WO2019162254A1

WO2019162254A1 - Arrangement of solar elements and method for interconnecting solar elements

Info

Publication number: WO2019162254A1
Application number: PCT/EP2019/054051
Authority: WO
Inventors: Hubert Volz; Frank Mammen
Original assignee: Turck Duotec GmbH
Priority date: 2018-02-20
Filing date: 2019-02-19
Publication date: 2019-08-29
Also published as: DE102018103740A1

Abstract

The invention relates to an arrangement of a plurality of solar elements and a plurality of switches, the switches being able to dynamically interconnect the solar elements to different electrical arrangements in different ways during operation, and to a method for interconnecting solar elements using switches, an interconnection or a performance difference between different solar elements being detected and the solar elements being classified into different groups according to their current performance or currently possible maximum performance or the current lighting conditions, and the solar elements of each group being interconnected.

Description

Arrangement of solar elements and method for interconnecting solar elements

The present invention relates to the energy management of an arrangement of solar elements, in particular a solar system and the heat management of plant components such as junction boxes in solar systems and in general a concept for interconnecting voltage-limited power sources.

Series switching of solar cells leads to problems with partial shading, since a shaded solar cell can block the flow of current of others and thereby damage itself.

Since these processes occur dynamically during operation, a rigid interconnection of the solar cells, as in the prior art, is problematic.

The presented dynamic interconnection is a further development of teachings from the publications DE102011055754A1 and WO2012163908A2.

Bypass diodes designed to protect single cells or cell strands function much like a voltage-controlled switch. In an integrated form, the z. B. known as a cool bypass switch.

A dynamic interconnection can solve further problems, which are named in the state of the art. These include protection for firefighters, as in the

JP2014068509 (A) as well as a power limitation as in US 2015155818 A1.

The problem of the so-called thermal runaways (thermal runaway with self-destruction) of bypass diodes is pointed out in EP1970965A1.

Starting from the prior art, the invention has for its object to design an electrical circuit concept, which avoids the disadvantages mentioned above from the prior art.

This object is achieved by an arrangement of a plurality of solar elements with a plurality of switches, wherein the switches, the solar elements in different electrical Dynamically interconnect devices during operation in various ways.

Thus, a dynamic interconnection concept is proposed, which performs an adaptation of the interconnection of solar elements during operation depending on the shading situation or power output of the solar elements.

In particular, the object is achieved by a solar cell arrangement comprising a plurality of solar elements, a plurality of switches for producing and interrupting electrical connections between the solar elements and a control unit, wherein the control unit is set up to interconnect the solar elements into different electrical arrangements by means of the switches. in particular dynamically interconnect during operation of the solar elements in different electrical arrangements with each other.

In addition, the object is achieved by a solar cell arrangement, wherein the solar cell arrangement comprises a plurality of solar elements and a plurality of switches for producing and interrupting electrical connections between the solar elements. The multiple switches are designed as diodes and can be controlled by an electrical voltage provided by the solar elements in order to interconnect the solar elements in different electrical arrangements.

The fact that the diodes are controllable by an electrical voltage provided by the solar elements means preferably that they are controlled exclusively by the voltage provided by the solar elements. In particular, the switches designed as diodes preferably do not require any logic element and, in particular, no control unit to be controlled, but can be controlled exclusively by the voltage of the solar elements. Preferably, one or more diodes are each associated with a solar element and are controlled by the voltage provided by the respective solar element. For example, the control of the switches designed as diodes can be carried out such that the electrical resistance and / or the permeability of the respective diode depends on the voltage of the solar element to which the diode is assigned. A solar element is a photo power source. The solar elements preferably comprise individual solar cells, groups of solar cells and / or solar modules. A solar cell preferably includes a photodiode so as to provide electrical energy. A solar cell is preferably a photoelectric current source, particularly preferably a photodiode in the photoelement operating mode. A solar cell preferably has a semiconductor junction, preferably a silicon semiconductor junction, with properties dependent on the irradiation light. The solar cell can have at least two electrical connections, from which a generator current dependent on the irradiation light can be removed. A solar cell group or group of solar cells is a number of solar cells, which is either fixed (then referred to as a string or string) or dynamically interconnected (then called a group) and can be controlled as a solar element. Preferably, a solar cell group is assigned a bypass diode (it provides an additional current path for photo currents that are not covered by the dynamic interconnection of the solar cell groups). A solar module is an arrangement of prefabricated solar cell groups or strings. All these solar elements can be at the same level, ie solar cells with one another, solar cell groups or strings with one another or solar modules with one another, or at different levels, ie solar cells with solar groups or strings and / or solar modules or solar cell groups with solar modules or also at the same level, ie solar cells with solar cells, solar cell strings with solar cell strings, solar cell groups with solar cell groups and solar modules with solar modules are interconnected.

This makes it possible to combine the solar elements, which have a similar shadowing, and in this way an optimized interconnection of solar elements with similar current characteristics can be made.

The solar elements in their dynamic interconnection then together form a solar generator which can switch the individual solar elements in parallel or in series and thus can optimize the current yield with simultaneous protection against overload as a function of the shading situation.

The control unit has the control logic for the switches. The control unit preferably comprises a microcontroller or microprocessor. By the control unit is It is preferably possible by means of at least some of the switches to be able to interconnect at least some of the solar elements into different different electrical arrangements during the operation of the solar elements in at least two different ways.

The switches are preferably electrically and / or electronically and / or optically and / or electromagnetically controllable - preferably wire / cable-bound - switches (units). The actuators of the switches are preferably relay contacts, drain-source paths of (MOS) FET or C-E paths of bipolar transistors. Preferably, other switches such as electromechanical switches (relays) or magnetic switches (transducers) are provided. Preferably, the switches can be controlled several times by the electronic control unit and can be switched over several times (can be switched on, switched off). The different electrical arrangements comprise a series circuit, a parallel circuit or a combination of series and parallel connection (group circuit), so that some solar elements are connected in series with each other and thus form a solar element group and other solar elements can be connected in parallel to this group. In this case, solar elements of approximately the same or preferably the same current intensity are preferably connected in series, preferably when the current intensity of the individual solar elements deviate from one another by no more than 10%. Solar elements are preferably connected in parallel if the output voltage of the different solar elements is as large as possible, preferably not more than 10% differ from each other.

If unequal solar elements are connected in parallel with respect to the voltage, equalizing currents occur, which reduce the efficiency of the solar generator and irreversibly damage it depending on the size of the currents. If different solar elements are connected in series with respect to the current intensity, then a part of the solar elements blocks and can thereby take irreversible damage. Therefore, solar elements with the same temperature, the same efficiency and also the same illumination are preferably dynamically selected by the control unit to belong to a group and connected together. Preferably, the interconnection of the solar elements takes place locally, whereby a high degree of freedom for the consideration of different shading scenarios for individual solar elements is achieved. Particularly preferably, an interconnection of solar elements can be provided which is set up for expected shading scenarios, ie that the interconnection of solar elements is preconfigured according to the expected shading scenarios. The dynamic interconnection is therefore preferably constructed according to the most frequently occurring types of shading. As a result, switches are saved compared with a local connection

The technical disadvantages of the prior art solar systems, which must be compensated by the prior art (that is to say on the output side) by means of downstream electronics, can be avoided by the present invention. Due to the variable electrical interconnection of the solar elements, the current output is optimized on the input side and not on the output side. In addition, the optional features such as emergency shutdown, intrinsic safety and AC output are already formed on the input side and no longer as an add-on on the output side. Particularly preferably, an n × m topology can be selected and individual solar elements can be freely configured with each other. If specific shading can be predicted on the basis of the specific application, the solar elements can be preconfigured in the expected geometry and subdivided along the shading boundaries into solar elements or solar strings in order to perform an interconnection of these solar elements thus formed. As a result, can be dispensed with overhead for a completely free interconnection and unnecessary switching elements for this specific application of shading can be saved. Preferably, the switches comprise transistors and / or MOSFETS and / or power MOSFETs.

MOSFETs are Metal Oxide Semiconductor Field Effect Transistors, and Power MOSFETs are a specialized version of a MOSFET optimized for the conduction and blocking of large electric currents and voltages (up to several hundred amperes and up to about 1000V, with a component volume of about one cubic centimeter). Switching is preferably also possible in the current-supplying operating state of the arrangement, so that too high a voltage at the switches / FETs up to approximately 2000 V can be avoided, which would otherwise lead to high RDSon (switch-on resistances) and power losses when using high-voltage MOSFETs would. The control unit preferably comprises a microprocessor and is set up to switch the switches in such a way that the electrical arrangement has a plurality of current / power levels, ie buses, to which the solar elements are connected depending on their current power output. In this way it is possible to combine the solar elements according to their power / output and to connect a bus which corresponds to this power / output.

The solar power of the solar elements is proportional to the lighting. Solar modules can be shaded by objects in the environment. These often have straight edges, whereby the shadows also have straight edges. In the simple case, one can form three classes of shading:

Unshaded solar elements

Fully shaded solar elements and

Partially shaded solar elements along a shadow edge

Thus, a division into three power buses is preferably made: High: 100% power = unshaded

Low: 30% current due to the diffuse background radiation with 30% share with full shading

Mid: 65 ± 30% current through lighting along a shadow edge Thus, in one group can be an equal number of solar elements, it can also be a different number of solar elements, if they have a different level. Preferably, N-power buses are combined into a power bus.

