WO2009092354A2

WO2009092354A2 - Spectrometric sensor

Info

Publication number: WO2009092354A2
Application number: PCT/DE2009/000057
Authority: WO
Inventors: Ralf Adelhelm
Original assignee: Pasan Sa
Priority date: 2008-01-22
Filing date: 2009-01-20
Publication date: 2009-07-30
Also published as: WO2009092354A3; DE112009000660A5; DE102008010010A1

Abstract

The invention relates to a multichannel detector for optoelectronically measuring the spectral radiation intensity of solar radiation or solar simulators for use in photovoltaics according to IEC 60891, IEC 60904 and ISO/DIS15387. The spectrometer which is provided with spectral isolation via a graduated filter can be used as a multiplex spectrometer and a spectral template apparatus, i.e. as a reference cell with prescribed spectral sensitivity.

Description

Spectrometric sensor

Summary

The multichannel detector according to the invention is used for the optoelectronic measurement of the spectral irradiance of solar radiation or solar simulators for photovoltaics according to IEC 60891, IEC60904 and ISO / DIS15387. The spectrum apparatus with a spectral rejection by means of a graduated filter can be used as a multiplex spectrometer and as a spectral template apparatus, i. be used as a reference cell with scheduled spectral sensitivity.

introduction

Radiometric and spectrometric measurements are crucial for the assessment of a photovoltaic plant (PV) in terms of its efficiency. Any percentage error in the determination of the irradiance means almost directly the percentage gain or loss of the monetary value of the test object.

Tests and test procedures are i.a. specified in IEC60891 and IEC60904 (as well as ISO / DIS 15387 for space applications) [Ossenbrink2003]. The classification of the solar simulator (IEC60904-9) and the reference solar cells (IEC60904-2) and modules (IEC60904-6) as well as their traceability (IEC60904-4) and the utilization of the spectral correction factor (IEC60904-7) are among the decisive quality features of a correct power measurement in PV.

By default, the determination of the spectral irradiance of the following radiation is required:

• the spectral irradiance of the solar radiation Esoiar (λ) in field measurements

• the spectral irradiance of the solar simulator EsoSim (λ) for use in the spectral correction factor

• the energy content of spectral bands for the classification of the simulator State of the art

For measuring spectral irradiances, a "spectrometer with detector" is used, The prior art uses conventional dispersing grating spectrometers and a matrix or array of photodiode or CCD single receivers The suitability of devices for photovoltaic measurement tasks has to be called into question because so far the results do not seem to be sufficiently trustworthy, as evidenced by the fact that no institutional laboratory has an accredited classification Solar simulator (IEC60904-9).

The problems with the spectrometers extend across the entire device: from the input optics, the light guide, through the dispersion, to the receiver and the signal processing. The dynamics, linearity and calibration are critical.

The weaknesses can be seen most clearly in the measurement of xenon lamps, where the almost continuous spectrum in the visible and the xenon lines of the near infrared are energetically difficult to determine. The question of the measuring accuracy of the spectra of solar simulators is also publicly conducted [BrandOδ].

It is noted here that the use of a dispersive spectrometer is responsible for most problems in determining the spectral irradiance. Conceptually, the use of a filter spectral apparatus is required. For the mentioned measurement task, in particular for fast measurements in the millisecond range for pulsed solar simulators, a multichannel filter spectrometer was developed [W. Zaaiman 94]. In 64 separate modules (each 30x30x118mm ³ ), the silicon detectors with individual filters (bandwidths from 10 to 100nm) and tube equipped and individually to measure electrically. The structural arrangement is correspondingly large and circumferential and therefore difficult to bring in the horizontal plane of a solar simulator.

A recently proposed reference solar cell [GM] has a planar optical sensor (solar cell), which detects the radiation behind a graduated filter with location-dependent transmittance. With a mechanical aperture through The planned opening geometry allows the radiation to pass, resulting in a planned spectral sensitivity of the detector. Six spectral templates are required to perform the classification according to IEC 60904-9.

