EP3769416A1

EP3769416A1 - Sensor module and method for sensing external influencing parameters, particular in the monitoring of photovoltaic systems

Info

Publication number: EP3769416A1
Application number: EP19705138.6A
Authority: EP
Inventors: Christian Hagendorf; Marko Turek; Jens Schneider
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 2018-03-19
Filing date: 2019-02-06
Publication date: 2021-01-27
Also published as: DE102018204150A1; MA52136A; WO2019179692A1; DE102018204150B4

Abstract

The invention relates to a sensor module for sensing external influencing parameters, in particular in the monitoring of photovoltaic systems, comprising at least one first solar cell (1) used for measurement, which is oriented toward a front side of the solar module, and at least one second solar cell (2) used for measurement, which is oriented toward a rear side of the solar module. The sensor module is constructed of largely degradation-free components in the region of the first and second solar cells (1, 2) and has a layered structure that approximates the layered structure of the photovoltaic modules of a photovoltaic system. By means of the proposed sensor module, reference data for external influencing parameters can be captured in the monitoring of photovoltaic systems, which reference data can be used to differentiate between operating states, general performance degradation, optical degradation and soiling in the monitoring of the PV system.

Description

Sensor module and method for detecting external influencing parameters, in particular during the monitoring of

Photovoltaic systems

Technical application

The present invention relates to a sensor module for detecting external influencing parameters, in particular when monitoring photovoltaic systems, the

at least one solar cell serving for the measurement, which is oriented towards a front side of the sensor module and has a layer structure which is connected to the

Layer structure of the photovoltaic modules of photovoltaic systems is approximated. The invention also relates to a method in which the proposed sensor module is used to detect the external influencing parameters.

The temporal change of the power or the energy yield of solar or photovoltaic modules is subject to a number of extrinsic and

intrinsic influence parameters. Extrinsic influencing parameters, also referred to as external influencing parameters in the present patent application, include varying environmental data such as daytime-dependent solar irradiation, ambient temperatures, cooling, wind and snow loads and certain properties of the respective PV system (PV: photovoltaic), such as solar cells. high electrical potentials in the string and

Shading. In the case of bifacial solar modules, the albedo, ie the diffuse reflection of solar radiation from the respective substrate of the PV Plant, a role, so represents another external influence parameter. Also pollution of the

Surface of the solar modules count in the present patent application to the external influence parameters. Intrinsic parameters include changes in performance over a longer timescale, for example due to the degradation of modulus

components. Examples are the light-induced

Degradation (LID) and the photoinduced degradation (PID) of the solar cells, the change of the polymeric

Encapsulation materials or the abrasion of the applied on the cover glass of the solar modules anti-reflection coating. These intrinsic and extrinsic parameters determine the respective operating state and degradation status of the solar or photovoltaic modules or of these comprehensive PV systems on different time scales and together influence the yield.

A long term evaluation and prognosis of

Yield data of a PV system requires a precise

Monitoring of the relevant parameters for the operating status and degradation status of the system. For this purpose, the power of the PV systems is usually recorded over time. Partially, additional extrinsic or intrinsic sensors are added

Parameter measured. However, the overlapping of the various factors and their temporal changes make it difficult to clearly distinguish between special operating states and degradation status. In particular, short-term temporal fluctuations due to extrinsic parameters, eg due to solar radiation or temperature, must be separated from long-term intrinsic degradation processes. State of the art

For the time-resolved monitoring of power or yield data as a function of solar radiation and the wind cooling of a PV system, different methods are already known. So some additional weather stations are used, the example, have a pyranometer, a temperature sensor and / or a pollution sensor. These weather stations then provide reference data for the time resolved power or yield measurement on

Inverter of the PV system in order to obtain independent data on the operating status of the PV system from the external influencing parameters.

US 2006/0085167 A1 uses a sensor module for recording the reference data, in which the light irradiation is detected with the aid of a solar cell and also the temperature is determined from the measurements on the solar cell. US 2010/0271199 A1 discloses the use of autonomous sensor modules with different sensors for monitoring structures. These

This document is not specific to PV systems and is intended to provide data on the condition of the monitored devices

Deliver structures.