A solar cell arrangement preferably comprises a connection for an intermediate consumer, preferably an inverter or a converter. About this connection, such an intermediate consumer can be connected. Preferably, an impedance converter is provided as an intermediate consumer with controllable or adjustable or self-adjusting optimum impedance as a function of the (average) impedance of the source (s), especially according to the MPPT method (maximum power point tracking). Furthermore, an operation of the solar generator is preferably provided as an inverter, which acts as a DC-AC / AV converter and converts the DC photovoltaic current of the solar generator into AC voltage. In this case, an inverter operating mode is particularly preferably used, with which an AC bus with medium frequencies of at least 50 kHz, preferably from 100 kHz, can be generated. In this way, in the event of a breakdown of the solar element, for example contact after an accident, the current can flow away via the skin and not via the heart. Preferably, in order to be able to use the customary 50 Hz output voltage inverters according to the state of the art for the power supply, a rectifier is connected upstream of the input of these inverters, which is the common current used in the prior art for the 50 Hz inverter supplies. A preferred embodiment is an active rectifier which has the advantage of higher efficiency over bridge rectifiers. Active rectifiers consist of transistor switches (NMOS) with suitable control unit and replace in their function the diodes of the bridge rectifier.

In a further embodiment, the solar generator can deliver the 50 Hz alternating current in the operating mode "stand-alone operation" (feed-in into a power island) while a possible "grid operation" (feed-in into the public power grid) is described above. In a further exemplary embodiment of the solar cell arrangement, the solar elements are arranged in an mxn, in particular a 2 × 2 or 3 × 3 topology, and the switches are arranged such that n solar elements can be connected in series in an mxn topology and thus form a string , Preferably, a bypass diode is connected in parallel with each of the n strings. Preferably, quadratic topologies are used so that m = n.

To be able to switch solar element groups in parallel, they must have the same voltage and therefore the same number of cells. With ideal power sources, the number of cells is negligible, but solar cells are power sources with intrinsic diodes connected in parallel. Therefore, a parallel connection of different numbers of solar cells can lead to equalization currents and thus to loss of yield, ie to lower the efficiency. Therefore, it is preferable to divide the solar elements or solar cells into n × n groups, since it is possible to construct cell strands or groups of equal length which can be connected in parallel without any disadvantage. In order to cover error cases in the circuit, each of these n cell strands is preferably connected in parallel with a bypass diode in each case. Preferably, a fourth diode is connected via the input and output of the electrical two-pole of the solar element. This reduces the diode losses. As a result, the current flow is ensured by the solar element at any time of dynamic interconnection, including during switching. In a further exemplary embodiment, the switches are arranged such that the solar elements can be interconnected in groups in the horizontal direction, in the vertical direction, in the diagonal orientation or at the corner. It is thus possible, for example, to group together the solar elements in a row, in a column, in the diagonals or the solar elements arranged at a corner in a square arrangement of solar elements arranged in columns and rows. Preferably, an equal number of solar elements are always interconnected in each case in a group, so that when selecting the diagonals, parallel diagonals are also grouped together. For example, with a 3x3 matrix with the elements 1.1 to 3.3, it is possible to have three groups at diago- nale orientation, namely the average diagonal consisting of the three individual elements 1.1, 2.2 and 3.3 and the respective adjacent solar elements 2.1, 3.1 and 3.2 and 1.2, 1.3 and 2.3. Also, the orthogonal division is conceivable, ie 1.1, 1.2, 2.1 / 1.3.2.2, 3.1 / 2.3, 3.2, 3.3. With an alignment over corner or an angular orientation, it is possible to form two groups of four solar elements, for example, the solar elements 1.1, 1.2, 2.1, 2.2 and 1.3, 2.3, 3.1, 3.2, 3.3. Particularly preferably, one cell from the group with five cells is left uncontacted in order to avoid undesired equalizing currents in a parallel connection of 4 + 5 cells and thus to have two groups of four groups in a parallel circuit. In the case of horizontal alignment, the three lines are grouped together (1.1, 1.2, 1.3 / 2.1, 2.2, 2.3 / 3.1, 3.2, 3.3) and in vertical alignment the three columns (1.1, 2.1, 3.1 / 1.2, 2.2, 3.2 / 1.3, 2.3, 3.3). This is correspondingly feasible for smaller or larger square arrangements. In a further embodiment, the switches are arranged so that some or all groups can be interconnected in parallel. If the groups consist of an equal number of solar elements that are similarly shadowed, they have the same maximum output current and are therefore similar. This allows the individual solar elements to be connected in series to form a group. If the output voltage of the different groups of solar elements is the same, they can be switched in parallel. It is thus possible, for example, in the case of a vertical shading of the first two columns 1 and 2, the groups of the first column and the second column to connect in parallel and then in series to the third (not shaded) group.

The object is also achieved by a method for the dynamic interconnection of solar elements with switches via a control unit, wherein a shading or a power difference between different solar elements (20) is detected, for. For example, by measuring by means of MPPT, the solar elements are classified into different groups according to their current performance or currently possible maximum power or the current lighting state, and the solar elements of each group are interconnected. By means of this dynamic interconnection of the solar elements during operation, groups of similar solar elements can be identified and interconnected in such a way that the individual solar elements larelemente take no damage and the overall arrangement of the solar elements has a high efficiency.

Specifically, it is possible, for example, to make a shading-adapted selection of solar cells or solar elements by defining a plurality of current classes / buses. Arrangements of solar elements may be shaded by objects in the environment. These often have straight edges, so the shadows also have straight edges. If you look at a partially shaded arrangement of solar elements, then you see

Unshaded solar elements

Fully shaded solar elements and

Partially shaded solar elements along a shadow edge Since the solar power of the cells is proportional to the lighting, it is preferable to divide them into three power buses:

High: 100% power = not shaded

Mid: 65 ± 30% current through lighting along a shadow edge

If the electrical interconnection runs parallel to a shadow edge, the power loss is lower than if the interconnection is perpendicular to it. In this case, a straight shadow affects all solar elements, even if they are only partially shaded. Therefore, it is preferably provided to combine the solar elements into groups of similar solar elements and then to interconnect them, so that the highest possible efficiency of the arrangement of solar elements is achieved.

Preferably, the rigid electrical circuitry of the environment is adapted by arranging the arrangement of solar elements or solar modules preferably horizontally or vertically. However, even if the environment produces preferably vertically aligned shadow edges, in winter you have snowboards on the solar panels. modules that produce horizontal shadow edges. The power output in winter is by no means low, since the solar modules are cold and have a high efficiency and the radiation can occur despite the cold with high radiation intensity. Therefore, a decision for an interconnection direction (= geometric orientation of the solar modules) is always only temporary optimal. By the claimed method, a solution is provided to achieve an optimized interconnection of the solar elements in these scenarios and thus on the one hand to protect the individual solar elements from damage and on the other hand to increase the efficiency of the arrangement of solar elements

For example, the expected shading alignments by buildings are:

Horizontal

Vertical

Diagonal

Diagonally rotated by 90 ° (orthogonal)

Angular or over corner

A dynamic interconnection is effected by a spatial combination of solar elements, in particular of solar cells, according to the geometrical shading orientation just described. The geometric division of the cell matrix is always as parallel as possible to a shadow edge. This is the strategy for cell division horizontally, vertically, diagonally, orthogonally. The geometrical divisions just listed are optimal for shading with straight shadow edges parallel to each other. Angular shadings, however, have two orthogonal shadow edges. These are preferably split up like diagonal shadows to keep the directional selection of cells simple. In the case of angular shading, it is preferable to carry out a location-independent division into three power buses and to carry out an electrical conversion of the power sources into voltage sources by means of three MPPTs for the electrical interconnection.

Preferably, a circuit-technical summary of the three power buses in one with downstream MPPT done. This method is used in order to make a single dipole from the three current busses high, medium, low, ie the three double poles (H, M, L-Bus), which consist of the interconnected strands, by way of example. This is done by optional series connection S1 + S2 + S3

Parallel connection S1 || S2 || S3

group circuit

Variant 1: S1 + (S2 || S3) Abbreviated notation: G1

Variant 2: S2 + (S1 || S3) "G2

Variant 3: S3 + (S1 || S2) "G3

In this way, a method is provided with which individual solar elements in an array of solar elements, preferably using MPPT are so switched together that the individual solar elements are estimated from irreversible damage, in particular by series connection of different current with respect to the solar elements and on the other hand the efficiency of the arrangement of solar elements is increased.

Preferably, the solar elements of a group are connected in series, more preferably, some or all groups are connected in parallel.

Particularly preferably, the solar elements will be switched so that at least one of the following functions is realized:

- alternately switching the polarity of the entire arrangement of solar elements, suitable for generating an alternating current;

- Generating an AC voltage greater than 50 Hz, in particular 300 kHz;

- Making the voltage free of the entire arrangement of the solar elements to the outside, i. an emergency shutdown;

- emergency shutdown when temperature exceeds a temperature monitoring of at least one of the solar elements, in particular for fire protection.

