In most cases, the Farm Installation account (used to install SharePoint) satisfies the permission requirements for the full installation process.
To identify the Farm Installation account
Note: By default, the SharePoint Central Administration v4 application pool is configured to run using the Farm Installation account.
Open IIS Manager.
For instructions, see http://msdn.microsoft.com/en-us/library/vstudio/bb763170(v=vs.100).aspx.
Under your server, click Application Pools.
Select SharePoint Central Administration v4.
Under Edit Application Pool, click Advanced Settings.
The Farm Installation account is indicated in the Identity row under Process Model.