Abstract: The present invention provides highly efficient solar energy collectors that use conductive fluids that are mixed with dark absorption pigmentation or objects. The pigmentation or objects are provided in the fluid itself, giving the fluid a dark appearance. A preferred embodiment relates to a method of capturing solar energy in the form of selective radiation surfaced (dark surfaced) microbeads, nanobeads, particulates or nano-particulates immersed and carried in a high temperature oil or other working fluid. The fluid containing these dark materials more readily absorbs solar radiation, and makes the absorbed radiation more readily available for transmission and use. Specially adapted enclosures are also provided for use with such fluids. Inexpensive methods of use and production of the fluids and enclosures are also provided.