From EP 2 647 055 Bl a sensor module for the detection of external influence parameters in

Monitoring of photovoltaic systems known which has a plurality of serving for measuring solar cells, via which the solar radiation and the temperature can be measured or determined as external influencing parameters. To determine the state of degradation proposed to integrate a device for generating a reference current. Since the solar cells used in the sensor module of EP 2 647 055 B1 are constructed from the same material as the solar modules of the PV system and thus degrade on the same time scale, the state of degradation of the solar modules of the entire PV system can be measured in this way by measurement on the sensor module. Plant closed. DE 10 2013 200 681 A1 describes a

Reference solar cell array, which has a solar cell with a front side facing the irradiation side surface and a back surface, which is not electrically contacted over the entire surface. By encapsulating the solar cell in a housing, a permanent preservation of the solar cell properties is to be ensured. The arrangement described can be used for calibrating solar cells or solar modules or for detecting external influencing parameters.

The object of the present invention is to provide a sensor module and a method for

Capture of external influencing parameters during

Specify the monitoring of photovoltaic systems, which can capture more accurate reference data on external parameters of influence in real time at the location of the photovoltaic system to be used as an evaluation reference for the photovoltaic system

To provide yield data analysis. Presentation of the invention

The task is with the sensor module and the

Method of claims 1 and 10 solved.

Advantageous embodiments of the sensor module and the method are the subject of the dependent patent claims or can be the following

Description and the exemplary embodiment.

The proposed sensor module has at least one first solar cell serving for measurement, which is oriented toward a front side of the sensor module, and at least one second serving for the measurement

Solar cell, which is oriented towards a rear side of the sensor module. The first solar cell thus detects light radiation from the front to the

Sensor module meets, the second solar cell detected - depending on the design of the sensor module - either on the back of the sensor module or structures below the sensor module reflected or scattered portions of the incident of the front light radiation.

The proposed sensor module is constructed from largely degradation-free components and has a layer structure with a front-side optically transparent cover, a first layer of a polymeric encapsulation material, a layer with the solar cells, a second layer of the polymeric

Encapsulation material and a back cover. Among the largely degradation-free

Components are components of the sensor module to understand that have a higher degradation stability than the corresponding components of the

Solar or PV modules of a PV system. It will thus be for the construction of the sensor module, for example Polymer materials are used, which have in terms of the important parameters for the yield of solar modules parameters, in particular the optical transmission of a higher long-term stability than the polymer materials used in solar modules of PV systems. These are usually more expensive

Materials such as polyolefin. In

Solar modules, however, is usually the cheaper EVA (ethylene-vinyl acetate) used. Furthermore, the solar cells are chosen such that they have as little as possible or only a very small PID and LID. This can, for example. By appropriate selection in the

Production of solar cells in conjunction with

corresponding measurements or by choice of

Manufacturing technology can be ensured. The front cover of the sensor module has no antireflection coating to avoid degradation by abrasion or abrasion of this antireflection coating.

The proposed sensor module is preferably in the outer dimensions to the dimensions of

Photovoltaic modules adapted in PV systems, so that the sensor module can be integrated instead of a photovoltaic module in a photovoltaic system. By connecting the sensor module with a suitable

Measuring device, current-voltage characteristics (IV characteristics) of the first and second solar cell can be detected, from which the short-circuit current, the open circuit voltage and the electrical power of the first solar cell and the short-circuit current and the open circuit voltage of the second solar cell determined as a function of time can be. this makes possible the detection of the incidence of light and also the temperature (operating temperature of the solar cell). Instead of

Evaluation of the short-circuit current and the open-circuit voltage, the temperature in the sensor module can also be integrated by one or more in the sensor module

Temperature sensors are measured directly. From the measurement on the second solar cell, the albedo can be determined, not only in bifacial

Solar cells is an important factor, but also the determination of the type of light (direct sunlight or diffuse light radiation due to cloud cover) allows. The present sensor module thus represents an optical-thermal multifunction sensor, which can be integrated directly into the PV system at the location of the PV modules due to its structure. The sensor module provides reference data for the evaluation of the optical-thermal losses or yields in situ and in real time. The reference data of the sensor module capture the short-term performance _V ariations by environmental conditions at the place of

Modules with high time resolution: solar or Lichtein radiation, ambient temperature, wind cooling and albedo. The structure with long-term stable, largely degradation-free components degradation-free precise reference data for incident light (optical

Losses) as well as module-specific operation

temperatures (thermal losses). The relevant optical losses include the abrasion of the antireflection coating, the polymer yellowing and the delamination. In a preferred embodiment, the sensor module also has at least one sensor for detecting the degree of soiling of the front-side optically transparent cover. Such sensors are commercially available and can be readily integrated into the proposed sensor module.

