Circuits and methods for limiting open circuit voltage of photovoltaic strings
AssigneeSunPower Corporation
InventorsKeith JOHNSTON, Zachary S. JUDKINS
Life of this patent
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Abstract
A photovoltaic string may include an open circuit voltage limiter that conducts current in one direction to provide a limiter voltage less than an open circuit voltage of the photovoltaic string, and that conducts current in the other direction. One or more open circuit voltage limiters may be connected across the photovoltaic string or across selected groups of solar cells of the photovoltaic string. The limiter voltage may be greater than a maximum power point voltage but less than the open circuit voltage of the photovoltaic string.
Claims20
A photovoltaic string comprising:
- a plurality of serially connected solar cells;
- a positive lead and a negative lead on opposite ends of the photovoltaic string, one end of the plurality of serially connected solar cells being connected to the positive lead and an opposite end of the plurality of serially connected solar cells being connected to the negative lead;
- and
- an open circuit voltage limiter across the plurality of serially connected solar cells, the open circuit voltage limiter having a positive terminal connected to the negative lead and a negative terminal connected to the positive lead, the open circuit voltage limiter having a limiter voltage less than an open circuit voltage of the photovoltaic string for current flowing through the open circuit voltage limiter in one direction and allows current flow through the open circuit voltage limiter in another direction.
A photovoltaic string comprising:
- a plurality of serially connected solar cells;
- and
- a first open circuit voltage limiter across a first group of solar cells in the plurality of serially connected solar cells, the first open circuit voltage limiter having a first limiter voltage less than a maximum voltage of the first group of solar cells for current flowing through the first open circuit voltage limiter in one direction and having a first positive bypass voltage for current flowing through the first open circuit voltage limiter in another direction.
A method of operating a photovoltaic string, the method comprising:
- providing a first open circuit voltage limiter across a first group of serially connected solar cells of the photovoltaic string;
- limiting a maximum voltage across the first group of serially connected solar cells to a first limiter voltage across the first open circuit voltage limiter for current flowing in a first direction through the first open circuit voltage limiter;
- and
- allowing current to flow through the first open circuit voltage limiter in a second direction opposite the first direction.
Dependencies are inferred from the claim text.