Policymakers in various countries often determine roadmaps, a sequence of intermediate goals to achieve their long-term renewable energy objectives. We study the influence of roadmaps on regulatory decisions and market functioning using laboratory experiments. We simulate a stylized electricity market with two generation technologies (a renewable “green” technology and a thermal source) whose share of renewable generation must increase over a 40-year period. Investments in thermal capacity are driven by subsidies and profitability, while green capacity investments solely depend on subsidies. Participants act as regulators and decide each year how many MWs of green and thermal capacity to subsidize while managing the trade-off between blackout risk, cost for customers and subsidies. We manipulate the presence and the time granularity of roadmaps.We find that roadmaps impact regulatory decisions and the resulting subsidies, but not the likelihood of achieving the long-term goals, illustrating that a given target can be reached by different trajectories with different costs. Therefore, policymakers should carefully consider the choice of intermediate objectives that impact paths toward greener energy in terms of trade-offs between governmental subsidies and market forces.