Performance and characterization of building integrated photovoltaic panels

Buildings consume more than two-thirds of the electricity in the United States. The incorporation of photovoltaics into buildings, referred to as building integrated photovoltaics (BIPV), offers an aesthetically pleasing means of displacing centrally located utility generated power with distributed renewable energy. Building integrated photovoltaics replace conventional building elements such as roof tiles, asphalt shingles, facade elements, and shading devices with photovoltaic modules that perform the same functions but also provide electrical power. A barrier to BIPV implementation is the lack of validated predictive tools to quantify the achievable energy savings. Building owners, architects, and designers need these predictive tools in order to make informed decisions about the economic viability of a proposed BIPV project. The Building and Fire Research Laboratory at the National Institute of Standards and Technology (NIST) is providing high quality experimental data for the development, validation, and improvement of computer simulation tools. Among the computer simulation tools available for predicting the performance of photovoltaic (PV) systems are IV Curve Tracer, developed by Sandia National Laboratories, and PHANTASM, authored by the University of Wisconsin. This paper describes NIST's BIPV "test bed" a facility that is used to measure the annual performance of different types of BIPV panels. Measurements are presented that compare the performance of four different cell technologies and document the effect of installing thermal insulation at the interior surface of BIPV panels. The annual performance of each BIPV panel is evaluated relative to its performance at standard rating conditions.