Hello Jack ,
From the question I understood that you are changing the "Module" in the "Module data" of the PV array to unser defined thereby you can define a new PV module and assuming that you might be using MATLAB 2019a
Module data -> Module -> user defined.
The PV array module that you are using is a masked block, it has it's own workspace hence directly giving varible values from Base work space.
In order to read the data from the base workspace follow these steps :
1 . In the field where the value has to be accessed from workspace ( here open circuit voltage )
2 . Then click on "Voc: Create..." which will lead you to this
Enter the value( < expression > , here I have given it an intial value of 40 ) you want to assign to the variable in workspace "Voc" and then press create
3 . This will create a variable Voc in work space as shown
This variable can now be called from SIMULINK as any other MATLAB variable