Weather Data

Weather data may be either selected from the existing National Solar Radiation Database (maintained by NREL), selected from HST’s Weather Database within View (which is a TMY3 library compiled by HST from various sources) or may be uploaded directly by the user. The application currently accepts user uploaded weather datasets in CSV format and that adhere to the TMY3 data format. See section on uploading TMY3 data for detailed description of this process. TMY3 datasets are hourly datasets for an entire year (8760 hours) and may be obtained from meteorological stations or from third party weather data vendors such as Meteonorm. If the user chooses to select a weather dataset from the National Solar Radiation Database or HST Database, the five nearest weather stations will be available to select from. A list of available TMY3 weather datasets can be found here: http://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3/

Note: The latitude and longitude used for the site during energy modeling is obtained from the TMY3 file and therefore may be different from the actual latitude and longitude of the site as defined by the site boundaries on the Site page. 

Ground Reflectance and Radiation

View uses the hourly ground reflectance (albedo) data within the weather dataset within the energy model. If the hourly albedo is not included within the dataset or is set to less than 0 or greater than 1, the model will default the albedo to 0.2 for that hour. 

The irradiance components used within the sky model may be chosen by the user within the user interface. The user may choose to run the simulation using one of the following options:

• Beam (DNI) and Diffuse (DHI)
• Total (GHI) and Beam (DNI)
• Total (GHI) and Diffuse (DHI)

By default, the sky model used within the simulation is set to Perez.