A controlled switching arrangement from a first mode of power transfer, in which an ecological power source (EPS) directly charges a battery during times of a utility power outage to a second mode of power transfer in which the EPS output is fully delivered through a grid-interactive inverter so as to provide A.C. power to the grid power connection. A single switching operation switches between power transfer modes as a function of an availability of the utility power output over the grid power connection such that a percentage of utility power output is supplied directly to the battery in the second mode so as to maintain the battery in a charged condition for use during the times of the utility power outage, and an off-grid inverter converts charge stored in the battery into A.C. power when the controller is switched to the first mode of power transfer.