Integrating Weather Resource Data

SAInt connects to several weather resource databases from different data providers, which allow the creation of high-resolution wind and solar power time series for different plant designs and locations where weather resource data are available. These publicly available weather databases are constantly updated. Thus, data for additional weather years with different temporal and/or spatial resolutions and different geographic locations will become available. Three sections of the main settings of SAInt are relevant for the weather resource data: the "data provider" that defines the settings of each weather resource data, the "collected weather data" which is the region of the window where details of the selected objects are reported, and the "generation profile from weather data" that calculates the generation profile time series.

For step-by-step guides on how to import data see the How-To "Collect weather data for a solar generator", the How-To "Collect weather data for a wind generator", and the How-To "Connect to Weather Resource Data Providers".

1. Connecting to a data provider

The user can access the entry point to connect SAInt to a data provider by selecting Settings Data Provider from the button . Each data provider has a unique server URL pointing to the relevant database as shown in Figure 1.

Figure 1. Data Provider tab in the Settings of SAInt.

The data provider tab allows the user to choose between solar or wind databases, and the relevant options are:

Select provider: The user can select from a list of multiple data providers for different weather resource databases. See Table 1 and Table 2 for more information on solar and wind weather data provider and their coverage area, respectively.
API key: To access some of the data services, the user must register with the data provider and obtain an API key. The API key must be passed to SAInt provided so that the user is authorized to request and retrieve the data.
Full name: First and last names of the user used during the registration phase.
Email: Email used during the registration phase.
Server URL: Links to the data provider’s server URL. Refer to Table 1 and Table 2 for the list of server URLs for solar and wind weather data providers, respectively. The list of server URLs can also be found in the DataProviderURL.txt file in the DataImport folder.
Year: Selection of different weather year(s) available from the corresponding weather resource database. For each database, SAInt shows the available options.
Interval: Selection of different temporal resolution(s) available for the corresponding weather resource database. For each database, SAInt shows the available options.
File extension: The option allows the user to define a custom file extension for the downloaded weather data file(s).
Info: The option provides information about the weather resource database, such as the geographical region(s) covered by the data provider.

The list of the weather data provider(s) selected in the data provider tab will be displayed in the collect weather data wizard. The wizard will not be available to the user if nothing is selected.

NSRDB and WIND Toolkit data providers require the user to register. The registration provides the login credentials (API key, etc.) that are necessary to retrieve data. Please access the data provider’s official website to register: https://developer.nrel.gov/signup/.
Login credentials are saved after the first time the user inputs them in SAInt.

1.1. Solar weather data provider

The current version of SAInt connects to the following solar weather data providers through their APIs:

NSRDB: The NSRDB is owned and maintained by NREL. The database allows users to collect solar resource data in different parts of the world, each with a different server URL. However, the same API key can be used for all the different server URLs. For additional information, access the NSRDB's website: https://nsrdb.nrel.gov/about/what-is-the-nsrdb.
PVGIS: The Joint Research Centre of the European Commission developed a web application that allows the user to get data on solar radiation and PV system energy production in most parts of the world. Users do not require login credentials to access the weather resource database. For additional information, access PVGIS's website at https://ec.europa.eu/jrc/en/pvgis.

The solar weather data providers allow users to collect solar resource data such as the global horizontal irradiance (GHI), the direct normal irradiance (DNI), the diffuse horizontal irradiance (DHI), the air temperature, and the wind speed. Figure 2 shows the geographical area covered by the different solar weather data providers. Each location (color) is associated with one (or more) weather data resources.

Figure 2. Solar weather data providers geographical area coverage for NSRDB. Refer to "NSRDB Viewer" for a comprehensive description of the area coverage. Refer to "PVGIS user manual" for details on the spatial and temporal coverage of the data.

Depending on the data provider, different weather years, and temporal and spatial resolutions are available for each location. Table 1 shows an overview of the available solar weather data providers.

Table 1. Solar weather data providers integrated into SAInt. The user must be registered and have an API key to access some links. The weather years and spatial coverage for the database PVGIS-NSRDB are different and only affect the Americas (above 20 °S) (see symbol *). PVGIS-ERA5 has a coarser spatial resolution and is used to cover the areas outside PVGIS-SARAH2 and PVGIS-NSRDB.
Data Provider	Weather Year(s)	Temporal Resolution	Spatial Resolution	Coverage Area (Color)
NSRDB - Full Disc	2019 - 2020	15, 30, 60 minutes	2 km x 2 km	Dark and Light Blue
NSRDB - PSM v.3	1998 - 2020	30, 60 minutes	4 km x 4 km	Light Blue
NSRDB - PSM v.3.2.2	2021	30, 60 minutes	4 km x 4 km	Light Blue (only USA)
NSRDB - PSM v.3 - Five Minute Temporal Resolution	2018 - 2020	5, 15, 30, 60 minutes	4 km x 4 km	Light Blue
NSRDB - India (Suny)	2000 - 2014	60 minutes	10 km x 10 km	Green
NSRDB - Europe and Africa (METEOSAT IODC PSM)	2017 - 2019	15, 30, 60 minutes	4 km x 4 km	Red
NSRDB - Himawari PSM v.3	2016 - 2020	10, 30, 60 minutes	2 km x 2 km	Orange
NSRDB - Puerto Rico	1998 - 2017	5, 30, 60 minutes	4 km x 4 km	Black
PVGIS	2005 - 2020 or 2005 - 2015*	60 minutes	4 km x 4 km*, 5 km x 5 km, 25 km x 25 km	latitude 60 °S - 74 °N

