T@B Solar Panel Roof Mount with Tilt-Able Brackets Mod for under $300

DougH

The 10-15% rule is a flexible guideline though. Some boating sites state tongue weight should be 7-10%. Sway is dictated by geometry and speed, so a 320 can usually be towed below 60mph at values as low as 7% without a hint of sway.  I have AGM batteries in the back, so run under 10% if running with empty tanks.  Never have had an issue even being passed by 18 wheelers on the highway... but I'm a slow driver.

AldebaranJill

DougH said:

The 10-15% rule is a flexible guideline though. Some boating sites state tongue weight should be 7-10%. Sway is dictated by geometry and speed, so a 320 can usually be towed below 60mph at values as low as 7% without a hint of sway.  I have AGM batteries in the back, so run under 10% if running with empty tanks.  Never have had an issue even being passed by 18 wheelers on the highway... but I'm a slow driver.

I am speaking from personal experience of sway happening when mine went below 10% - when I was at 9% I experienced some sway and had to redistribute weight to get to 11%.  Given all other variables (we drive different roads and different tow vehicles) I would not encourage others to run below 10% without evaluating. My sway was not due to wind of passing trucks.  

DougH

Hope the situation wasn't a scary one! 

There have been quite a few posts of late speaking to the risks of a <15% tongue weight to potential SUV choices, or to risk of adding batteries or bikes or solar towards the back of the rig. I was attempting to offer that circumstances may vary, some combinations need 12%, and some may live with 8%.  But certainly, as you say, only with careful evaluation.  Folks should know they can feel safe buying smaller Nucamp products and adding equipment to meet their camping needs without needing a three quarter ton truck and WD hitch.

jmiller808

DigitalSorceress said:

@jmiller808  Nice setup. I almost got a Victron controller like that but ended up with something slightly bigger.. Have you ever had worries/issues with water getting into the compartment?

Initially I was worried about it and was considering making a case to put it in that would protect it from water. After just completing a round trip from Colorado to Nova Scotia, Canada and back which included some torrential rain in New York I'm no longer worried because it stayed dry.

That said, I do plan on rearranging things in the box a little including putting a mesh bottom in and relocating propane to the outside of the tub to give some storage room. When I do that I'll either move the controller to inside next to fuse box or center it more in the tub and put it in something more water proof.

DigitalSorceress

@AldebaranJill  Oh, I'm not a bit worried about the weight of the panel back there making my tongue too light. I just recently put a second battery up on the Boondock deck and plan on adding a second propane bottle..

The panels together weigh 30 lbs.. though I do not know how to calculate the wind load .. so I don't quite know if I'll get lift, downforce, drag or .. nothing .. I'm going to be really careful with it till I've had a chance to get it on the road some...

I started by bonding the two together



2x 40" long 2" Aluminum L channel 1/8" thick arranged into a T and bolted to the "inner" panel frame and to each other with  M8-1.25 14mm stainless screws with washer and lock washer and nut

2x 36" long 1" Aluminum L channel 1/8" thick one at the top of the panls and one at the bottom.. giving horizontal strength. these were bolted in with 1/4" coarse thread machine screws with pan heads (stainless) with washers, lock washers and nuts



I bought the Renogy mounting frame but found it was too lightweight .. so I decided to make the bottom rails out of more of that 2" Aluminum L channel

Bottom rails: 2x 48" (May cut down to 42 later) 2" L channel 1/8" thick

Rails on panel were the ones from the Renogy kit.. mounted those to the panels with more 1/4" Stainless pan head screws (1") with nuts, washers and lock washers

prop rails were from the renogy kit.. the kit came with these M8-1.25 stainless hand knobs. but strangely without the nuts etc.. so I bought stuff at Lowes

I used U bolts (1/4" stainless 1 & 1/4" U bolts) .. 4 of them to mount the rails to the Yakima rack.. and it's VERY sturdy in the "travel" position

It takes me only a couple minutes to unscrew the bottom two hand bolts and rearrange into "deployed" position

Here's a better angle of the deployed position.. Looks almost like I did it on purpose


I need to wire it all up, but that's the easy part.. hard part is figuring out where I am going to run the wires.. I may do a temp wireup for the time being since my next big event will be the one where I need to pull the whole damn panel array off the back of the camper anyway..