According to the prior art, the commercial reference solar cells with a particularly large height of more than 15mm. This is a constructive feature, which results from the integration of the socket in the housing. In principle, this height must be minimized so that the reference cell does not protrude from the measuring plane. More elaborate reference cells therefore have a thin area with solar cell and a thicker area with built-in sockets. If the sockets are in a screwed-on housing [GM], the device loses its compact size.

task

As an embodiment of said reference solar cell ([GM], claim 13) with scheduled spectral sensitivity, a plurality of individual electrically isolated solar cells are provided behind the graduated filter: "The reference cell according to the invention with a suitable set of spectral templates and / or a multiplicity of solar cells under the spectral template permit this Multiplexing method for determination of spectral irradiances /

In the mentioned document was not recognized and not named that this embodiment of the reference cell is a novel spectral apparatus. The spectral apparatus is a new mix of one

• Filter spectrometer used as a narrow or broadband photometer and a

• Spectral template device with location-dependent gradient filters with separate optical area sensors (photocells).

Such a novel device requires a (large) area and homogeneously detecting sensor, which, for practical reasons, is NOT otherwise used for optical measurements.

With this knowledge of the actual possibilities of this embodiment, a construction of the spectral apparatus is now necessary, which meets the special requirements of og. Applications is fair. These include the demands:

1.) Ensuring high measurement accuracy and associated reproducibility 2.) Possibilities of error analysis or simple characterization of the optical sensor

3.) Consideration of the mentioned standards

4.) compact, in particular flat design,

5.) Suitability for pulsed and stationary solar simulators as well as field measurements

6.) Multifunctionality.

In the sense of the demand for multifunctionality, an adaptation to the solar simulators to be tested with different irradiance levels, eg low light, 500VWm ² or 100OVWm ^{2 may be} significant. Another requirement is that the spectrometric sensor can be optimally adapted to the conditions of calibration and actual measurement. For example, as expected, the output signals of the individual photocells are different in size due to their production spread, but also due to the appropriate filtering. Therefore, a "suitable" resistor is chosen and placed in the immediate vicinity of the photocell.A (currentless) voltage measurement is unproblematic in terms of contact resistance.

Another object is to make a permanent solid electrical connection between the resistor (shunt) and the solar cell and still provide a person of ordinary skill an easily accessible way to replace the resistor.

Spectrometric sensor

The task is solved with the inventive construction of the spectrometric sensor (SMS) in detail as follows.

As is known, the spectral apparatus [GM] consists of the two-dimensional photocells, the graduated filter and one or more spectral templates. In order to be suitable for pulsed and stationary solar simulators (requirement 5), the spectral apparatus is not expanded to a spectrometer, ie the electrical signal measurement and processing of the optical sensors are entirely dispensed with. This makes sense because each solar simulator for the actual test objects also accredited voltage measuring devices are available, which are adapted to the simulator. ldR will thus limit the simultaneous measurements of multiple channels, but this is correct with respect to requirement (1). According to the invention, the spectral apparatus preferably has seven photocells, which takes into account the possible spectral resolution in a simultaneous measurement. According to the invention, the seven photocells are selected in terms of size of the active area and position such that the seven photocells substantially absorb the radiation of the seven spectral bands of [0.4 μm; 0.5μm], [0.5μm; 0.6 μm], [0.6 μm; 0.7μm], [0.7μm; 0.8μm], [0.8μm; 0.9μm], [0.9μm; 1.0μm] and [1.0μm; 1.1 μm] (requirement 3). For this, a corresponding mathematical calculation for surface and position must be carried out from the characteristics of the gradient filter.

