MEASUREMENT OF CURRENT-VOLTAGE CHARACTERISTIC CURVES OF SOLAR CELLS AND SOLAR MODULES
First Claim
1. A method for measuring characteristics of a solar cell or solar module, said method comprising:
- applying a light pulse having a light intensity to said solar cell or solar module such that a terminal current is produced at the terminals of the solar cell or solar module;
increasing a terminal voltage at the terminals of said solar cell or solar module during the falling side of said light pulse, said increasing terminal voltage being dependent upon said terminal current or upon said light intensity;
maintaining a constant stored charge within said solar cell or module during said falling side of said light pulse through use of said increasing terminal voltage; and
measuring said terminal current and said terminal voltage at a plurality of intensities during said falling side of said light pulse.
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Abstract
A solar cell or solar module is measured during a short pulse of light in such a way that the resulting data for current and voltage at each light intensity is the same as would be measured under steady-state illumination conditions and therefore predictive of the actual performance of the solar cell or solar module in sunlight. A varying voltage is applied to the terminals of the solar cell during a light pulse so that the instantaneous current at a given voltage and light intensity during the light pulse is the same as would be measured under constant illumination at that same given intensity. A constant voltage is modified by a small signal correction that is proportional to the terminal current. Or, the small signal correction is proportional to the light intensity. An analog feedback circuit is constructed using the terminal current or light intensity for feedback in order to provide the requisite varying voltage. The varying voltage may also be supplied by digital synthesis.
177 Citations
20 Claims
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1. A method for measuring characteristics of a solar cell or solar module, said method comprising:
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applying a light pulse having a light intensity to said solar cell or solar module such that a terminal current is produced at the terminals of the solar cell or solar module; increasing a terminal voltage at the terminals of said solar cell or solar module during the falling side of said light pulse, said increasing terminal voltage being dependent upon said terminal current or upon said light intensity; maintaining a constant stored charge within said solar cell or module during said falling side of said light pulse through use of said increasing terminal voltage; and measuring said terminal current and said terminal voltage at a plurality of intensities during said falling side of said light pulse. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for measurement of current and voltage of a solar cell or solar module at instantaneous intensities, said apparatus comprising:
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a light source that generates a light pulse having a light intensity; circuitry that facilitates measurement of a terminal current at terminals of said solar cell or solar module; means for performing the function of increasing said terminal voltage at the terminals of said solar cell or solar module during the falling side of said light pulse, wherein said increasing terminal voltage is dependent upon said measured terminal current or upon said light intensity, and wherein said increasing terminal voltage operates to maintain a constant stored charge within said solar cell or module during the falling side of said light pulse. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method of making a solar module comprising:
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producing a solar module; applying a light pulse having a light intensity to said solar module such that a terminal current is produced at the terminals of said solar module; increasing a terminal voltage at the terminals of said solar module during the falling side of said light pulse, said increasing terminal voltage being dependent upon said terminal current or upon said light intensity; maintaining a constant stored charge within said solar module during said falling side of said light pulse through use of said increasing terminal voltage; measuring said terminal current and said terminal voltage at a plurality of intensities during said falling side of said light pulse; and rating said solar module using said measured terminal current and terminal voltage, said rating occurring at the end of production of said solar module. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification