The President has called for solar systems to reside on top 1 million roofs by the year 2010 as one goal towards addressing global climate change. There are a number of commercially available products and system designs from the PV industry that comply with most of these standards.
Fire is a major concern among building inspectors.
PV modules placed on roofs are required to carry the same, or higher, UL fire rating as the roofing material itself. Therefore, Class C roofs only require modules with Class C or higher. Class B roofs can carry Class B and higher and so on. It's our understanding that, according to the Uniform Building Code, most commercial roofs in the U.S. should use Class B or higher roofing material.