Due to the structure of the proposed sensor module, in particular by the comparable layer structure, the sensor module can be integrated at any position in the string of photovoltaic modules of the PV system. The reference data are thus obtained at the location of the PV system and thus form the local optical and thermal ambient and operating conditions

(Inclination, shading, wind cooling, temperature, albedo, pollution / cleaning, etc.) with high

Precision down. A suitable recording and billing of these reference sensor measured values or reference data with the performance data of the respective PV system enables a quantitative, rapid and separate evaluation of short-term optical-thermal Leistungsfluk

tuations and the long-term optical degradation of PV modules and their cause. The adjustment or the correlation of the PV systems with the reference data allows identification of degradation

losses and degradation types with little effort and is suitable for remote maintenance. In this way, measures for optimizing revenue in operational management can be planned and implemented in a targeted and timely manner.

In the proposed method, at least the current-voltage characteristics of the first and the second solar cell are measured by means of a measuring device connected to the sensor module, and from this reference values for the monitoring of the

Photovoltaic system or a photovoltaic module as a function of time. This is it preferably the short-circuit current, the

No-load voltage, power, albedo and temperature. Optionally, when using a sensor for detecting the degree of contamination in the sensor module and the degree of contamination can be determined as a reference value.

The proposed sensor module and the associated method are preferably used in the continuous monitoring of PV systems in operations management and maintenance. Also a use in the monitoring of individual photovoltaic modules and the

Evaluation of sites for PV systems, Minder

achievements or the yield optimization is possible for a limited time.

Brief description of the drawings

The proposed sensor module and the

associated methods will be explained in more detail using an exemplary embodiment in conjunction with the drawings. Hereby shows:

Fig. 1 is a schematic representation of a

exemplary structure of the proposed

Sensor module.

Ways to carry out the invention

With the proposed sensor module can be

Capture or determine reference data for external influencing parameters of a PV plant as a function of time, which then separates them from short-term optical-thermal power fluctuations and

Long-term optical degradation of the PV modules during power or yield monitoring of these modules

enable. The sensor module supplies long-term stable and degradation-free measured values, in particular short-circuit current reference measured values (IscREF).

No-load voltage reference values (VocREF), power reference readings (PREF), albedo reference readings (A), temperature readings (T), and optional fouling reference readings (S) on the solar cell (s) in the sensor module. Some of these reference readings can be taken directly from a corresponding sensor in the sensor module, such as the temperature through a separate temperature sensor or the level of contamination by a separate clogging sensor. Other reference measurement data such as the albedo or the short-circuit current (Isc) are from a

Measurement of the I-V bright characteristic of the inverted-induced degradation-free solar cell (backside orientation) determined or derived. For example, the short-circuit current characteristic IscREF of the second, i. to the back-oriented solar cell, determine from the measured I-V characteristic of this solar cell. From this value can then be the

Derive albedo value for the PV system. At the same time, the correlation between direct and indirect solar radiation can be determined by temporal correlations of the IscREF values of the two solar cells. If no temperature sensor is used, the temperature can be determined by means of the values for Isc and Voc (no-load voltage) of one of the solar cells of the sensor module. For this purpose, the different Isc and Voc dependency of the solar cell on single-beam temperature and temperature in the laboratory. Conversely, the irradiance and the temperature of Isc and Voc can then be determined by measuring both values on the sensor module. The irradiation can alternatively be detected via a separate irradiation sensor.

The proposed sensor module has a

similar structure as the photovoltaic modules of the photovoltaic system. This ensures that the determined with the sensor module optical-thermal properties Isc and P comparable to those of

Photovoltaic modules are. FIG. 1 shows a schematic sectional view of the construction of the proposed sensor module from the different layers. In this example, the sensor module has a first solar cell 1 with front-side orientation, a second solar cell 2 with rear-side orientation, a temperature sensor 3, for example

laminated thermocouple, as well as a pollution sensor 4, which are arranged in the structure of Figure 1 in a layer 7 with the solar cells 1, 2.

