Permissions for Power Shell

Getting Started SharePoint 2013 Management Shell

Click Start, click Microsoft SharePoint 2013 Products, and then click SharePoint 2013 Management Shell

Permissions

Before you can use the Add-SPShellAdmin cmdlet to grant permissions for users to run SharePoint 2013 cmdlets, verify that you meet all of the following minimum requirements:

•  You must have membership in the securityadmin fixed server role on the SQL Server instance
• You must have membership in the db_owner fixed database role on all databases that are to be updated.
• You must be a member of the Administrators group on the server on which you are running the Windows PowerShell cmdlet.
•   If you do not have membership in the SharePoint_Shell_Access role or WSS_Admin_WPG local group, use the Add-SPShellAdmin cmdlet to add the WSS_Admin_WPG group in all front-end web servers in the SharePoint farm and the SharePoint_Shell_Access role. If the SQL Server database does not have a SharePoint_Shell_Access role, the role is automatically created when you run the Add-SPShellAdmin cmdlet. After you run the Add-SPShellAdmin cmdlet, users can run SharePoint Windows PowerShell cmdlets in a multiple-server farm environment.
•  When you install SharePoint 2013, the user account from which you run the installation is granted the appropriate permissions to run Windows PowerShell cmdlets. If any users have not been added to run a Windows PowerShell cmdlet, you can use the Add-SPShellAdmin cmdlet to add them.
•  You must run the Add-SPShellAdmin cmdlet for all databases to which you want to grant access. If no database is specified, the farm configuration database is used. If you do specify a database, the farm content database will be included in addition to the farm configuration database that you specify.
• To see a list of all of the SPShellAdmin cmdlets, from a Windows PowerShell command prompt, type Get-Command -Noun SPShellAdmin or Get-SPShellAdmin

Reference: http://technet.microsoft.com/en-us/library/ee806878%28v=office.15%29.aspx