Patent ID: 8269374

Claim:
A method for balancing respective outputs of an ecological power source (“EPS”), a grid power connection, and a D.C. battery so as to minimize conversion losses, comprising: providing a first mode of power transfer in which the EPS output directly charges the D.C. battery during times of a utility power outage; providing 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; controlling in a single switching operation the first and second modes of power transfer as a function of an availability of the utility power output over the grid power connection, the single switching operation including the step of: switching an interlocked arrangement of a grid-interactive inverter and an off-grid inverter so that when one of the grid-interactive and off-grid inverters is turned on the other is turned off, wherein the EPS is switched from a straight-to-A.C. inverter connection via the grid-interactive inverter while in the second mode of power transfer to a straight-to-D.C. connection to charge the battery while in the first mode of power transfer in order to maintain a one-step conversion in both the first and second modes of power transfer; wherein a percentage of utility power output over the grid power connection is supplied directly to the battery when the controller is switched to the second mode of power transfer so as to utilize the output of the grid power connection as a source to maintain the battery in a charged condition for use during the times of the utility power outage, and wherein 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; and trickle charging the battery through the grid power connection in the second mode of power transfer.