THANK YOU SO MUCH for the inspiration!

AldebaranJill

@DigitalSorceress This is just awesome and I am beyond delighted that my mod has inspired others to also mount flat panels! Yours looks wonderful and I look forward to hearing how they worked.

If you are curious about the aerodynamics, perhaps putting little streamers onto the panels and having someone video from the rear while driving. It would be interesting to see which way the streamers were flowing. Mine has had no discernible impact and perhaps since our leading edges are pretty similar, it won’t have a noticeable effect. Wonderful write-up and photos! ☺️

DigitalSorceress

@AldebaranJill  I had folks on the T@B Facebook forum say how wonderful they thought it was and I pointed back to this forum to give credit where credit is due ..

Part of me wonders if I should have just gotten on 170w panel.. I ended up spending a LOT just to bond the two 100s together..

$48 worth of aluminum tubing and probably altogether another $50 on just nuts and bolts... (seriously that stuff is spendy .. especially at Lowe's and Home Depot)

If I were to do this one again, I'd get one 170w panel and avoid all that extra nastiness. Who knows? maybe sometime I will. Get a roof rack for the truck and move this monstrosity there and put one.. wait why am I doing this .. when will I be satisfied? when I can run my AirConditioner 24/7 and still have power to charge all the things!!!! yes 1500w should be enough... I'll just cover my TV and T@B and maybe have  a friend drive a big flatbed beside me?..    OH I have the sickness, don't I?

sqrpeg

Great job, @DigitalSorceress! I, too, was inspired by @AldebaranJill ’s mod, and for over a year now we’ve had a 100W Renogy rigid panel mounted on the back of our 2018 320S Boondock. I used the same Windy Nation legs that Jill did, but fabricated additional mounting rails for them that clamp onto the Yakima cargo basket that came with our Boondock.

I’ll try to post a more detailed writeup with pics soon - but in the meantime regarding wire routing: I chose to avoid doing a permanent wiring solution altogether, since our panel mod is intended to be remote-deployable anyway. Instead I built a 30ft portable cable from 10/2 SJOOW power cord and Renogy MC4 connectors, and we just hook the panel up as part of our camp setup routine. The cable connects to a short MC4-terminated pigtail for the controller in the front tub, runs along the ground and up to the rack and panel in back, with the excess coiled out of the way beneath the trailer. YMMV but for our minimal needs and very basic system, any voltage drop from the longer-than-necessary cable run hasn't been an issue.

DigitalSorceress

So, this friend of mine who is really smart .. I mentioned my question about air flow/ lift vs resistance etc..  I was thinking maybe he'd have a really geeky reply...

Instead, he made me "fridge art"

he seems to think there will be more faster air flow over the top, causing lifting force on the panel

I'm totally gonna put that on my wall next to the very excellent "Dr. Snake" drawing left for me by the daughter of the previous owner of this house.

DigitalSorceress

@sqrpeg  I have thought about that possibility (Just running the cables ad-hoc .. I will test that out.. I don't know if MC4 cables "like" being disconnected / connected that often, but eh, I'm willing to risk it.. they're cheap enough (gotta get some spare ends and practice making them

(I make my own coax and Ethernet cables all the time, so what's one more connector type to learn?)

pthomas745

One thread by @MuttonChops had a simulation of the air flow over the 320 compared to the 400, and had a graphic showing "theoretical" air flow around both models.

https://tab-rv.vanillacommunity.com/discussion/6315/time-to-say-hello-another-320-is-on-order/p1

As far as "downforce" and spoilers go, you really have to put on some speed before those things take good effect. 

AldebaranJill

@bamboofly and others....here are the PDF's that I was sent when I originally did my modification to help me locate the crossbeams. Now, yours may be different, so be forewarned - but you can also always get the inside humid when it's cold outside and the condensation stripes on the ceiling should be able to show you where they are. And if you ever drill a hole a miss, well, I've done that and just used some JBWeld smooshed into the hole and moved on :-)

And my solar modification is still totally going strong, no issues. I've updated the controller to a Victron MPPT Bluetooth, and that's it. Often I don't even need to raise it up to get back to fully charged. And if my panel ever goes bad, I can just easily replace it - I'm very happy I went in this direction versus the flexible panels. It may not be as pretty, but it's more functional and maintainable - and that's what matters to me.

Hope these files help!