Ballast-mounted PV arrays: Phase 2 final report

The expansive flat rooftops of industrial and commercial buildings across America offer the largest, most secure, and potentially least-cost real estate opportunity to install massive amounts of solar photovoltaic generation in the building sector. Unfortunately, mechanical penetration of roofing membranes is very expensive and perceived by building owners and operators to increase the likelihood of leaking. In response Ascension Technology has pioneered the development of low-cost ballasted approaches for mounting PV arrays. Recently, however, we have experienced our first two instances in which strong winds have moved our arrays on rooftops and heightened our interest, and the PV industries' need, to develop zero-penetration mounting techniques that are more secure, yet remain low in cost. In this PV BONUS project, Ascension Technology and its partners addressed wind loading on solar panels and the suitability of using frictional forces between ballast trays and roofing materials to resist PV arrays sliding on rooftops. The primary goal of the project is to capture the potential cost savings made possible by ballast-mounting by showing under what conditions it can satisfy wind loading concerns. A secondary goal is to address a more geographically constrained concern regarding withstanding seismic forces