How do I set a postgresql password in pgpass.conf for the Administrator account on Windows Server 2008?

I have a pgpass.conf file that works well for my default user. It is in C:/Users/myuser/AppData/Roaming/postgresql/pgpass.conf. It reads like so;

localhost:5432:*:postgres:password1

I have a process that runs under the Administrator account. When I run whoami under this process I get nt authority/system. I want to be able to access the database from this process but it gets stuck because it needs a password. I have tried putting the above pgpass.conf into C:/Users/Administrator/AppData/postgresql/pgpass.conf and C:/Users/Administrator/AppData/Roaming/postgresql/pgpass.conf but it does not work. Is this the correct place for this file? Am I even able to do this as the Administrator. Unfortunately I cannot change the user that this process runs under.

See what echo %APPDATA% outputs when you're logged with this account.

As an alternative, you can point the PGPASSFILE environment variable to the location of the file, wherever it it, or even set the PGPASSWORD environment variable with the password itself to avoid that file altogether.

The Environment Variables and The Password File sections from the doc give the details.