A transient model of a solar powered solid adsorption refrigerator using activated carbon/methanol adsorbent/adsorbate pair, developed from first principles, is presented. It is based on the thermodynamics of the adsorption process and the heat and mass transfer equations of the collector/generator/adsorber components and simplified idealization of the condenser and evaporator components. The resulting equations were transformed into explicit finite difference forms for easy implementation on a personal computer in BASIC. The numerical model computes the collector plate, bond, and adsorbent temperatures, quantity of methanol generated and the solar COP. The model is validated by comparing it with actual field performance data taken from Anyanwu's work. [Design, construction and test run of a solid adsorption solar refrigerator using activated carbon/methanol working pair, Ph.D. Thesis, University of Nigeria, 1996]. The peak plate and tube surface temperatures and methanol generation are predicted to within 3%, 2.5% and 4%, respectively. The peak times and time for commencement of generation were accurately predicted. Based on the observed agreement between measured and predicted values, parametric study of the refrigerator system was undertaken in order to optimize the design. (C) 2001 Elsevier Science Ltd. All rights reserved.