How does pressure affect PVWatts output?

  • ale.ara
  • Topic Author
More
08 Feb 2024 06:57 - 09 Feb 2024 22:43 #12877 by ale.ara
Hi Paul, 

I've been trying to format a weather file; I added all elements mentioned in the  weather data elements  page, but noticed the output of pvwattsv8 was not quite right, after playing around with the weather file I found that if I added the pressure column on the weather file the output was correct. What confuses me is that the  weather data elements  page says that PVWatts doesn't use the atmospheric pressure from the weather file, but the pressure seems to affect the output.
Here's my output and code:
 
Attachments:
Last edit: 09 Feb 2024 22:43 by pgilman.

Please Log in or Create an account to join the conversation.

  • pgilman
More
09 Feb 2024 23:00 - 09 Feb 2024 23:05 #12885 by pgilman
Replied by pgilman on topic How does pressure affect PVWatts output?
Hi Alejandro,

I tested PVWatts in SAM 2023.12.17, which runs the pvwattsv8 module with the attached test weather file that contains no pressure data.

A also ran your test script with the weather files you provided, and pvwattsv8 seemed to run with both weather files you provided:

 

The slight difference between the annual energy for the two cases is due to the code that calculates plane-of-array irradiance from the input DNI and DHI data: When the weather file does not include atmospheric pressure data, it sets the pressure to 1013.25 mb (sea level pressure).

Best regards,
Paul.

p.s. If you want to include an image in your posts on this forum, please attach the image as a file and then insert it into the message. Copying and pasting the image directly into the message does not work.
Last edit: 09 Feb 2024 23:05 by pgilman.

Please Log in or Create an account to join the conversation.

  • ale.ara
  • Topic Author
More
12 Feb 2024 02:19 #12886 by ale.ara
Replied by ale.ara on topic How does pressure affect PVWatts output?
Thanks Paul! 

Please Log in or Create an account to join the conversation.

Moderators: pgilman
Powered by Kunena Forum