SMB installed two Kyrocera solar panels on the front part of the roof along with a Blue Sky controller during the initial build last summer. I provided a self-designed roof-mounted combiner box and the Yakima 4H MightyMount brackets to attach the panels to Thule load bars. I just finished installing two more panels on the rear part of the roof as seen below.
Following the directions in the Kyocera KD135SX-UPU solar panel installation manual, I purchased stainless steel
hardware to fasten the aluminum panel frames to the load bars using more MightyMounts. The square hole in the MightyMounts dictated the use of 5/16" carriage bolts. I also used, flat washers and lock nuts. Shown below on the left is how each of the four locations were done. On the right is how SMB did the front panels. I have been curious since picking up the vehicle why SMB chose to install the MightMounts upside down
, and decided to investigate the details.
What I found was rather shocking and resulted in my replacing their bolts with the proper ones. They used 1/4" non-stainless carriage bolts, a flat washer and a plain nut. Because no lock washer or lock nut was used it only took between 1/3 to 2/3rds of a turn before the nuts were free to spin off! In addition, the square portion of a 1/4" carriage bolt below the head is so small it can be hand-turned in the square hole of the MightyMounts. That further compromised the installation in that there was no way to reliable tighten the nuts because you can't put a wrench on the head of a carriage bolt!
So do consider looking carefully at your install regardless of whether yours are on Thule bars or not. Not only would the loss of a panel at speed be an expensive loss, it would be more serious than that for anyone following you. It cost me $7.62 for the stainless hardware of the correct size to redo the two front panels. I guess then that SMB saved less than $5 or $6 by going the cheap, and in my opinion dangerous, route. I for one paid enough money for my build that I think such cost-cutting (or lack of knowledge?) is sad, sad, sad.
6/3/2012 Addition: When I noticed the problems with SMB's install of the two from panels last year, I had already installed the two rear panels with plain nuts and lock washers. So at that time the front panels used lock nuts and the rears lock washers. When I recently rechecked the tightness of all the panels the lock nuts on the forward panels had some stiction before I could tighten them further indicating that they had not lossened in the last year. Nevertheless, I still tightened all eight of them about 2/3 of a turn each. However, at the rear panels I could see that some of the lock nuts were strong enough to have distorted the plastic MightyMount brackets so some were on the verge of allowing the plain nuts to loosen. So I replaced the plain nuts and lock washers with lock nuts. Now at all 16 locations each carriage bolt is fastened with flat washer followed by a lock nut. I highly recommend using lock nuts with these plastic brackets!
2008 E-350 6.0L diesel:
Bought new in 2010, 4x2, 4.10 LSD, HD spring-lift all 'round,
Cruiser II Top, 6'7" inside, full-time upper bed w/ kind'a EB50 layout, cozy 4-season rig
540 W of Kyrocera w/ Blue Sky 3024iL, 3x100 AmpHr AGM's
4 cf fridge, nuker, water heater, compressor
stove top, furnace Travel: https://www.lugnutlife.wordpress.com