Weather data may be either selected from the existing National Solar Radiation Database (maintained by NREL), an HST International Database (maintained by HST and compiled from various publicly available weather data sources) or may be uploaded directly by the user. The application currently accepts user uploaded weather datasets in CSV file format that adhere to the TMY3 data format. 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.
Selecting a National Solar Radiation Database or HST Database Dataset
Step 1: Within the Project Design Environment, Click Site on the left Navigation Bar and move the map to focus on your site area.
Step 2: Click Weather within the Project Controls Widget and choose NREL Solar Database or HST Database as the weather source.
Step 3: Select the desired weather dataset from the dropdown list of Weather Stations. All datasets in the dropdown are TMY3 datasets from actual weather stations. By default, weather stations are listed in order of distance from the site. When a station is selected, the map will refocus to show the weather station location.
Step 4: Select the desired Irradiance Data from the dropdown menu. For National Solar Radiation or HST Database weather stations, HST suggests leaving at the default Beam & Diffuse setting.
Step 5: Click Save. Data entered may be lost if not manually saved.
Uploading Your Own Weather Dataset
Before attempting to upload a weather dataset, it is important to ensure the file and data within the file are in the correct format. The file type should be a CSV file. The file may be opened and edited prior to uploading in either a text editor or in Excel or similar spreadsheet software. However, it must be saved as a CSV file before uploading.
Additionally, the data within the CSV file must adhere to the following rules so that it may be read properly by SAM:
- The file should contain exactly 8762 rows of data.
- The first row of data should contain general site information and should adhere to the requirements defined in the table below. This is slightly different that the requirements defined by NREL’s User Manual for TMY3 Datasets (http://www.nrel.gov/docs/fy08osti/43156.pdf)
- The second row of data should contain data headings and should adhere to NREL’s User Manual for TMY3 Datasets (http://www.nrel.gov/docs/fy08osti/43156.pdf)
- Rows 3 through 8762 should contain the hourly data for the year.
| Spreadsheet Cell | Description | Requirements |
| A1 | Weather Station ID | No requirements. Can be any number or left blank. HST will overwrite a unique station ID number to this cell once it is uploaded. |
| B1 | Name of Location | No special formatting required. Can even be left blank. This is typically the site location name or name of the weather station |
| C1 | Name of State or Country | No special formatting required but must be non-blank. A blank cell will return an error. This can be the two letter state code or may be the name of a country |
| D1 | Time Zone | This is the time zone in numerical format with respect to Greenwich (GMT), negative west |
| E1 | Latitude | Site latitude in DD.ddd format. Permissible range is 90 to -90 |
| F1 | Longitude | Site longitude in DDD.ddd format. Permissible range is 180 to -180 |
| G1 | Elevation | Site elevation in meters |
Step 1: Within the Project Design Environment, Click Site on the left Navigation Bar and move the map to focus on your site area.
Step 2: Click Weather within the Project Controls Widget and choose User Defined Database as the weather source.
Step 3: Click Upload Weather File and navigate to the CSV file location. Once the weather file has been successfully uploaded you will receive a confirmation popup message stating that the file has been successfully uploaded. By default, the weather file that has just been uploaded will be selected and loaded into the project.
Step 4: Select the desired Irradiance Data from the dropdown menu. Some weather datasets contain only two irradiance components, while others contain all three. If only two irradiance components are present within the user uploaded file, it is critical to select the appropriate irradiance componenents. The System Advisor Model (SAM) software within HST will automatically compute the missing irradiance data during the simulation, but it needs to know which data is present.
Step 5: If necessary, user uploaded weather files may be deleted. To do this, select the desired weather dataset from the Select Weather Station dropdown menu. Once a weather dataset has been selected, the Delete Weather File button may be clicked to delete that weather file. A popup message will be displayed to confirm that the file has been deleted.
Step 6: Click Save. Data entered may be lost if not manually saved.
Note- Once a user has uploaded a weather dataset, it is available to all users within the same company account. The Select Weather Station dropdown will display all user uploaded weather stations.