Successful renewable energy projects are crucial to bring the cleaner and sustainable environment of this universe. Owed to this, world's countries and policymakers are trying hard to double the current share of renewable energy consumptions (18.3%) by 2030, which has been resulting in the construction of multiple renewable energy projects. This study identifies multiple critical success factors (CSFs) and their influences mechanisms, required for renewable-energy projects. Using a sample of 272 firms working on renewable energy projects in Pakistan, a quantitative and causal study was undertaken to identify the efficiency (short-run success) and effectiveness (long-run success) mechanisms of critical success factors in renewable energy projects. Structural equation modeling (SEM) was applied to test and verify hypothesis. The results show that though the efficiency and effectiveness of critical success factors in renewable energy projects are equally important, the effectiveness (long-run success) in renewable energy projects is mainly depends upon the efficiency (short-run success) of the critical success factors (CSFs) involved in such kind of projects. The study expected to contribute towards and widen up the existing knowledge base for the renewable energy projects by adding on the findings regarding the influences mechanisms of critical success factors.