Right Panels for RV Application

Re: Right Panels for RV Application

@Photowhit, Bill & John: Thank you all for the input . . . now I have even more to read and think about.

On my 27' travel trailer, I have a wide-open space from the A/C cover forward that is approximately 8' wide x 9'8" long. Of course, I wouldn't want to use all of that space for PV panels and lose all walking space. I was originally thinking that three of the Kyocera 250w panels laid out edge-to-edge could cover ~5'6" x 9'9", but it forces the last panel right up to the A/C cover and/or over the front of the coach, slightly.

Alternatively, I'd mount the panels parallel to the long dimension of the coach with the walkway up the middle. With just two panels, there would be no possibility of shading from the A/C cover. If I added panels three and four, however, it would become an issue with at least one of the panels, some of the time.

I do intend to incorporate a tilting option into the build, but I do understand the concern with potentially high desert winds. It seems logical to have this option, though, as long as it's well-engineered and constructed.

I spend summers in Colorado and winters in Arizona. If I do travel further north, it would only be during the summer. I was born and raised in Colorado and my enthusiasm for winter left me many years ago, so there's little prospect that I would ever venture north of, say, 35°N latitude. :cool:

It seems I'll need to give up on the idea of using both a TriMetric monitor and a matching SC-2030 charge controller. That's OK, though, since I'm way too green at all this to be making hard and fast selections of equipment at this stage. Bill, I appreciate the links you provided to the various MPPT controllers. I'll do my best to read and retain as much of it as I can. I did look at the Rogue MPT-3048 you seemed to highlight and I'm impressed with what I've read so far.

Since the solar panels will be mounted on the forward or "tongue-end" of the roof and the batteries will be located on the tongue, the separation is less than 10'. I was thinking of locating the charge controller in the pass-through bay that's at the very front of the coach (so less than two feet from the batteries). And I understand about using the appropriate wire gauge to minimize line loss.

In that regard, however, I'm unclear on best location for the inverter/charger. Like most RVs, the shore power cord is located at the rear of the coach on the driver's side. The panel is on the other side of the coach, under the stove/oven, so it's about 18' from where the batteries and charge controller will be. I was considering locating the inverter/charger in the same storage bay at the front of the coach adjacent to the charge controller, shunt, etc. and running the wire from the inverter under the floor/frame through PVC conduit, then back up through the floor into the space under the stove where the present panel is located.

I don't have an AH rating and wattage estimate yet, Bill, and while I know this will probably sound bass-ackwards, I intend to install a system that will generate the greatest amount of power for the most effective allocation of $, then adapt my off-grid lifestyle to the power available. For example, the laptop I use is on almost constantly and I display it on a 32" TV, but I intend to replace both before I go boondocking with an iPad mini. That represents a huge difference in power demand. And by changing the refrigerator and water heater to propane and dispensing with the microwave altogether, there's almost nothing else that requires power . . . but I want to have a respectable amount available anyway, just because. I also carry a Honda 1000w gas-fueled generator that I hope to never need.

Again, I appreciate the input you've all been kind enough to post. I'm learning as quickly as I can, and I hope you'll bear with me as I get up to speed.

TJ

Re: Right Panels for RV Application

rich wrote: »

Just thought about throwing in my 2 cent solution to tilt, I simply will be using hinges on-top of my z mounts that hinge them up in the landscape orientation..this plan came about after several prototype tilting frames ...they were all in my opinion far to heavy....anyway, hope that helps.

Thanks for your post, Rich. I've thought about how I want to mount the panels to incorporate the tilting option and I'm inclined to do it in a way that will allow me to tilt them in opposite directions. What I mean by that is I don't want to have to always face the rig in the same direction (typically east, so that the door is on the north side) to tilt the panels to the south, because there will undoubtedly be those times where that isn't possible. On those occasions when the rig is pointed west, I'd still like the option of tilting the panels to the south.

I don't think this is a difficult problem to solve, though. As I see it, it will just be a matter of using different length flat metal arms on the north side of the panels to achieve the optimum tilt for the location and time of year, regardless of whether the rig faces east or west. Any other orientation would seem to dictate leaving the panels flat.

The thing I'm struggling with is the advisability of ganging the panels together into a single panel-mounting frame. The likelihood of occasionally high desert winds threatening the panels, mentioned earlier in this thread, is real - and it seems logical that mounting the panels into a "uni-frame" structure would probably compound the danger.

It's something I don't need to decide on right away, though, and I hope to get more information before a decision has to be made. Exactly how the panels are laid out on the RV's roof will have a lot to do with it, of course.

TaoJones

Re: Right Panels for RV Application

Photowhit wrote: »

In essence the panel system operates on the amp running through it, Amps x Volts = Watts, so if you have a 30 amp Charge Controller, It will handle a (12v x 30 amps = ) 360 watt array in 12 volt system voltage, or a (24 x 30 720watt array in a 24 volt system or a 1440 watt array in a 48 volt system. Same charge controller...different system voltages. Hope this helps.

