RV Trip Planning Discussions

Go Back   iRV2 Forums > RV SYSTEMS AND TECHNOLOGIES FORUMS > Going Green
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 06-19-2016, 10:02 AM   #1
Senior Member
 
Join Date: Nov 2015
Posts: 752
New solar install, do I need Air Dams?

So, I've been reading everything I can get my hands on about installing solar in an RV and I've started the plunge. With my past military electronics experience I was able to dust Ohm's law, remember the difference between series and parallel and remember vividly what happens when you short out the black and red wires. My plan is to build a system capable of handling approximately 1000 watts without rewiring, so hopefully, that will explain the large wires and controller for the initial build.

Thus far, I've upgraded my battery bank from 2, 232 Ahr 6v GC2 batteries to 4 (purchased 6 months apart), installed them into a new box and ventilated it. I have built the battery connecting cables using 2/0 welding cable and crimp on connectors making sure all of the interconnect cables are the same length. I installed two Blue Sea bus bars, one on either end of the battery box, where the positive and negative ends of my battery array connect to the outside world.

I have also installed the Bogart Trimetric 2030-RV monitor. I found a nifty idea for a roof top combiner box (bottom of the page) using a two gang exterior junction box with 2, 3/4" outlets for cabling. I also got a waterproof cover with gasket and two, 10 position bus bars. The bus bars fit inside the box between the screw posts and with the lid on, there is no way the box can be shaken that will allow the bars to come into contact with each other.

I have also purchased 2, 20' lengths of #4 welding wire to transport my electricity from the roof to the Morningstar TS-MPPT-60 controller I have yet to purchase. I have plenty of 2/0 cable to connect the controller to the battery bank. A 60A air conditioner disconnect box also remains on the purchase list, with appropriately sized fuses of course, to act as my fuse and disconnect so I can isolate the panels from the controller using 1 fuse and the controller from the batteries using the other.

Last night, I picked up two pristine Suniva OPT260 panels from a commercial solar installation company in my area, for $60 each. Isc = 9.01A, Imp = 8.52A, Voc = 38.3 and Vmp = 30.5. They included 25 feet of 1 1/4" aluminum equal leg angle bar stock that they had left over from a job long ago. I plan to fashion my panel mounting brackets from it. So much for what I have done and plan to do...

The roof of my 5er is domed so no matter how I mount my panels, the supports on one side will be longer that the supports on the other (there is no room down the center for these sized panels). I haven't measured that out yet but I'm estimating the panel will be about 3" from the roof on the interior side and as much as 6" on the exterior edge. I have read exactly 1 story on this forum about some unlucky soul who either had a spontaneous panel removal while driving down the road or the theft of a panel from the roof of their Class B. I've also read several threads, primarily in the motorhome forums, about installing air dams to keep the wind out from under their panels, to prevent them from "lifting off". (Lift off would be bad for my 5er but potentially fatal for a following vehicle's occupants!)

Do you think an air dam is necessary or do you think, with the materials at hand, I could build mounts strong enough to overcome any lift I'm likely to encounter? If a dam is necessary, how would you fashion it and do you have any pictures you can share?

Thanks in advance for any advice.

Roy
__________________
2012 Dodge C3500 DRW 4x4 Long Box, WeatherGuard 90 Gal transfer tank, B&W Companion Hitch
2012 Keystone Montana 3100RL, 520W Solar, 460AH batteries, Morningstar MPPT 45 CC, Bogart 2030RV monitor.
drdarrin is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 06-19-2016, 10:41 AM   #2
Senior Member
 
Join Date: Nov 2013
Posts: 937
Air dams have another excellent usage. You will not rip off your panels if you misadvertently drive under low hanging branches/vines. We ripped a panel loose this spring as we got into Izamal, Yucatan. We plan to install these in the future. Have seen a few good photos of these but cannot remember where.
Reed and Elaine
Reed Cundiff is offline   Reply With Quote
Old 10-12-2016, 10:46 AM   #3
Senior Member
 
Join Date: Sep 2016
Location: Monrovia, CA
Posts: 150
If you don't drive over 65 there isn't much to worry about from an aerodynamic standpoint. Probably not worth the trouble.* However, I had not thought of low hanging branches! Yikers! That might get me up on the roof! I would definitely make sure to anchor the dam only to the panel itself or, preferably, the panel's supports so as not to drill any more holes in the roof. All you really need to do is screw a flat piece of 18 gauge sheet metal onto the leading edge of the panel so that metal comes down to within 1/4" of the roof. You could caulk that gap but leaving it un-caulked would hardly hurt anything aerodynamically but a branch could still snag it and caulk is CHEAP!

signed,
retired-pilot

*even the occasional downhill spurt of 70-75 isn't that big of a deal.
__________________
Gammel
2020 ORV 21RWS
2016 F150 Lariat FX4 Ecoboost shortbed
Gammel is offline   Reply With Quote
Old 10-12-2016, 11:12 AM   #4
Senior Member
 
