Secondary reflectors for solar collectors and methods of making the same

A method for defining a profile of a secondary reflector configured to receive a light from a field of primary reflectors and direct the light to an absorber tube, the method comprising:

• defining an aperture width for the secondary reflector;
• a first step of defining a vertical position of an edge surface point of the profile, relative to a horizontal axis, x, on which the plurality of primary reflectors is located;
• a second step of calculating a reflected beam spread distribution at the edge surface point resulting from the primary reflectors;
• a third step of calculating a principal incidence of an incoming light relative to the edge surface point;
• a fourth step of calculating a subsequent surface point of the profile based on the principal incidence;
• and
• repeating the second step, the third step, and the fourth step, in series, until the profile is defined as a plurality of surface points across the width of the aperture, wherein:
• defining the secondary reflector aperture comprises:
• calculating a primary reflector acceptance angle for an outer-most primary reflector, n, by βnpr=4·σtotal;
• and
• calculating the required aperture width by a2nd≅ln·sin(βnpr), wherein:
• the primary reflector acceptance angle receives at least 95% of the light reflected by the outer-most primary reflector n, assuming the light reflected by the outer-most primary reflector, n, has a Gaussian distribution,
• σtotal is the total estimated or measured optical error RMS,
• a2nd is the required aperture width, and
• ln is the distance between the outer-most primary reflector and the secondary reflector;
• the principal incidence is defined as an angle at which a maximum amount of power provided by the light from the primary reflectors is delivered to the absorber tube,
• the repeating is completed n times where n>2,
• the profile of the secondary reflector minimizes reflective losses to the absorber tube by accounting for the reflected beam spread, and
• the secondary reflector is manufactured to have a shape approximating the profile.