When i place biofarm in factorissimo building i have error in console.

Error while running event Factorissimo2::script_raised_build (ID 78)
Factorissimo2/control.lua:1309: attempt to index field 'items_to_place_this' (a nil value)
stack traceback:
Factorissimo2/control.lua:1309: in function 'cancel_creation'
Factorissimo2/control.lua:864: in function <Factorissimo2/control.lua:832>

Game don't crash, but save don't load if mod settings is changed.

I looked at the mod code.
Farms consume more electricity at night, for this the author entered the solar panel into the farm (reduces electrical consumption during the day), and does not work at night (electricity consumption increases)

The mod factorissimo prohibits solar panels inside itself. So when we put the farm in the factory, the factory tries to remove the solar panel inside the farm.

Inside Factorissimo there is a check for the solar panel, if you add an exception for the solar panel of the farm inside it (entity.name she has a "bi-bio-farm-hidden-panel"), then everything will work.

https://pastebin.com/YBUyJmGD

This issue does not occur in standard Factorissimo2, you seem to be using using notnotmelon's unofficial electric network overhaul branch. Please raise this issue with the branch author.

This has been fixed. Thanks for the report