PJStough's Avatar
 
Join Date: Oct 2015
Posts: 1,178
Quote:
Originally Posted by Gammel View Post
If you don't drive over 65 there isn't much to worry about from an aerodynamic standpoint. Probably not worth the trouble.* However, I had not thought of low hanging branches! Yikers! That might get me up on the roof! I would definitely make sure to anchor the dam only to the panel itself or, preferably, the panel's supports so as not to drill any more holes in the roof. All you really need to do is screw a flat piece of 18 gauge sheet metal onto the leading edge of the panel so that metal comes down to within 1/4" of the roof. You could caulk that gap but leaving it un-caulked would hardly hurt anything aerodynamically but a branch could still snag it and caulk is CHEAP!

signed,
retired-pilot

*even the occasional downhill spurt of 70-75 isn't that big of a deal.
We have had solar panels on our roof for almost six years now, and no airdams, or no need for them. I have even scraped some tree branches across them with no issue. Sounds like over kill to me, but if it makes you feel more comfortable, then I would do it.
__________________
Paul J Stough Iowa
2005 Winnebago Voyage 38J
PJStough is offline   Reply With Quote
Old 10-12-2016, 12:25 PM   #5
Senior Member
 
Join Date: Nov 2015
Posts: 752
New solar install, do I need Air Dams?

We did our first real trip since installing the panels, without air dams, and had no problems. I can see where they might be useful with low hanging branches but so far, being aware and some judicious tree trimming has solved that issue.
__________________
2012 Dodge C3500 DRW 4x4 Long Box, WeatherGuard 90 Gal transfer tank, B&W Companion Hitch
2012 Keystone Montana 3100RL, 520W Solar, 460AH batteries, Morningstar MPPT 45 CC, Bogart 2030RV monitor.
drdarrin is offline   Reply With Quote
Old 10-12-2016, 04:26 PM   #6
Senior Member
 
Smitty77's Avatar
 
Join Date: Aug 2010
Location: Over the next hill, around the next curve...
Posts: 4,871
We have four out of our 5 panels mounted to a conventional home roof racking system. We straddle the shower solar skylight with our four panels, following that side of the coaches roof edge. From memory, we have about a 5" gap at the highest point of the panel, from where the roof gradually curbs away towards the side.

I did have both front (for backing) and front air dams fabricated, and installed. Was not worried about the wind itself and panel lossage, it was all for the protection of the trees.

I;ve been glad I had them two or three times now. Sometimes, it seems usually early in the season (Before the host of other Class A's and or Fivers 'trim' the lower hanging branches!), or in some parks late in the season (Park may have trimmed the driving pathways and sites for the season, but over the months, they grow back in.) - we've had no choice but to 'softly' brush our way thru low hanging limbs.

The air dams protect the panels, and as all of the wires are tucked under the panels along the roof, the wires too - from getting snagged.

A simple sheet of metal, with about a 2" bend, 3M 5200 to our Fiberglass roof. Has held up now well for going on 4 years.

Best to you - and enjoyed reading about your solar!
Smitty
__________________
07 Country Coach Magna Rembrandt 45' ISX600
Roo II was our 04 Country Coach Allure 40'
OnDRoad for The JRNY! Enjoy life...
Smitty77 is offline   Reply With Quote
Old 10-14-2016, 12:14 PM   #7
Senior Member
 
Timon's Avatar
 
Join Date: Jul 2014
Location: Tustin, CA
Posts: 1,012
If the panels are very close to the roof you can get away without air dams but if you mount them higher I'd use air dams. This really comes into play with RV that have a lot of curve in the roof. You may only be an inch in the middle but you could be several inches near the outside edge.

Remember most AC have a sloped front end and it's not just for airflow but to help keep branches from snagging the ACs. It's the same for Solar.
__________________
John (N6BER), Joyce, Lucas (Golden Retriever mix), Bella (Great Pyrenees) and Lance (Great Pyrenees).
Tustin, CA
Timon is offline   Reply With Quote
Old 10-22-2016, 05:30 PM   #8
Member
 
tlaffourtit's Avatar
 
Thor Owners Club
Ford Super Duty Owner
Join Date: Sep 2014
Location: Mount Laurel, N.J.
Posts: 65
my panels are 7 inches off the roof in the middle and 9 inches on the out side. it's been 2 years so far with no problems.
Attached Thumbnails
Click image for larger version

Name:	20150723_191654.jpg
Views:	162
Size:	170.5 KB
ID:	142309   Click image for larger version

Name:	20150723_191716.jpg
Views:	162
Size:	161.3 KB
ID:	142310  

__________________
2015 Thor Ace 30.2
1240 watts solar/batteries 1450AH
Sue and Tim Affourtit
tlaffourtit is offline   Reply With Quote
Old 10-23-2016, 11:50 AM   #9
Senior Member
 
Join Date: Nov 2013
Posts: 937
If you do not back in under trees or go on secondary roads in Yucatán ( where we tore a 235 W panel loose but not off) or near Palenque (where we did tear off a forward mounted video) you probably do not need "air dams". If you do primarily boondock, as we do 12 months a year, for last nine years you might want air dams aka limb/twig blockers.
Reed Cundiff is offline   Reply With Quote
Old 10-23-2016, 03:03 PM   #10
Senior Member
 
Join Date: Jul 2016
Posts: 573
Those Suniva panels are a great option even at full price, at $60 that is almost paying you to take them. What a great find.

