Dear Carla,
1. SAM uses the SAM CSV format for weather files. You can find a description of the format in SAM's Help system, under Weather Data in the table of contents, or on the SAM website
Weather data page
under "Weather File Formats."
The SAM CSV format supports weather data with between one-minute and 60-minute time steps. SAM determines the time step from the number of weather data rows in the file. For sub-hourly data, be sure to include a Minute column in the file. The Minute column is necessary for sun position calculations.
2. Yes. SAM's simulation uses one year of weather data. If you have data for multiple years, you can run a separate simulation for each year. You can use the LK script to run simulations with multiple weather files, available for download on the
Samples page
to automate the process.
3. SAM is designed to work with a weather file that starts on January 1st and ends on December 31, so for best results, I would recommend using January-through-December data. SAM assumes the first time step is the first one of the year. For 15-minutes, the first time step would be the one that ends at 0:15. However, because the solar performance models use the time stamp data (Year, Month, Day, Hour, Minute) rather than the Row number for sun position calculations, the performance models should work with a weather file that starts at any time of the year. The financial models, on the other hand, require January-through-December data to apply time-of-use data to the correct time steps.
Best regards,
Paul.
