A micro grid system comprises a secondary energy source and a power controller. The secondary energy source is associated with the micro grid, and the secondary energy source is configured to generate first DC power signal. The power controller is in communication with the secondary energy source and an electric grid, and configured to receive first AC power signal from the electric grid and the first DC power signal from the secondary energy source and to output a second AC power signal to loads in communication with the power controller. The power controller comprises a frequency converter configured to change frequency of the second AC power signal, a processor, and a memory configured to store instructions that, when executed, cause the processor to control the frequency converter to change the frequency of the second AC power signal.