Any tips on my setup?

[SunEagle]

@Suneagle: Ha good point. That's a pretty bad picture of it though. Its perfect for my girlfriend and I: 2 offices (one in the back with awesome panorama views of the beach usually) and another table in the middle, and we sleep in the roomy bed above the cab. Its a 24 foot Class C. For my girlfriend and I I'd call it just right. My previous camper was a Hitchhiker III 5th Wheel very much like TX's, and personally I'm glad for the downsize, but those are because of personal factors like driving on winding Route 1 in California all the time, and slideouts when parked on the beach become a maintenance hassle. My trailer after that was a 45 foot 1956 Spartan. Now *that* was an awesome trailer!

As far as Sunking's new misinterpretations of my needs and statements, I'll just say that I certainly wasn't suggesting that 250 watts would be enough for TX's trailer. Personally I'd go 600 watts of solar (or 900 if you want to go nuts) and a 2000 watt Honda EU for emergencies and call it a day, but I know that diverges from the Platonic ideal of solar systems. But if you don't realize that the way I'm suggesting is the standard high-end way of outfitting RVs, and furthermore that it works awesomely (and is in fact overkill), then you don't have enough experience with the topic at hand (solar for RVs). Ok fine, the Honda EU is cutting corners, but personally I think its an improvement over most RV gennies.

And it's absolutely mind boggling that he still doesn't understand that I'm adding panels to an existing system, so keeping my existing controller, especially when it will very likely work just fine, is, at a minimum, the best way to start. It's also mind boggling that he really feels the need to rant about my controller in like 20 posts. This is also pretty mind boggling.



It's hard to believe that that's a serious statement. Just to name a few reasons to compromise in an RV solar install:

- price (usually the biggie)

- space (also a massive factor)

- simplicity (for example, wiring batteries for 24 volts is usually more efficient, but that doesn't mean its worth the expense, labor and added complexity)

And there's a bunch of miscellany like using your equipment at hand when possible.



Unless, as I explained a bunch of times, you have shade issues! And unless you already have a controller that will probably work just fine with the panels in parallel, so you don't see the need to spend an additional $600 just because some internet blowhard is oddly desperate to get his point across.

I'm seriously questioning his motivations at this point.

Well like I said my wife prefers a little more room in ours and it has a lot of space below to store my portable solar panel system if we decide to go off grid during our long trips. But it also has a 5000 watt genny and the alternator does a real good job keeping the batteries up to snuff. The solar is just a fun (but expensive) project I built for the home because I did not listen to the experts here before I opened my pocket book. Live and learn.

[Wrybread]

> it has a lot of space below to store my portable solar panel system if we decide to go off grid during our long trips

Oof, portable solar systems in RVs are a massive pet peeve of mine. It seems to me that the roof is the best place to store panels anyway.... With the added benefit of not having to do anything once you arrive where you're camping.

But yeah, with a smaller RV I've found the secret is maximum space efficiency. And I'm lucky in that my girlfriend has the same taste in this stuff as I do. We try to take lessons from the RVs in Europe and Japan, and not the usual American behemouths. With garbage disposals! Gotta love American ingenuity sometimes. And, incidentally, only in America is a 24 foot RV considered "small".

That said, if winding roads aren't an issue, and storage isn't an issue, then yeah big RVs are awesome.

Personally I'm not a fan of generators, unless you need a mission critical backup like TX's office. Or unless you need air conditioning (which, granted, covers a lot of people, but I've been living on the Pacific coast for so long I forgot what AC feels like). I think that what most campers are using their generator for could easily be done with solar. It drives me nuts when someone is parked under full sun in cool temperatures with their generator running. We take roadtrips almost every weekend, with frequent long (over 7 days, often longer) stays in one place without moving, and I've never even come close to running out of power with my single 300 watt panel. And the compartment where the generator used to live makes an awesome battery bank and tool shed. The purpose of this expansion is to power my fridge, since we leave it on 24/7/365 (even when we're not using the camper, since we leave food in it) and the propane costs add up, and it sure does suck when it runs out unexpectedly and you arrive to a camper stinking of rotten food.

[Wrybread]

Incidentally, I think you might be a good illustration of my theory that over complicating solar scares people away from using it. You're the moderator on a forum dedicated to solar, and yet your RV doesn't have a permanent solar installation. That's completely amazing.

