Stimulating technological diversity is often an important part of sustainable energy policy. In this paper we study the process of technological change between the exploratory and the growth phase of development for eco-innovations. Technological diversity is considered important in this phase to promote innovation and prevent lock-in. However, little is known about the specific level of diversity that should be maintained and for how long this diversity should be maintained. This is however an important issue because while in the early phases of development technological diversity needs to be stimulated (exploration) in order to ensure the development of technological innovations, in later phases convergence (exploitation) is necessary when the most promising options are allowed to further evolve through incremental improvements. In order to get more insight in the processes that take place within this phase of development we first give an overview of the literature focusing on expected patterns of technological diversity that occur during the life cycle of a technology and we then present a simple model that captures some of these dynamics and allows us to generate diversity patterns that occur in different situations.