Internally baffled integrating sphere cosine collector

Cosine collector designs based on internally baffled integrating spheres have been difficult to evaluate in the past due to the expense and difficulty of building the spheres and measuring their angular response. A Monte Carlo model has been developed that enables integrating sphere designs to be evaluated relatively quickly and efficiently. The model was applied to an integrating sphere employing an internal conical baffle. The angular response and overall throughput of the sphere as predicted by the model are presented and discussed. Construction of the sphere was recently completed and the relative angular response was measured in the field. A solar radiometer was used to determine the solar irradiance at the entrance aperture of the sphere, enabling the response of the sphere to be found as a function of the solar zenith angle. Results of the measurement are presented and compared with the model results.