I attended an outstanding webinar on digital signage given by Peter Kaszycki of MRI. In the webinar he mentioned that the morning or evening sun in winter can be as bad for an LCD as the noon day sun in summer. I found some interesting data to back that up.
the ambient air was 24 degrees. The light on the side of the house is a reflection from the windows of a neighboring house. The issue of solar radiation and reflections has been well studied in the vinyl siding industry as it is a common cause for product replacement. The LCD being new to outdoor environments will experience the same conditions.
An important additional point to consider... because solar radiation is delivered at the speed of light rather than being conveyed by air currents or thermal conduction, the surface of the vinyl siding or the LCD can equilibrate with the current level of solar radiation within 10 minutes. Unlike heat transfer from the ambient, there are no thermal conduction issues or boundary layer effects. So, if some other surface happens to reflect directly on your digital signage installation for only twenty minutes; but the wrong time of day 20 minutes; that can be enough to cook your installation. Further, as contact burns can be almost instantaneous above 145 degrees and everyone assumes that every large LCD within reach is a touch panel, there could be some consumer complaints as well.