This paper evaluates the impact of changes in Mexican energy policies on the Mexican innovation systems ability to support renewable energy technologies, through a comparative case study on geothermal and solar photovoltaic technologies. The study examines the effectiveness of government policy in each case by exploring how changes in policy have affected the development of their respective innovation systems. The analysis is facilitated by a technology innovation system framework. The main source of data is primary data from an online survey of 61 experienced energy experts in Mexico in 2019, complemented with desktop research. Results suggest that changes in government priorities have a strong influence on the development of these two technologies. The development of these technologies in Mexico is determined by their innovation systems resilience and adaptability to the changing policy landscape. Policy instruments that encourage knowledge formation serve as critical for the continued development of renewable energy technologies in Mexico. This study contributes to the literature on innovation systems in Mexico, on comparing two renewable energy technologies, and on developing countries policy and innovation contexts.