Clear, Opal or Bronze Polycarbonate?

We are about to build a lean-to and are wondering about the materials to use. We have read that 16mm triplewall is the best polycarbonate to use but is the colour of the walls and roof important? We are hoping to grow unusual tropical stuff and tropical fruit as well as a few bedding plants. Will a bronze roof be of benefit? Should the sides be opal or clear? Its all so confusing!:cnfs:

 

http://www.greenhousewarehouse.com/16mm-Triplewall_B22SQP.aspx

Thanks for answering, the only place we have to put it is in a small 7ft square area that used to be reserved for the dog's 'use', it is under one of the kitchen windows and has its own drain and was concreted to slant towards the drain. It is facing west and has some plant obstruction - a 12ft Torbay Palm (Cordyline?) and a 7 ft Trachycarpus, both sited next to the left corner in the raised garden. I would send a photo but our daughter 'borrowed' our digi camera.

Our son is a joiner and he mentioned the use of bronze glass in conservatories and reckons it reflects heat back in winter and keeps the scorching rays out in the summer so we think it must be more than just tinted but we don't know anyone who can verify that it would work well in a greenhouse, especially one that will have some shading already.