In this paper, a concentrating photovoltaic system (CPV) by using a compound parabolic concentrator and a monocrystalline solar module has been designed and studied theoretically under a concentration ratio of 3.16x. The performance the system is studied over the course of the day from 8:00 AM to 16:00 PM for 12 months under Iraq-Baghdad conditions. Current in a short circuit (Isc), voltage in an open circuit (Voc) as well as maximum power (Pm) are calculated with and without a concentrator under constant solar module temperature (25°C). The results indicated that the optimum value of output power can be obtained on June 21, which is about 246.9W for CPV. In the second part, the effect of solar cell temperature within a range of 25 °C−115 °C on its performance has been studied for the optimum day of the year, June 21st. The output power of the device may be viewed in CPV is 246.9 W in comparison to the flat PV module, which gives 83.44W under solar cell temperature of 25°C and decreases to 125.3W and 40W under cell temperature of 115°C for the CPV and flat module, respectively.