Systems and methods for photovoltaic direct current (DC) bus control

A PV bus system, comprising:

• a central inverter unit;
• a plurality of PV buses coupled to the central inverter unit;
• a plurality of PV strings coupled to the central inverter unit via the plurality of PV buses, respectively;
• a plurality of batteries coupled to the plurality of PV buses, respectively;
• and
• a plurality of DC/DC controllers coupled between the plurality of batteries and the plurality of PV buses, respectively, each of the plurality of DC/DC controllers comprising:
• a processor;
• and
• a memory having stored thereon instructions, which, when executed by the processor, cause a DC/DC controller to:
• determine that a local maximum power point tracking (MPPT) control is enabled;
• in response to determining that the local MPPT control is enabled, start an MPPT mode timer;
• perform MPPT;
• determine that the MPPT mode timer is greater than a predetermined period;
• and
• in response to determining that the MPPT mode timer is greater than a predetermined period, hand off MPPT control mode to a next DC/DC controller.

A fixed DC bus system, comprising:

• a plurality of modular inverters;
• a fixed DC bus coupled to the plurality of modular inverters;
• a plurality of PV strings coupled to the plurality of modular inverters via the fixed DC bus;
• a plurality of MPPT controllers coupled to the plurality of PV strings, respectively, each MPPT controller of the plurality of MPPT controllers including a PID control stage and a droop stage having a droop gain;
• a plurality of batteries coupled to the fixed DC bus;
• and
• a plurality of DC/DC controllers coupled between the plurality of batteries and the fixed DC bus.