Calliope.model() from existing model issue, Windows OS

[ddahawkins-TUDelft]

Description

Hello. Whether an issue with the code itself, or just the documentation, I encountered issue with creating a Calliope model with calliope.model(...) from a previous model.

I was attempting to run a model in 'plan' mode and then use the capacity outputs from that model in a new model in 'operate' mode. Although it states that this is possible, it is not immediately clear from the documentation how to do this. Apologies, I do not have this code any longer to upload but to explain...

I created a plan model object: model_plan = calliope.model('model.yaml', ...)
Then built and solve: model_plan.build() >> model_plan.solve()

I then tried to create an operate model object, taking the model_plan as an input argument for the 'model_definition' parameter i.e.: model_operate = calliope.model(model_plan,...)

This failed.

I expected this to work as the dev5 documentation (https://calliope.readthedocs.io/en/v0.7.0.dev5/reference/api/model/?h=calliope.model#calliope.Model) for calliope.model() suggests that 'model_definition' can be a string, path, dictionary, or xarray dataset. With model_plan, a calliope model object, being an xarray dataset, I expected it to be a valid argument. Instead I received 'encoding' errors which may or may not be unique to the Windows OS. I did notice in the calliope backend a few times where UTF-8 was hardcoded for os.reads but not os.writes. Perhaps it may be better to use OS default or at least make this encoding consisting for writing and reading.

What i have later been informed is that instead of importing the model_plan object, I could have saved this file as a .netcdf and run the calliope.read_netcdf('model_plan_path') as the input parameter for 'model_definition.' If this is the case, it is not clear from your documentation and in any case, i feel it is good practice that one should be able to import the object and not have to write>read in order to access an object for re-runs.

Apologies if any of the above if unclear, happy to discuss!

Kind regards,
Dano

Related links

-https://calliope.readthedocs.io/en/v0.7.0.dev5/reference/api/model/?h=calliope.model#calliope.Model

...

Version

v.0.7.0.dev5

Proposed change

The simplest short-term solution might be an example in the documentation of chaining models i.e. running 'operate' from the output of a 'build.'

Further, a clear explanation within the calliope.model() documentation to explain the precise format of xarray permissible for the model_definition parameter.