Preferably, a set of the solar elements form a module and a microcontroller or programmable microprocessor realizes at least one of the following functions: - Monitoring of operating status, current, voltage, temperature or hardware check of at least one of the solar elements and the electronics for the dynamic interconnection (self-check);

- Realization of a SMART module with a set of solar elements forming a module;

- Arc detection and module shutdown;

- theft protection and location detection;

- monitoring the exceeding of the operating temperature and initiation of lightning protection measures;

- Visual and / or acoustic identification, if the module is defective.

Preferably, the plurality of switches are formed as a diode matrix circuit.

The diode matrix circuit is preferably designed such that the solar elements are connected to one another as an m × n matrix, as described above, and can be interconnected in different arrangements. For example, the matrix may be formed as a 3 x 3 matrix. In this case, the diode matrix circuit has the advantage that a dynamic interconnection of the solar elements can take place, wherein the interconnection or a change in the interconnection preferably takes place automatically by means of the diodes controlled by the voltage of the solar elements, without the intervention of a control unit being absolutely necessary. This offers the advantage that the dynamic interconnection can be carried out particularly efficiently and in particular in a passive manner. Furthermore, this offers the advantage that the dynamic interconnection and its change can take place particularly quickly, since no previous calculations by means of a control unit are required, which first determine the suitable interconnection in view of the present shading of the solar elements and then one For this purpose, calculate the appropriate interconnection of the solar elements.

The solar cell arrangement preferably comprises at least one pole turner, wherein the solar cell arrangement is designed to at least partially parallel the plurality of solar elements by means of the pole turner. In particular, the pole wheel is designed to at least partially repolder the solar elements within an mxn matrix, in particular within a 3 × 3 matrix, in order to distinguish between a parallel matrix. To change lelschaltung and a series circuit at least some of the solar panels. This offers the advantage that even if, for example, a full shading is present, ie if all the solar elements (the mxn matrix) are shaded and therefore the voltage of all solar elements is low, an interconnection of the solar elements can be achieved in an advantageous arrangement. For example, in the case of full shading, the diode matrix circuit would lead to an arrangement of the solar elements, in which all the solar elements of the solar cell array are connected in series, which may be detrimental to the current flow through the solar elements. In the case of full shading, the solar elements, such as the strands of a mxn matrix, can then be switched at least partially in parallel by means of the pole changer, so that a sufficient current flow through the solar elements can be maintained and in this way a more efficient operation of the solar cell - Can be achieved lenanordnung than would be the case with the series connection of the Solarelemen- te. For example, the solar elements of the solar cell array may be arranged in a plurality of strings, which are all connected in series, for example, in the case of complete irradiation or illumination of the solar elements, ie in the case of unshaded solar elements. By means of the pole turner, one or more of the strings can then be reversed in full or partial shading, so that the strings are no longer connected in series but at least partially, preferably completely, in parallel, which may be advantageous for partially or fully shaded conditions.

According to a preferred embodiment, the solar cell arrangement has a first strand of solar elements or solar cells and a second strand of solar elements or solar cells connected in parallel to the first strand, the second strand having a smaller number of solar elements or solar cells than the first strand , Furthermore, the solar cell arrangement according to this embodiment has a diode which is arranged in series with the second string and in parallel with the first string. This offers the advantage that a parallel connection of several strands is made possible, which have a different number of solar elements, without causing a compensating current between the arms of the parallel connection due to the different number of solar elements or solar cells or such a compensating current at least reduced. A field of application for dynamic interconnection is the increase in yield of solar systems. Another field of application is the thermal relief of bypass diodes. This makes the use in difficult environments, such as in a solar facade makes sense, as in this way an undesirable heating of the air space behind the cold facade can be reduced or avoided. This can in particular help prevent the reaching and / or exceeding of a limit temperature at which damage to the solar facade can occur, for example at or above temperatures of 75 ° C. or 90 ° C. For example, the achievement and / or exceeding of such high temperatures can result in bypass diodes being insufficiently cooled and thus being damaged. This risk can be reduced by an optimized dynamic interconnection, since the bypass diode current can preferably be considerably reduced and, with particular preference, can be substantially completely eliminated. For example, it can be accomplished that in the bypass diodes only the reverse current of the diode flows, which is typically in the range 10E-3 to 10E-6 amperes.

Preferably, a conventional electronic circuit, as described, for example, in US 2014/0375145 A1, can be used to operate a solar cell arrangement with additional electronics for a dynamic interconnection, for example with a diode matrix circuit and / or a polarity reversal circuit. Preferably, the circuit is designed to be able to provide sufficient electrical energy for the additional electronics of the solar module, even with full shading of a solar module.

For example, a circuit according to US 2014/0375145 A1 can be used, as for example in the figure of the summary of the US

2014 / 0375145A1. If the strands V1 to V3 are each 20 cells long, the voltage across a cell string is 12V, since the voltage of a cell in the maximum power point is usually 0.6V. The three strands V1 to V3 thus comprise a total of 60 cells. As switch P a PMOS or PNP transistor could be used. Also, an electromechanical relay could be used. The switch P could alternatively also be mounted between the diode D1 and the cell string V1. When the voltage between contacts 2 and 3 below a Threshold drops, then you can open the switch P, whereby the voltage at D4 with respect to contact 3 increases again or at least not below a wide range (3V to 30V) adjustable threshold decreases. In addition, will

Auxiliary power stored in the capacitor C1, so that one has several seconds to minutes time to initiate the switching operation of the switch P.

It is understood that the above and below explained embodiments and features are to be considered not only as single and disclosed in the respective combinations explained, but also in other technically feasible combinations. In particular, the preferred features, which are disclosed in example with respect to a solar cell arrangement having a control unit, are also to be regarded as disclosed with respect to an embodiment with switches configured as diodes or with diode matrix circuitry.

Embodiments of the invention are explained below with reference to the drawings.

Show it:

1 shows a solar cell string with bypass diode,

2 shows a solar module with 3 solar cell strings with bypass diodes,

3 shows a circuit symbol and equivalent circuit diagram of a solar cell,

4 shows a power and voltage curve of a partially shaded module,

5 shows a power and voltage curve of an unshaded module,

Fig. 6 shows a solar generator with parallel solar cell strings, thereof a string shortened electrically

7 shows the operating points for a return current under and without load,

8 shows a solar system with one serial diode per solar cell string,

9 is a group circuit,

10 shows a solar cell arrangement with further diodes,

11 solar modules in series connection according to the prior art,

12 shows a dynamic series connection of solar cells with the same maximum current and division into 3 different current levels,

13 shows a solar module with a summary of the three power buses of FIG. 12 in one Power bus through MPPT

14 shows a series connection of solar modules of the type from FIG. 13

15 shows a rigid series connection of solar modules with MPPTs according to the prior art,

16 shows a horizontal shading with dynamic interconnection, with bypass diodes in Dickman circuit, see US Pat. 6225793 Serial No. 09545328 Fig. 17 is a circuit diagram for a simulation of a series circuit,

18 shows an example of a temporal sequence of shading,

Fig. 19 enlarges the sequence of shading,

20 is a power curve of a 3x3 solar cell group,

21 is a power curve of a 3x3 solar cell array orthogonal,

22 shows an example of a vertical shading,

23 shows an example of a diagonal shading,

FIG. 23 a diagonal shadowing groups, FIG.

FIG. 23b shows groups of currents for orthogonal diagonal shading, FIG.

24 shows an example of an angle-shaped shading,

Fig. 25 MOS switch,

FIG. 26 shows an interconnection concept for the dynamic interconnection, FIG.

27 shows an arrangement of solar elements according to a preferred embodiment with a crossbar distributor (serial, parallel, all group circuits G1..G3),

28 shows an arrangement of solar elements according to a preferred embodiment with a simplified group circuit (only G1 and G3),

29 different arrangements of the solar elements along shadow edges, FIG. 30 a pole reversal circuit for AC output,

FIG. 31 shows a circuit of cell strings in parallel connection with different number of solar cells), FIG.

32 is a diode matrix circuit with Polwender,

33 a Polwender,

FIG. 34 shows a solar cell arrangement without polarity reverser for the crossbar distributor according to FIG. 26, FIG.

35 to 38 solar cell arrangements with preferred cell divisions for 120VDC system voltage and with different numbers of solar cells in 3 x 3 Matritzen, 39 shows a solar cell arrangement with diode matrix circuit and Polwenderschal- device.

Solar modules according to the prior art are designed for ideal installation in a solar system. This includes the lack of shading, a homogeneous orientation in a direction of the flats and sufficient ventilation. If this is not the case, then significant yield losses and electrical and thermal stress for the plant. In freestanding solar systems, the lighting situation can be improved by mechanically tracking the solar cells or solar modules with so-called trackers. In solar modules, which are attached to the building (BAPV Building Attached Photovoltaics such as rooftop systems and also BIPV Building Integrated Photovoltaics such as solar façades) is not or only with difficulty possible. When mounting on a building envelope, shadowing is to be expected already for geometric reasons (projections, bay windows, chimneys, antennas, etc.). According to the state of the art, shadowed parts of the building envelope are therefore often left out. This problem is inventively solved in that instead of the mechanical tracking a concept of electrical tracking of the system is presented. Thus, moving and thus error-prone parts can be avoided.

