replacing a glass garage roof with polycarbonate

[irban]

I need to replace my leaking garage roof with polycarbonate. The garage is the full length of the side of the house ( will take a mini and family car nose to tail). but which shade of polycarbobnate is the best. I have narrowed it down to clear and opal. What are the benefits/disadvantages of each of these. The thickness I intend to use is 25mm. Any advise/ information would be most welcome

[buildersmate]

This sounds like a sloping car-port with the slope away from the house.
Polycarbonate may be a suitable material if the garage is sealed (not open both ends but for the width and length you are talking about you will have to use the proper aluminium bars to hold the material down and you may have to hold down the middle of each panel at the bottom with a plastic 'button' - to prevent the polycarbonate being buffeted by wind.
I don't see what difference the colour shade makes - it is personal taste.