... well, the term "self-sufficiency" is in effect a sort of a "philosophic-abstract" concept, everything so far depends on how much you consume compared with how much you can actually generate.
Now, going back to a practical point of view: did you make any actual measurement on how much power you get out of your device let say at 20 km/h?
From my son/e-werk combination I can't get more than 2.75W.

Cheers.