This paper summarizes the lessons learned during the GREDOR project, a four-years research project funded by the Public Service of Wallonia (Belgium), Department of Energy and Sustainable Building. The lessons are summarized in terms of the project organization, proposed algorithmic solutions for technical problems together with the results, and observations and recommendations to the governmental bodies and energy regulator. The project consortium is carefully composed so the partners represent major stakeholders acting on electric distribution systems supported by two research institutions and an engineering solution provider. The composition allows reconciliation of conflicting objectives among different stakeholders in order to define their interactions and help governmental and regulatory bodies to set the rules. The focus of this project is on the distribution system operators with the objective to define their optimal investment, operation, and real-time control while taking into account the objectives and practice of other stakeholders acting on their systems. The aim is to find the optimal global societal benefit. A standard test system and a model of apart of real-life system in Belgium are used to illustrate proposed algorithmic solutions for technical problems. Some of developed IT solutions are designed as open tools available for the use by all interested in similar problems.