Database design - load multiple excels daily
If the data needs to be clean and relational before being presented in your UI, I'd use SSIS to handle reading, cleaning, inserting your data into SQL Server, handling rejects, and archiving the input files.

If your data does not need to be clean/relational before presenting in the UI, then a NoSQL solution might work for you.

By the way, Excel is horrible to work with as an input file format.  You might want to see if you can receive the data as CSV or some other flat file format.