Direct liquid-immersion cooling of concentrator solar cells was proposed as a solution for receiver thermal management of concentrating photovoltaic (CPV) and hybrid concentrating photovoltaic thermal (CPV-T) systems. De-ionized (DI) water, isopropyl alcohol (IPA), ethyl acetate, and dimethyl silicon oil were selected as potential immersion liquids based on optical transmittance measurement results. Improvements to the electrical performance of silicon CPV cells were observed under a range of concentrations in the candidate dielectric liquids, arising from improved light collection and reduced cell surface recombination losses from surface adsorption of polar molecules. Three-dimensional numerical simulations with the four candidate liquids as the working fluids, exploring the thermal performance of a silicon CPV cell array in a liquid immersion prototype receiver, have been performed. Simulation results show that the direct-immersion cooling approach can maintain low and uniform cell temperature in the designed liquid immersion receiver. The fluid inlet velocity and flow mode, along with the fluid thermal properties, all have a significant influence on the cell array temperature. (C) 2011 Elsevier Ltd. All rights reserved.