Building Integrated Photovoltaic (BIPV) Roofs for Sustainability and Energy Efficiency

The objective was to study how well a building integrated photovoltaic BIPV roof, mainly consisting of photovoltaic PV laminates bonded to a polyvinyl-chloride PVC membrane, performed as PV and roofing systems. The project focused on studying three BIPV systems, but additional sites were surveyed for ancillary information and comparison. In-person roof surveys using the ROOFER Engineered Management Systems approach and laboratory testing based on ASTM D 4434 tests were used to evaluate roof longevity. Energy output and weather data were used to evaluate PV performance. Temperature and air conditioning system data was collected at one location. ROOFER identified a number issues with the PVC part of the roof, but was insufficient for unanticipated issues with the PV system, such as PV adhesive failures. The PV system performed as expected, but is highly susceptible to soiling in low-slope roof applications. The BIPV system was shown to produce an overall reduction in roof temperature, but the air conditioning saving analysis was inconclusive due to problems with the facility that was studied. A computer model was used to estimate what savings could have been achieved and additional models were used to estimate the savings in other U.S. climates. This BIPV system is no longer commercially available, but similar implementations still exist and will benefit from the lessons learned during the study.