In principle, Auger recombination should constitute the ultimate limiting mechanism for concentrator photovoltaic performance as optical concentration, and hence current densities, are raised to progressively higher values. In reality, however, the effect will be rate-limiting only in indirect-band-gap solar cells—a point well established for silicon but not yet explored for germanium which comprises the lowest-energy junction in today's ultraefficient commercial multijunction concentrator solar cells. Detailed calculations of when Auger recombination should play a substantial role are presented, and reinforced by existing data.