1.2. Wind weather data provider

The current version of SAInt connects to the following wind weather data providers through their APIs:

WIND Toolkit: The WIND Toolkit is owned and maintained by NREL. The datasets allow users to collect wind resource data in different parts of the world, each with a different server URL. However, the same API key can be used for all the different server URL. For additional information, access the WIND Toolkit’s website: https://www.nrel.gov/grid/wind-toolkit.html.

The wind weather data providers allow users to collect wind resource data such as wind speed, wind direction, air pressure, and air temperature at different locations and heights. Figure 3 shows the geographical area covered by the different wind weather data providers. Each location (color) is associated with one (or more) weather data resources.

Figure 3. Wind weather data providers geographical area coverage for the Wind Toolkit by NREL.

Depending on the data provider, different weather years, and temporal resolutions are available for each location. Spatial resolution is set to a grid of 2 by 2 kilometers. Table 2 shows an overview of the available wind weather data providers.

Table 2. Wind weather data providers integrated into SAInt.
Data Provider	Weather Year(s)	Temporal Resolution	Coverage Area (Color)
WIND Toolkit - Mexico	2007 - 2014	60 minutes	Dark Blue
WIND Toolkit - India	2014	15, 60 minutes	Dark Purple
WIND Toolkit - Central Asia	2015	15, 30, 60 minutes	Dark Brown
WIND Toolkit - Offshore California	2000 - 2020	5, 15, 30, 60 minutes	Light Red
WIND Toolkit - Offshore Great Lakes	2000 - 2020	5, 15, 30, 60 minutes	Orange
WIND Toolkit - Offshore Hawaii	2000 - 2020	5, 15, 30, 60 minutes	Black
WIND Toolkit - Philippines	2017	60 minutes	Dark Yellow
WIND Toolkit - Vietnam	2016	60 minutes	Light Yellow
WIND Toolkit Data - Continental USA	2007 - 2014	5, 15, 30, 60 minutes	Dark Red
WIND Toolkit - Offshore Gulf of Mexico	2000 - 2020	5, 15, 30, 60 minutes	Light Blue
WIND Toolkit - Offshore Mid Atlantic	2000 - 2020	5, 15, 30, 60 minutes	Cyan
WIND Toolkit - NW Pacific	2000 - 2020	5, 15, 30, 60 minutes	Light Green
WIND Toolkit - Offshore North Atlantic	2000 - 2020	5, 15, 30, 60 minutes	Dark Green
WIND Toolkit - Southeast Asia	2017-2021	15, 30, 60 minutes	Light Purple

2. Collecting weather data from a data provider

Once a connection between SAInt and a data provider has been defined, as described in Section 1, the user can collect weather data directly within SAInt via the collect weather data wizard, as shown in Figure 4. PV and WIND weather resource data need to be collected separately since one collect weather data wizard (either for PV or WIND) can be accessed at a time. In the same session, different weather data providers can be accessed for each object of the same type.

Figure 4. Collect weather data wizard for solar and wind resource data.

The main options of the collect weather data wizard are:

Object: This option provides a list of the solar or wind generators selected to collect the weather resource data.
Weather data provider: This option shows which data provider will be used to collect the weather resource data.
Status: The field reports any issues with the object properties defined by the user or connecting and downloading data from the data provider.
Message: The field provides the user with feedbacks on any issue in the definition of the object properties or while downloading the weather resource data.
Action: The option allows the user to define whether to consider an object when downloading data. Continue will consider the object when downloading the weather resource data, while Skip will skip the selected object.
Property editor: The option opens the property editor of the selected object allowing the user to edit the properties of the object.
Weather data provider setting: The option opens the data provider wizard, allowing the user to edit the configuration of the weather data providers.
Execute!: The option downloads weather resource data and saves the corresponding files in the project folder.

Before downloading any data, the user should ensure all objects' status is Ready or any action is set to Skip, if needed. Once the weather data file has been created, the status will change to Downloading and Done. If an error occurs, the status changes to ServerError, and a message is provided.

