Caravan power usage of tv with austar's my star box

We previously had just the basic austar box in our caravan taking power from a projecta 300 watt pure sine wave inverter. We upgraded to the austar Mystar box and suddenly the power usage seems to have increased significantly. The specs on the Mystar box say 50 watt max (don't have the old box anymore so don't know what it was). Is this a hungry beast?
Not looking for comments re why we have this in a caravan - we just do!
Obviously, this is only a concern when relying on solar (which is probably 85% of the time)