Aeternus, thank you for the explanation! It is so obvious that a new pole forms a 2nd electrical grid. And your workarounds over this situation sound reasonable.

So, this is not a bug.

Hello.

Here is initial setup. 2 solar panels give 120 kW. Everything is OK:
Img1.jpg
Now let's add another pole, which will touch both solar panels:
Img2.jpg
And finally let's remove wire from the newly added pole:
Img3.jpg
Notice that electric network (when clicked on initial pole, which is ...