Regarding Solar PV System Selection

No LEED does not provide such a baseline level of efficiency.

I am not aware of any organization that does provide this information as each system is different and there are often good reasons for selecting more or less efficient equipment. More efficient usually costs more but takes up less space. Less efficient costs less. You need to look at the system as a whole and determine what combination of equipment best meets you needs.

I generally talk to multiple vendors like I would for procuring any product.

SunPower is saying the score more points than any other manufacture, does anyone have any experience using their cradle to cradle certification to score additional LEED points?

I think that contributes to one of the materials credits.