The present presentation focuses on crystalline solar cells, where the situation is the most problematic due to the high currents. Solar modules consist of a series connection of solar cells. Solar cells are not voltage but current sources. A solar cell provides a Lichtein radiation proportional electrical current. Ideal current sources have an infinitely high output voltage According to the usual rules of electrical engineering, one would have to switch parallel current sources. However, since the solar cells have only a low real output voltage of about 0.6 V at the maximum power point (MPP), they are still connected in series (as a string) in order to achieve technically usable input voltages. The output voltage of such a series circuit from solar cells may currently be up to 1500 VDC. The same applies to individual solar modules, which are often connected in series, in order to deliver a voltage that an inverter can usefully convert to a grid-compatible AC voltage. Is a solar cell in this series - consisting of z. For example, when 2000 solar cells are shaded, they not only supply a small amount of electricity, but worse, they also block the large current flow of the remaining unshaded solar cells. It breaks down rather than yielding to the flow of electricity. This is an essential feature of power sources. However, the output voltage of the unshaded cells is large enough to force the current through the shaded cell. In order to protect the shaded solar cell from self-destruction, bypass diodes are inserted in sections in the series circuit, which bypasses the "excess" current around the shaded solar cell. Such a section of an arrangement of solar cells, referred to as a solar cell string (SZS), comprising an electrical series connection of 20 solar cells SC is shown in FIG. On the right in the circuit diagram is the bypass diode D1.

SZS according to the prior art consist of 20 or 24 solar cells. When connecting the solar cells in series, the best solution in terms of energy yield is to provide each solar cell with a bypass diode. To reduce the purchase price of the solar module, however, SZS are used with a bypass diode (Fig.1). The shaded cell sees in the bypass case, the voltage of all remaining solar cells of the SZS plus the forward voltage of the bypass diode. The number of solar cells in a SZS is therefore limited by the blocking voltage of the solar cells used. Solar modules made of crystalline solar cells therefore exist z. B. from 3 SZS with 3x20 = 60 or 3x24 = 72 cells.

Figure 2 (Source: wdwd - Own work, CC-BY-SA 4.0,

https://commons.wikimedia.org/w/index.php?curid=3930368l) shows a solar module consisting of three solar cell strings SZS (PC1, PC2, PC3). in a standard solar module. The middle SZS (PC2) is shaded and the current I therefore flows through the bypass diode D2. From a fire protection point of view, solar cells are a source of danger: solar cells or modules are sources of ignition because electrical energy flows through them and at the same time they carry the fuel in the form of their organic content in the form of embedding and reverse side foils. They are approved according to electrotechnical standards and usually - due to the usually untested residual capacity and fire class - they have no general construction supervisory approval.

This complicates the technical approval as a solar facade or solar roof with integrated solar modules (BIPV) The electrical characteristic of a solar cell can be obtained by electrical equivalent circuit diagrams. There are more or less detailed equivalent circuits for a solar cell. For the basic understanding, the simplest of all equivalent circuit diagrams is sufficient, as shown in FIG. 3 (source: Von Degreen from the German-speaking Wikipedia, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid= 7724909). The switching symbol is shown on the left and the equivalent circuit consists of a light-controlled current source and a diode for limiting the voltage. As a result, an illuminated solar cell shorts its own photocurrent when idle. The output voltage of the solar cell corresponds to the forward voltage US of the diode. In the case of partial shading, as shown in FIG. 4, despite the bypass diode, a large power loss results in the solar module, since the solar cells (current sources) are connected in series and not in parallel. The power curve P (MPP) and voltage curve U (MPP) for the situation from FIG. 2 are shown. The maximum power is removed from the solar module when the lighting-dependent maximum current of the shaded solar module group PC2 is taken. If you increase the load current through the load resistor RL, then the output voltage and thus the power drops signifi cant from. 9A was assumed for the short-circuit currents of the solar cell groups PC1 and PC3 and 30% for the shaded solar cell group PC2. Due to the diffuse background radiation of about 30% light intensity, the current of PC2 does not drop to zero.

In comparison, FIG. 5 shows the voltage and power curve of the unshaded solar module. Again, the power curve P (MPP) and voltage curve U (MPP) for the unshaded solar module according to FIG. 2 are shown. It can be seen that the maximum power in FIG. 4 is only 30% of the unshaded maximum power from FIG. 5, although only one SZS (PC2) is shaded. It can therefore be stated: The loss of yield due to shading can be considerable despite the bypass diode, even if only one cell (or SZS) is shaded. Without calculation, only by eye one may be tempted to assume that the output power is still approximately between 66% and 77% of the maximum power, which corresponds to the proportion of the proportion of "failed" solar cells. In reality, however, the bill gives only about 34% of the maximum power

The cause of the strong drop in partial shading yield is the rigid electrical series connection of the solar cells within the solar modules and increasing with the current voltage drop across the bypass diode D2 in Fig. 2 and the voltage drop across the electrical wiring of the solar module.

The bypass diodes can be located in the solar junction boxes, which are firmly bonded to the solar module. Due to the waste heat concept of the solar junction boxes according to the approval standards EN 50548 and EN 61730, a so-called thermal runaway of the bypass diodes can occur because the temperature dependence of the diode reverse current is not taken into account and only with the standard EN 62979: 2016 attracted attention.

After a thermal runaway, the bypass diode is broken or defectively short-circuited. In case of interruption and partial shading, the affected cell group can then be irreversibly destroyed.

In the event of a short-circuiting defect of the bypass diode and partial shading, it depends on the operating situation whether the junction box with the defective bypass diode is thermally overloaded. The short circuit of the damaged bypass diode is not perfect and often produces the triple waste heat of an undamaged diode in bypass mode.

Figure 6 (Source: SMA http://files.sma.de/dl/7418/Rueckstrom-UEN083010.pdf) shows a solar generator, consisting of parallel SMS (solar module strings), which connected to an inverter (right). Operation takes place with a short-circuiting bypass diode.

During operation, the inverter will remove current from the solar module string (SMS) that is operating at full voltage, as shown in FIG. 7, so that relatively little current flows in the shortcut that is shortened by the short circuit. However, if the inverter is switched off, a significant compensation current flows in the form of reverse current in the solar system, which can not be switched off according to the state of the art without additional electronics (solar module string diode). The shutdown of the inverter is done in part by the network operator of the public power grid. The solar power supplier has no influence in this case.

FIG. 7 shows the operating points return current with load (operating point OP1 => lrev = 9A) and without load (operating point OP2 => lrev = 27A).

In particular, when the solar system is a solar façade, a short circuit of modules in the event of an accident is conceivable (eg in the event of a crash of an automobile with the solar façade). The flow of equalizing currents can make rescue measures difficult or even impossible as long as the sun is shining.

Such errors can be met with string diodes, as shown in Figure 8, which represents a solar system with one string diode per string.

However, string diodes cause a loss of energy during normal operation of the system, because they heat up and it is not certain whether their function is monitored in practice. Ie. they can fail to conduct and the failure is hardly recognized during normal operation by a slight reduction in the output of the system. In the event of a conductive failure, the solar system continues to supply power, but increased heat dissipation of the string diode, which could be detected, for example, by temperature monitoring of the string diode, and in the event of a disruptive failure there is no current flow, which is easily recognizable by the power breakdown of the solar system. For the sake of cost savings, string diodes are not always installed. Another potential failure in solar systems is the failure of solar connectors and the loss of cable isolation due to marten bite. In the sem error can form an arc that burns a long time (order of 30 minutes) and does not go out. In the US, such situations are encountered with the use of arc detectors, which are mandated by NEC 2014 (National Electric Code 2014 and following). At present, there are hardly any arc detectors in Europe.

DC arcs do not go out as easily as AC arcs due to the lack of voltage zero crossing. Therefore, a solar module with AC output has advantages in this regard.

The type of cable routing within the solar modules results in an area in which voltages can be induced by magnetic fields. In nature, such magnetic fields are generated by lightning near field impacts, which can then damage the bypass diodes and other parts of the system. Following errors can then be arcs in the solar system, when the sun shines again.

In the following an electrical circuit concept is proposed, which the o.g. Avoid disadvantages or a cheaper solution than existing systems.

Depending on the lighting situation of the solar modules, the circuit concept switches dynamically adapted series, parallel and group switching of the solar cells within a solar module and generally also of solar modules within solar generators, as well as in general the connection of voltage-limited current sources.

This means solar cells, which are connected in series at one time, can be switched dynamically and switched in parallel at a different time. Likewise vice versa and possibly optional for more than two solar cells. The latter allows dynamic group switching.

