We undertake a qualitative empirical study of the solar photovoltaic (PV) industry in order to investigate the role of diversity in stimulating innovation and diffusion. Based on evolutionary-economic concepts, we identify the main dimensions and components of diversity in the solar PV industry. Using nine indicators and additional information about recent developments regarding technologies, markets and actors (countries and firms), the dynamic potential is assessed for the various solar PV technologies. It is concluded that the dominant trend is an increase or maintenance of diversity among solar PV technologies, which likely contributes positively to innovation and diffusion. We discuss the implications of taking into account the role of diversity of solar PV in the design of energy policies.