Collection and storage of direct spectral irradiance and DNI datasets with high temporal resolution for CPV energy yield assessments

We describe the acquisition and database architecture for direct normal irradiance (DNI) and direct spectral irradiance datasets collected at an outdoor test site at the University of Ottawa. The objective was to build a database of local measurements made across a range of air mass values and atmospheric conditions for energy yield analyses applicable to Concentrated Photovoltaics (CPV) systems. Approximately 422,000 spectra and concurrent meteorological data have been recorded in the SUNLAB database for the two year operation period as of March 2013. Energy yield comparisons using measured spectra and those derived from Canadian Weather for Energy Calculations (CWECS) Typical Meteorological Year (TMY) and Canadian Weather Energy and Engineering Data Sets (CWEEDS) datasets demonstrate significant year-to-year variations, with TMY estimates underestimating 20-year historical assessments by ~7%.