Reverse bias protected solar array with integrated bypass battery
AssigneeUnited States of America as Represented by the Administrator of the National Aeronautics & Space
InventorGeoffrey Landis
Life of this patent
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Abstract
A method for protecting the photovoltaic cells in a photovoltaic (PV) array from reverse bias damage by utilizing a rechargeable battery for bypassing current from a shaded photovoltaic cell or group of cells, avoiding the need for a bypass diode. Further, the method mitigates the voltage degradation of a PV array caused by shaded cells.
Claims21
1-42. (canceled)
A method of protecting a photovoltaic array from damage from partial shading, said method comprising the steps of:
- providing a photovoltaic array comprised of a plurality of modules connected in series for providing an electric current, wherein each of said modules includes a rechargeable battery having at least one rechargeable cell connected in parallel with a photovoltaic battery having at least one photovoltaic cell;
- utilizing a light source for lighting said array, wherein, during a temporary shading of one or more, but not all, of said modules, the remainder of said modules remain lit by the light source;
- and
- each of said batteries included in said one or more shaded modules shunting at least some portion of said electric current during said temporary shading, wherein said shunting protects said array from damage.
A method of protecting a photovoltaic array from damage due to temporary partial shading of said array, said method comprising the steps of:
- providing a photovoltaic battery including at least one photovoltaic cell;
- providing a rechargeable battery including at least one rechargeable cell, said rechargeable battery connected in parallel with said photovoltaic battery;
- utilizing said photovoltaic battery to generate energy during a lighting period;
- sizing said rechargeable battery with a storage capacity sufficient for providing energy during a period of the temporary partial shading of said array, but not sufficiently large for providing energy during most of an eclipse or nighttime period;
- and
- said rechargeable battery shunting at least a portion of an array current from said photovoltaic battery to protect said photovoltaic battery from damage during said temporary partial shading.
A method of protecting a photovoltaic array from damage due to temporary partial shading of said array, said method comprising the steps of:
- providing a photovoltaic battery including at least one photovoltaic cell;
- providing a rechargeable battery including at least one rechargeable cell, said rechargeable battery electrically connected to said photovoltaic battery;
- and
- operating said array such that said rechargeable battery shunts at least a portion of a current of said array from said photovoltaic battery to protect said photovoltaic battery from damage when said photovoltaic array is at least partially shaded.
A method of using a photovoltaic array including a plurality of photovoltaic cells and also including a plurality of rechargeable cells, said method comprising the steps of:
- using said array to provide power in an environment that includes a first period of shading wherein only a subset of said photovoltaic cells is shaded, said environment also including a second period of shading wherein all of said photovoltaic cells are shaded, said second period being much longer than said first period, said environment further including a third period where at least said subset of photovoltaic cells is not shaded;
- and
- operating said array such that one or more of said rechargeable cells supply current for said array during said first period to avoid damage to said shaded photovoltaic cells, but wherein, during said second period, said rechargeable cells have insufficient stored energy for supplying said current to said array during the entire second period, and further wherein, during said third period, said subset of photovoltaic cells provide energy to at least some number of said rechargeable cells for charging said some number of rechargeable cells.
Dependencies are inferred from the claim text.