Solar??? - Page 4

1der · 02-24-2015, 09:27 AM

Greg: Thank you for the info. Where can I find the SCT / NOCT info for panels? I checked various panel makers and do not see that info listed. Yes, the LG spec sheet lists it. What I would like to know is how 219.75/300.8 compares to other panels. Perhaps there is a better panel out there for this application.

The balance is between price/watts vs true efficiency vs dimensions for mounting (width being the primary constraint for single or multiple panel set up). The LG300N at $375 seemed to hit a sweet spot. Not purchased yet, so open to other suggestions. Thanks!

Ray

boywonder · 02-24-2015, 01:34 PM

I'm sure the SCT/NOCT stuff explains why my 130W panel only puts out about 7 amps in full sun. 7X12 is nowhere near 130W.

Not to derail this thread, but I'd be curious to know what connector others are using to penetrate the PH roof (or whatever roof you have). I'm not too excited about the std issue Perko connector...

I've tried to find a cable strain relief with a long threaded body to penetrate the roof, but have so far come up empty handed.......

**daveb** · 02-24-2015, 01:51 PM

Quote:

Originally Posted by Chance

Thanks for sharing your plans. I think you hit on why I keep having a hard time justifying solar at all. We are more travelers than stay-in-one-place campers, and have never (that I can recall right now) stayed more than two nights and the day in between at a site that didn't have shore power. Most often it's just the one night without shore power.

As much as I'd like to find a use for solar for our next van, I'm having a hard time if I remain objective. It seems that if I apply the funds towards more house battery capacity I come out ahead for our intended use.

I'd still pre-wire for solar. Good selling point down the road for the cost. But I really think having a small panel to supplement the alternator charge is worth it for battery maintenance if you plan to go with AGM type batteries.
In one case I know of, a person installed 2 inverters. One is set up just as any typical build which the larger inverter runs off shore power or the house supply, takes care of the heavy loads like the microwave, and supplies the multi stage charging when hooked into shore power. The second inverter is powered off the vehicle alternator and supplies a lower amp maintenance charger to charge the house battery while on the road. There are several ways to configure such a setup The main issue I see with this is it's not automatic and you might forget to switch it one way or the other. But he gets a smart charge out of the deal while driving, can totally control the charge and he has a back up inverter with a single AC socket (powered off the starting battery system) that can be used if needed.
[edit]There is also that Sterling device one of the members installed.
I still think a small solar panel goes a long way in keeping you from having battery maintenance issues for when the vehicle sits between trips but some people house their vans.

**daveb** · 02-24-2015, 01:58 PM

Quote:

Originally Posted by boywonder

I'm sure the SCT/NOCT stuff explains why my 130W panel only puts out about 7 amps in full sun. 7X12 is nowhere near 130W.

Are you saying you think it should put out more? That is right in the ballpark from what I've seen.

**daveb** · 02-24-2015, 02:07 PM

Quote:

Originally Posted by boywonder

Not to derail this thread, but I'd be curious to know what connector others are using to penetrate the PH roof (or whatever roof you have). I'm not too excited about the std issue Perko connector...

I've tried to find a cable strain relief with a long threaded body to penetrate the roof, but have so far come up empty handed.......

Would this work?
http://www.fisheriessupply.com/aqua-sig ... watertight

rallypanam · 02-24-2015, 02:24 PM

I used these, and went through van roof under the penthouse roof:

http://www.westmarine.com/buy/ancor-mar ... 75_003_512

Scalf77 · 02-24-2015, 02:29 PM

Ray,
If the panel specification does not say it would be STC, That is the chosen industry measurement method. As more people use solar and wonder where all their watts are, more vendors are starting to post NOCT data. Pretty much all panels are going to be in the same range. Your panels is 73% and the Kyocera 140 watt panel is 72%. Nothing wrong with your panel choice.

Boywonder,
yes, that is probably the biggest part of it, obviously mounting location, controller type, controller efficiency and things such as cable voltage loss have a big impact also.

