RU2054636C1 - Method of testing photoelectric parameters of photocell unit - Google Patents

Abstract

FIELD: electronics. SUBSTANCE: method comprises steps of applying illumination onto an active surface of all photocells in order to evaluate quality of separate photocells; then placing a member for differential illumination between the light source and active surface of the photocells; scanning the active surface of the photocells; measuring their output voltage; removing the light source; applying a bias voltage on each photocell, being tested, and measuring dark current, being occurred in the circuit. EFFECT: enhanced accuracy of parameter testing. 1 cl, 2 dwg

Description

 The invention relates to methods for testing blocks of solar cells, and more specifically to methods for testing the integrity or testing for the presence of a failed element in the matrix of solar cells.

 Known methods for monitoring the photovoltaic parameters of photodiodes included in the circuit, and methods for controlling the dark currents of individual photodiodes (photodiode FD-292 TU 3-1174-88, Gorokhov V.A. Semiconductor devices and their application / Edited by Ya.A. Fedotov, M. Sovetskoe Radio, vol. 10, 1961).

 A disadvantage of the known methods is the inability to control the dark current of each photocell in the unit at the end of their installation.

 Closest to the invention, the technical solution is a method of testing a block of photocells, including applying light to the active surface of all the elements, placing the differential lighting element between the light source and the active surface of the elements, moving the differential lighting element along the active surface, measuring the output voltage (US Pat. No. 3,630,627, C. G 01 J 1/42, H 01 J 39/12, 02.27.70).

 The closest technical solution does not provide and, as a result, does not allow monitoring the dark currents of photodiodes, which is why the method is not suitable for assessing the quality of photocell blocks at relatively low light levels and, as a result, low photocurrents (less than 1 μA).

 The aim of the invention is to control the quality of the block of solar cells by providing the ability to control the dark currents of each solar cell in the block.

 The goal is achieved in that according to the method, after applying light to the active surface of the photocell block, placing the differential lighting element (illuminator) between the light source and the active surface of the photocells, scanning the active surface of the photocells and measuring the output voltage, the lighting is removed and the dark current is monitored when direct or reverse bias voltage of a magnitude at which the equations of the forward and reverse branches becomes identical.

 The method of monitoring the photoelectric parameters of the block of solar cells is illustrated in figures 1 and 2, which shows the inclusion of photocells for element-by-element control of dark currents in the block.

 The proposed method for monitoring the photoelectric parameters of the block of solar cells is as follows.

 On the active surface of all elements serves lighting. Then, a differential lighting element is placed between the light source and the active surface and moved along the active surface, measuring the output voltage in order to assess the health of the unit. After that, the lighting is removed, bias voltage is applied to each monitored photocell included in the common circuit, and the dark current arising in the circuit is measured. In this case, the control of the dark current is carried out according to the schemes presented in figures 1 and 2 as follows.

 In the absence of bias voltage, the current in the circuit is close to zero. After applying a voltage, the value of which is experimentally selected such that the forward and reverse currents flowing through the diodes VD2 and VD1 (figure 1) and VD1 and VD2 (figure 2), respectively, are provided when the polarity of the applied bias voltage changes, the current increases. The current value in each case is measured by device A and on the basis of this, the quality of the photodiodes is evaluated according to a pre-selected criterion for the maximum allowable value of the dark current.

 An example implementation of the method.

 On the active surface of the elements VD1 and VD2 serves lighting. Then, between the light source and the active surface of the elements VD1 and VD2, a differential lighting element is placed and moved along the active surface, measuring the output voltage and determining the operability of the unit from it. After that, the lighting is removed. In the absence of bias voltage, the current in the circuit is 1-2 nA. After applying a bias voltage of 0.1 V, the current in the circuit rises to values of at least 10 nA. The maximum value of the dark current of any photodiode, determined from the operating conditions of the device, should be no more than 50 nA. The maximum value of the dark current of any photodiode (the resulting current in the circuit) for any polarity of the applied bias should not exceed 50 nA. Photodiodes whose dark currents exceed 50 nA for a given device are removed from the device and replaced.

 The proposed method for monitoring the photoelectric parameters of the block of solar cells allows you to evaluate the quality of individual solar cells directly in the assembled circuit.

Claims (1)

 METHOD FOR CONTROL OF PHOTOELECTRIC PARAMETERS OF A PHOTOCELL ELEMENT, according to which illumination is applied to the active surface of all elements, a differential illumination element is placed between the illumination source and the active surface of the elements, the active surface of the elements is scanned, the output voltage is measured, characterized in that the illumination is removed after the output voltage is measured, the illumination is fed, fed the bias voltage for each monitored photocell, at which the forward and reverse currents are identical, measure the dark current in bschey chain, comparing it with the reference value and the comparison results reveal unsuitable photocells.

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