The Smart Grid initiative aims at transforming the public power grid to a flexible and intelligent energy utility. With this advancement, numerous applications can be implemented which are hard - if not impossible - to realize with today's technologies. For instance, in case of rolling blackouts, the power supply of critical infrastructures such as hospitals or traffic lights, can be prioritized immediately over private households and the grid's structure reshaped accordingly. Moreover, the energy grid becomes participative by enabling traditional consumers to feed back energy generated by their private solar panels and wind turbines. We argue that when coupling smart grid stakeholders with a social network, even more advanced use cases provide unmatched energy saving opportunities. Online platforms enable a plethora of novel application use cases, such as energy saving campaigns and competitions, utilization of friends' solar power, and coordination and sharing of energy consumption plans. In this paper, we introduce a social overlay model for smart grids, present its implementation using service-oriented architectures, and evaluate scalability and applicability.