TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Apparatus: The passive optical compensator comprises a refracting element distal from the receiver, and a total internal reflectance element proximate to the receiver. The refracting element is monolithic with the total internal reflectance element. It comprises an external surface proximate to the primary concentrator and configured to refract light received from the primary concentrator; and the total internal reflectance element comprises a side surface configured to reflect light to an internal surface that is proximate to the receiver. The external and side surfaces are curved or straight. Light exiting the internal reflectance element through the internal surface is concentrated and/or more homogenous relative to the incident light. The apparatus further comprises a second side surface configured to direct light back to the curved external surface for reflection to the internal surface. The second side surface is disposed proximate to an edge of the secondary passive optical compensator. The refracting element is located proximate to a center of the secondary passive optical compensator. The refracting element comprises an annulus disposed around the center, where the annulus comprises: (i) a first external surface configured to refract light received from a center portion of the primary concentrator; and (ii) a second external surface configured to refract light received at oblique angles from peripheral portions of the concentrator, where the first and second surfaces are configured to reflect the refracted light to an internal surface of the total internal reflectance element, the internal surface proximate to the receiver. The apparatus further comprises a reflective element positioned at a center of the passive secondary optical compensator. It further comprises a raised reflective ring positioned at an edge of the passive secondary optical compensator and configured to reflect light to the refracting element. The apparatus further comprises a divergent optical compensator positioned above a central region of the secondary passive optical compensator. The secondary passive optical compensator comprises refracting elements located distal from the receiver and configured to communicate light to a respective total internal reflectance elements located proximate to the receiver. The refracting elements offer different surface areas to light received from the concentrator; and each of the total internal reflectance elements is configured to produce approximately a determined magnitude of irradiance to a corresponding respective photovoltaic cell of the receiver. The total internal reflective elements are arranged in an array configured to receive light from respective refracting elements; and the photovoltaic cells are arranged in a second array comprising strings and corresponding to the array of the total internal reflectance elements. The total internal reflective elements are arranged in a radial array and an internal surface of each total internal reflectance element proximate to the receiver has an aspect ratio of (length in a radial direction/length in a circumferential direction) greater than 1.5; and an aspect ratio of a surface of the photovoltaic cells matches the aspect ratio of the internal surfaces of the total internal reflectance elements. The secondary passive optical compensator comprises a first glass portion distal from the receiver, and a second polymer portion proximate to the receiver. The code of the computer-readable storage medium is configured to partition the receiver into the cells based upon input selected from a geometric bound specified by a user, a size of the receiver, a void in the bounds of the receiver, a number of cells, a desired concentration factor, an energy conversion cell dimension, and/or a cell geometry. It is also configured to create the refractive surfaces based upon input selected from an expected amount of concentration, geometric bounds including a starting value and a thickness limit of the secondary optic, a starting value, and a limit on curvature in a particular axis. The code of the computer-readable storage medium is further configured to create the second surfaces based upon input selected from maximum and minimum angles of taper, and/or a size and shape of an active area of the cell. The computer-readable storage medium has further stored code configured to optimize at least one of the following factors based upon a merit function: a curvature of the refractive surface, a profile of the second surface, or a position of the cell relative to the second surface.