I obviously could be wrong, but I suspect its because you think its a big undertaking. I'm not talking to you here, but to people who are considering solar for their RVs in general: The beauty of solar is that it absolutely isn't complicated. Get a couple of 300 watt panels (or even just one). If you want to save some money and are somewhat handy with a multimeter, don't be afraid of Craigslist. Personally I think the Tracer 40A MPPT charge controller is just fine for most installs, but obviously that's debatable. Get an Outback if you want to be sure and want room to grow, but in my opinion that's overkill. And no, you don't need to comprehend the minutia of how an MPPT charge controller works to use one, but you should wrap your head around the gist. Get 2 or 4 Trojan T105 batteries (I'm a big fan of 4 of them), and unless you're powering a small village wire them for 12 volts. If you want to go nuts read a few of Sunking's rants, but I have a feeling they've led to more systems never being built than built. And the ones that were built were over-built and over-priced. For a much more reasoned source of information you might hit Arizona Wind & Sun (or similar high end solar dealer), and buy your parts from them if you have more money than knowledge of electricity and time to research.

And it bears repeating that a lot of the info spouted by Sunking isn't there to help people with their solar installs. This is his assessment of solar on RVs:

Solar is just for show and tell or for extending long stays. You still need a generator or Isolator to get charged up dry camping for extended periods.

That is, simply put, completely wrong, and a shocking statement coming from someone who should know better.

In another thread he called the solar industry a scam.

He's not here to advocate for solar, or even to empower people using it. He's here to grind his bag of axes and try to scare people into taking him seriously. And of course I'm not saying that every one of his rants are misinformation (though many are, as sensij awesomely demonstrated in this thread), but they sure are above and beyond what's necessary for an RV solar install. And they sure do ignore the fundamental fact of how well solar installations on RVs in the real world work.

[jflorey2]

Incidentally, I think you might be a good illustration of my theory that over complicating solar scares people away from doing it. You're the moderator on a forum dedicated to solar, and yet your RV doesn't have a permanent solar installation. That's kind of amazing.

Not that amazing to me.

I have two solar power systems on my home. The first is a 10kW system that I don't mess with much. The second is a ~1kW experimental system that feeds into either a Kid (and then to a 48V bank + an Outback GVFX) or to several Enphase inverters. It's an experimental system that I run tests on for my work. The longest it has remained the same is about 18 months.

When I had an RV I had an assortment of thin film panels that totaled about 300 watts. They stored under the bed. When we stopped we'd lay them out wherever got the best sun. It would run the fridge and a few lights and that was about it.

I think many people who are involved in solar have something similar - a system that's not quite complete, used for either testing or occasional use.

[Sunking]

You absolutely use Vmp when evaluating operating efficiency and transmission loss. Voc only matters relative to the charge controller's specification, and as we've already established, two 24 V panels in series is fine on this controller in locations that don't get too cold. Surely you are familiar with 2014 NEC 690.7(A).

Stop the nonsense Sensi I do not give a crap about Vmp and has nothing to do with what I am talking about. With his two 300 watt panels in series Voc exceeds his controllers Voc limit period end of discussion. That is exactly what the NEC is telling you and has nothing to do with Vmp. If you do not know the difference between Vmp and Voc, get out of the biz.

[sensij]

Sunking, maybe you missed the math showing that the temp corrected Voc is less than 50 V. Two panels in series, in this location, is safe for a 100 Voc controller.

Voc varies with temperature. You'll see a temperature coefficient on the panel's datasheet... typically around -0.3%/K, or -0.14 V/K. If the panels are 46 Voc at STC (25 deg C), it needs to be adjusted for the minimum temperature they'll see. Minimum design temp for Stockton is -3 deg C (see link below), so that would be a 3.92 V increase, raising the 46 Voc panel to 49.92 V. Two panels in series just barely clears the 100 Voc limit for the Tracer charge controller.

http://www.solarabcs.org/about/publi...map/index.html

[Wrybread]

I think many people who are involved in solar have something similar - a system that's not quite complete, used for either testing or occasional use.

Mind boggling.

(As is Sensij's patience.)

[Sunking]

Sunking, maybe you missed the math showing that the temp corrected Voc is less than 50 V. Two panels in series, in this location, is safe for a 100 Voc controller.

The Controller VOC is 92 volts. His panel Voc is 46 volts @ 25C. Personally I do not care if he wires them in parallel or series. He does not know what he is doing and you know it.

At 40 degree F he goes above 100 volts.

[Wrybread]

The Controller VOC is 92 volts. His panel Voc is 46 volts @ 25C. Personally I do not care if he wires them in parallel or series. He does not know what he is doing and you know it.

Yet more mind boggling misinformation from Sunking. I fully know my controller isn't ideal as I've said about 50 times now. But I also know that it's likely to work well enough for my purposes. If it doesn't, guess what: I can make adjustments.