The term solar element includes here as the smallest unit a solar cell. Alternatively, it can also mean a dynamically and electrically linked group of solar cells be, the z. B. form a solar module. A solar module, which consists of several strands, or groups of strands and solar cells, can also form a solar element. Statements that are therefore made for solar cells or modules are usually valid for the other element. The electrical connection can, but does not have to be done by electrical or electronic switches. Magnetic linkage using transformers with multiple windings and also with the help of transducers is just as conceivable in addition to other physical effects. Thus, solar cells, as well as solar modules, can be interconnected with the switch arrangement described by way of example below

Accordingly, such a switch arrangement, for. For example, in a solar module, a plurality of electrical switches that can electrically connect each individual solar cell with other solar cells or solar cell groups in series, in parallel or in a group circuit. Each solar module consists of a lot of solar cells. In the dynamic interconnection, subsets are formed from this total quantity, which do not have to be geometrically close. These subsets are interconnected in series, parallel and group switching depending on the lighting so that the maximum energy can be extracted from the solar module. At the same time, this reduces the energy loss in the bypass diodes and thus lowers the operating temperature of the junction boxes.

In Figure 9 (Source: Source: http://elektrotechnik-fachwissen.de/grundlagen/gruppenschaltung.php) a combination of series connection (left) and parallel connection (right), which group circuit is called, is shown.

This concept may not be as optimized in terms of yield as a bypass diode per solar cell, but the option of providing a large number of switches with additional functionalities, such as self-diagnostic AC modules, integrated solar module shut-off and dormant solar modules when idle the electronics (switch assembly) again attractive.

A preferred technical solution for the switching elements are semiconductor switches. These solar cell groups are preferably connected together in such a way that the flow of current through shaded cells is not hindered and as a result little or no current flows through the bypass diode. This reduces the electrical and thus in particular thermal stress for the system and increases the power yield compared to a rigid electrical connection with bypass diodes.

FIG. 10 (source: WO2012163908A2, FIG. 5) shows the use of additional diodes as semiconductor switches, through which fewer solar cells than usual are bridged during shading.

An embodiment of the proposed electrical wiring concept provides completely free interconnectability of solar cells / elements in all possible combinations. This would require a lot of switches. In the following, an interconnection concept with more than one current level (power bus line) is presented.

FIG. 11 shows a solar module according to the prior art. Voltage sources in electronic devices often have lines with different voltage levels (voltage levels), which in the present case are also referred to as buses. Accordingly, it is also possible to build different current bus lines in circuits with current sources. Solar modules according to the prior art have only one power bus line, as shown in Figure 11, in which from 20 or 24 solar cells (power sources) in series a solar cell string 26.1 to 26.6 (SZS) is formed. The solar cell string 26.sub.i, indicated by the dashed circle in the figure, consists of 20 solar cells connected in series and one diode. Since the solar cells all have a slightly different output current, even with the same illumination, bypass elements D1 to D6 (bypass diodes or smart bypass diodes) are required, which compensate for the output current difference.

A preferred concept is to dynamically interconnect the solar cells such that a solar module has a plurality of current outputs. The solar cells are subdivided into groups of current which, depending on the lighting, have a high current (H bus), a medium current (M bus) and a low current (L bus). FIG. 12 shows such a model of a solar module with dynamically interconnected solar cells, which are divided into three power bus lines H, M and L (high, mid, low). The bus lines lead to an inverter 40 with three independent inputs. Preferably, three separate inverters or one inverter with three separate inputs can be used. Since the efficiency of an inverter depends on the input current, it is preferable to use a specially optimized inverter for each of the groups H, M and L. The solar module 27.1 or 27.2 works in this interconnection as a power source

This would have a solar module 27.1 or 27.2 this type 6 connecting cables. This is not optimal due to a very complex wiring that is prone to error during installation (cable noise, mating error, especially if many switches are required).

FIG. 13 shows an arrangement in which the number of connection lines is reduced to 2 units by interposing electrical energy converters. A remedy is to place the bus lines on a DC / DC converter, whose output represents a voltage source. These transducers, which are each located on the solar module 27, can then be connected in series without difficulty. These DC / DC converters must be able to automatically find the optimum operating point of the solar cells. These types of transducers are called MPP trackers. (MPPT or Maximum Power Point Tracker) and turn the power source solar module into a power source. FIG. 13 thus shows the model of a solar module 27.1 with dynamic interconnection. The currents are split into three power bus lines (H1, M1, L1) within the module. In the dashed circle, the solar element group 25 is shown on the power bus H1. Accordingly, the solar element groups on the other power bus lines are constructed. Each of these lines has its own Maximum Power Point Tracker (MPPT-H, MPPT-M, MPPT-L). The output of these trackers, which are connected in series with each other, makes this solar module 27.1 a voltage source. Even with a rigid electrical connection, the use of MPPT on the modules leads to a higher current output of the solar system compared to the standard circuit in FIG. 11. With a dynamic interconnection as in FIG. 13, this yield can be further increased. In addition, as shown in Figure 14, a plurality of such solar modules 27.1 and 27.2 according to Figure 13 (possibly dynamically) are interconnected, for. In series. Since the outputs form voltage sources, a series connection of voltage sources is shown here.

There are preferably three concepts for dynamic interconnection: 1) conversion of the current sources into voltage sources by electronics (implicitly performed in the MPPT and shown in FIG. 14), 2) splitting the current sources into equal currents e.g. High, Mid, Low and 3) combining the current sources into only one power bus according to the method described in FIG.

Commercially available modules are already supplied interconnected and can not be configured. This means that the interconnections of the SZS in the solar module are firmly connected in series. The possibilities for an interconnection according to o.g. Figures would be better if connection options were freely accessible.

Nevertheless, as shown in FIG. 15, such modules can be cluttered with MPPTs. Rigid series connected modules can thus be connected in series using MPPT.

With dynamic interconnection, the fineness of the subdivision into different power buses can be arbitrarily resolved. Each power bus requires an MPPT because the number of cells in a power bus group varies with the lighting and the bus voltage is different and variable. Each solar cell can be connected in series to one of the power buses. With complete freedom of choice for the connection to power buses, the number of required switches or MPPTs is high.

It is therefore proposed as an additional improvement that, in order to save MPPTs, the power buses and also the solar cells within the solar module are also connected in parallel and group circuits in addition to the series connection.

This only requires one more MPPT per solar module. In this extreme case, the solar module would become the power source again. When looking at the DC / DC converter at Module output omitted, strings of solar modules with dynamically interconnected solar cells can no longer be connected in parallel because their output voltage varies depending on the lighting. The dynamic interconnection of solar modules within the solar system is therefore preferably carried out analogously to dynamic cell interconnection.

The number of required switches can be reduced by restricting to suitable interconnection options for the most common shading geometries. The disadvantage of this is that you lose some performance over the optimal solution.

In the following, an interconnection concept with only one current level (power bus) is presented. Fig. 16 describes the method and interconnect geometry for Concept 3), i. Summary of the 3 power buses High, Mid Low in only one common power bus. In the following it is worked out, how many solar cell elements one wants to connect together as a group. The number of switches and the complexity of the tax increase with this number.

The number of switches can be reduced by grouping the solar cell elements within a solar module into small groups. These groups can be an n × n cell matrix, in the simplest case a 2 × 2 cell matrix. Other embodiments are conceivable. As an example, the wiring concept is explained on a 3 x 3 cell matrix. A large number of these 3 x 3 cell matrices then form a solar module.

Other implementations of quadratic (n x n; n element of natural numbers) or rectangular (n x m; n and m element of natural numbers) cell matrices are conceivable.

The 3 x 3 cell matrix has the special feature that it can be connected in three vertical, three horizontal or optionally also in three diagonal series circuits (strings), each time the same number of solar cells and thus have the same solar cell string voltage. This facilitates the parallel connection and group switching of these cells within the cell matrix. The solar cells are connected in such a way that their geometric arrangement runs parallel to a shadow edge. This introduces a classification that represents a practice-relevant approximation.

The types of interconnection can be seen in a 3 x 3 cell matrix as shown in FIG. 16 for a horizontal course of shading, i. H. a shadow wandering in a vertical direction. On the left is the shaded image of the solar cell matrix, on the right the dynamically selected interconnection for the respective shading situation (a) to (e).

In an unshaded state (shading situation a), the 3 horizontally arranged strands 26.1, 26.2 and 26.3 are connected in series, on the one hand not to hinder the flow of current (keep bypass diodes as de-energized and minimize waste heat), and on the other hand to generate the highest possible voltage.

For this purpose, the following method is preferably used:

Step 1: Determine the maximum current of the best-lighted solar cells. These come in the series connection (left part of the group circuit of FIG. 16)

Step 2: Connect the remaining cells in parallel so that the sum of the partial currents becomes as high as possible.

Step 3: If all cells in the group are "evenly lit", form a series circuit of all. The cells are considered to be "even" when they have a current deviation of less than 30%, preferably less than 20%, most preferably less than 10% of the maximum current.

In the shading situation (b), in which the first strand 26.3 is partly shadowed, it is connected in parallel to another strand (here 26.2) and together with the series-connected strand 26.1 forms a group circuit, so that no more destructive current flows through the line partially shaded strand 26.3 is forced. In the shading situation (c), in which the second strand 26.2 is partially shaded, both partially shaded strands 26.2 and 26.3 are connected in parallel. In the example, there is no longer any dynamic switching between the circuit for the shading situation (b) and the shading situation (c), since the setpoint connection is already present in accordance with the shading situation (b).

With a freedom of choice of the interconnection, as in the shading situation (b) or (c), presumptions about the future shading can preferably be made in order to perform the parallel connection of the strands, which would also be favorable in the case of a subsequent shading situation.

