This paper presents a study on the optical properties of direct absorption solar collector (DASC) modules with different geometrical configurations considering absorption elements. Three DASC module models, namely flat plates, circular tubes, and tri-prisms, were established and solved using the Monte Carlo method and Mie theory. The accuracy of the results was well verified with the reference data. The results show that the DASC with Si absorption elements exhibited higher absorbance than the DASC with TiO2 absorption elements. It is observed that SiO2@Ni nanofluid exhibited the highest absorbance and lowest reflectance, while TiO2 nanofluid displayed the lowest absorbance and highest reflectance. The absorbance of the nanofluids decreases and the reflectance of systems increases with the increasing particle size of the nanofluid. At incident light angles of 0° and 15°, tri-prism collectors outperform other geometric configurations of collectors. At 30° and 45°, circular tube collectors perform best. At 60° and 75°, flat plate collectors show superior performance. Overall, the tri-prism collector using SiO2@Ni nanofluid coupled with Si absorption elements can improve the efficiency of solar energy utilization compared to the other types of solar collectors.