Instead of opening a workbook in Microsoft Office Excel Web Access on a Web Part Page, you can open a workbook in Web browser view. Web browser view is a convenient way to display the workbook in the browser. For example, you may want to confirm the contents of a workbook that you just uploaded to a document library, or another user added the workbook and you are not familiar with the workbook contents. When you open a workbook this way, you display a Web page (xlviewer.aspx) that automatically uses the Excel Web Access Web Part for you.
Open the document library that contains the workbook.
Point to the workbook item.
Click the arrow next to it.
Click View in Web Browser.
Tip: You may want to change the default action when you click an item in a document library to open the workbook in Web Browser view. On the document library toolbar, click Settings, click Document Library Settings, click Advanced settings under General Settings, and in the Browser-enabled Documents section, select Display as a Web page.