An energy storage system, comprising: a plurality of battery modules, electrically connected in parallel, said plurality of battery modules having an inverter electrically connected thereto to form a plurality of battery modules and inverter combination, the inverter having an AC output connected to one or more energy consuming devices, a renewable energy source connected to the plurality of battery modules, and an AC input connected to a power grid, each battery module of said plurality of battery modules having electrical properties similar to the remaining battery module(s), and each battery module having a maximum power output rating equal to or greater than a continuous maximum output power rating of the inverter, wherein the plurality of battery modules and inverter combination is configured to operate: 1) in an over-charge mode if a voltage V, detected from said battery module is > a sustainable high voltage limit V H of the inverter, wherein the inverter function is stopped in the over-charge mode until a lower voltage limit V H ' is reached; 2) in an over-discharge mode if the detected voltage V < a preset voltage V L, wherein the inverter is disconnected from the plurality of battery modules in the over-discharge mode and the AC input connected to the power grid is connected to the one or more energy consuming devices, while disconnecting the plurality of battery modules; 3) in a recharge mode if the detected voltage V < a preset voltage V" and if a time of day T is within a preset range R, wherein the plurality of battery modules is recharged from the AC input connected to the power grid in the recharge mode; and 4) in a normal operating mode if the detected voltage V is < V H and if the detected voltage V is > V L and if the time of the day T is not in the preset range R, wherein the plurality of battery modules is connected to the inverter for providing energy through the inverter AC output to the one or more energy consuming devices in the normal operating mode. a plurality of battery modules, electrically connected in parallel, said plurality of battery modules having an inverter electrically connected thereto to form a plurality of battery modules and inverter combination, the inverter having an AC output connected to one or more energy consuming devices, a renewable energy source connected to the plurality of battery modules, and an AC input connected to a power grid, each battery module of said plurality of battery modules having electrical properties similar to the remaining battery module(s), and each battery module having a maximum power output rating equal to or greater than a continuous maximum output power rating of the inverter, wherein the plurality of battery modules and inverter combination is configured to operate: 1) in an over-charge mode if a voltage V, detected from said battery module is > a sustainable high voltage limit V H of the inverter, wherein the inverter function is stopped in the over-charge mode until a lower voltage limit V H ' is reached; 2) in an over-discharge mode if the detected voltage V < a preset voltage V L, wherein the inverter is disconnected from the plurality of battery modules in the over-discharge mode and the AC input connected to the power grid is connected to the one or more energy consuming devices, while disconnecting the plurality of battery modules; 3) in a recharge mode if the detected voltage V < a preset voltage V" and if a time of day T is within a preset range R, wherein the plurality of battery modules is recharged from the AC input connected to the power grid in the recharge mode; and 4) in a normal operating mode if the detected voltage V is < V H and if the detected voltage V is > V L and if the time of the day T is not in the preset range R, wherein the plurality of battery modules is connected to the inverter for providing energy through the inverter AC output to the one or more energy consuming devices in the normal operating mode. 1) in an over-charge mode if a voltage V, detected from said battery module is > a sustainable high voltage limit V H of the inverter, wherein the inverter function is stopped in the over-charge mode until a lower voltage limit V H ' is reached; 2) in an over-discharge mode if the detected voltage V < a preset voltage V L, wherein the inverter is disconnected from the plurality of battery modules in the over-discharge mode and the AC input connected to the power grid is connected to the one or more energy consuming devices, while disconnecting the plurality of battery modules; 3) in a recharge mode if the detected voltage V < a preset voltage V" and if a time of day T is within a preset range R, wherein the plurality of battery modules is recharged from the AC input connected to the power grid in the recharge mode; and 4) in a normal operating mode if the detected voltage V is < V H and if the detected voltage V is > V L and if the time of the day T is not in the preset range R, wherein the plurality of battery modules is connected to the inverter for providing energy through the inverter AC output to the one or more energy consuming devices in the normal operating mode.