Temperature control of solar cells at high concentrations is a key issue. Short-term efficiency drop and long-term degradation should be avoided by effective cooling methods. Liquid immersion cooling eliminates the contact thermal resistance of back cooling and should improve cell performance. A 250X dish concentrator with two-axis tracking was utilized to evaluate a new CPV system using de-ionized water for immersion cooling. Time-dependent temperature distributions of the PV module of high power back point-contact cells were measured, as well as the I-V curves. The cooling capacities of the liquid immersion approach are very favorable. The module temperature can be cooled to 45 degrees C at a 940 W/m(2) direct normal irradiance, 17 degrees C ambient temperature and 30 degrees C water inlet temperature. The temperature distribution of the module is quite uniform, but the electrical performance of the cell module degrades after a fairly long time immersion in the de-ionized water. (C) 2010 Elsevier B.V. All rights reserved.