...has great potential, but I have yet to find a listed [by UL] system that works architecturally.

PV glass is a compelling material.  Solar cells are sandwiched between two layers of solar glass and can serve as a canopy, curtainwall, or safety glass.  The most recent example of this is Renzo Piano's new Academy of Sciences project in Golden Gate Park.

The problem?  These modules are said to "comply with UL 1703".  They can't be connected to the grid without a UL listing, or a field evaluation using listed components.  The City and County of San Francisco are tough on un-listed assemblies.  UL has stated they will not do a field evaluation on a custom glass/glass pv component, requiring it to go through the six to nine month, $25 to $50K listing process for the entire range of modules being utilized.

There needs to be a better fix--even though this material is more expensive, on a $/W basis, than typical modules, the fact that it is doing double duty as a canopy actually makes it far more valuable.

Schuco and Open Energy were showcasing this type of product at Solar Power 2007.  Both shrugged when I asked if their products were UL listed.  Sounds like an opportunity to me.  You can do a field eval from listed components--but the components of a module are a pv cell, and the connecting conductors.  Maybe that is the solution--get the components listed.