The weather resource data for solar and wind generators are retrieved according to the latitude and longitude properties of the object(s).

Select multiple generators by pressing SHIFT in the model explorer or object table to retrieve weather resource data.
Select all solar or wind generators by clicking on the base object (e.g., solar generators or wind generators) in the model explorer.

2.1. Weather data file

The collect weather data wizard creates an individual weather data file for each object (PV or WIND) that is saved in the same location as the electric network files, in a folder named WeatherData. Each file is saved in a comma-separated format with the following naming convention: GenType_ObjectID_Lat_Lon_Year_TimeInt.Extension.csv. The weather resource data file is then used to create a time series profile of the solar or wind generator’s hourly (or sub-hourly) generation.

The name of a weather data file cannot be modified since SAInt uses it to create the generation time series profiles.

Solar weather data file example: Figure 5 shows an example of a solar weather data file collected from NSRDB. The red boxes (year, time resolution, latitude, and longitude) highlight the properties set by the user for the specific object. The blue boxes show the local time zone of the data, negative to the West of Greenwich. The weather variables (GHI, DHI, DNI, wind speed, air temperature, and solar zenith angle) are related to the pair of latitude and longitude coordinates closest to the ones defined by the user for the solar generator in SAInt.

Figure 5. Example of the general structure of the solar weather resource data collected from NSRDB.

Wind weather data file example: Figure 6 shows an example of a wind weather data file collected from WIND Toolkit. The weather variables (e.g., pressure, wind speed, wind direction, and air temperature) are related to the pair of latitude and longitude coordinates closest to the ones defined by the user for the wind generator in SAInt.

Figure 6. Example of the general structure of the wind weather resource data collected from WIND Toolkit.

3. Generating a profile based on weather data

The generate profile from the weather data wizard, shown in Figure 7, calculates the power generated by the solar or wind power plants, generating a time series profile of the hourly (or sub-hourly) generation. It can be accessed via the context menu of a solar or wind generator.

How are solar profiles generated in SAInt?

SAInt uses the System Advisor Model (SAM) developed by NREL to calculate solar PV generation profiles. SAM is a techno-economic model designed to facilitate decision-making for people involved in the renewable energy industry. The PVWatts (no financial model) model is implemented. This model generates time series data representing the solar PV system’s electricity production over a single year. The simulation timestep depends on the weather data file’s temporal resolution. More detailed information about SAM is available at the website: https://sam.nrel.gov.

How are wind profiles generated in SAInt?

SAInt has a built-in wind power performance model to calculate a wind power plant’s power generation time series. The wind weather resource data is used as an input, in addition to the wind turbine power curve and the turbine’s hub height.

A generation profile time series is created if the generator has a weather data file.
A wind turbine power curve is required for calculating the generation profile of a WIND object.

Figure 7. Generate profile from weather data wizard for solar and wind generators.

The options for the generator profile from the weather data wizard are:

Object: The option provides a list of all the solar or wind generators selected to collect the resource weather data.
Weather data provider: The option shows which data provider was used to collecting the weather resource data. If no weather data was collected, the user an error message is provided.
Status: The field diagnoses any issues with the object or weather data file.
Message: The field gives the user feedback on any issue in the definition of the object properties or while downloading the weather resource data.
Action: The option allows the user to define whether to consider an object or not when calculating the generation profile. Continue will consider the object during calculation, while Skip will skip the selected object.
Property editor: the option opens the property editor of the selected object and allows editing of the properties of the object.
Export: The option allows the user to create import files for the profile and scenario event(s) of the generator(s). If a scenario file is open during this process, the user can directly add the generator profile and scenario event(s) into the scenario file.
Weather data provider setting: The option opens the data provider wizard, allowing the user to edit the configuration of the weather data providers.
Execute!: The option calculates the generation profile time series that is saved in the profile table.

Before creating the generation profile, the user should ensure all objects' status are Ready or action is set to Skip if needed. Once the profile time series have been calculated, the status and action will change to Processed and Done, respectively. If an error occurs the status changes to Invalid. The profile can be assigned to either a PSET or PMAX scenario event for the solar and wind generators.

When successfully exporting profile and/or scenario event(s) for the selected generator(s), the log file reads "Export of Profile and Scenario Event(s) for the selected Generator(s) completed" if both "export events" are selected, or "Export of Profile for the selected Generator(s) completed" if only one of the two "export events" is selected.

When missing values are present in the source data, retrieved from the weather data provider, SAInt performs a linear interpolation of the available information. The user is informed by a message in the Log Window stating, for example, "N/A or missing values in "wind speed at 10m (m/s)" column have been linearly interpolated using the existing data".

If the entire record is missing and no interpolation is possible, the user is informed by reporting an error message stating "The given array is too small. It must be at least 2 long. Parameter name: x" in the "Message" box of the weather data window.