Previously NASA was looking at 20-30 years to get solar sails that are 250 meters by 250 meters or 400 meters by 400 meters.
Spiderfab will use robots to assemble structures in space.
Spiderfab on orbit assembly can reduce the mass of space structures by 30 times.
This will enable solar power arrays with over 120 watts per kilogram. This is needed for fast solar electric interplanetary missions.
Spiderfab can also enable solar sails that are over 1000 meters in diameter.