In the shading situation (d), if the shadow has covered the whole module and continues to shade unevenly, then the same rule applies to the interconnection as described in scenarios (b) and (c).

In a next step, if the shadow has completely and evenly covered the module (shading situation (s)), the strands can be switched back into series or parallel from the point of view of freedom from destruction; FIG. 16 shows a parallel connection. Advantageously, a pure parallel connection of the strands takes place at low power, so that the least possible current flows through the bypass diodes, see FIGS. 4 and 5. When a bypass current occurs, this means a large power loss.

It can be seen from FIG. 16 that solar cells which are always illuminated as light as possible (or capable of being used) are combined. In the example shown, the solar cells can always be combined in a horizontal direction due to the horizontal shadow line. For this case, no switches would need to be provided, which could separate 3 horizontal strands of the solar cells and connect them differently. The geometric division of the cell matrix is preferably carried out as parallel as possible to a shadow edge. This is the strategy for cell division horizontally, vertically, diagonally, orthogonally. The geometrical divisions just listed are optimal for shading with a shadow edge. Angled shadows have 2 shadow edges. These are split like diagonal shadows around the Direction selection of the cells easy to keep. This division is not optimal for angular shadows.

This concept can be applied to all larger units, so also matrices of solar modules (instead of individual solar cells) can be connected in this way.

In the following, a proof of the possible increase in energy due to the dynamic interconnection concept is presented by means of simulation calculations.

In order to prove the usability of the proposed interconnection method, a simulation model is set up. It consists of three groups of three solar cells each, which are interconnected in series, parallel and group circuits. The model simulates a horizontal or a vertical shading of a 3 x 3 solar cell group as an example.

FIG. 17 shows a circuit diagram for the simulation in the special case of series connection. V1-V4, B1 and V6 generate auxiliary variables for the calculation, which are needed for later finding the maximum power at each time. They are intended for the number of the simulation.

The drawn bypass diodes D4, D10 and D14 over the cell matrix can be replaced by a switch which operates by a controller as if it were a diode. In integrated form, this is called the Cool Bypass Switch, which can also be set up discretely.

For the bypass elements different trade names exist, eg. B. "Cool Bypass Switch", "Smart Bypass Diode" or "Ideal Bypass Diode". This refers to a NMOS with charge pump and controller in a housing. This can alternatively also be replaced by a MOS switch.

A shading sequence with temporal offset is introduced into the model, which simulates the shading following the time profile of the three solar cell groups S1, S2 and S3, as shown in FIG. 18 in a chronological sequence of the shading. shown in a fictional solar system. A section of the diagram from FIG. 18 is shown in FIG. The shadow is almost a solar cell wide.

In Figure 20, the power of the unshaded 3 x 3 solar cell group is shown in a partial shading parallel to the long axis of the module in series connection as a solid line. The dotted line shows the series connected solar cell group with temporally continuous partial shading. The power drops from 176 watts to 149 watts. This corresponds to the state of the art. By group switching at appropriate times, the power can be increased to 156 watts. This corresponds to a power increase of 0.77 watts per cell. The parallel connection of the solar cells brings here no performance increase. The unshaded system is drawn in a series connection in a solid line.

If the solar module has been mounted rotated by 90 ° with the same shadow geometry, then all three SZS are shaded simultaneously. This situation is illustrated in FIG. 21 and shows the power of the 3 × 3 solar cells when the solar module is mounted perpendicular to the shadow edge. The solid line, the power output at full illumination, the dotted power output of the module in the case of series connection of the cell groups and the dotted line show the power output when the cell groups are connected in parallel.

When shading occurs, the power drops from 176 watts to 96 watts. By paralleling the three cell groups, the power can be increased to 110 watts. This corresponds to a power increase of more than 1.5 watts per cell. The time-dependent optima are shown in FIG.

An odd number of groups / strands would be unfavorable if there is an antiserial circuit of the matrices such that zero U, ie no voltage, is present from the module. An antiserial circuit is when you connect two voltage sources with the same pole. This results in a two-terminal with zero voltage. This connection makes sense if you want to achieve that the output voltage is zero volts. This is a sensible way to switch off a solar system. But it is also due to short circuit and interruption of the solar cells, the short circuit according to DIN VDE AR2100-712 should be made only at short notice. Preferably, the number of solar cells per matrix strand is the same, because otherwise a current flow preferably takes place in the shorter strand, which would lead to equalization currents and power loss.

In the following, further categorizations of the types of shading occurring in practice (besides shading by a horizontal shadow line) are listed. If restricted to certain categories, switches can be saved.

The electrical connection concept of the vertically shaded cell matrix, as shown in FIG. 22, corresponds to the interconnection concept shown above with horizontal shading in a different orientation. Thus, it is shown in FIG. 22 that a vertical shading can be treated electrically like the horizontal shading.

Another special case is diagonal shaded cell groups, as shown in FIG. FIG. 23 converts a diagonal shading into a horizontal shading by dividing the solar cells according to FIG. 23 a, which in turn are dynamically interconnected according to the method according to FIG. 16. In the case of diagonal shading, the cells of a 3 × 3 cell matrix, as shown in FIGS. 23 a and 23 b, are combined into groups of currents 11 to 13. FIG. 23a shows the power groups for a shading process according to FIG. 23 (third image). FIG. 23b shows the power groups for a shading process in the orthogonal direction, from bottom left to top right, and thus treats the diagonal shading rotated by 90 ° and electrically converts it into horizontal shading. These power / power groups are linked in series, in parallel or in group as shown above.

Angularly shaded cell matrices, as shown in Figure 24, are preferably split into three groups like diagonally shadowed cells of the same geometry. The downside is wasted performance. Optimally, solar cells are grouped according to their lighting. Since the diagonal diagonal wiring is optimized for diagonal shading, you give away power in the case of angled shading. However, the profit is still higher than with the rigid interconnection after Thus, FIG. 24 deals with the angular shading and converts it into a diagonal shading according to FIGS. 23 a or 23 b, and thus electrically again into a horizontal shading according to FIG. 16.

A large number of cell matrices are interconnected to form a solar module and the principle of dynamically interconnected solar cells can be applied analogously to these cell matrices. The principle of dynamic interconnection can also be applied to the solar modules as a higher-level cell matrix in a solar system. As already mentioned, the term solar element can hereby include both solar cell life and solar module level.

The division of the solar cells into n x n cell matrices influences the number of solar cells in a solar module. With a division into 3 × 3 = 9 cells, a number of 72 = 8 × 9 cells is preferred. When divided into 2 x 2 cells, a number of 15 x 4 = 60 cells is preferred. 60 and 72 cells are the usual number of cells in standard modules.

By way of example, FIG. 26 shows a SPICE model for a 3 × 3 cell matrix, which includes the dynamic interconnection, but not the method concept of FIG. 16. On the left side of the block diagram are 3 bypass diodes (the fourth is missing), a jumper distribution which realizes the series, parallel and group switching, as well as a pole turner for antiparallel switching, disconnection or also alternating current generation.

The pole turner allows the solar element to be completely isolated (i.e., turned off), thereby producing an intrinsically safe solar module that provides power only after the previous enable signal. Solar systems can be completely switched off. This is also new compared to the prior art, which accomplishes this interconnection by additional electronics.

Furthermore, solar elements can be switched together in such a way that they remain electrically conductive, but do not supply any output voltage because they compensate each other (anti-serial connection). The Polwender can also be used for the generation of alternating current. An alternating current with a frequency of more than 100kHz significantly reduces the risk of muscle cramps and cardiac arrest / fibrillation.

In the middle of Fig. 26, the geometric selection of the solar cells from the exemplary 3 x 3 cell matrix is for the division into horizontal, vertical, diagonal and 90 ° -twisted diagonally (orthogonal). Figure 25 is an incomplete section of the required crosstalks within the 3 x 3 cell group of Figure 26 and includes a small portion of the switches.

Due to the optional communication (enable signal) and the power optimization method, the overall circuit preferably has a microprocessor which can interconnect the 8 pieces of 3 × 3 cell matrices horizontally, vertically, diagonally, rotated through 90 ° diagonally and also angularly. This is called a Smart Module. By default, the solar system can be rigidly interconnected with Smart Modules. Preferably, a dynamic interconnection of the solar modules is provided, which can be connected horizontally, vertically, diagonally, diagonally 90 ° twisted, angle-shaped or block-shaped as needed.

Further variants of the wiring variants described provide further advantages:

Solar cells with the same illumination are preferably grouped into groups. The groups are preferably connected in parallel. If the entire module is not shadowed at once, then the bypass elements are not in operation in this operating mode. Optionally, the output voltage of dynamically interconnected solar modules can be raised to a normal level by an integrated DC / DC converter.

Due to the dynamic interconnection, the polarity of the solar module can be reversed in stages. As a result, the solar module on its own already supply alternating current. This alternating current can serve with a few additional components DC / DC converter or MPP tracker to form. Alternatively, the solar cells can be connected in such a way that no voltage is emitted out of the solar module to the outside, whereby it is then in a safe resting state. Operation is initiated by external communication. Thus, an intrinsically safe solar module with integrated emergency shutdown can be realized.

