Ok, so to be fair and challenge my own grouchiness on the topic, I've done some research to find out some facts. Overall, this topic is a complex one with many 'ins' and 'outs' and engineering tradeoffs.
Here goes for the statistics which I can sort of relate with:
1) Solar escape velocity is 618 km/s;
2) The mean velocity of the solar wind is about 145 km/s with a few particles reaching 400 km/s. (So presumably, this would be the primary motivating force behind solar sails … reminder: there is photon pressure, as well .. not sure about its net contribution, though);
3) The termination shock of the Solar system is around about 80 to 100 AU.
4) At 100 AU, a typical solar sailcraft speed would be about 70 km/s, (theoretical figure, and well below escape velocity);
5) The max ion propulsion thrust achieved so far, is about 10 N (flight proven);
6) The max solar sail thrust varies (depending on distance from the sun) between 9 to 230 km/s⌃2 (from 1 AU to 0.2 AU) - theoretical only;
7) The max ion propulsion delta-v is greater than about 100 km/s (flight proven);
8) The max solar sail delta-v is greater than about 40 km/s (theoretical);
It would seem that there are three theoretical ways of getting the solar sailcraft moving fast headed out of the Solar System. The first requires usage of:
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an additional propulsion system to send the folded-sail sailcraft to the perihelion of an elliptical orbit; there, the sail is deployed with its axis parallel to the sun-light for getting the maximum solar flux at the chosen distance.
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This may be why they are incorporating a secondary ion propulsion system in the next generation of Ikaros. (??)
It seems that the main design issue at the moment is being able to produce a sail light enough to do the job and getting a sail predictably deployed, in situ. At the moment, the goal for the sail mass is about 2 g/m⌃2 which hasn't been achieved yet although, this is not too far beyond present technology constraints.
Cheers