WO2012168250A4

WO2012168250A4 - Method for assessing potential induced degradation of solar cells and photovoltaic panels

Info

Publication number: WO2012168250A4
Application number: PCT/EP2012/060615
Authority: WO
Inventors: Henning Nagel
Original assignee: Schott Solar Ag
Priority date: 2011-06-05
Filing date: 2012-06-05
Publication date: 2013-03-07
Also published as: DE102011051091A1; WO2012168250A1; DE102011051091B4

Abstract

The invention relates to a method for assessing potential induced degradation of solar cells and photovoltaic panels. In a first method step of said method, a first electric current is applied to a solar cell or to a photovoltaic panel, and, after the elapse of a first time interval, an electric characteristic of the solar cell or of the photovoltaic panel is measured. If the change in the electric characteristic or in the potential induced degradation derived therefrom exceeds a pre-defined first threshold value, the solar cell or the photovoltaic panel undergoes a second method step, in which the solar cell or the photovoltaic panel are subjected to different environmental conditions than during the first method step, preferably to simulated realistic operating conditions, and an electric characteristic of the solar cell or of the photovoltaic panel is measured, said electric characteristic being used to assess the potential induced degradation of the solar cell or of the photovoltaic panel.

Claims

CHANGED CLAIMS

received at the International Bureau on 19 December 2012 (19.12.2012)

Method for evaluating the high-voltage degradation of at least one solar cell or a photovoltaic module (8), in which method

in a first method step, a first electrical voltage is applied between the solar cell and a counterelectrode or between the cell matrix of the photovoltaic module and the counterelectrode and an electrical parameter of the solar cell or of the photovoltaic module is measured after a first time interval has elapsed;

the solar cell or the photovoltaic module is transferred to a second method step, if the change in the electrical characteristic or the high-voltage degradation derived therefrom exceeds a predetermined first threshold, and

the solar cell or the photovoltaic module in the second process step is subjected to ambient conditions other than during the first process step and an electrical characteristic of the solar cell or the photovoltaic module is measured, based on the high voltage degradation of the solar cell or the photovoltaic module is evaluated, with the other environmental conditions during the second process step realistic operating conditions of the solar cell or the photovoltaic module are simulated, which vary over time.

Method according to claim 1, wherein parameters or variables acting on the solar cell or the photovoltaic module for simulating realistic conditions of use are varied stepwise or gradually periodically on the basis of predetermined day and night lengths.

A method according to claim 2, wherein the parameters or quantities acting on the solar cell or the photovoltaic module are at least one of an electrical voltage applied to the solar cell or the photovoltaic module and an ambient voltage.

MODIFIED SHEET (ARTICLE 19) 25

include temperature.

4. The method of claim 3, wherein the voltage applied to the solar cell or the photovoltaic module electrical voltage is a DC voltage.

5. The method of claim 4, wherein the voltage applied to the solar cell or the photovoltaic module DC voltage during the predetermined day length is at least -300 V and during the predetermined night length is 0 V and / or wherein

the prevailing ambient temperature during the predetermined day length is at least 45 ° C, and lower during the predetermined night length.

6. The method of claim 1, wherein in the first process step further, an elevated temperature of greater than 60 ° C and a high relative humidity greater than 60% is applied, preferably a temperature of 85 ° C and a relative humidity of 85%.

7. The method according to any one of the preceding claims, wherein the first electrical voltage is a DC voltage which is at least -500 V and preferably about -1000 V.

8. The method of claim 1, wherein the first predetermined time interval is at least one week, and preferably about four weeks, and wherein the predetermined first threshold is at least 1%, preferably at least 2% and more preferably 5.0%.

9. The method according to any one of the preceding claims, wherein the prevailing relative humidity in the second process step is greater than 60% and preferably 85%.

10. The method according to any one of the preceding claims, wherein at least the second method step is carried out in a climatic chamber (19).

MODIFIED SHEET (ARTICLE 19) 26

1 1. The method according to any one of the preceding claims, wherein the first method step is carried out until the change in the electrical characteristic or the high-voltage degradation derived therefrom is within a predetermined range.

12. The method of claim 1 1, wherein the change in the electrical characteristic or derived therefrom high voltage degradation is in a range between 4% and 10%.

13. The method of any one of the preceding claims, wherein the electrical characteristic is a voltage-current characteristic (UI) and / or a parallel resistor (R _s hum) and / or at a predetermined light output actually generated electrical power of the solar cell or the photovoltaic module is.

14. The method according to any one of the preceding claims, wherein a conductive elastic plastic (1) on the front of the solar cell or the photovoltaic module (8) is pressed and this is used as a counter electrode, in particular the electrical voltage between the plastic (1) and solar cell or cell matrix is applied in the photovoltaic module.