The two solar cells 1, 2 are here

In the case of the first solar cell 1, they are used for measuring IscREF, VocREF and PREF and, in the case of the second solar cell 2, for measuring the albedo (A). The fouling sensor 4 provides a fouling value S for normalizing the

Pollution dependence of IscREF (S). The two

Solar cells 1, 2 and in the present example, the pollution sensor 4 and the temperature sensor 3 are between two layers 6, 8 of a high-quality, long-term stable polymer encapsulating material

embedded. The encapsulation material is chosen so as to avoid optical degradation of the encapsulation material (yellowing, delamination).

The contamination sensor 4 can be completely integrated in the sensor module (reflection measurement) or optionally also by an additional external

Light source 10 are excited, as in the

Example of Figure 1 is indicated.

On the front side, the present sensor module has a front glass 5 without antireflection coating in order to avoid a dependence of the value of IscREF on the state of the antireflection coating. Of the

Temperature sensor 3 is used to measure the temperature in order to normalize the temperature dependence of IscREF (T). At the back of the sensor module, a cover layer 9 is provided, which is formed either of glass or foil - according to the structure of the photovoltaic module of the PV system. The glass-glass or glass-film module structure is chosen in each case so that it has comparable optical-thermal properties, such as the photovoltaic modules of the PV system in which it is used (Isc (T) ~ IscREF (T) and

P (T) ~ PREF (T)). Due to its construction can one

Such sensor module can be integrated in a simple manner flat in an existing PV system. In an advantageous embodiment, the

Sensor module in different formats are designed so that it can be integrated without gaps in PV module surfaces. The sensor module can also be here have additional solar cells, which can be integrated into the string of PV modules of the PV system for additional power generation. It is then full with a corresponding number of solar cells

functional power generating module designed and interconnected in the string. Only the solar cells used for the measurement are not used for power generation, but are with the measuring device

connected. In this way, the sensor module better maps the thermal operating state of the entire system and it is also possible in a simple manner to additionally measure measured values for currents and voltages in the module string. The sensor module is in the proposed

Method read by an electronics or a Messein direction, wherein the I-V bright characteristic of the first solar cell (front-side orientation) is detected and used to determine the reference characteristics IscREF and the power PREF under the respective conditions at the site. The temperature T in the sensor module is either measured directly via the temperature sensor 3 or - as already described above - based on the Isc / Voc values of the first solar cell

certainly. From the I-V bright characteristic of the second

Solar cell (backside orientation) becomes the

IscRückREF reference parameter from which the albedo value is derived.

The sensor module provides long-term stable,

degradation-free reference data that match the parameters of the PV system measured during monitoring

compared and in a temporal correlation analysis for the differentiation between operating conditions, general performance degradation, optical

Degradation and soiling can be used. By evaluating the I-V characteristic of the

degradation-stable first solar cell (front orientation), the short-circuit current IscREF and the power PREF generated.

The inverted laminated degradation-stable second solar cell (backside orientation) delivers by evaluation of their I-V curve a measured value for back light incidence IscRückREF. From this, the method determines values for the albedo A as well as short-term variations due to indirect radiation components. In addition, measured values for the temperature T of the solar cells and for the contamination S of the module surface are detected or determined. The recordings are made as a function of the time t.

According to the following table, these reference values of the sensor module provide time-resolved ones

Characteristic values for the operating state of the photovoltaic modules of the PV system (solar radiation, temperature). Through a correlation with time - resolved characteristics of the

Overall System (Isc (t), P (t)) provides information on overall performance degradation and optical losses through degradation of the antireflective coating (ARC) and polymer degradation as well as pollution / soiling losses.

In a special embodiment of the proposed sensor module, several degradation-free first solar cells (front orientation) can each be laminated in different encapsulation materials, for example also with black and white backsheets, in order to obtain the respective light capture (IscREF characteristic values) and the power (PREF). Characteristic values) for specific module structures (cell-to-module ratio).