Now that is clear . . . thank you for that, Photowhit.

Re: Right Panels for RV Application

Ralph Day wrote: »

Also not to forget how the weight of panels will affect the total weight of your trailer and the tongue weight. Don't want to over weight the trailer or the tow vehicle capacity. A couple of hundred pounds of panels and added battery weight will cut down your trailer cargo capacity, and the added tongue weight will reduce the tow vehicle's load capacity.

Ralph

You're absolutely right about that, Ralph . . . weight considerations are always in the front of my mind whenever I think about adding something to my RV. Although this RV's tongue has carriers for a pair of Group 27s, I only use one. If I go with two 6v Crown batteries, the weight will be nearly identical. If I opt to go with 4, however, that will place twice the battery weight on the tongue. And as the charge controller, inverter, etc. will be just behind the tongue and the panels will be on the roof just behind the front of the trailer, all this added weight is being placed toward the front of the coach.

I currently tow with a Chevy Silverado 3/4 ton HD pickup, but there may be a one-ton diesel in my future. I've always been careful about keeping the added cargo down, and I only make long passages with empty tanks. Each tank is 40 gallons, so that represents a potential 120 gallons x 8 1/3 pounds/gallon, or 1000 pounds. It's silly not to empty the tanks before setting out, then carrying that excess weight up some pretty steep hills here in the west.

TJ

Re: Right Panels for RV Application

Thank you for the tip on the Kill-A-Watt meter, Bill, and the link as well. It looks like an economical way to get a clear picture of what sort of power usage the current components are demanding.

I had started this thread by noting that I had read all of HandyBob Shearer's blog . . . I was hoping (and maybe expecting) that someone might post an opinion on Mr. Shearer's strongly held point-of-view. His site is http://handybobsolar.wordpress.com/ and though he can seem cantankerous at times, I think he's just frustrated because he's seen so many installations that were all wrong and is of the opinion that many of the people who are doing those installations are either incompetent or intentionally leading trusting souls astray just so they can sell them more and more stuff that will never give them the power independence they're seeking.

And where Mr. Shearer constantly advises those who ask that they should first get a TriMetric monitor, that doesn't seem to be the generally accepted view (if I'm reading this thread correctly). Is there something about the Bogart Engineering products that renders them less-than-adequate for their designed function? Am I just on the wrong track thinking I'd make the TriMetric the brain in my system? Are the Bogart Engineering products just OK, but there are other, better-suited or more cost-effective products I should be considering?

Thanks again for all your in depth knowledge and willingness to share it, Bill.

TJ

Re: Right Panels for RV Application

Thank you for your thoughtful reply, as always, Bill. I think I understand your point regarding the TriMetric monitor . . . the programming of it can, perhaps, be a bit intimidating for some users. I carefully read the instructions online here: http://www.bogartengineering.com/sites/default/files/docs/TM-2030Install%20Instructions3-18-14%20%281%29.pdf . . . and while it's thorough, it didn't seem to be beyond my abilities.

I suppose it's a bit like your observation about creating system designs on paper, though . . . intellectual concepts and hard reality don't always sync up perfectly.

I served as a moderator and admin on a sailing forum a few years ago and hate online misunderstandings, so to the extent my bringing HandyBob into the conversation created some confusion, maybe the following will help clear things up:

Bob Shearer (aka HandyBob, a name others gave him that stuck) is a former full-time RVer who had formerly worked as an electrical engineer and in electrical equipment sales before he retired. When he and his wife began full-timing and moved up to a 31' fifth-wheel, he was determined to figure out why it was that the coach had 345 watts of solar panels, but the batteries quickly went dead if they ran anything beyond a few lights - forcing them to head to an RV park to recharge. All that was in the 2000-2003 period.

Because the system that was already on their coach was installed by the "Grandfather of RV solar power," the first thing Bob learned was that the man who literally wrote the book on RV solar was clueless about how to make solar charging work and didn't actually live full-time in an RV himself. After he did solve the problem, though, the Shearers never used an RV park again and never bought a generator, either.

HandyBob has since stopped full-timing to build a home in Montana, also fully-dependent on solar. They continue to live in their fifth-wheel while they build up their mountaintop property to meet their needs. Somewhere in his blog, HandyBob put in a good word for NAWS. Because he is so acutely aware of the charlatans who seem to outnumber the honest people in the solar industry, his recommendation carried a lot of weight with me and indirectly led me to this forum.

* * *

I'll order a Kill-A-Watt meter, Bill, and note what the readings indicate. I do understand, though, that conserving energy is a far-better solution than buying and installing a system that will generate all the voltage a thoughtless energy user could ask for.

TJ