Microgrid, a promising component of smart grid, will potentially yield a free electricity market. This paper proposes a novel construction for a community microgrid (MG) by deploying a virtual power bank which consists of household storage batteries and which mediates the communications between the MG and the macro-grid (MA). Households, representing the distributed energy resources (DER) and the demand side, are considered the MG prosumers (i.e. they are the consumers and the potential energy producers). In this paper, Nash Equilibrium strategies which minimize a linear combination of the households' energy generation cost, energy consumption cost and revenue of sold energy are found via an application of mean field control theory. The decentralized community microgrid optimization (MGO) problem via mean field control is configured for both flat rate and time of use macrogrid pricing mechanisms.