Hey Dio,
You do have to create an area and ensure transformation & resources is enabled in the "scope and scale " tab in the settings screen. Input the specifications of the solar plant- capacity, maximum availability, capacity credit, historical production etc under processes in the transformation branch. You also need demand data for this generated power.
Run the results and you should be able to see the power generated from the solar power plant.
Under Learn/Training materials here on the LEAP website, there is a downloadable exercises pdf which goes into more details about this.
Hope this helps.
Regards,
Valentine