The feasibility of near-term renewable targets will depend upon the time taken to get projects completed. Very few studies assess total project lead-times for renewable energy projects. This study investigates the determinants of lead-times for 170 onshore wind and solar PV projects completed in Australia between 2000 and 2023. We track multiple project stages and estimate the impacts of changes in ownership, experience, approval processes, rule changes, and a commissioning process that differs by size of generation. Australia has had a notable improvement in lead-times. Solar projects that commenced before 2010 had an average lead-time of 83 months (min: 63, max: 102). This decreased to 41 months for solar projects (min: 19, max: 75) that commenced after 2016. Onshore wind projects took longer to develop. Project lead-times were 136 months (min: 50, max: 200) when they commenced before 2005. This decreased to 53 months (min: 20, max: 85) for projects starting after 2016. Pre-construction lead-times decreased notably for both solar and wind, which implies that the approval process did improve. There is evidence from one jurisdiction that this did occur, particularly for onshore wind projects. Over the same period, commissioning lead-times were similar for wind projects but have increased for solar projects. On average, commissioning took up to 7 months longer after a change in the re-iterative process of tests and equipment changes to meet generator performance standards. Changes in project ownership occurred often (38% of projects) but this had little impact on lead-times. Accurate estimates of lead-times are important for investors, project-owners and policymakers. Yet, they are rarely reported.