Use of solar reflecitve shades (harmful to windows?)?

Question:We moved into a new house and they had some reflective shades installed to keep out the heat and glare. They are shiny on the sunny side and tinted on the inside. When trying them out they seem to work well at keeping out the heat and brightness but we have been told they are bad for dual pane windows. Supposedly the heat/light gets reflected back into the windows and causes damage. Is this true? Why would they sell them if they do this?

Answers:
If there is any plastic on the inside of the window (not between the glass) such as grilles or a glazing bead, the extra heat could be a problem. Also could be a problem for vinyl windows due to the extra heat trapped between the blinds and the window. It should not be a problem for the glass units, they are designed to take a fair amount of heat.