Tranfer Data 200xl files in single worksheet(fast method)Req

Question

I have around 200 xlsb workbooks and would like to copy data from them and paste in a master workbook. After transfer data the size of master workbook would be about 1 million rows and 55 columns on one sheet. Sometimes I needed to use 2-3 sheets in master workbook to transfer all data from those 200 excel files.  I am wondering is there any fast way to read and write data in excel. I tried with arrays in C# to read data but arrays does not fill up with data. Can someone help me.

 

 Method:1 (not work)

<object[,] valueArray = xlRangeDB.Value2;>

Method:2 (not work)
<object[,] valueArray = (object[,])xlRangeDB.get_Value(XlRangeValueDataType.xlRangeValueDefault); >