The Netherlands is moving away from a gas-based energy infrastructure, with regulations in place to ensure timely transition to a clean energy system. Because the majority of residential energy consumption goes to space heating, multiple pathways are proposed by government planning agencies, such as implementing individual heat pumps or collective district heating networks (DHNs). Because grid congestion limits the speed of heat electrification and the availability of green gas or hydrogen is uncertain, it is expected that many DHNs will have a substantial electrical demand. This work investigates the impact of DHNs on medium voltage grids in 2035, by analysing the behaviour of heat sources and heat storage and creating a Python model to simulate the behaviour of both a DHN and a medium voltage substation with hourly resolution. Multiple scenarios are defined, with different heat sources and operational strategies for heat storage. The results indicate that the original sizing of the heat storage might be too small and that increasing its size by 5 times leads to significantly lower fuel costs, substation peak loads, reinforcement costs and congested energy volume, because the annualised costs of heat storage is an order of magnitude lower than the total costs of heat production. Because the location of the heat consumers can extend beyond the operational area of a medium voltage substation, the connection point between heat sources and the substation is critical and should be investigated early on in the design phase of a DHN.