Recently, energy behaviour is being considered as an important key performance indicator when studying mobile networks. Reducing their operational cost is becoming more essential due to the huge increase of traffic accompanied by the increase in the electric bills. In this paper, we are going a step forward to study the possibility of a new type of energy behaviour of renewable energy-powered base stations in the Smart Grid environment. We use renewable energy and energy storage and we employ the concept of delay tolerant users to provide ancillary services to the Smart Grid. Based on real data from the French power grid, results show that the achieved profit from providing ancillary services exceeds the electric bill and leads to a negative net cost.