The impact of unsteady solar intensity and ambient conditions on operation and performance parameters of an aqua-ammonia absorption chiller of 5 kW cooling power is explored. Unsteady analysis for five representative days in summer and winter in Dhahran, Saudi Arabia, is presented. The results give the variation of the absorption-chiller parameters every one hour. The absorption chiller comprises a dual (ammonia and ice) storage system to ensure cooling effect during nighttime. This storage system consists of an ice tank, one ammonia tank and two aqua-ammonia tanks. Capacity of these tanks and the required solar collector area are computed for 24-hour operation per day at a constant 5 kW cooling power. The results show that, for the given cooling power and ambient conditions, the coefficient of performance is better in winter than in summer (0.57 as compared to 0.39) but the required solar collector field area is more in winter than in summer. (C) 2014 Elsevier Ltd. All rights reserved.