The evolution of renewable energy demonstrates that development of energy systems is not a deterministic process dictated by technology but equally shaped by societal and cultural forces. Key instruments in this process are energy scenarios that describe hypothetical future systems and pathways from the present to this future. Against this background, this paper transfers the sociological concept of fictional expectations to energy scenarios capturing how scenarios, although these are not accurate forecasts, are treated by actors "as-if" and serve as a basis for seemingly rational decisions regarding an unknowable future. As a result, different scenarios compete for credibility to influence decision-making and steer development of the energy system in their favor.These insights on energy scenarios are applied to draw consequences for developing and applying bottom-up planning models, the quantitative tool energy scenarios generally build on. The paper concludes that bottom-up planning models should be open and accessible, minimize and be transparent about bias, aim for a large scope to be policy relevant, not apply stochastic methods just for the sake of adding complexity, and limit the representation of non-technical factors to input assumptions and the interpretation of results.