Furthermore, additional functions may also be provided in the sensor module or integrated or measured in the sensor module. So is the

Possibility to evaluate electrical losses such as shunts, LID / PID or cell breaks by detecting Rser, Rshunt reference values (Rser: series resistance) of the degradation-stable solar cell. The module materials can during proposed sensor module also interchangeable

be applied (glasses, films, polymers) to adapt these components in each case to the photovoltaic modules of a PV system or to use the sensor module also for testing these components in a climatic chamber or in the field. The

Sensor module may be equipped with a self-sufficient power supply, which may be formed for example by one or more integrated solar cells and a storage battery. Furthermore, the sensor module can also be provided with a device for wireless data transmission, for example via a mobile radio connection,

be educated. Since the sensor module is designed to be resistant to degradation, are essentially the short-term

Variations of IscREF and PREF recorded taking into account the ambient conditions and the operating conditions T and S at the location of the PV system. The measured data are recorded as time series and transmitted for further processing and compared with the data of the PV system Isc and P. The reference data generated by the sensor module can also be used as a measure of the optimal overall system performance under the respective operating and location conditions.

Reference sign list

1 first solar cell (front side orientation) 2 second solar cell (rear side orientation)

3 temperature sensor

4 pollution sensor

5 front glass

6 Long-term stable polymer

7 layer with solar cells

8 long-term stable polymer

9 back glass or foil

10 light source

Claims

claims

1. Sensor module for detecting external influence

parameters, especially when monitoring

Photovoltaic systems comprising at least one first solar cell (1) serving for measurement, which is oriented towards a front side of the sensor module, and at least one second measuring cell (2) oriented towards a rear side of the sensor module,

wherein the sensor module in the region of the first and second solar cell (1, 2) from largely

degradation-free components is constructed and a layer structure with a front-side optically transparent cover (5), a first layer (6) of a polymeric encapsulation material, a layer (7) with the solar cells (1, 2), a second layer (8) of the polymeric Encapsulating material and a back cover (9).

2. Sensor module according to claim 1,

characterized,

in that it has at least one sensor (4) for detecting a degree of soiling of the front-side optically transparent cover (5).

3. Sensor module according to claim 1 or 2,

characterized,

that there is at least one temperature sensor (3) having .

Sensor module according to claim 3,

characterized,

in that the at least one temperature sensor (3) is formed by one of the solar cells (1, 2)

Sensor module according to one of claims 1 to 4, characterized

that the front side is optically transparent

Cover (5) no anti-reflection coating

having .

6. Sensor module according to one of claims 1 to 5,

characterized,

that outer dimensions of the sensor module to outer dimensions of photovoltaic modules of

Photovoltaic systems are approximated or correspond to it, so that the sensor module can be integrated instead of a photovoltaic module in a photovoltaic system.

7. Sensor module according to claim 6,

characterized,

in that the sensor module has further solar cells which are connected in the sensor module in such a way that they can contribute to the power generation of the photovoltaic system when integrated in a photovoltaic system, and has connections through which the solar cells flow

Currents and / or voltage applied to the other solar cells voltages can be measured. of claims 1 to 7, characterized

in that it has a plurality of first and second measuring cells (1, 2), the

Regions in the sensor module differ by different Liche encapsulation materials and / or front and / or back covers (5, 9) in the layer structure of the sensor module. 9 sensor module according to one of claims 1 to 8,

characterized,

that it can be connected to a measuring device, with which at least current-voltage characteristics of the first and the second solar cell (1, 2) can be detected, from which a short-circuit current and an electrical power of the first solar cell (1) and a short-circuit current of the second solar cell (2) can be determined as a function of time. 1 0. Procedure for recording external

Influence parameter, in particular in the monitoring of photovoltaic systems or photovoltaic modules, with a sensor module according to one of the preceding claims,

in which with a measuring device at least

Current-voltage characteristics of the first and second solar cell (1, 2) measured and used to determine reference values for the monitoring of the photovoltaic system as a function of time.

1 1. A method according to claim 10,

characterized, that the reference values are short-circuit current, power, albedo and temperature.

12. The method according to claim 10 or 11,

characterized,

that when using at least one sensor for detecting the degree of contamination (4) in

Sensor module also the degree of pollution than

Reference value is determined.

13. The method according to any one of claims 10 to 12,

characterized,

that the sensor module instead of a

Photovoltaic module is integrated into the photovoltaic system.

14. The method according to any one of claims 10 to 13,

characterized,

the layer structure of the sensor module in the region of the first and second solar cell (1, 2) is selected such that it matches the layer structure of the photovoltaic modules of the photovoltaic system

is approximated in terms of optical-thermal properties.