Research on photovoltaics focuses on the development of new and improved device characterization methods for various cell technologies and the improvement of measurement science to reduce uncertainties associated with the power rating. The research program includes the characterization of photovoltaic cells and modules to determine their electrical response to ambient temperature, irradiance level, solar spectrum, and angle of incidence, and the role of defects and cell imperfections on short- and long-term performance The characterization is conducted both outdoors, under selected meteorological conditions, and indoors using solar simulators, optical and electrical modulation in frequency domain, and advanced spectral response methodologies. Comparisons are made and research is conducted to improve indoor measurement techniques to better approximate results obtained under outdoor conditions, and understand failure mechanisms in the cells. Innovative approaches to understanding device lifetimes and long-term reliability of photovoltaics are being explored.

Long-term outdoor performance data are being gathered for various photovoltaic technologies with an emphasis on building integrated photovoltaics. In combination with a full complement of site meteorological data, these data are being utilized to improve and validate computer simulation models used to predict the annual energy production of photovoltaic systems in various climates, applications, and orientations. The data are also being used to capture the ratio of the annual production of various photovoltaic technologies to the power rating at a specified set of rating conditions.