The external measured value acquisition firstly requires signal conditioning of the photocell by means of a suitable shunt resistor and, secondly, a separable electrical connection becomes necessary. Both are achieved according to the prior art in the housing of a reference solar cell by means of resistance and plug-socket connection, but this would violate the requirement 4. There are seven times to make two electrical connection, since there is no need for a common electrical ground (requirement 1 and 6). According to a more compact, in particular thinner design of the device is achieved (claim 4) by the resistor is placed directly on the photocell (claim 1), but the male-female connection removed from the housing and wired into a second housing (Breakout Box) is used. The spectral apparatus can be positioned and attached separately to the breakout box. It is also a simpler handling of the male-female connection possible without the surface of the aperture and filter of the spectral apparatus to touch negligently. According to the cable from the resistor to the breakout box is permanently electrically connected and only a few decimeters long (claim 1). The cable shield is electrically connected to both housings (requirement 1).

According to the invention, the breakout box carries the 14 sockets of the leads to the photocells at a distance from each other such that by means of conventional shorting plug, the adjacent channels can be connected in series (claim 6). Thus, the adjacent voltage values can be added analogously from the seven spectral ranges (no common electrical mass, see above), which again represents the entire spectral apparatus with a suitable spectral template Reference solar cell with scheduled spectral sensitivity makes use (requirement 6).

Since the gradient filter i.d.R. an individual characteristic with regard to the transmittance and spatial assignment is also the geometric positioning of the photocells under the filter individually. Preferably, the filter should also be able to be measured on specially suitable instruments (claim 1 and 2) or otherwise used (claim 6). According to the invention sits the filter (typical dimensions 25mm x 200mm) in a separate holder that allows proper handling (requirement 1). If the filter can be moved over the row of photocells, there is another measurement possibility that allows a variation of the localized sizes. This allows further multiplex measuring methods (requirement 6) and in the simplest sense an error analysis of the device (requirement 2). In order to enable the local displacement of the filter, the spectral apparatus is designed so that the filter holder can be moved as a slide over the photocells mechanically (preferably slidably mounted).

With this mechanical arrangement of solid housing and sliding filter carriage, only a single one of the photocells can be used in a series of measurements. If, according to the invention, an opening is provided in the rear wall of the spectral apparatus, other detectors or light guides can receive the filtered radiation as a function of the filter position and thus of the transmittance (requirements 1, 2, 4 and 6).

A thin-film temperature resistance is permanently fixed in the middle photocell and the preferably four electrical lines according to the invention passed in conjunction with the cables of the photocells in the breakout box.

The consideration of different levels of irradiation (requirement 6) for the "closed" photocells is solved as follows: The housing 11 of the SMS (drawing) has one or more cavities which provide space for the resistors.The housing may advantageously consist essentially of two parts exist, one Base plate and a main part. The main part has in particular the slide bearing of the filter holder and the fitting holes for filter holder and spectral template.

According to the invention, the main part has an opening which is equipped with a lid. If the cover is removed (preferably unscrewed), the opening of the main part gives free access to the resistors, but expedient not on the photocells (requirement 1). By means of this structural feature, it is no longer necessary to remove the entire main part of the base plate in order to reach the resistors. The visually relevant part of the SMS remains advantageously untouched. Even with a different division of the housing (see drawing of the utility model DE 20 2005 020905.8) is a separate opening to the chamber of the resistors advantageous.

According to the invention, the resistors of the photocell are each held with individual terminals with screw connection. These terminals are potential free, i. insulated against the housing and allow screwing the two wire ends of the resistor (in the case of a round design). This feature advantageously allows an easily detachable but permanently stable electrically conductive connection of solar cell and resistor. Advantageously, the surfaces of the screw terminal and the resistance wire ends can be gold plated. Advantageously, the single terminals with screw connection provide one or more knock-out points (solder tag, contact point, bonding point) which allow the connection of the photocell and the (stranded) cable to the breakout box.