An operating mode "AC module" is made possible by corresponding switching of the switches and thereby the generation of an AC voltage / current. The frequency does not necessarily have to be 50 Hz. Increasing the frequency to preferably 300 kHz has the advantages that transformers for voltage separation or transducers can be smaller and therefore cheaper and, when in contact with the system voltage in the event of an accident, the currents flow through the skin and not via the heart (skin effect). , A cramping of muscles would not take place then. This makes the system voltage less dangerous for people than conventional systems. Incidentally, the alternating current facilitates automatic extinction of arcs in the event of a fault due to its current zero crossings.

The above-mentioned operating modes are preferably controlled by a microcontroller or microprocessor. Therefore, with little additional effort, a communica- tion network of the solar modules with further advantages is conceivable. If, for example, an external fire occurs, this information can be reported to all modules by temperature monitoring. They can then automatically switch off even before the fire has hit the entire system. The status of all modules can be reported to a control panel. This can z. Operating status, current, voltage, temperature, hardware check and optionally other parameters.

Each solar module can register in the form of a homepage. This is a SMART module in the Internet of Things, which is integrated into the SMART Home feasible.

The microprocessor preferably takes on the task of arc detection and module shutdown. The microprocessor preferably assumes the function of theft protection and a location message.

The microprocessor preferably monitors the hardware so that it protects itself. This can include the exceeding of a maximum operating temperature as well as lightning protection measures.

The firmware of the processor is preferably kept up to date by updates.

A fault condition is preferably communicated to the outside by corresponding electronic communication or alternatively or additionally also visually or acoustically, so that the search for the faulty module is shortened in large installations. In this way, an optimized arrangement of solar elements with dynamic interconnection has been provided during the operation of the solar elements as a function of their current performance characteristics and a method for controlling such an arrangement of solar elements. FIG. 27 shows an arrangement of the solar elements according to a preferred embodiment with a crossbar distributor. In this arrangement, the solar elements are assigned to different shunting levels, whereby series, group and parallel circuits of the solar elements are made possible. FIG. 28 shows an arrangement of the solar elements according to a preferred embodiment with a simplified group circuit. This enables the types of wiring, series connection, G1 and G3 group switching and parallel connections as shown in Figure 31. In the patch panel (Fig. 28 bottom left), the geometric center of the 3x3 matrix is assigned to the patch panels ZS2 + and ZS2-. The circuit shown, the number of switches required compared to the crossbar distributor according to Figure 26 can be limited. The circuit shown has, for example, 27 switches. FIG. 29 shows a schematic representation of various arrangements of the solar elements according to preferred embodiments. According to the left arrangement, the solar elements are connected in such a way that they are present in an arrangement of three vertically extending strands. According to the second arrangement from the left, the solar elements are connected in such a way that they are present in an arrangement of three horizontally extending strands. According to the two right-hand arrangements, the solar elements are connected in such a way that they give diagonal strands, the strands in the third arrangement running diagonally from left to bottom right in the third arrangement and diagonally from bottom left to top right in the right arrangement. For example, according to a preferred embodiment, a dynamic interconnection can be carried out in such a way that a change is made between the arrangements shown in FIG. Optionally, further interconnections or arrangements can be provided according to which solar cell strings or the solar elements can be connected in order to optimize the efficiency of the solar cell arrangement in the case of a present shading.

FIG. 30 shows a schematic representation of a solar cell arrangement according to a preferred embodiment, which is referred to as a pole-reversing circuit. The pole turner is arranged and / or formed in such a way that the geometric center of the 3 × 3 matrix can be switched back to the maneuvering planes ZS2 + and ZS2- by means of the pole turner. The geometric center of the 3x3 matrix is given to a pole turner in the lower left corner according to the circuit shown. By this circuit series, group and parallel circuits can be realized. The pole turner, which can be seen at the bottom right in FIG. 30, can generate alternating voltage at the output of the solar module.

FIG. 31 shows a circuit of cell strings or strings 26a, 26b, 26c according to a preferred embodiment. The strands 26b and 26c are connected in series in such a way that they form one arm of a parallel circuit. In the other arm of the parallel circuit, the strand 26c and a diode D4 are connected in series. Preferably, such a circuit is realized with a pole changing circuit and / or a diode matrix circuit. This circuit has the advantage that diodes with one or more strings can be connected in series and in this way strands of different lengths or with a different number of Solar cells can be connected in parallel, without disadvantageous balancing currents arise. Furthermore, this circuit has the advantage that a plurality of arms can be connected in parallel with a respectively different number of strings 26 connected in series, and compensation lines between the arms of the parallel circuit are nevertheless caused thereby. Instead of strings 26, solar cells and / or groups can be connected in this way in the same way.

Likewise, a comparable circuit is possible in which the arms of the parallel circuit are horizontal and, accordingly, the diode is connected in series with line 26c parallel to the two series-connected lines 26a and 26b.

FIG. 32 shows a schematic representation of a circuit according to a preferred embodiment which combines a diode matrix circuit and a pole reversal circuit. Due to the diode matrix circuit, the circuit is set up to connect the solar elements by means of diodes independently in an arrangement adapted to the shading conditions. In this way, the diode matrix circuit makes it possible to realize a passive, dynamic interconnection of the solar cells or groups or strands. The diodes are controlled by the voltages generated by the solar cells. Only with a full shading of the entire 3x3 matrix or of all solar cells, the diode matrix would lead to a disadvantageous interconnection, since the diode matrix in this case would switch the three strands in series, which would result in a large electrical resistance for the current flow and The current is therefore diverted via diodes within the diode matrix. In the case of full shading, it is therefore anticipated that the three strings will be switched in parallel by means of the pole wander in order to allow a sufficient current flow even with full shading. For this purpose, the circuit is preferably set up to up-shift the middle strand in order in this way to switch the three strands in parallel, which would otherwise be connected in series, ie without a pole reverser and only with the diode matrix circuit. In this way, a combination can be realized with a combination of the diode matrix circuit and a pole changing circuit, in which the solar cells can be dynamically connected with great flexibility and which ensures a suitable interconnection or arrangement of the solar cells or solar elements under all shading conditions , The switches S6 and S7 shown in FIG. 32 are not mandatory and may be dispensed with according to another preferred embodiment. The diode matrix circuit provides the best yield with partial shading and also offers the advantage that the number of required components can be kept low. Only with full shading does a splitting of the solar elements by means of a pole turner into current groups lead to a better result. With a combination of the two types of circuit, therefore, the yield can be optimized for all shading conditions, and yet the number of components required, in particular the need for switching elements such as MOSFETs and diodes, can be reduced.

Table 1

Table 1 shows an overview of the yields of the different circuits at different shading ratios, as well as the required number of diodes and switches. FIG. 33 shows a schematic illustration of a pole turner according to a preferred embodiment. While a pole turner is integrated into the mxn matrix or 3x3 matrix for a pole turner circuit described with reference to FIG. 30 and a combination of diode matrix circuit and pole turner circuit described with reference to FIG. 32, in such circuits and / or other circuits Polwender be formed, which is arranged at the output of the mxn matrix or 3 x 3 matrix. In particular, a plurality of mxn matrices may be formed in the solar cell array, each having a pole turner at the output of the mxn matrix. If necessary, solar cells or solar elements or matrices can be bridged via these pole changers at the outputs, for example if they have a defect. In particular, defective 3 × 3 matrices can be bridged by means of the pole turner if they contain defective solar cells or are completely defective. This can be achieved, for example, by switching the left Flalb bridge of the pole reverser shown in FIG. 33 to high impedance and switching both switches SW to passage in the case of the right Flalb bridge. For this task the Flap bridges can be exchanged in their function.

FIG. 34 shows an arrangement according to a preferred embodiment, which shows the division of solar cell groups along a shadow edge and thus the division of the solar cells into the three current groups High, Mid and Low according to FIG. With such a circuit, one strand and / or individual solar cells can be isolated within a 3 × 3 matrix by switching the switches SW to interrupt.

Solar cell arrays with 60 cells, which are often standard modules, typically have three strings with a cell split of 20 solar cells in each row, which can be bridged with a diode, such as a bypass diode. When using 3 × 3 matrices, it is advantageous if the number of solar cells in the vertical direction is a multiple of the number three. This is the case with 72 cells, and with 60 cells, two lines in the top 3 x 3 matrix are unfilled. Either the partially filled 3 x 3 matrices or a series of solar cells are omitted and space has thus been created for a strip of electronics in the solar module (this corresponds to a 54-cell solar module) or the gaps in the 3 x 3 matrix are bridged with short circuits (this corresponds to a standard 60 cell module). This results in a simplified switch concept, because, for example, the diagonal circuit and also the perpendicular cross-connection are not meaningful and bridged switches can be omitted.

