panels we put in last year. Evan has quite a detailed install for two pannels as do I on http://www.airforums.com/forums/f448...ort-62608.html
My install starts on post #69 on page 5 of this thread.
For your questions,
10gauge from the panels to the connector box, 8guage from there inside to the controller and batteries. I did not use any conduit as the wire was "marine grade" made to be outdoors. I do have a cut-off swithch at the controller, this provides you the option as needed. I do recommend a fuse, mine is on the battery connectionn line.
Hope it gives you ideas and an options. Whether you use the connector box for the roof drop or opt for the refer vent install...wiring is fairly easy. I can scan my plans and e-mail ya...we're looking to add two panels to the Safari when she come out for sea trials...
Love ours, to date we have no leaks, no problems.

[masseyfarm]

When I was updating the Clipper #137, I installed the new 100W X 2 panels and ran the leads to a junction box on roof and on down the fridge vent with #10 to the MPPT controller. I wanted do the long run with #8 or #6 from the MPPT controller, (which I had mounted as close as possible in the fridge area), to the battery bank, located on the other side of the MH at the rear. A distance of about 30' with all the routing challenges. After a day of exploring the route, I changed the plan and ran twin sets of #10 wire under the cabinet wardrobe and across to the engine bay and on to the #2 battery bank. Shorter route by about 10'.
The #10 wire, twinned, was a lot easier to pull around the corners and was not bulky getting through the tight spots. Anywhere it was exposed to movement, I enclosed it with the spiral plastic wrap.
The MPPT controller is fused, and I installed another fuse at the battery bank to protect the wiring and batteries in case the long run did get grounded by accident.
For the benefit of yourself and future owners, ALWAYS DOCUMENT YOUR UPDATES WITH PICTURES AND SPECIFIC INSTRUCTIONS so that future minor maintenance can be preformed without excessive labour expense.

[masseyfarm]

For the benefit of yourself and future owners, ALWAYS DOCUMENT YOUR UPDATES WITH PICTURES AND SPECIFIC INSTRUCTIONS so that future minor maintenance can be preformed without excessive labour expense.

Note in the previous post, the 2 small 9V panels in the lower right of picture.
These are wired direct, and independent, to twin fans located in the lower fridge vent cavity and assist in air flow up over the fridge coils.
I found that when caught in a ferry lineup, or parked anywhere, with the fridge side exposed to the sun in the heat of summer, that the movement of air was difficult with the result of poor fridge preformance.
I also installed a 12V fan in the upper fridge cavity, (powered off the #2 battery bank) that is manually controlled with a rocker switch installed in the fridge control panel. This is to assist in the same air flow, if the fridge is being used often on a darker day when the solar fans may not be running at full capacity.
The air flow is hard to quantify, but the fridge temp. (monitored by remote sensor) tells me the system is working much better than what we experienced in the early days of ownership.

[mello mike]

Thanks for all of the replys. Last question: Did you mount your panels to the roof by drilling into a rib or just the skin?

The wiring part will be very easy, just had a few questions before proceeding with the installation.

[masseyfarm]

Originally Posted by mello mike

Thanks for all of the replys. Last question: Did you mount your panels to the roof by drilling into a rib or just the skin?

The wiring part will be very easy, just had a few questions before proceeding with the installation.

I made my own mounts after cutting aluminum square tube lengthwise. I was then able to position and secure the mounts directly into the aluminum roof truss on the Clipper, with Sikoflex for caulk.

There will be some considerable wind resistance/turbulance, on the roof so you must get into the aluminum ribs to secure anything attached there if possible. Any movement and you will have a leak before you loose the attachment.

When doing the design plan, keep wind resistance in mind and locate everything to give the least resistance.

Good Luck
Dave

[elfirebob]

Mike,
We used the Very High Bond (vhb) 3m tape supplied with the stainless adjustable rocker brackets from AM Solar. We did not drill the panel brackets. Cleaned and prepped ah la instuctions. bullit-proof.
We did drill and Dicor the connector/drop box install w/ stainless screws.
Let me know when you do your install, I'm out of service for about 8 weeks right now...

[mello mike]

Has anybody used this CW Combiner box available from AM Solar? This mounts on the side of a refrigerator vent. Not sure if this is small enough to mount on the side of a 70s Airstream refrigerator vent.

Solar Panel Roof Combiner Boxes for use with RV Solar Electric Battery Charging Systems

[mello mike]

Originally Posted by mello mike

Has anybody used this CW Combiner box available from AM Solar? This mounts on the side of a refrigerator vent. Not sure if this is small enough to mount on the side of a 70s Airstream refrigerator vent.

Solar Panel Roof Combiner Boxes for use with RV Solar Electric Battery Charging Systems

Just for the record, this box fits, with plenty of room to spare, on the side of my Sovereign's refrigerator vent.

[BarnacleBill]

Originally Posted by masseyfarm

I made my own mounts after cutting aluminum square tube lengthwise. I was then able to position and secure the mounts directly into the aluminum roof truss on the Clipper, with Sikoflex for caulk...

How do you find the roof truss?

Bill T

[wrochdvm]

Thanks for the great posts. We just bought our first AS (25' SS) and will take delivery in the next couple weeks. My wife and I have been sailing for the last several years but a fire at the marina destroyed our beautiful 38' Shannon Ketch. We are taking advantage of this mixed blessing to begin one of our long term goals, land cruise to as many national parks as we can between Massachusetts and Alaska. We plan to set out next April.

Our sailboat had a single 80 watt panel that performed very well, so we are very interested in adding solar to our AS. Your posts and link to AM Solar was very helpful.

Thanks again.

[masseyfarm]

Originally Posted by BarnacleBill

How do you find the roof truss?

Originally Posted by BarnacleBill

Bill T

Bill:
Before you drill any holes you have to research the mount area and document what you find. Determine where the wire is going and mount panels accordingly.
Pull our a roof lamp, and take off the inside cover of the AC. This will give you a good idea where the truss are located. On the Clipper, I ran a piece of hard wire along the conduit in the roof cavity to measure where the cross truss was. Measure and record. (next time -- it will be nice to just look at the results on file rather than research it again)
So you determine, the truss is front and back of every opening, (AC, Skylight, Vent fan, and may be odd distances in between.
When on the roof, use the previous info and use you rubber hammer to confirm by lightly tapping along until you hear the solid sound of a truss underneth.
On my solar upgrade it was easy, as the anchor truss ran front and back of the skylight.

Dave