-greg

E350 · 02-24-2015, 02:55 PM

Mine are already installed, but this has been sitting in my Amazon cart for a while now. Glue it down with some E6000 Adhesive and I would think you would be good for at least ten years based on my experience with that adhesive.

http://ecx.images-amazon.com/images/I/6 ... L1500_.jpg

http://www.amazon.com/gp/product/B00...=AU5MW0P13QZ5V

REF · 02-24-2015, 03:24 PM

I've also used one of these along with silicone, there's several sizes, not sure what I have.....

Attwood Corporation 66399-3 1-13/16" Stainless Steel Clamshell Vent https://www.amazon.com/dp/B0000AYGZ9/re ... 7ub09YG6WZ
https://www.amazon.com/dp/B0000AYGZ9/re ... 7ub09YG6WZ

Viva · 02-24-2015, 03:31 PM

On roof penetrations, I like to use something like a Cable Clam from Blue Sea. I'm used to that sort of thing from boat decks. Folks also use those pinned Perko connectors on boats, but they always seem to prove trouble-prone. However if it is a connection for something that needs to be removed frequently.... well, that's why people use them.

Newmar also makes their own version of a Cable Clam, including a "huge" one that can allow for multiple cables in one (the Blue Sea can also possibly accept multiple cables, but their largest one is still smaller than the largest Newmar). I bought the large Newmar because I had a pre-existing hole in the roof and it would completely fill said hole, so, how convenient.

One could also potentially use Blue Sea Feed Through connectors if the top side of the connector was going to come up into a junction box from below (otherwise I'm not super keen since the connection would be exposed).

I noticed the AM Solar combiner box simply has a square hole in the bottom of it and then you are supposed to match that up with a hole in your roof and just caulk the box to the roof around it. That doesn't really thrill me, but many others have used their box so it clearly can work.

Unless my plan changes (always possible) I'm going to come right through the roof (Newmar fitting) with cables (no combiner box on roof) and then have my junction area inside the rig (in a cabinet). I'll also jump up to a larger cable size there, and then up to yet a larger size between the controller and the pos/neg bus (because at that point it goes down to 12 volts, so amperage goes up).

For starters I'm going to try a series parallel setup (four panels, two series pairs) just because I want to experiment with it. That will give me around 36 volts coming from the panels to the controller. I'm going to leave it open to changing to parallel setup (with only needing to change the roof wires. With my distances, I'll use a #2 feed down from the roof (will work for either series or parallel), and then 2/0 or maybe 1/0 from the controller to the pos/neg bus (because I want to put the controller in a spot that is around 6' from the busses). From the controller to the batteries won't change for parallel or series/parallel because that is at 12 volts regardless.

I want to keep the voltage drop at 1.5% or lower. That sounded easy at first but when I added all the various legs together, it was very easy to get up over 2% or even 3% (so I went to bigger wire size - luckily had it on hand already).

My projected setup now has around .5% on the roof, .2% on the down wire, .4% on the run from controller to batteries, and .4% through the battery jumpers. So that's around 1.5%. I have a fudge factor though, as I used the STC panel ratings. But, I have room to add one more 100 watt panel, so I wanted the extra headroom. I hope I'll be fine as is though - certainly going to try it. I want to go with a Vitrifrigo 130 compressor refrigerator, so that'll be my "tyrant" in terms of power usage. I have 375 amp hours of battery (3 x Lifeline GPL31XT). I wanted a bit more panel than battery. I'm a night owl, so I figured if I had more battery than panel, I "could" use that extra power and then I would have to worry about putting it back (or chronic undercharging). This way I figure (but we'll see how it really shakes out...) I should have enough solar power to feed the necessary items (refrigerator, some computer use), and when there is more power (sun) I'll get to use the luxury more (more computer time!), but I won't be likely to end up with a big deficit that the panels can't put back. Also it would be tough to fit a fourth battery, and I don't need the extra 75#.

We'll see how it all pans out...