Another erfiπdungsgemäße execution of the task can be solved by means of a specially created board. The electrical lines of the board, the solder pads, solder tails and or similar connection components are designed so that the electrical leads to the solar cell and the break-out box can be independent of the contacting of the resistor for the life of the SMS, while the resistor is soldered or can be screwed.

According to the invention, the contacting of the resistor from the rest of the necessary wiring or wiring is sufficiently removed to prevent any defective heat flow during the soldering process or sufficient space for use of tools (crimping tool, bonding) or to exclude any mechanical stresses.

drawings

With these structural specifications, the construction of the spectral apparatus according to the invention as shown in the drawing results

Drawing "Fig.1" shows schematically the spectrometric sensor according to the invention (spectral apparatus) in plan view with adjoining spectral template.

Drawing "Fig.2" shows the spectrometric sensor (spectral apparatus) according to the invention in section with an attached spectral template.

10 Spectrometric sensor

11 housing with photocells, resistors and thin-film temperature resistance PtIOO and inserted filter slide

12 housings with sockets for contacting the photocells and the PtIOO

13 multi-core shielded cable

21 Position and size of a photocell, which is not visible through the overflow filter

22 gradient filter

23 Holder of the filter in design as sliding carriage

24 Direction of the linear displacement of the filter holder / filter carriage

26 Top of housing and position of underlying resistor (resistors not shown)

27 Position of the hole in the rear wall of the housing (not visible in supervision)

28 dowel pin for the filter carriage

29 one of the four dowel pins for the spectral template

30 Spectral template with four mating holes for exposure to 11 and an aperture that limits the field of view of the photocells 40 cable assembly with shielding

50 separate breakout box

51 four sockets for contacting the thin-film temperature resistor PtIOO

52 twice seven sockets for contacting the seven photocells

53 two jacks of adjacent photocells, which can be brought into electrical connection by means of a shorting plug, as well as all other neighboring photocells

60 spectral template

61 Photocell with two electrical conductors without further components

62 filter holder / filter slide

advantages

Compared to the reference solar cell according to [GM], the object of the invention provides the advantages (1) of ensuring high measuring accuracy and associated reproducibility, (2) possibilities of error analysis, (3) alignment with the cited standards, (4) compact design, ( 5) suitability for pulsed and stationary solar simulators as well as field measurements and (6) multifunction capability

Only a single spectral template is needed instead of six to perform a classification according to IEC60904-9. Several subcells of a multiple solar cell can be simulated with only one spectral template. The SMS has a low height, although a variety of sockets is necessary. The force-acting (negligent) handling of the jacks does not endanger the optical components.

Due to the construction according to the invention of the housing and the inventive construction of the contacting of the resistor with the solar cell can be advantageously achieved that

1) any resistor is easily accessible to remove or replace it if necessary,

2) each photocell can be operated as an "open" and "closed" reference cell,

3) the adjustment of the resistance can be made easily, 4) a permanent electrical connection is given without change in the contact resistance and so in total

5) the multifunctionality is increased.

Together with a voltage meter, the spectrometric sensor SMS becomes a spectrometer. Without using a template, or using only a single template, the SMS can be considered a 7-channel broadband spectrometer. If the voltage measurement can be correspondingly fast, e.g. be carried out in the millisecond range, or take place simultaneously on multiple channels, creates a short-term spectrometer or simultaneous spectrometer.

The classification for solar simulators for photovoltaics (IEC 60904-9) has broad limits with regard to the spectral reproduction of solar radiation. The following maximum deviations when comparing the energy contents of AM1.5global with the simulator spectrum in the spectral bands [0,4μm; 0.5μm], [0.5μm; 0.6 μm], [0.6 μm; 0.7μm], [0.7μm; 0.8μm], [0.8μm; 0.9μm], [0.9μm; 1.1μm] are allowed: +/- 25% for a class A simulator, +/- 40% for class B and +100% / - 60% for class C. This tolerant version of a specification already allows a spectral classification according to IEC60904- 9 with the SMS (without or) with only one template. In particular, the measurement of flashers, i. pulsed solar simulators, possible. This is already sufficient for a simple outdoor calibration of the SMS. In improvement of IEC60904 - 9 the interval [0,9μm; 1.1 μm] with a width of 200nm and 100nm apart, also divided into two sections.

