PHOTOVOLTAIC UNITS, METHODS OF OPERATING PHOTOVOLTAIC UNITS AND CONTROLLERS THEREFOR
First Claim
1. A photovoltaic unit comprising;
- a first sub-unit, anda second sub-unit series-connected with the first sub-unit,wherein the first sub-unit and second-sub-unit each comprise one of a single solar cell and a series-connected plurality of solar cells, andwherein the first sub-unit further comprises a supplementary power unit connected in parallel with the respective solar cell or plurality of solar cells.
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Abstract
The present invention relates to the field of photovoltaic systems with solar cell (s) or modules having insolation differences or mismatch. Each solar module is formed by placing a large number of solar cells in series. The PV system is then formed by placing a number of solar modules in series in a string and sometimes by placing multiple strings of series-connected solar modules in parallel, depending on the desired output voltage and power range of the PV system. In practical cases, differences will exist between output powers of the solar cells in the various modules, e.g. due to (part of) the modules being temporarily shaded, pollution on one or more solar cells, or even spread in solar-cell behaviour that may become worse during aging. Due to the current-source-type behaviour of solar cells and their series connection these differences will lead to a relatively large drop in output power coming from the PV system. This invention addresses this problem by adding DC-DC converters (803) on a single or multiple solar-cell level that source or sink difference currents thereby increasing the output power of the complete PV system. In embodiments, the efficiency of photovoltaic systems with solar cell (s) or modules is improved by compensating for output-power loss caused by insolation difference and mismatch.
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Citations
21 Claims
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1. A photovoltaic unit comprising;
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a first sub-unit, and a second sub-unit series-connected with the first sub-unit, wherein the first sub-unit and second-sub-unit each comprise one of a single solar cell and a series-connected plurality of solar cells, and wherein the first sub-unit further comprises a supplementary power unit connected in parallel with the respective solar cell or plurality of solar cells. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of operating a photovoltaic unit comprising a first sub-unit comprising at least one solar cell, a second sub-unit series-connected with the first sub-unit and comprising at least one solar cell, and a supplementary power unit connected in parallel with the at least one solar cell of the first sub-unit,
the method comprising: -
determining a difference between a photo-generated current produced by the first sub-unit and a photo-generated current produced by the second sub-unit , and controlling the supplementary power unit to supply current in dependence on the difference between the photo-generated current produced by the first sub-unit and the photo-generated current produced by the second sub-unit. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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Specification