System and method for limiting photovoltaic string voltage

A method of connecting photovoltaic (PV) modules to an inverter, the method comprising:

• providing a plurality of photovoltaic (PV) module stages, each PV module stage comprising a plurality of PV modules connected together in series, the plurality of PV module stages connected together to form at least one string of series connected PV module stages;
• connecting an inverter to a power grid and charging a corresponding dc-link voltage to a predetermined value to establish a power grid current;
• connecting one or more first PV module stages selected from the plurality of PV module stages directly to the inverter and regulating the output voltage of the directly connected first PV module stages to a maximum power point level;
• connecting one or more additional PV module stages selected from the plurality of PV module stages directly to the inverter while the first PV module stages are directly connected to the inverter;
• removing the direct connection of the first PV module stages to the inverter subsequent to connecting the one or more additional PV module stages to the inverter, such that both the first PV module stages and the one or more additional PV module stages are connected in series to the inverter via the one or more additional PV module stages, and regulating the combined output voltage of the connected first PV module stages and the one or more additional PV module stages to the maximum power point level.

A method of connecting photovoltaic (PV) modules to an inverter, the method comprising:

• providing a plurality of photovoltaic (PV) module stages, each PV module stage comprising a plurality of PV modules connected together in series, the plurality of PV module stages connected together to form at least one string of series connected PV module stages;
• connecting an inverter to a power grid and charging a corresponding dc-link voltage to a predetermined value to establish a power grid current;
• connecting one or more first PV module stages selected from the plurality of PV module stages directly to the inverter and regulating the output voltage of the directly connected first PV module stages to a maximum power point level;
• disconnecting the one or more first PV module stages from the inverter;
• connecting one or more additional PV module stages selected from the plurality of PV module stages directly to the inverter subsequent to disconnecting the one or more first PV module stages from the inverter such that both the one or more first PV module stages and the one or more additional PV module stages are connected in series to the inverter via the one or more additional PV module stages, and regulating the combined output voltage of the connected one or more first PV module stages and the one or more additional PV module stages to the maximum power point level.

A method of connecting photovoltaic (PV) modules to an inverter or dc-dc converter, the method comprising:

• providing a plurality of photovoltaic (PV) module stages, each PV module stage comprising a plurality of PV modules connected together in series, the plurality of PV module stages connected together to form at least one string of series connected PV module stages;
• connecting an inverter or dc-dc converter to a power grid and charging a corresponding dc-link voltage to a predetermined value to establish a power grid current;
• short circuiting the output of all but one PV module stage within a string of series connected module stages such that only the output of the single PV module stage without a shorted output is connected directly to the inverter or dc-dc converter and regulating the output voltage of the directly connected PV module stage to a maximum power point level;
• removing in succession, the short circuit across the output of each PV module stage within the string of series connected module stages having a short circuited output;
• and
• connecting in succession, the outputs of the PV module stages without shorted outputs together in series as the PV module stages without shorted outputs become available;
• connecting to the inverter or dc-dc converter in succession, the output of the series connected PV module stages without shorted outputs as they become available;
• and
• regulating in succession, the combined output voltage of the series connected PV module stages without shorted outputs to the maximum power point level as they become available.