Krishna et al. (Sol. Energy Mater. Sol. Cells 65 (2001) 163) have recently developed an heterojunction n-C/p-Si in order to achieve low cost and high-efficiency carbon solar cell. It has been shown that for this structure, the maximum quantum efficiency (25%) appears at wavelength lambda (600 nm). In this paper, the dependence of I-V characteristics of this heterojunction solar cell on illumination intensity and temperature has been systematically investigated. An estimation of the stability of the solar cell with temperature has been made in terms of the temperature coefficient of I-sc and V-oc. The intensity variation study has been used to estimate the series resistance R-s of the solar cell. The effect of illumination intensity on I-V of n-C/p-Si heterojunction is more complex because the carrier lifetime and the carrier mobility of amorphous carbon are small and also because drift of carriers by built-in electric field plays an important role in these cells. Therefore, the conventional analytical expression for I-V characteristic is not applicable to such solar cells. These structures will not obey the principle of superposition of illuminated and dark current. The experimental results have been analysed by developing empirical relation for I-V. The temperature sensitivity parameters alpha, the change in I-sc and beta, the change in V-oc per degree centigrade have been computed and are found to be 0.087 mA/degreesC and I mV/degreesC, respectively. This suggests that the heterojunction n-C/p-Si has good temperature tolerance. The value of series resistance has been estimated from the family of I-V curves at various intensities. The R-s is found to be approximate to12 Omega, which is on the higher side from the point of view of photovoltaic application. (C) 2002 Elsevier Science B.V. All rights reserved.