A more accurate determination of the energy content in the individual spectral bands requires a correction of the spectral sensitivity of the seven individual sensors (photocell and transmission) to increase the spectral purity. This is achieved by a special spectral template, called 100nm template. It allows a largely constant spectral sensitivity in the corresponding spectral range, whereby the measurement result can be regarded as energy content. This makes the SMS a spectroradiometer. According to the invention, this is possible with only a single spectral template, which also allows simultaneous measurements. If the spectral templates are used only in the form of individual slots, a narrow-band spectrometer is produced, which represents the preferred variant, in particular for the calibration of the SMS. If one considers a single measuring channel, then this is based on a planar solar cell with a part of the graduated filter with location-dependent transmission. The single slots allow a legitimate transmitted radiation to pass. Through a systematic variation of the transmission profile in a series of measurements with subsequent measurement processing, the SMS fulfills the task of a multiplex spectrometer in the Hadamard method.

The individual photocells of the SMS can be measured separately in 7 channels, but are also suitable for series connection: the typical output signals in the millivolt range are matched by the selection of suitable resistors (shunts) to each other, so that the use of short-circuit plugs in the breakout box gives a meaningful sum of the individual channels. The resulting spectral response (SR) of the SMS results from the spatially resolved transmission of the gradient filter and the SR of the photocells.

Using a special spectral template with a specific geometric opening, a correspondingly specific spectral sensitivity (SR) is achieved. Thus, a given SR can be recreated by means of a spectral template. The SMS is transformed into a solar cell with spectral sensitivity by means of a spectral template. Here, too, the channels can be individually measured or even a template for a series connection interpret. This also creates a single output signal for a SR.

In the case of solar cells with several pn junctions, typically tandem solar cells or cells with up to 6 transitions (development for space application), the special spectral properties must be taken into account when measuring the current-voltage characteristic. In particular, the procurement and calibration of detectors for the near infrared have so far been problematic and not standardized. The SMS allows any subcell of a multiple solar cell in its spectral To simulate sensitivity. Depending on the position of the band edges, several subcells can also be used simultaneously by a template. Series connection or separate measurement of the individual channels takes place accordingly.

The determination of actinic irradiances for the spectrometric investigation of multiple solar cells and the determination of the actinicity (DIN 67519) are possible with the SMS.

The reproduction of the color vision of a visual observer for photometry, ie the measurement of color values, takes place in a corresponding procedure.

Furthermore, the slide with graduated filter can be moved linearly over the photocells in a mechanically sliding manner and removed from the device for further measurement and other measurements. By varying the displacement of the filter carriage, it is also possible to measure adjacent spectral ranges below 400 nm and above 1100 nm. Also, a sensitivity analysis of the measurement results can be carried out very quickly, which lends itself when used as a broadband spectrometer. Due to the symmetrical design, even the carriage can be inserted in the alternative manner, which leads to a new assignment of the individual photocells to the spectral regions. Also, only a single solar cell can be evaluated as a detector under the linearly displaceable graduated filter. This comes very close to the original use of the graduated filter, which dates back to a time when the use of only the smallest area detectors was common.

The possibilities of the spectral templates, the electrically separated photocells and the possible series connection of the individual channels results in the use of the spectrometric sensor SMS as

• 7-channel broadband and narrow band spectrometer

• Multiplex spectrometer in the Hadamard method

• Meter for actinic irradiances and color values

• Reference solar cell with a selectable spectral sensitivity

The overall properties of the SMS spectrometric sensor make it suitable for use as a reference solar cell and spectrometer. fonts

[GM] Utility Model 20 2005 020 905.8

[Ossenbrink 03] H. Ossenbrink, Calibration Procedures, 3rd World Conference on Photovoltaic Energy Conversion, Osaka, 2003

[Brand 05]. Brand, Hit by the Peaks, Photon International, Nov. 2005.

