Most countries intending to replace traditional energy sources with renewable energy sources have started to make major investments in this field. Since renewable energy is a sector requiring large amount of investment costs, evaluation of investment risks are extremely important to make the best investment decisions. However, as risk assessment is a process based on expert judgments, the indecisiveness and cognitive bias of the experts should be eliminated. Therefore, a modified Failure Mode and Effect Analysis (FMEA) based on the prospect theory and interval-valued intuitionistic fuzzy Analytic Hierarchy Process (AHP) is introduced to assess the risks in renewable energy investments for the first time. As a result of the proposed risk assessment approach, renewable energy investment risks are prioritized by effectively overcoming the indecisiveness and cognitive bias of experts. (c) 2021 Elsevier Ltd. All rights reserved.