Principles of cylindrical concentrators for solar energy

Ideal cylindrical light collectors are trough-like reflecting wall light channels of a specific shape which concentrate radiant energy by the maximum amount allowed by phase space conservation. We propose a principle for maximally concentrating radiation onto a tube receiver of general shape. Employing this principle, we give a general prescription for designing concentrators appropriate to such tube receivers. This design may have advantages for solar-thermal and photovoltaic applications.