The Case for Custom TMY’s: Examples using the NSRDB
Manajit Sengupta& Aron Habte
National Renewable Energy Laboratory, Golden, CO, United States

A Typical Meteorological Year (TMY) essential represents a hourly compilation of median months constructed using multi-year datasets. While TMY’s are generated from Global Horizontal Irradiance they are used for PV modeling for various Plane of Array (POA) representations. This paper shows that a POA TMY generated with corresponding POA irradiance timeseries information produces significantly different results when compared to a POA TMY generated by transposing a TMY dataset. In some months the differences can be over 3%. These results point to the need for generating TMY’s using POA irradiance timeseries representing the orientation at which PV panels will be deployed.