PyPSA-Eur: Unexpected clustering behaviour when IT is included

[Tom Kra]

Dear PyPSA-Community,

for my research I want to build a power model of France and Germany and their neighbouring countries. For this, France and Germany should contain 5 nodes each and the neighbouring countries the least amount of nodes. As far as I know this should be 2 nodes for DK, ES, IT each and 1 for the remaining countries each. For the clustering I am using the focus weight option.

My problem is that in the final network, the nodes are not distributed as I defined. FR, DK, DE, IT in particular show discrepancies (base_21_no_IT/_2). You can see, as far as I remove IT from the model the model is built as expected (base_23). I could not find any question like this in this group so I want to ask you following questions:

1. Did somebody face similar observations? Does somebody know how to get the expected behaviour?
2. Has somebody an idea why corsica is only considered for custering when IT is? Is it because it is possibly only connected to the grid of IT?

Please bear with me if I have made any obvious mistakes; I am still quite new to the PyPSA-Eur universe. If you need any further information, please feel free to write to me and I will be happy to provide it. I am very grateful for any advice!  😊

Best regards and happy holidays!

Tom