Preferred cell divisions are shown by way of example in schematic representations in FIGS. 35 to 38. For some applications, such as for solar facades, a low system voltage of the solar cell array, for example of 120 V DC, is preferred in a case of accident and / or accident, a danger emanating from the solar cell array, such as a risk of electric shock due to high electrical voltage, limit. Preferably, for solar cell arrays, a 3 x 3 cell group is further selected as the matrix. The division of the cell group within the 3 x 3 matrix is optional. In the following, exemplary possible divisions of the solar cells of 72-cell standard modules are explained, by means of which a 3 × 3 matrix can be realized. FIG. 35 shows a solar cell arrangement according to a preferred embodiment, which comprises 3 SMART 72-cell solar modules, which are arranged horizontally next to one another. According to Figure 35, the parameter N is selected for the number of rows per group N = 1, i. a group comprises only one solar cell. A 3 x 3 matrix therefore comprises 9 solar cells, each individual solar cell being considered as one group.

FIG. 36 shows a further solar cell arrangement according to a preferred embodiment, which comprises 3 SMART 72-cell solar modules. In each case two vertically stacked solar cells are combined to form a group. Accordingly, N = 2, so that each group comprises two solar cells.

FIG. 37 shows a further solar cell arrangement according to a preferred embodiment, which comprises 3 SMART 72-cell solar modules. There are four of each vertically stacked solar cells combined into a group. Accordingly, N = 4, so that each group comprises four solar cells.

FIG. 38 shows a further solar cell arrangement according to a preferred embodiment, which comprises 3 SMART 72-cell solar modules. Eight solar cells are grouped together, four vertically one above the other and two horizontally next to each other. Accordingly, N = 8, so that each group comprises eight solar cells. Such a number of solar cells offers the advantage that exactly one 3 × 3 matrix can be realized with a solar module with 72 solar cells. With three such modules, three 3 × 3 matrices of groups of eight solar cells each can be realized.

Depending on the choice of the parameter N, a different number of switches, such as MOSFETs and / or diodes, within the SMART solar modules or the solar cell assembly is necessary. The electrical resistance of the switches can reduce the yield of the plant. The calculations take into account an electrical resistance of 9 milliohms for the supply lines (3 modules each with 2 pieces 1 meter 4mm ² solar cables each with 0.5 milliohms for the solar connector pairs). On the one hand, the finest possible cell division (N as small as possible) is desirable in order to be able to realize the most flexible dynamic interconnection possible. On the other hand, the lowest possible number of switches (N as large as possible) desirable to minimize the manufac turing costs and the electrical resistance. For the resistance of the switches was set 1 milliohms. Choosing N = 1 (a solar cell is one element or group of the 3x3 matrix) will require a large number of switches. This leads to a decrease in the yield of the solar generator due to the many switches in unshaded operation (for example 6 am to 11 am and 1 pm to 6 pm). The increase in performance during shading compensates for almost this loss of income. However, the interconnectivity with such a fine division of the groups can not overcompensate the losses, so that with respect to the yield a choice of N = 1 is not worthwhile, but splits with several solar cells per group may be more advantageous. For the yield or the efficiency of a solar cell arrangement, it may therefore be advantageous to reduce the switching losses by a large number of switches. This can be done, for example, as described above, by combining several solar cells into one group. Alternatively or additionally, a different division of the matrix may also be advantageous.

FIG. 39 shows a preferred solar cell arrangement in a schematic representation, which is based on a diode matrix circuit and a polarity reversal circuit. The solar cell array is characterized in that it has only eight switches. The voltage controlled switches are referred to as diodes D1 to D4. These may preferably be formed as diodes, or particularly preferably be designed as a transistor switch (MOSFETs). Alternatively, the switches can be designed as Cool Bypass Switches or as Smart Bypass Diodes.

The solar cell arrangement according to FIG. 30 offers the advantage that the parallel connection of strands of different lengths, i. of strands having a different number of solar cells, as described for example with reference to Figure 31, and only requiring eight switches.

A crossbar distribution circuit according to FIG. 27 can thus be designed according to preferred embodiments such that switching elements are saved. In particular, the following circuits can be realized:

• Simplified group circuit according to FIG. 28 or as

Polwenderschaltung according to Figure 30 or as

Diode matrix circuit with Polwender according to Figure 32 or as

Pole reverser circuit with simplified diode matrix according to FIG. 39

The geometric distribution of solar cell groups along a shadow edge is preferably in all variants the circuit according to FIG. 34, which moreover can insulate individual solar cells or groups of solar cells from the current flow. LIST OF REFERENCE NUMBERS

1 arrangement of several solar elements

10 switches (SW, Sx)

20 solar element

22 solar cell

25 group

26, 26a, 26b, 26c strand

27 solar module

30 control unit

40 inverters

SC, Sx solar cell

D, D1, Dx (bypass) diode

SZS, PC _X solar cell string

I electricity

RL load resistor

MPP Maximum Power Point

P (MPP) power curve to determine the power in the MPP

U (MPP) Voltage curve to determine the voltage in the MPP

SW, Sx switch

MPPT Maximum Power Point Tracker

Claims

claims

1. Solar cell assembly (1) comprising

several solar elements (20),

a plurality of switches (10) for producing and interrupting electrical connections between the solar elements (20) and

a control unit (30)

characterized in that

the control unit (30) is arranged to interconnect the solar elements (20) in different electrical arrangements by means of the switches (10).

2. Solar cell arrangement (1) according to claim 1, characterized in that the control unit (30) is set up by means of the switch (10) to interconnect the solar elements (20) dynamically during operation in different electrical arrangements with each other.

3. Solar cell arrangement (1) according to one of the preceding claims, wherein the solar elements (20) comprise individual solar cells, strands of solar cells (26) and / or solar modules (27).

4. Solar cell arrangement (1) according to one of the preceding claims, character- ized in that

the switches (10) comprise transistors and / or MOSFETs and / or power MOSFETs.

5. Solar cell arrangement (1) according to one of the preceding claims, wherein the control unit (30) is arranged to switch the switches (20) such that the electrical arrangement has a plurality of current / power levels to which the solar elements (20 ) are switched on depending on their current power output.

6. Solar cell arrangement (1) according to one of the preceding claims, further comprising

a connection for an intermediate consumer.

7. Solar cell arrangement (1) according to one of the preceding claims, characterized in that

the solar elements (20) are arranged in a mxn, in particular a 2 x 2 or 3 x 3 topology, and the switches (10) are arranged such that, in the case of an mxn topology, n solar elements (20) can be connected in series and thus form a group (25).

8. Solar cell arrangement (1) according to one of the preceding claims, characterized in that the switches (10) are arranged so that the solar elements (20) in the horizontal direction, in the vertical direction, in diagonal orientation or corner in groups (25) are interconnectable.

9. Solar cell arrangement (1) according to any one of claims 7 or 8, character- ized in that

the switches are arranged such that some or all of the groups (25) can be connected in parallel with each other.

10. A method for dynamically interconnecting solar elements (20) with switches (10) via a control unit (30), wherein

a shading or a difference in performance between different solar elements (20) is detected,

the solar elements (20) are classified into different groups according to their current power or currently possible maximum power or the current lighting state, and

the solar elements (20) of each group are interconnected.

11. A method for interconnecting solar elements (20) according to claim 10, characterized in that

the solar elements (20) of a group (25) are connected in series.

12. A method for interconnecting solar elements (20) according to any one of claims 10 to 11, characterized in that

some or all groups (25) are connected in parallel.

13. A method for interconnecting solar elements (20) according to any one of claims 10 to 12, characterized in that

the solar elements (20) are switched so that at least one of the following functions is realized:

alternately switching the polarity of the entire array of solar elements (20) capable of generating an alternating current;

- Generating an AC voltage greater than 50 Hz, in particular 300 kHz;

- Production of the absence of voltage of the entire arrangement of the solar elements (20) to the outside;

- emergency shutdown when temperature exceeds a temperature monitoring of at least one of the solar elements (20).

14. A method for interconnecting solar elements (20) according to any one of claims 10 to 13, characterized in that

a lot of the solar elements (20) form a module and

a microcontroller or programmable microprocessor realizes at least one of the following functions:

- Monitoring of operating status, current, voltage, temperature or hardware check at least one of the solar elements (20) including the own electronics;

- Implementation of a SMART module with a set of solar elements (20), the one

Form module;

- Arc detection and module shutdown;

- theft protection and location detection;

- monitoring the excess of operating temperature and initiation of lightning protection measures;

- Visual or audible identification if the module is defective.

15. Solar cell arrangement (1) comprising

several solar elements (20), and

a plurality of switches (10) for making and breaking electrical connections between the solar elements (20), the plurality of switches being configured as diodes and controllable by an electrical voltage provided by the solar elements to differentiate the solar elements (20) into different electrical arrangements - interconnect with each other.

The solar cell device (1) according to claim 15, wherein the plurality of switches are formed as a diode matrix circuit.

17. Solar cell arrangement (1) according to claim 15 or 16, further comprising at least one pole turner, wherein the solar cell arrangement is designed to at least partially parallel the plurality of solar elements by means of the pole turner.

18. Solar cell arrangement according to claim 17, wherein the solar cell arrangement (1) is adapted to at least partially parallel the solar elements in a full shading of the solar elements.

19. Solar cell arrangement according to one of claims 15 to 18, comprising:

a first strand of solar elements,

a second strand of solar elements connected in parallel with the first strand, the second strand having a smaller number of solar elements than the first strand;

a diode connected in series with the second string and with the first

Strand is arranged in parallel.