Tilt = Latitude Question

I am using SAM for the first time. On the PV Subarray tab there is a tilt=latitude check-off box in the Tracking and Orientation section. Should this box be checked when using a horizontal single axis tracker? 3 of us looked at the Help screen and we could not figure out what to do. Thank you.

No. For a subarray with one-axis tracking about a horizontal axis, you should set the tilt angle to zero.

If you check the Tilt = Latitude check box, SAM will assume that the trackers rotate the modules about an axis tilted from the horizontal at an angle equal to the latitude in the weather file.

Best regards,
Paul.

Hi, What should be my input (latitude and azimuth) for the following cases;

1) Fixed Flat Plate PV
2) One Axis Flat Plate PV (East to West tracking)
3) One Axis Flat Plate PV (North to South tracking)

Thanks

Hello,
The answer to your question depends on where the system is located, and what tilt angle you would like to model. The latitude is determined by the weather file. The diagrams on the PV Subarrays page show the angle conventions for the array azimuth and tilt angle input values.
For a detailed description, see "Tracking and Orientation" in the PV Subarrays Help topic. Here is a link to the copy of the Help system on the SAM website:

• 
  PV Subarrays

1. For a fixed, south-facing array (typical for northern hemisphere locations), tilted at 30 degrees from the horizontal, choose Fixed, Tilt = 30, and Azimuth = 180. 
2. For a similar configuration but with east-to-west tracking, choose 1 Axis, Tilt = 30, and Azimuth = 180. For one-axis tracking, you also need to specify a value for the tracker rotation limit.
3. A north-south one-axis tracking configuration is unusual. You could try the 1 Axis option with the Azimuth = 90, and see whether the tracking angles are what you expect them to be.
You can see graphs of the hourly surface angles for each subarray after you run simulations by clicking Time Series on the Results page, and showing the following output variables:

• 
  Subarray [n] Surface tilt (deg)
• 
  Subarray [n] Surface azimuth (deg)
• 
  Subarray [n] Axis rotation for 1 axis trackers (deg)

Best regards,

Paul.

How can I get the annual energy output of a fixed photovoltaic system for a location that has no clouds throughout the year? Is there any option to set the settings of the weather file to no clouds?

Thanks Paul.

Hello,

SAM uses solar radiation data from a weather file. If you have a weather file for a location that never has clouds, then you could use SAM to calculate a system's annual energy for a cloudless location. However, I doubt there is a weather file for a location that has no clouds for an entire year.

You could use the Time Series graph on the Results page to find a cloudless day if you want to see the daily profile for a day with no clouds. (You can right-click any graph to export data from the graph to use in a spreadsheet program or other software.)

Best regards,
Paul.