Honestly, you might want to read up on the straw man fallacy. Its when you misrepresent someone's argument and then shoot it down. You do it *every* *single* *time*.

[Sunking]

Yet more mind boggling misinformation from Sunking..

Misinformation? It is called SPECS from the manufacture and proper safe engineering. Not SWAG from a shade tree mechanic.

[Wrybread]

> Misinformation? It is called SPECS from the manufacture.

Once again you've set up a straw man. The misinformation I was referring to is a) your theory that I think the Tracer is an ideal controller (I don't), and b) that I'm planning to wire the panels in series (I'm not).

Now lets all stand back and let Sunking formulate his next straw man argument.

[sensij]

Misinformation? It is called SPECS from the manufacture and proper safe engineering. Not SWAG from a shade tree mechanic.

From Page 22 of the manual:

Specs.JPG

Two panels, in series, in this location, meets both the 25 deg environment temperature requirement and the minimum operating environment temperature requirement for this charge controller.

I'm not agreeing or disagreeing with any decision the OP has made. Your knowledge and willingness to share that knowledge has helped a countless number of forum participants and visitors, even when your message isn't well received... that is not in question here. However, that are some points in dispute in this thread that do not appear to be your finest work, and I've tried to chip in some clarifications. Time to move on to the next one, don't you think?

[Sunking]

Time to move on to the next one, don't you think?

Yes I do sensi. But let me ask you this. Do you recommend taking equipment to the edge. As a professional I cannot do that. If you buy wire like THHN to do 240/120 volt work what is it voltage rating? 600 volts right. Do you use THHN on a grid tie system operating at 500 volts? Most likely you se PV wire rated for 1000 volts because you do not want to take any chances. You are held responsible if something happens and would have no defense in a court of your peers pushing limits. So don;t ask me to do it.

I do not know the Temp Coef of his panels as it has not been specified. I do know about what it should be because all 300 watt panels are 72 cells and at 40 F you go over 100 volts and there is no way a professional engineer is going to endorse that any more than a doctor will recommend you smoke. Well maybe if you are over 60 with lung cancer in Hospice.

It is all a moot point with 3 panels, as 2 is ore than the controller can handle without clipping. 3rd panel is just a waste. Like I said he got on my radar claiming to have 20 years experience. You know what happens to pretenders here giving bad advice. 2 mods have told him he is wrong along with 4 engineers. He will not last much longer before they ban him if he keeps it up.

Not personal sensi, you have been around here long enough to know that. I will not tolerate unsafe advice, practice, and pretenders. Wrybread is all 3 of those.

[Wrybread]

Like I said he got on my radar claiming to have 20 years experience. You know what happens to pretenders here giving bad advice. 2 mods have told him he is wrong along with 4 engineers. He will not last much longer before they ban him if he keeps it up.

Ah, here come the straw men. I never claimed to be an expert, just that I'm not new to solar and have been working with solar (not professionally) for 20 years. It was you who injected "expert" into that, and then spent countless posts trying (in vain as it turns out) to make an upgrade that's still in the planning stages look foolish.

If you review your posts, your arguments boil down to:

- I'm wiring the panels in series and exceeding the specs

- or I'm wiring the panels in parallel because I don't know about the benefits of wiring them in series

Both your premises are wrong.

[SunEagle]

Incidentally, I think you might be a good illustration of my theory that over complicating solar scares people away from using it. You're the moderator on a forum dedicated to solar, and yet your RV doesn't have a permanent solar installation. That's completely amazing.

.

Not really. I don't see solar as being necessary to enjoy my RV. I also don't want to mount the panels to my roof because I might want to park in the shade. Having my panels mobile allows me to move them into the sun and point them in any direction I want as well as "track the sun" if I choose.

Also being in Florida my wife (who really like the A/C unit) gets to be comfortable which means I have to find a place to plug the RV into the grid or use the genny. Which is just fine with me because it is pretty quite and does not use that much fuel.

Solar is a hobby for me. I have been rubbing elbows with it since the mid 70's when I worked as a lab tech in a research center at the University of Delaware during my senior year. I got credit for a senior project on studying sheet resistivity of Cadmium Sulfide Thin Film cells which also allowed me to co-publish a paper with the National Science Foundation. I still work on solar projects that are mostly Utility sized MW arrays. So I would say solar is in my blood.

I may not be an expert but with 40+ years in the electrical power industry and working with solar I think I have a little hands on experience to understand both sides of this technology.