The impact of heat spreader (H.S) size, microchannels (MICs) configurations and utilizing nanoparticles (NPs) on the performance of concentrated photovoltaic (CPV) cooled by the spreader-microchannels system is performed in this work. The spreader is inserted among the photovoltaic (PV) and the MICs with various area ratios (A.R) of the spreader to the PV. Three various configurations for the cooling water flowing inside the MICs is considered (parallel flow and counter flow of two and four paths). The influence of utilizing SiC nanoparticles with the water coolant on the cooling system (H.S-MICs) performance is performed. A 3D mathematical model of the total system (PV-H.S-MICs) is constructed and solved by utilizing ANSYS-Fluent software and a validation of the numerical solution of the mathematical model is also presented. The results reveal that parallel coolant flow inside the MICs has lower PV temperature, higher efficiency and output power. Nevertheless, it has lower temperature uniformity over PV surface at low Reynolds number (Re) with respect to the counter flow. Increasing A.R augments the PV efficiency, output power and temperature uniformity particularly at low Re where rising this A.R from 1 to 7 raises the PV net power by around 100.6%, 83.2%, and 58.1% for counter with four paths, counter with two paths and parallel flow, respectively at Re = 5. Utilizing SiC nanoparticles with the cooling water inside MICs augments the PV efficiency, and reduces the maximum PV temperature and temperature difference over the PV surface. For parallel flow, using nanoparticles rises the PV net power by about 9.2% and 2.6%, at A.R = 1 of the H.S, and around 0.3% and 1.5% at A.R equal 7, for Re equal 5 and 85, respectively compared to water without SiC nanoparticles.