Analytical expressions have been derived for the effective radiator emissivity and view factor of a given optical cavity geometry as a function of radiator emissivity and reflectance of the shield and TPV device. Using these expressions, accurate predictions of the device optical response (JSCand Qabs) have been made for two different cavity configurations (Au shield and TPV device shield). Also, the measured and calculated results show that placing a TPV device into an array of TPV devices will lower its output performance by at least 1.7&percent; (relative) compared to that measured using a Au shield. © 2003 American Institute of Physics