There was updated presentation on near term solar sails at FISO (Future in Space Operations) Telecon at the University of Texas at Austin by Bruce Campbell. Nextbigfuture also reviews the Spiderfab robotic assembly in orbit capability which could enable 1 kilometer diameter solar sails for dramatically superior space capabilities. A rudimentary interstellar solar sail is possible with a 400 meter diameter. So a 1 kilometer solar sail would have 6.28 times the area of the 400 meter sail.
The FISO Presentation did not consider the NASA NIAC – Innovative Advanced Concepts Spiderfab in orbit assembly
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.