The volumes of intermittent renewable energy sources (RES) and electric vehicles (EVs) are increasing in grids across Europe. Undoubtedly, the distribution networks cope with congestion issues much more often due to distributed generation and increased network use. Such issues are often handled by unit re-dispatching in short term and grid expansion in long term. Re-dispatching is, however, not always an appropriate solution for local distribution networks since the limited generation units are mostly RES of uncontrollable volatility. Recovering the incurred investment costs on the other hand would trigger an increase of the network tariffs. A possible solution is to defer such an investment by utilizing the demand side resources. The FlexMart model, developed and suggested in this paper, provides the ability for the Distribution System Operator (DSO) to purchase demand flexibility offered by residential consumers. Two feeders with different topologies are tested and the ability of the suggested mechanism to provide benefits for the involved stakeholders, both the DSO and the consumers, is demonstrated. The developed empirical model, works as a long-term planning tool and has the ability to provide an optimal combination of physical expansions and flexibility dispatch to reassure the stable and secure operation of the grid. (C) 2016 Elsevier Ltd. All rights reserved.