on my coach, i have installed 11 large solar panels, see http://bbs.wenxuecity.com/auto/472533.html. the front one is 61.5" wide cross the coach side to side. when coach is moving, especially when head wind is strong, say at 40 mph, and i am driving at 60 mph, that is a combination of 100 mph wind hitting the panel. two months ago when i did the panel upgrade, i did notice that 2 of the 4 front bracket anchor screws backed out about a quarter turn pushing up the dicor. i re-tightened them and re-dicored. i thought it's necessary to protect the panel with a front air dam.
after discussing with a few friends, i came with a simple solution. below is a quick report with some photos, hopefully this provides some hints to the fellow rvers in case anyone attempts to do it down the road...
(1) got a 3 inches x 2 inches x 10 ft roof-to-wall galvanized flushing sheet metal, for $6.57 at home depot.
(2) calculated the length. in addition to the length of panel (dam length), add 3 inches to each end to tuck backward. my total length was 61.5 + 3 + 3 = 67.5 inches.
(3) the leftover was to be glued to the inside of the dam so to make it more rigid.
(4) considered the panel brackets and cut out the areas on the sheet metals.
(5) glued the two pieces together with "fuze it" ($6.97 at hd). let sit overnight
(6) attached the dam to panel frame. i planted a 5/16" galvanized screw to the middle of the front panel frame, and cut a slide channel on the dam back side. when installed, a support at the middle was in place in addition to that at two ends.
(7) affixed two ends to the panel sidings with 3/16" rivets
(8) i wrapped the front dam center edge with a wiper blade protector and dicored the edge where it touches roofing. notice the curved roof, only the middle section of the dam touches roof.
now it is completed. hopefully the coach will get a better aerodynamics and eliminate the possibility of loosing screws again .
happy trails!
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a side note about solar performance:
at 10:00 am today in a regular sunny day in southern part of the country i took a pair of photos on the charge rates. one showed 67.4a, another 31.5a. at this time of year, and in early morning, i am getting nearly 100a downflow bulk!! (in summer time i might get 130a - 140a rate). 
