I used 5 of those brackets to hold my 14.5 lb panel on. It's been on about a year and 5000 miles. We're currently in Florida and the heat hasn't been a problem. I check the panel regularly and it has remained secure. That VHB tape is nothing short of amazing.
I really liked that the brackets are height adjustable, as my PH top was not even close to being flat. The adjustable brackets also allowed me to put a slight tilt on the panel to help it shed rain.
Leaving for Seattle in a few weeks, with a month or more in Utah. We can give you an update in another 5000 miles.