Energy and utilities companies find themselves in a paradoxical situation in which their traditional business models are losing profitability, and they must advocate energy efficiency and climate-protection goals, and thus encourage their customers to save energy. As a result, they must partially cannibalize their business models and experiment with new models and techniques. Energy Informatics (EI) offers promising business opportunities that alleviate the concerns of energy companies about traditional revenue streams. However, recent discussions on this issue lack proof of concept and success determinants. This business case study fills this gap by describing the journey of German energy company Energiequelle, which established a sustainable business model based on EI. On the basis of our interview data, we analyzed Energiequelle’s EI strategy and stakeholder management and present six lessons learned. We believe that our practice-oriented research provides profound insight, especially to high-level executives and policymakers.