One method to create a surface that is evenly illuminated by solar radiation is to charac­terise the solar flux distribution about the focal region of the concentrating system. The easiest method to achieve this is by a theoretical simulation recreating all of the compo­nents of the optical systems particularly the reflected solar beam.

For this paper we used the mod­elling package described in [11].

The code recreates the terrestrial solar beam for any location and time of day [12], and provides a convenient infrastructure to model the optical components of a dish concentrator including the imper­fections in the mirrored surface and the effect that these imperfec­tions have on the reflected solar beam. The code traces a gener­ated sunshape through the optical components of the concentrator to any predefined quadric (or planar) surface. The output of the simu­lation is an intensity map on that given surface. The characterisics of this individual simulation are described in Table 1 and the code can be downloaded from <www. physics. usyd. edu. au/~buie/>

The focal region of our specific concentrator was divided up into 200 horizontal slices evenly spaced between the points 0.3 m above and below the focal point. Using the code in [11] the flux distribution on each of these slices was calculated (Figure 1a). Each of the slices were then concatenated (Figures 1b) to form a large block of data (or data cube), that completely characterises the flux about the focal region for planar surfaces.

Each individual point in the generated data cube represents a point in space about the focal region. The box bounding the cube is 0.3 x 0.3 x 0.6 m with the focal point as its centre. The data cube contains 400 x 400 x 200 points in the x, y,z directions respectively (z-direction represents up) resulting in a total of 3.2 x 107 points (250Mb). The value of each of those data points literally represents the amount of energy passing through the lower surface of a small cube surrounding that point’s position in space.