The long term performance of building integrated photovoltaic panels is measured "in-situ"using the Building Integrated Photovoltaic Testbed, located within the south wall of a a building located on the NIST campus in Gaithersburg, MD. The facility provides comparison between different building integrated photovoltaic panels when exposed to identical meteorological conditions. Up to nine panels can be evaluated simultaneously. Comparisons are based on energy production, operating temperature, heat flux, and characteristic current versus voltage (IV) curve traces. This "test bed" initially consists of crystalline, polycrystalline, amorphous, and silicon film building integrated photovoltaic products. Two identical panels of each photovoltaic cell technology, one insulated and one un-insulated, are currently installed. Meteorological instrumentation includes two precision spectral pyranometers, one precision infrared radiometer and two radiatively shielded type-T thermocouples. An ultrasonic wind sensor is used to measure the magnitude and direction of air movement in a vertical plane. Two systems are used to monitor the building integrated photovoltaic test bed. A "test bed" data acquisition system is used to measure the output signals of the outdoor meteorological instruments, the heat flux transducers, the panel temperature sensors, and two radiatively shielded indoor ambient temperature sensors. This data acquisition system scans the sensors and records the data every five minutes. The second data acquisition system is a custom built photovoltaic measurement system, referred to as a multi-tracer. The multi-tracer simultaneously loads and collects electrical performance data on multiple PV panels. The multi-tracer can operate with a maximum of 14 panels connected.
The building integrated photovoltaic test facility is capable of evaluating up to nine building integrated photovoltaic panels simultaneously. The size of the panels can vary up to a maximum of 1.38 m by 2.36 m. The multi-tracer can dissipate up to 2400 watts. User selectable load options include: (1) peak power tracking, (2) fixed voltage operation, (3) user specific voltage profile and (4) unloaded or open circuited.
This testbed may be available for use by those outside NIST, but it must be operated by EL staff. Collaborative programs may be arranged on cost reimbursable basis.