A project is underway at the University of New South Wales aimed at producing a 20% efficient silicon solar cell. A prerequisite for obtaining such a significant increase in cell efficiency is the improvement of the open circuit voltage of these cells. Two techniques are described which have produced experimental devices with open circuit voltages of 69OmV or higher. These high voltage techniques have been combined with other high efficiency design features to produce silicon cells with independently measured energy conversion efficiencies in excess of 19% under standard terrestrial test conditions (direct beam AM1.5 spectrum, 100mW /cm/sup 2/, 28/sup 0/C).