A 100 meter to 150 meter solar array that is attuned to the lithium ion will be about 70% efficient.
JPL is working on the gridded lithium ion arrays to achieve 60,000 ISP.
There is work on 60 meter deployable solar arrays.
This system will achieve a speed of about 260 kilometers per second (almost 0.01% of light speed) and enable the fast 10-12 year mission to 500 AU gravitational lens and manned missions to Jupiter in 1 year travel time.
Here is a video of a new talk by John Brophy starting at 1:15:40 of the video.