As a decorative painter, I can think of lots of options. What kind of room are we talking about? Is the panelling currently painted? Is it in good condition? Are you shooting for a casual or a formal look?

What level painting skills do you have - novice or experienced? How much prep and how many coats are you prepared to do?

We had that same problem. My wife and I cleaned the panel with TSP and let it dry. We primered with three coats. ( The dark panel looked like it wasn't covering) And painted with two coats. We did use a 3/4 inch nap roller. Turned out great. You can't tell it's panel from a few feet away.