Integrating existing diesel station with renewable energy (RE) technologies into a hybrid system has been an attractive solution towards mitigating greenhouse gases emissions problem of diesel power system. Apart from offering cleaner power supply, hybrid systems could also contribute towards reduction of diesel fuel cost. Application of insight-based Power Pinch Analysis (PoPA) method to integrate diesel plants and RE systems with the aim to minimise total generation and runtime of diesel generator has been proposed. This work utilises an extended PoPA tool called the Probability-Power Pinch Analysis (P-PoPA) to achieve the supplementation of RE technologies with existing diesel system. P-PoPA can provide accurate results as those established from the PoPA approach within a shorter time of analysis as it eliminates the manual matching of power sources and demands step. Correction factors based on all possible routes from the RE sources and the diesel generator to the demands are computed to determine the minimum diesel power target for the integrated system. Result of an illustrative case study shows that 31 % saving in the diesel fuel requirement can be achieved after the integration of the existing diesel plant with RE systems. The result of the P-PoPA method is accurate with an only 0.61 % difference to the result targeted using the conventional PoPA technique.