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Questions on Tracker Wind Stow Algorithm


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PVsyst v7.4.0

Most of the below questions and feedback are compliments of T. Townsend (paraphrasing is mine):

1.) What's the assumed height of the wind speed? This is as important to know as the wind stow wind speed threshold.

2.) It it accounting for wind speed gusting? Or is it simply basing it on an hourly average wind speed? Namely, what duration of wind speed is used in the algorithm, and what duration is expected for the user input of wind stow wind speed (e.g., 3-sec gust or 1-hr avg)?

3.) Is it changing tilt to the user-inputted tracker stow position value (thus affecting, e.g., IAM losses) or is it assuming power is zero? Initial testing indicated the former, however, it's likely that such high wind events will be complemented (e.g., in the 8-24 hours following the event) by a utility outage. Certain gust events may cause spot power outages while higher gust events cause widespread outages.

4.) Initial testing indicated that a custom user input of wind stow wind speed (e.g., 6 m/s) changes by itself back to the original PVsyst-default value (12 m/s). If so, we assume this is a bug.

5.) In the hours with hourly (TMY aka TGY) wind speed exceeding 12 m/s, no impact of wind stow was observed. Maybe this relates to some of the questions above. Or it could be a bug. We're not sure.

6.) The help menu description of this new feature is quite limited hence several of our questions.

7.) Trackers commonly stow for both wind and hail. Do you have any plans to address tracker hail stow in PVsyst (so we don't have to include it in applicable cases via a post-processing algorithm external to PVsyst)?

Edited by kjs55
Slight editorial
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P.S. (because the time that's granted for editing posts in this new PVsyst Forum is unfortunately still very limited, i.e., it very quickly expires following submission - roughly 1-min. only vs. the previous PVsyst Forum which nicely allowed edits to posts indefinitely):

I was just going add a quick note onto question #7 to say that trackers often follow a different tracker stow algorithm depending on whether the event relates to wind or hail.

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