Focal region measurements of the 20 m tiled dish at the Australian National University

Focal region characterisation of a 20 m² point focus dish concentrator having approximately 2300 flat, 10 cm square mirror tiles as its reflecting surface has indicated a focal flux distribution having a flat-topped peak with approximately Gaussian limbs. A peak concentration of 970 suns was evident, while a dish optical efficiency of 74% was measured, which is a direct indication of the average dish reflectivity. Total integrated power of 14.8 kW was measured under the focal flux distribution. Predicted fluxes using a ray trace algorithm (COMPREC) developed at the Australian National University (ANU) and utilising 2.0 mrad surface slope error showed a good approximation to the measured distribution. The value of 2.0 mrad also compared well with a photogrammetrically predicted value of 1.8 mrad.