What’s wrong with this picture?

[ainley53]

I still get dizzy trying to get my head around this solar and electrical stuff but here’s my game plan. There’s a quiz at the end. I’m going to put a flat roof on my motorcycle trailer. The roof will be a sheet of 3/8” or ½” plywood (4’ x 8’) or something of similar dimensions. I have 4 Renogy 100 watt Monocrystalline panels which measure 47” x 21.3” each which I’ll mount side by side on the plywood. I’ll run the cables from the panels to a bus bar inside a junction box located on the passenger side of the sheet of plywood at the midway point and wire the panels in parallel. From the junction box I’ll use 30 feet of a Coleman 10/3 AWG exterior extension cable with a 10 AWG in line 30 amp blade fuse just before the charge controller. I’ll use Anderson pole connectors near the junction box so I can unplug from the solar panels while driving although I could probably fasten the cable to the luggage rails on my SUV with some zip ties and just leave the panels plugged in. I’m still debating on whether or not to install a continuous duty solenoid with an on/off switch on the car. The charge controller is an SC-2030 PWM with temperature sensor from Bogart Engineering and a TM-2030-RV TriMetric battery monitor. From the charge controller to the batteries (a pair of 6v Lifeline AGM @ 220Ah each) I’ll use less than 2 feet of 8 AWG from a set of jumper cables with a 50 amp in line blade fuse. From the batteries to the inverters I’ll use 2 or 3 feet of 4 AWG with a 100 amp ANL in line fuse for each inverter. The inverters are a Morningstar 300W pure sine wave and a Power Simple 1000W pure sine wave. There will be a 500 amp shunt on the negative cable between the batteries and the charge controller and inverters. The ground cable will be fastened to a large bolt on the floor of the SUV where the front passenger seat used to be bolted. The batteries are there now, sitting end to end, with my tool chest along side of them.

So today’s quiz is: Will this work? What have I done wrong? What have I left out? What should I do differently?

And please don't be afraid you may hurt my feelings. You won't. I can take my Dunce cap and go sit in the corner if I need to.

 

[c_hasbeen]

this quiz requires that new math they tried teaching back in the late 70's...I missed that day at school

 

[ainley53]

That makes 2 of us. LOL.

 

[GotSmart]

That is a lot of power.  What are you running?

 

[highdesertranger]

I would say, loose the plywood. build your rack to hold the panels without the plywood. why do you need 30' of cable from the panels, are your batteries that far away? highdesertranger

 

[ainley53]

I would say,  loose the plywood.  build your rack to hold the panels without the plywood.  why do you need 30' of cable from the panels,  are your batteries that far away?  highdesertranger

I could loose the plywood but having it gives me the option of being able the tilt the solar array in all 4 directions by mounting the plywood with a pinned hinge (similar to a door hinge). The pins will need to be the kind with a hole through one end for a cotter key. I can pull the pins on three side and prop the array up with pieces of premeasured flat metal bars. Maybe 3 or 4 hinges on each long sides and 2 on the short sides.

It's 25 feet from the center of the motorcycle trailer to the front floorboard of my SUV. The extra 5 feet is in case I decide to keep the array plugged in full time I'll need a little slack between my SUV and the trailer for cornering.

As for "that's a lot of power" you may be right but everyone keeps saying to buy as much solar power as you can and this is as much as I can fit on a 4" x 8" sheet of plywood which is what will fit over my motorcycle trailer without hanging over anywhere. I originally planned on putting two 100W panels on the roof of my SUV but decided I could use that space for a cargo box to store winter clothes and other items not frequently needed. Plus "the roof on the trailer" let's me double the amount of power I can have.

These panels were chosen solely because of their dimensions. They're the only ones I could find that let me put 4 of them together on the space I have available. I'm just really lucky that they're top quality panels and 100W each to boot. And they were on sale for $135 each.

Better to have more than I need than not to have enough.

 

[ainley53]

How much voltage drop am I going to have using 30 feet of 10AWG cable from four 100W Renogy panels to my charge controller? Should I use 8 AWG instead? Specs for the panels are here:

http://www.renogy-store.com/Solar-Panel-100W-12V-Mono-p/rng-100d.htm

 

[Optimistic Paranoid]

30 feet of 10 gauge wire is way too long and way too thin.

https://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/

You'll have to scroll way down into the article to find the part about wiring.

Regards
John

 

[MikeRuth]

Could we see a pic of the trailer or a few? I may have missed it but is there any way to put your batteries in the trailer? Easier to run 110 out than 12 volts.

