Saving an array or class to disk
 

Can someone point me in the right direction. I hope this makes sense.

I have an excel addin that reads 18,000 rows x 18 columns of worksheet data.
Each several rows is copied int an instance of a class (oneitem).

I either create an array of this class or Icreate another class(allitems)
to hold the array of class(oneitem).

Everytime I want to re-run the function that need this data, I have to go
through all the steps to initialize the class data;

I guess I could write the data sequentially into a text file or another
worksheet, but it seems to be overwork.

Is it possible to write the class to disk? In binary. What is the best way
to save data between the times the addin is run.