Creating and configuring the Secure Store Service for Excel Services in Microsoft SharePoint Server 2010 is often a complicated process. I’ve recently revised the Configure Secure Store Service for Excel Services (SharePoint Server 2010) article on TechNet to provide an easier administrative experience for this process.
In Excel Services 2010, the Secure Store Service is required anytime you connect to and use an external data source. Keep in mind that the Secure Store Service is one of many SharePoint Server services and is independent of Excel Services.
Excel Services uses an instance of the Secure Store Service in the following scenarios:
With an unattended service account
With an Office Data Connection (ODC) file or embedded in an Excel workbook
Both of these scenarios are shown in separate sections of the revised TechNet article. The required steps for each scenario are shown at the beginning of each section and the procedures in each section show the exact steps that are required for the scenario.
Let us know if the updates helped, or if there are other issues that we provide documentation solutions for.