 

[ainley53]

You are absolutely correct Optimistic Paranoid. I went back and read HandyBob's article for a third time. Found the answers. I could squeeze by with #6 AWG for 28 feet, but #4 AWG would be much better. Trying to absorb too much, too fast is seldom a good thing. Thanks for the pointer.

 

[ainley53]

MikeRuth, pictures and specs can be found here: http://www.baxleycompanies.com/SB001.html

I'm not sure that's possible. These at 6 volt batteries wired together for a 12 volt system so they need to be next to each other. At 66 pounds each that's 132 pounds more weight on one wheel/tire than the other. Not sure that's a good idea. Plus I'd have to put the charge controller, battery monitor and inverters out in the open since the trailer is not an enclosed type trailer. Pretty sure that's not a good idea. But I'm certainly open to suggestions. That's why I'm on this website and not somewhere else. If anyone in the world has the answers, it's the people on this website. I've a least learned that much.

 

[akrvbob]

If you run them in series (72 volt) and buy a MPPT controller the 10 gauge would probably work. I'd use a MPPT no matter what. PWM wastes 33% of your power. It's like buying the 4 panels and mounting one of them upside down so it doesn't work.
Bob

 

[Seraphim]

Same question - why are house batteries in the SUV? House batteries in the trailer with the shortes possible run from panels to controller to batteries. Only cable from SUV you need is if you're going to use the alternator as a charge source to the batteries.

 

[ainley53]

Same question - why are house batteries in the SUV? House batteries in the trailer with the shortes possible run from panels to controller to batteries. Only cable from SUV you need is if you're going to use the alternator as a charge source to the batteries.

See post #11 and feel free to correct me if I'm wrong. I am a newbie, after all.

 

[ainley53]

If you run them in series (72 volt) and buy a MPPT controller the 10 gauge would probably work. I'd use a MPPT no matter what. PWM wastes 33% of your power. It's like buying the 4 panels and mounting one of them upside down so it doesn't work.
Bob

Having never even seen a solar panel before, I could be totally wrong, but my understanding is that if the panels are wired in series and anything happens to one of them, like a shadow on one of them, I lose production from all of them like a string of Christmas lights. You're right about the volts, but my amps would only be 5.29 amps. If they're wired in parallel, I only lose production from the one panel with an issue. My volts stay the same at 18.9 but my amps become additive, so I get 21.16 amps which is why I chose to go with a PMW instead of MPPT. I also realize I'm never going to see 100% of anything from the panels to the controller. I am the newbie and that's why I'm here. To learn.

 

[Seraphim]

See post #11 and feel free to correct me if I'm wrong.  I am a newbie, after all.

My apologies, missed the line about being an open trailer

 

[GotSmart]

Putting a flat roof over that will cause you problems. Such as the wind will catch the roof and lift it. Think Kansas ~~~

That trailer is designed the way it is for a reason. Spending the money to buy that custom unit and adding a sheet of plywood would be extremely acquard.

Panels are not like the new christmas lights, but more like the older expensive sets where if one light goes out the others still work. Otherwise solar farms would have problems.

What does the roof of your tow vehicle look like?

 

[ainley53]

Putting a flat roof over that will cause you problems.  Such as the wind will catch the roof and lift it.  Think Kansas ~~~
That trailer is designed the way it is for a reason.  Spending the money to buy that custom unit and adding a sheet of plywood would be extremely acquard.
Panels are not like the new christmas lights, but more like the older expensive sets where if one light goes out the others still work.  Otherwise solar farms would have problems.
What does the roof of your tow vehicle look like?

I got the motorcycle trailer a year ago, used, for $2k. I had only planned on a three week motorcycle tour of Colorado at the time, not van dwelling full time. The tow vehicle is a 2008 Saturn Outlook with roof rails and cross bars. I plan on putting a cargo box on the roof of the Saturn. My original plan was to put the two Renogy RGN-100P panels on the roof of the Saturn and use a single Trojan 200Ah 12 volt AGM battery. I'm hoping the combined weight of the trailer and everything on it will be enough to keep it planted on the road. Trailer 460 Lbs, Motorcycle 550 Lbs, Solar panels 66 Lbs, two 5 gallon cans (1 gas, 1 water) 80 Lbs = 1156 Lbs. Payload of trailer is 1250 Lbs. I could always load a couple more boxes on the trailer and get it closer to it's max payload.

Granted, a roof on the trailer will not be pretty; but I'm more interested in functional.

 

[ainley53]

It will be easier to correct a problem now than after I hit the road.

 

[GotSmart]

What do you plan on powering? do you really need that much power? Perhaps two flex panels on top of the cargo box?

A open roof on the trailer will make it like a sail. There is a reason you do not see anything going down the road with that design.