Using energy at the source has always been my pet dream
Noting like using the sun directly as an energy source
Excellent information on Parabolic Solar Reflectors around the world by Dr. Ashok Kundapur
Dr. Kundapur talks about 3 types of parabolic construction
(i) Shallow parabolas, where the focus is outside the rim of the reflector,
(ii) Asymmetrical parabolas, which are partial parabolas, and
(iii) Deep parabolas, where the focus is within the rim of the reflector
Quite an interesting variety with quite some variations.
Check it out, you may want to build your own.