15. The method of claim 14, wherein the plastic (1) is applied with a predetermined and evenly distributed over the surface of the respective solar cell or the respective photovoltaic module pressure.

16. The method of claim 15, wherein the pressure of the plastic (1) against the solar cell or the photovoltaic module is greater than 0.3 kPa.

17. The method according to claim 15 or 16, wherein the pressure by means of a plate (7) over the surface of the solar cell or the photovoltaic module (8) is made uniform.

18. The method according to claim 15 or 16, wherein the pressure over the surface of the first photovoltaic module (8) by means of a second photovoltaic module, which against the

MODIFIED SHEET (ARTICLE 19) 27

first photovoltaic module (8) is pressed, is uniformed, wherein the conductive elastic plastic (1) is located between the two photovoltaic modules.

19. The method of claim 18, wherein between the cell matrix of the second photovoltaic module (17) and the conductive elastic plastic (1) is also applied an electrical voltage.

20. The method according to any one of claims 14 to 17, wherein the DC voltage from a high voltage source (20) by means of at least one electrode (17) to one of the front of the solar cell or the photovoltaic module (8) facing away from the conductive plastic (1) becomes.

21. The method according to any one of claims 1 to 14, wherein the front side of the photovoltaic module in the first process step and / or in the second process step is covered with water or sprayed with water.

22. The method according to any one of claims 1 to 14, wherein the front side of the photovoltaic module is covered with wet cloths.

23. The method of claim 21 or 22, wherein the water or the water of the wet wipes contains salts to increase the electrical conductivity.

24. The method of claim 21, 22 or 23, wherein the water or the water of the wet wipes is used as the counter electrode.

25. The method according to any one of the preceding claims, wherein a module frame of the photovoltaic module is used as a counter electrode.

26. The method according to any one of the preceding claims, wherein the conductive plastic is a styrene or polyurethane-based plastic or a foamed plastic, for example a foam, prepared in particular under inert gas atmospheres, in particular noble gas atmospheres.

MODIFIED SHEET (ARTICLE 19) 28

27. The method of claim 1, wherein the conductive plastic is a conductive rubber or silicone.

28. The method according to any one of the preceding claims, wherein the conductive plastic does not stick, in particular does not adhere to the solar cell or the photovoltaic module.

29. Use of the method according to any one of the preceding claims in the production of solar cells or photovoltaic modules, wherein only such solar cells or photovoltaic modules may be used, the change in the electrical characteristic or derived therefrom high-voltage degradation either after the first process step, the first predetermined Threshold does not exceed or after the second process step does not exceed a second predetermined threshold.

30. The use of claim 29, wherein the second predetermined threshold is less than or equal to the first predetermined threshold.

31. Device for evaluating the high-voltage degradation of at least one solar cell or a photovoltaic module (8), in particular for carrying out the method according to one of claims 1 to 28, with

a grounded bottom plate (16) which is designed such that a rear side of the solar cell or of the photovoltaic module (8) rests thereon,

a pressure plate (7) for applying a pressure against the bottom plate (16), a voltage source (20) for generating an electrical voltage, a counter electrode (1), which is conductively connected to the counter electrode (1) applied to the electrical voltage to become, and

a measuring and control device (23), wherein

the measuring and control device is designed so that

in a first method step, a first electrical voltage is applied between the solar cell and the counterelectrode or between the cell matrix of the photovoltaic module and the counterelectrode and an electrical parameter of the solar cell or the photovoltaic module is measured after a first time interval has elapsed;

MODIFIED SHEET (ARTICLE 19)

29

the solar cell or the photovoltaic module is transferred to a second method step if the change in the electrical parameter or the high-voltage degradation derived therefrom exceeds a predetermined first threshold value,

the solar cell or the photovoltaic module is subjected to different environmental conditions in the second method step than during the first method step, and

an electrical parameter of the solar cell or the photovoltaic module is measured, based on the high voltage degradation of the solar cell or the photovoltaic module is evaluated, with the other environmental conditions during the second process step realistic operating conditions of the solar cell or the photovoltaic module are simulated in time vary.

32. The apparatus of claim 31, wherein the counter electrode (1) of a resilient, electrically conductive plastic) is formed between the pressure plate (7) and on the bottom plate (16) resting solar cell or one on the bottom plate (16) Photovoltaic module (8) is arranged and pressed by the pressure plate (7) against the solar cell or the photovoltaic module (8).

33. Use of the device according to claim 31 or 32 in a device for the production of solar cells or photovoltaic modules, wherein only such solar cells or photovoltaic modules may be used, their change in the electrical characteristic or derived therefrom high-voltage degradation either after the first process step the does not exceed the first predetermined threshold or does not exceed a second predetermined threshold after the second method step.

MODIFIED SHEET (ARTICLE 19)