Receiver Secondary Reflector
Because Sun is not a point light source, in Linear Fresnel Reflector Systems the primarily reflected solar radiation beam is always diverging. In addition, if the reflective elements are not plane but curved the reflected beams’ diverging nature is even more enhanced. As a result, its cross section is always larger than reflectors’ effective area. Moreover, the fact that the radiation reflected from the furthest reflectors must travel long distances until impinging onto the receiver results in even larger beam cross sections. For this reason, Linear Fresnel Reflector Systems require wide absorbers, or, at least, receivers with wide openings and secondary concentrating devices. The latter are reflectors that have a specific shape allowing them to redirect the primarily reflected solar radiation that cannot hit the absorber back on it.