The central problem that this paper addresses is the rapid and precise calculation of the energy and particle flux for detailed-balance photovoltaic applications. The calculation of energy and particle flux is essential to modeling the efficiencies and efficiency limits of solar energy conversion devices. Computing flux with the canonical Bose-Einstein integral is time consuming and, without due care, prone to error. The approach given herein, transforms the Bose-Einstein integral into a linear combination of incomplete Riemann zeta integrals. The numerical package that implements this method is benchmarked for precision by a number of means. These include comparisons between the Riemann zeta functions, and previously recorded values of solar cell limiting efficiencies from the literature. The rapidity of the numerical package is gauged by comparing the duration of flux calculations to other calculation methods. (c) 2006 Elsevier Ltd. All rights reserved.