Solar panel -what size

We have recently purchased our first ever caravan and it is fitted with a solar panel. I have got the handbooks and info on everything for the van apart from the solar panel. How can I tell what wattage it is?  I have checked under the front bunk and it has a solar technology charge/controller and regulator fitted. All lights are on so obviously it's doing it's job of trickle charging but what is wattage output from the panel. Any ideas where I can check. Thanks