The National Institute of Science & Technology has launched a multi-year mobile tracking program to obtain performance data needed for photovoltaic cells used on the exterior of buildings.ROCKVILLE, Maryland, US, 2001-09-04 [SolarAccess.com] The National Institute of Science & Technology has launched a multi-year mobile tracking program to obtain performance data needed for photovoltaic cells used on the exterior of buildings. To tap the solar reflective heat that can be found on building walls on a hot day, builders and renewable energy experts are integrating PV cells into the exterior of the building envelope to generate electricity. NIST says PV modules are increasingly considered as replacements for conventional facades, roof tiles, asphalt shingles or shading devices. The project involves a mobile tracking PV test facility, a meteorological station and a building-integrated PV testbed. The mobile facility records the effects of the angle, temperature and solar spectrum on the electrical performance of various solar panels. The meteorological station measures solar radiation, wind and temperature conditions during the performance monitoring of building-integrated panels. The testbed conducts side-by-side comparisons of four different types of PV panels: crystalline, polycrystalline, silicon film and amorphous silicon. Each PV technology is represented in the testbed by two panels: one without any thermal insulation behind it (representative of window and skylight applications) and one insulated to simulate opaque wall applications. The electricity generated by each of these eight panels, and the coincident meteorological conditions, will be recorded every five minutes for one year. NIST researchers are using the data to improve computer simulation tools that predict the performance of building-integrated PV for various geographic locations and building orientations. Officials say the implications could be considerable, since residential and commercial buildings use 40 percent of the electricity consumed in the United States.