It is possible for trace amounts of it to be retained as an atmosphere on the moon-which would be extremely rarefied, due to its low gravity, I am very sceptical about the author's claim that there exist huge reservoirs of He3 absorbed in the moon's regolith. Anyway, it is easier to fuse hydrogen, from a practical viewpoint because it is much more easily obtainable. Now onto solar energy. Now you have got some of your science wrong when you mention exploiting solar energy. That is, converting light into electricity.
Solar wind is a stream of charged sub-atomic particles, eg protons.
Solar winds are produced by activities on the sun's surface, sunspot activity for example, not because of gravity. As I said, the application of this study is applied to research into nuclear fusion. We are still a longway off from maintaining a fusion reaction. However, experiments with plasma has led to constructions of such devices to contain plasma, such as a torus ring. There this is no question if using it to extract energy from the solar wind.