The high concentration of solar radiation on the multijunction solar cells used in the highly concentrated photovoltaic modules cases a very high cell temperature. Also, high cell temperature operations overall performance and increase thermal stresses. Therefore, an efficient cooling arrangement is mandatory to achieve a higher net output power from the high concentrator photovoltaic structures. In this work, the comprehensive three-dimensional (3D) model was developed and manipulated to investigate the performance of an HCPV system under the active cooling scheme to figure out its ability to handle effective heat dissipations. Various novel cooling microchannels manifold designs were numerically investigated and compared in the term of cooling down a densely packed high concentration photovoltaic. The solar cell type is the latest product of AZURSPACE triple junction of 3 × 3 mm2 solar cell. A 64 multijunction solar cells (electrical efficiency of 42.3% at cell temperature 25 °C) module were considered in this work. The influence heat sink design, channel dimensions, and inlet flow rate on the cooling performance of the manifold heat sink device were examined. The same external dimensions are considered, and the flow was laminar and the inlet temperature 25 °C for all designs for a reasonable comparison. the heat sink material the maraging steel. The concept of dividing the heat sink area to many segments is adopted to improve the heat removal capacity. The concept of channel width variation along the flow stream length was studied. The heat sinks including rectangular channels were adopted as they are easy to be fabricated. The limitations of 3D metal printing and pumping requirements were considered for all proposed designs where the minimum channel width is 0.8 mm. The comparison between all studied designs is highlighted concerning surface average temperature surface temperature uniformity and pressure drop.