This communication analyses some of the results observed for metal/n-CdTe interfaces in the mid-1980s, which could not be interpreted at that time. These observations are analysed on the basis of new understanding using a new model proposed for CdS/CdTe thin film solar cells. The observed behaviour of current voltage characteristics of electrical contacts to n-CdTe under electrical and illumination stresses are explained and the effects of these changes on CdS/CdTe solar cells are discussed. Future research directions for the development of CdS/ CdTe solar cells are proposed and the way forward for improvement of stability and lifetime of solar cells is suggested. A summary of recent electrical contact work on metal/ Cu(InGa)(SSe)(2) interfaces is also presented and similar behaviour is reported. (C) 2004 Elsevier B.V. All rights reserved.