PAN file parameter gets changed by PVsyst when opening file in v7.0.16

[smeredith]

Hi,

First off, I'm using PVsyst version 7.0.16.

I'm trying to modify a PAN file based on a third-party PAN file that I was provided. When I opened the PAN file in PVsyst, I noticed that the RSerie parameter got changed from 350 to 500. As an experiment, I didn't make any edits to the file and immediately closed it in PVsyst. I then opened the PAN file in a text editor and saw that the value was still 350.

But then I re-opened the PAN file in PVsyst, made some edits to the PAN file (I didn't change RSerie), then saved the file as a new file. When I opened the PAN file in a text editor, the value had changed to 500.

This seems like a bug that's unique to version 7, because I did the same things in version 6 and I had no problems there.

[smeredith]

Just wanted to give an update.

Today I was opening a manufacturer-provided PAN file in 7.0.16, and I noticed that PVsyst again changed a parameter when I opened it - this time it was Voc (went from 53.5 to 31.2).

Additionally, I noticed that when I went to change the number of cells in parallel from 1 to 2 and the cell area from 328.9 to 165, that PVsyst also changed the following parameters:

1. RSerie (went from 0.255 to -2.781)

2. Gamma (went from 1.151 to 4.620)

3. muGamma (went from -0.0004 to 0.0200)

I updated my PVsyst version to 7.0.17 and the error still persisted.

[eye4u]

Hi,

I'm wondering if you've solved the problem. I have exactly the same problem as you did.

Thank you.

[smeredith]

Hi eye4u,

No, unfortunately this problem has persisted at least through 7.0.17. I haven't downloaded 7.1.0 yet, so I can't say for sure if the problem has been fixed in that version.

For now, I need to use PVsyst 6 to edit any PAN files.

[smeredith]

This post is old, but I think is still relevant. I can give some background to those that are experiencing this error.

PVsyst is constantly changing the way that it determines the default values for the single-diode parameters Rseries, Rshunt, and Rshunt at g=0. The implication is that you may get a different default value for a parameter if you open the PAN file in version 6.88 vs. if you open that same PAN file in a later version.

This is not a problem if you are opening the PAN file in the same (or a similar) version that it was created in - but I would argue based on the wide variety of versions I've seen used to create PAN files - that this is rarely the case. This is why I argue in a different post that PVsyst needs to either do away with default values for these parameters or else come up with a consistent methodology for determining default values regardless of PVsyst version. Because if you don't, you're going to end up with a different module model for the same PAN file depending on what version you're using.