Sunlight concentration on photovoltaic cells causes a substantial increase in the cells' temperature, which leads to a significant reduction in performance and irreversible decay of solar cells. Therefore, a novel cooling method based on two-phase flow boiling in monolithic double-layer microchannel heat sinks is developed to experimentally investigate the thermal regulation of concentrator photovoltaic systems. Two different designs of heat sinks, namely parallel and counter flow configurations, are integrated on the back-side of a photovoltaic module. Ethanol and Novec-7000 with standard boiling temperatures of 78.4 degrees C and 34 degrees C are examined as coolant fluids. The influences of varying the simulated solar light concentration ratio, coolant flowrate, coolant type, and heat sink design on the solar cell temperature distribution are experimentally investigated. The results indicate that two-phase flow boiling significantly reduces the maximum cell temperature, attains a uniform solar cell temperature distribution, and improves electrical efficiency. Furthermore, the microchannel heat sink flow arrangement affects the variation of solar cell temperature. Experimental results confirm that the parallel flow configuration attains effective cooling only at higher flowrates compared to the counter flow configuration. The findings of this study demonstrate the potential of two-phase flow boiling for the thermal management of concentrator photovoltaic systems.