This paper presents a numerical investigation on attic heat gain reduction by using thermoelectric modules intearated in a conventional roof solar collector (RSC). This system, called thermoelectric roof solar collector (TERSC), is composed of a transparent glass, air gap, a copper plate, thermoelectric modules (TE) and rectangular fin heat sink. Due to the incident solar radiation, a temperature difference is created between the hot and cold sides of TE modules that generates a direct current. This current is used to drive a ventilating fan for cooling the TE-RSC and enhancing attic ventilation that reduces ceiling heat gain. The system performance was simulated using TRNSYS program with new TE and DC fan components developed by our team and compared to a common house. Simulation results using real house configuration showed that a TE-RSC unit of 0.0525m(2) surface area can generate about 9W under 972W/m(2) global solar radiation and 35 degrees C ambient temperature. The induced air change varied between 20 and 40 and the corresponding ceiling heat transfer rate reduction is about 3-5W/m(2). The annual electrical energy saving was about 362 kWh. Finally, economical calculations indicated that the payback period of the TE-RSC is 4.36 years and the internal rate of return is 22.05%. (c) 2004 Elsevier Ltd. All rights reserved.