Making decisions on a sound basis in early phases is one of the most difficult challenges in the product development process, especially when dealing with immature concepts. Moreover, life-cycle cost can be influenced up to 70% by decisions taken during the conceptual design phases. The need for reliable multi-criteria decision aiding methods is thus greater in these phases. Various multi-criteria decision aiding methods are proposed and used in the literature. The main criticism of these methods is that they usually produce contradictory results for the same problem. In this work, seven widely used multi-criteria decision aiding methods (weighed sum, weighted product, Kim and Lin, compromise programming, TOPSIS, quadratic mean and ELECTRE I) are analysed. This analysis was based on a real industrial case to develop a solar collector. The proposed multi-criteria decision aiding methods were compared in terms of three criteria deemed relevantin the relevant context: (1) adaptation of the type of results the multi-criteria decision aiding method is expected to bring, (2) correct handling of input information and (3) adaptation of the degree of compensation. Based on these criteria, it was proven that weighted product is the most appropriate multi-criteria decision aiding method in our case. In addition, it has been demonstrated that sensitivity analysis can improve the benefit of using the multi-criteria decision aiding method chosen when dealing with imprecise information due to immaturity of concepts.< Réduire