IMHO, they are one of the best PV panels on the market, and even made in the USA to boot.

Since you are going to use an MPPT controller, you can even just wire them in series if you like. This provides lower wiring loss and the use of the MC4 connectors and wires from the panels down to the charge controller.

If you think that sometimes one will potentially be in the shade while one is still in the sun, then wiring them parallel will probably be better.
harryn is offline   Reply With Quote
Old 10-23-2016, 10:52 PM   #11
Senior Member
 
Join Date: Nov 2015
Posts: 752
I did wire them in parallel and I used 4 gauge wire from the roof to the disconnect and charge controller. My panels are 2" above the roof on the edges and less in than that in the center since the roof is curved. We've been very happy that we can run our toaster and microwave off the inverter. For minutes obviously. So far, we're very happy not to have to depend on shore power or our generators for 120V. The generators are for backup only now.
__________________
2012 Dodge C3500 DRW 4x4 Long Box, WeatherGuard 90 Gal transfer tank, B&W Companion Hitch
2012 Keystone Montana 3100RL, 520W Solar, 460AH batteries, Morningstar MPPT 45 CC, Bogart 2030RV monitor.
drdarrin is offline   Reply With Quote
Old 12-14-2016, 06:51 PM   #12
Senior Member
 
Winnebago Owners Club
Join Date: May 2015
Location: Plaskett Creek USFS Campground CA Hwy 1
Posts: 507
My memory of wind dynamics leads me to believe that air passing over and under the panels is better than dams. (But air dams look soooooo cool!)
__________________
2015 Winnebago Minnie 2101DS travel trailer & Chevy Tahoe LTZ, 300 watts of WindyNation solar (parallel) with MPPT controller, 2 Trojan T-125s, TALL flagpole and a great attitude…SoCal based. Perfer USFS, BLM, COE, USF&WS, NPS & state park campgrounds.
LarryW21 is offline   Reply With Quote
Old 12-16-2016, 07:09 AM   #13
Senior Member
 
Timon's Avatar
 
Join Date: Jul 2014
Location: Tustin, CA
Posts: 1,012
Quote:
Originally Posted by LarryW21 View Post
My memory of wind dynamics leads me to believe that air passing over and under the panels is better than dams. (But air dams look soooooo cool!)
I was thinking about that however I don't think that's an issue. First you're not the shape of a wing where the longer air flow is on top which created a lower pressure on the top which would give lift. Actually with the air dam it should be creating a low pressure area under the panels which would tend to hold them tighter to the roof.

What we really need is someone trained in fluid dynamics to explain this.

My brother-n-law does a lot of work with amateur rockets, not model as they are toys, so it likely has a lot more knowledge in fluid dynamics, although he's not trained in it, than I do so I'll talk to him about it.
__________________
John (N6BER), Joyce, Lucas (Golden Retriever mix), Bella (Great Pyrenees) and Lance (Great Pyrenees).
Tustin, CA
Timon is offline   Reply With Quote
Old 12-16-2016, 02:20 PM   #14
Senior Member
 
Winnebago Owners Club
Join Date: May 2015
Location: Plaskett Creek USFS Campground CA Hwy 1
Posts: 507
Timon, interesting points. Wouldn't we want no upward or downward air pushing our solar panels? Sooooo....wouldn't no dams facilitate that best?
__________________
2015 Winnebago Minnie 2101DS travel trailer & Chevy Tahoe LTZ, 300 watts of WindyNation solar (parallel) with MPPT controller, 2 Trojan T-125s, TALL flagpole and a great attitude…SoCal based. Perfer USFS, BLM, COE, USF&WS, NPS & state park campgrounds.
LarryW21 is offline   Reply With Quote
Reply

Tags
install, solar



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Install/Not Install Power Plug okie143 iRV2.com General Discussion 21 02-13-2015 02:45 PM
Joseph OR to Hell's Canyon Dams Open Toussaint Camping Locations, Plans & Trip Reports 0 05-23-2013 03:34 PM
New Solar System Install kellylipp Going Green 16 07-01-2012 07:44 PM
Want to install built in vac in Itasca Horizon 40AD, like to know how factory install kbdavidson Winnebago Industries Owner's Forum 12 06-30-2011 09:13 PM
Install 50' antenna install for Tire Sentry NEED HELP TOJOS Alpine Coach Owner's Forum 4 09-23-2008 09:18 AM


All times are GMT -6. The time now is 12:20 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.