[Zaaiman 94] W. Zaaiman, H.A. Ossenbrink, M. Mertens, SpectraCube: a near spectroradiometer for pulsed simulator spectral mismatch corections, is WCPEC, Hawaii, 1994

Claims

Expectations:

(1) Optical multi-channel detector in the sense of a spectral apparatus and in the sense of a reference solar cell (IEC60904-2) consisting of several flat photocells arranged side by side, a graduated filter above them and one or more spectral templates with a planned aperture, characterized in that exactly seven electrically separated photocells in their position and size (the active area) in relation to the linear graduated filter are attached and tailored in such a way that the seven resulting spectral sensitivities largely cover the corresponding seven wavelength ranges [0.4μm; 0.5μm], [0.5μm; 0.6μm], [0.6μm; 0.7μm], [0.7μm; 0.8μm], [0.8μm; 0.9μm], [0.9μm; 1.1 μm], i.e. the spectral sensitivity generates a measurable signal in the wavelength range in question and outside of this the signal disappears.

(2) Optical multi-channel detector in the sense of a spectral apparatus and in the sense of a reference solar cell (IEC60904-2) consisting of several flat photocells arranged side by side, a graduated filter above them and one or more spectral templates with a planned aperture, characterized in that an independent holder holds the graduated filter housed, this holder is reproducibly fixed in the original position with a removable pin and this holder can be moved linearly as a slide-bearing slide above the photocells, whereby the assignment of the photocells to the location-dependent transmission of the graduated filter is changed as planned.

(3) Optical multi-channel detector in the sense of a spectral apparatus and in the sense of a reference solar cell (IEC60904-2) consisting of several flat photocells arranged next to one another, a graduated filter above them and one or more spectral templates with a planned aperture opening, characterized in that the resistors belonging to the photo cells have an electrical connection in their immediate vicinity and the live measuring lines of all photo cells in the network (shielded multi-core cable) reach the two measuring sockets per photo cell in a housing only a few (two to three) decimeters away.

(4) Spectrometric sensor according to claim (3), characterized in that the opposite polarity sockets of adjacent photocells have exactly the same distance (19mm in the case of 4mm laboratory plugs) that an electrical series connection of adjacent photocells is created using conventional short-circuit plugs, i.e. up to seven photocells in Series can be connected to an output signal.

(5) Spectrometric sensor according to claim (2), characterized in that the back of the housing, in the sense of a base plate on which the photocells are positioned, has an additional free area with a hole that allows the insertion of an additional detector or a radiation recording (light guide). makes it possible to use the linearly movable filter slide for spectral separation in other applications.

(6) Spectrometric sensor according to claim (2), characterized in that the slide-mounted filter holder is built symmetrically and can therefore be moved above the photocells in at least two variants.

(7) Optical multi-channel detector according to one or more of the preceding claims, characterized in that the housing has an opening (to be provided with a cover) which allows access to the underlying resistors in order to be able to remove or replace them without having to open other parts of the apparatus.

(8) Optical multi-channel detector according to one or more of the aforementioned claims, characterized in that the resistors are each located in screw terminals or the connection points of the resistors are spatially separated from the further necessary wiring in such a way that a simple process (screwing, soldering, crimping) creates a permanent connection of the resistors without this process having a harmful influence (heat, mechanical stress) on the rest of the device.

(9) Optical multi-channel detector in the sense of a spectral apparatus and in the sense of a reference solar cell (IEC60904-2) consisting of several flat photocells arranged next to one another, a graduated filter above them and one or more spectral templates with a planned aperture, characterized in that claims (1) , (2), (3), (4), (5), (6), (7) and (8) all or selected in a single device.