How about 15 feet above the parking lot, so a lost truck driver does not destroy them.
From my experience getting solar on my roof, it has been quite trying. Pretty sure the next time will be much easier, but there was so many venders that I had to walk away from. Getting a national system would be a nightmare to deal with. The biggest problem I found was cost. Made a mistake and finance through a vender. Opps cost of project skyrocketed, they did not care, you have financing. Had to runaway from a national company vendor because of that.