Expanding and minimizing panels on a Dashboard

I'm looking for guidelines when it comes to web app dashboards.

Specifically I'm designing a dashboard which has 3 main panels, these panels are expandable so the users can view each panel in more detail (see my rough sketch).

As you can see on left is the main dashboard, and on the right is a expanded panel.

Now my question is when the user is the the expanded view (right side image), should they still be able to view the other two panels albeit scaled down? Or should they have to collapse/shrink the expanded view?

Additionally, the reason for expanding the panels is so the user can view a large amount of data in a table, thus, the size of the panel should be as large as possible to minimize the amount of scrolling (if any).

Many thanks for your thoughts.