Time Step for SAM Model Simulations

Hi Pablo,
Could you [url=mailto:sam.support@nrel.gov?subject=Subhourly%20Weather%20File%20for%20Testing%20(from%20Support%20Forum) t=_self]email me[/url] a copy of your weather file?
Best regards,

Paul.

Dear Paul,

No problem, I've just sent to you an email with my wheather file. I've sent the email to the following email adress: sam.support@nrel.gov

Regards,
Pablo

Dear Pablo,
Thank you for sending the file. It is correctly formatted, and works with the detailed photovoltaic model.
I must apologize for saying that the CSP models in SAM 2014.11.24 support subhourly simulations. Only the detailed photovoltaic, PVWatts, and solar water heating models will work with subhourly weather files. We hope to have the CSP and other models working with subhourly data for the next SAM update.
UPDATE 2/17/2015: SAM 2015.1.30 supports subhourly simulations for the detailed photovoltaic, PVWatts, concentrating PV, and physical trough performance models.
Best regards,

Paul.

Dear Paul,

Following with this issue, I have tried to create a .smw file with 15 min time-step wheather data to simulate it with SAM 2014.1.14, the version you told me that worked with subhourly data for physical trough models. For creating the wheather file, I have used as reference the file "NV El Dorado Hourly", which I have found in the wheather library of SAM 2014.1.14.

Here below I try to explain what I did to create the wheather file, because at the end it didn't work properly:
-First of all, I adapted the wheather data to .smw format, as you can see in the following example of the 35040 rows:
17,-999.,-999.,50.6,1.4,353,1053,0,0,0,-999.
17,-999.,-999.,50.8,1.4,353,1053,0,0,0,-999.
17,-999.,-999.,50.9,1.4,353,1053,0,0,0,-999.
17,-999.,-999.,51.1,1.4,353,1053,0,0,0,-999.
17,-999.,-999.,51.3,1.4,353,1053,0,0,0,-999.
17,-999.,-999.,51.5,1.4,353,1053,0,0,0,-999.
- I kept the header of file "NV El Dorado Hourly" with these data as you can see in the following example:
723860,"Clark/El Dorado",NV,-8.0,35.796245,-114.974334,548.64,3600.,2010,0:30:00,
17,-999.,-999.,50.6,1.4,353,1053,0,0,0,-999.
17,-999.,-999.,50.8,1.4,353,1053,0,0,0,-999.
-I imported the wheather file in SAM and run the physical trough model and it worked properly
-I changed the header
-I run the model with the changed header and tried to run the model and it didn't work (the message was Simulation error!...check your inputs and try again)

I checked where was the problem and I think that it has something to do with the latitude, longitude or time zone, because it is when I change that data when the model doesn't work.

I've sent you an email with my wheather file .smw, please could you tell me where is the problem and how can I solve it?

Thank you very much in advance.

Best regards,

Pablo.

Dear Pablo,
There are a few potential problems with your SMW file:
1. There should be 12 columns of data. Your file has 11: I think the snow depth column is missing (you can use the -999 flag for that).
2. The dew-point and wet-bulb temperatures are -999. That will cause the physical trough model to fail because it requires valid values to calculate heat losses and other values.
3. The last column in the header should be the mid-point of the time step, which for 15-minute data would be 0:7:30.
4. The location name should be in quotes, e.g., "Clark/El Dorado".
You may be interested in the standalone version of SAM's data viewer. It is called DView and is available as a free download from NREL , you can use it to display graphs of data in a time series file. It does not recognize the SMW format, but if you copy the SMW file and replace the header with column headings like Tdry, Twet, GHI, DNI, etc., it will display the data.
Best regards,

Paul.

Dear Paul,

Thanks again for your quick answer. I've tested all combinations to create my .smw and finally I can tell you that I am not able to create it or it is impossible to run it in a parabolic trough physical model in SAM 2014.1.14.

The .smw file works properly with parabolic trough physical models changing no matter what input, but it doesn't work when I change the "time step" or the "start time". I've tested even with data of "Clark/El Dorado" only changing the "time step" or the "start time" and it doesn`t work. It doesn't matter the value I put instead of 3600 sec or 0:30:0, it doesn't work in any case.

The only thing that comes to me to solve this mess is that you send me by email an example of .smw file with 15 min time step in order to take it as reference.

Please, could you send me this example of .smw file?

Thanks in advance.

Regards,
Pablo.