To deploy stuff you have to use the action groups. You enable them by updating your construction building (I think), there are the basic action groups and the advanced one. With the basic you can already deploy panels and stuff. During the rocket assembling you'll see the action groups window just beside the "crew" and "building" tabs. You just have to choose an action group option (lights, for example) to add your panels and etc. Then the next time you turn on your lights, the panels will be deployed as well.