Photovoltaic power conditioning units
AssigneeEnecsys Limited
InventorsPaul Garrity, Asim Mumtaz
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Abstract
We describe a photovoltaic (PV) panel system comprising a PV panel with multiple sub-strings of connected solar cells in combination with a power conditioning unit (microinverter). The power conditioning unit comprises a set of input power converters, one connected to each sub-string, and a common output power conversion stage, to provide power to an ac mains power supply output. Integration of the micro-inverter into the solar PV module in this way provides many advantages, including greater efficiency and reliability. Additionally, embodiments of the invention avoid the need for bypass diodes, a component with a high failure rate in PV panels, providing lower power loss and higher reliability.
Claims20
A photovoltaic (PV) panel system comprising:
- a PV panel in combination with a power conditioning unit for providing ac power from the PV panel,
- wherein the PV panel comprises a string of series connected solar cells having first and second connections to either end of said string and having at least one tap connection between the first and second connections to define a plurality of sub-strings of said string, each sub-string having an electrical connection at either end,
- wherein said power conditioning unit comprises:
- a set of input power converters, one input power converter for each substring of said plurality of sub-strings, each input power converter having a pair of dc input connections connected to either end of a sub-string, each of said input power converters having a power output;
- a common output power conversion stage coupled to said set of input power converters to provide an ac output from said power conditioning unit;
- a sensor to sense one or both of a voltage on a sub-string and a current provided by said sub-string;
- and
- a bypass controller coupled to said sensor to control an input power converter connected to said sub-string to reduce or stop power conversion by said input power converter from said sub-string.
A method of providing power from a photovoltaic (PV) panel, the PV panel comprising a plurality of sense-connected sub-strings of solar cells, each said sub-string comprising a plurality of series-connected solar cells, the method comprising:
- supplying power from each said sub-string to a common dc bus using a set of input power converters, one input power converter for each said sub-string, wherein said supplying is controlled by using a plurality of sub-string maximum power point tracking (MPPT) control loops, one sub-string MPPT control loop for each input power converter of said set of input power converters;
- and
- converting power from said dc bus to an ac power output from said PV panel, wherein said converting is controlled by using at least one ac power output MPPT control loop.
A photovoltaic (PV) panel system comprising a PV panel in combination with a power conditioning unit for providing ac power from the PV panel,
- wherein the PV panel comprises a string of series connected solar cells having first and second connections to either end of said string and having at least one tap connection between the first and second connections to define at least two sub-strings of said string, each sub-string having an electrical connection at either end,
- wherein said power conditioning unit comprises a circuit on a circuit board mounted within an environmentally sealed enclosure on said PV panel, wherein said circuit board is connected within said enclosure to said first and second connections and to said at least one tap,
- wherein said power conditioning unit further comprises:
- a sensor to sense one or both of a voltage on a sub-string and a current provided by said sub-string;
- and
- a bypass controller coupled to said sensor to detect shading of said sub-string and, responsive to said detection, to control an input power converter connected to said shaded sub-string to reduce or stop power conversion from said shaded sub-string.
Dependencies are inferred from the claim text.