Battery management strategies that reserve a certain capacity for power outages are able to increase the energy independence of a smart home. However, such strategies come at a certain cost, since these storage strategies are less flexible and energy from the grid may have to be bought at a high price, even though locally produced energy is still available in the battery, but reserved for power outage periods. This paper evaluates the cost of energy independence in smart homes with local energy generation, local storage, stochastic grid outages and seasonal demand and production profiles. As case study we use a house with matching demand and production. We provide a seasonal dependent battery management strategy, that reduces the costs of surviving grid outages. Compared to a system that maximizes self-use, the costs to achieve a survivability of 99.999% are approximately 41 euro per year for 1 MWh demand.