阅读说明：本技术 具有改进的总效率的光伏装置 (Photovoltaic device with improved overall efficiency ) 是由 马克西米利安·弗莱舍 罗兰·波勒 埃尔弗里德·西蒙 奥利弗·冯西卡德 于 2019-08-28 设计创作，主要内容包括：本发明涉及一种具有钙钛矿光伏电池的光伏装置和尤其这种装置的效率。在此提出,光伏装置例如在投入运行时首先在偏压运行状态中工作,在所述偏压运行状态中,将偏压施加到光伏装置的钙钛矿光伏电池上。偏压或为此所需的能量可以有利地从与钙钛矿光伏电池相关联的功率电子装置中获取。(The present invention relates to a photovoltaic device having perovskite photovoltaic cells and in particular the efficiency of such a device. It is proposed here that the photovoltaic device, for example when put into operation, first operates in a biased operating state in which a bias voltage is applied to the perovskite photovoltaic cells of the photovoltaic device. The bias voltage or the energy required for this may advantageously be taken from the power electronics associated with the perovskite photovoltaic cell.)

1. A photovoltaic device (1) having:

-a perovskite photovoltaic cell (110) for converting light L impinging on the perovskite photovoltaic cell (110) into an output voltage U1, the output voltage U1 being tappable at electrical terminals (115) of the perovskite photovoltaic cell; and

a control unit (130) for operating the photovoltaic device (1),

wherein

-the control unit (130) is set up to monitor whether the photovoltaic device (1) exhibits a situation listed in a list of specific situations and to operate such that upon occurrence of a specific situation a bias operating state of the photovoltaic device (1) is triggered for a preset period of time, in which bias operating state an electrical bias from an energy source (121, 121') is applied to a photosensitive element (111) of the perovskite photovoltaic cell (110).

2. Photovoltaic device (1) according to claim 1,

it is characterized in that the preparation method is characterized in that,

the power electronics (120) of the photovoltaic device (1), which represent the energy source (121, 121'), convert an output voltage U1, which is provided by the perovskite photovoltaic cell (110) when irradiated with light L, at least in a normal operating state of the photovoltaic device (1), into an output voltage U2 which can be tapped off at the output of the power electronics (120).

3. Photovoltaic device (1) according to claim 1 or 2,

it is characterized in that the preparation method is characterized in that,

the energy source (121, 121') is an energy store from which the energy required for providing the bias voltage can be extracted.

4. Photovoltaic device (1) according to claims 2 and 3,

it is characterized in that the preparation method is characterized in that,

the energy store (121) is integrated into the power electronics (120) and is in particular designed as a capacitor or as a battery.

5. Photovoltaic device (1) according to claim 3 or 4,

it is characterized in that the preparation method is characterized in that,

the control unit (130) is designed to operate the photovoltaic device (1) such that, at the latest after a predetermined period of time, at least a part of the voltage U1 provided by the perovskite photovoltaic cell (110) when irradiated with light L can be used for recharging the energy store (121, 121').

6. Photovoltaic device (1) according to any one of claims 1 to 5,

it is characterized in that the preparation method is characterized in that,

the control unit (130) is designed to operate the photovoltaic device (1) such that the bias voltage is applied in a bias voltage operating state

-is constantly applied at the perovskite photovoltaic cell (110); or

-pulsed at the perovskite photovoltaic cell (110), wherein a set of bias voltage pulses is applied such that no bias voltage is applied between two bias voltage pulses following each other, respectively, wherein a parameter representative of the instantaneous efficiency of the perovskite photovoltaic cell (110) is measured at least between some bias voltage pulses, and wherein the bias voltage operating state is terminated for the case that the measured instantaneous efficiency is greater than a preset threshold value; or

-applied such that a preset amount of charge flows into the perovskite photovoltaic cell (110).

7. The photovoltaic device according to any one of claims 1 to 6,

it is characterized in that the preparation method is characterized in that,

the list of specific cases includes:

-the perovskite photovoltaic cell (110) is put into operation, and/or

-the perovskite photovoltaic cell (110) lacks irradiation, wherein a light sensor (116) is provided for measuring irradiation light impinging on the perovskite photovoltaic cell (110), wherein the light sensor (116) is connected to the control unit (130) in order to transmit sensor data for the control unit (130), and the control unit (130) is set up to evaluate the sensor data and compare it with an irradiation threshold value, wherein below the irradiation threshold value there is a specific situation of lack of irradiation of the perovskite photovoltaic cell (110) and/or

-a situation in which a measured variable representing the instantaneous efficiency of the perovskite photovoltaic cell (110) is below a preset efficiency threshold of the perovskite photovoltaic cell (110), and/or

-a situation in which the instantaneous output voltage U1 of the perovskite photovoltaic cell (110) is below a preset minimum output voltage U1min, wherein a voltmeter (120) for measuring the output voltage U1 of the perovskite photovoltaic cell (110) is provided, wherein the voltmeter (120) is connected with the control unit (130) in order to transmit voltage measurement data for the control unit (130), and the control unit (130) is set up in such a way that the voltage measurement data are evaluated and compared with a voltage threshold value, wherein below the voltage threshold value, a specific situation exists in which the preset minimum output voltage U1 is below, and/or

-the lapse of a preset period of time since the last occurrence of the specific situation.

8. The photovoltaic device as set forth in claim 7,

it is characterized in that the preparation method is characterized in that,

the control unit (130) is designed to operate the photovoltaic system (1) in such a way that, in the event of a specific situation in which the perovskite photovoltaic cell (110) is not irradiated, the bias operating state is triggered only when the irradiation measurement value is above a further irradiation threshold value BS' after being below the irradiation threshold value BS.

9. A method for operating a photovoltaic device (1) according to claim 1,

wherein it is monitored whether the photovoltaic device (1) exhibits a situation listed in a list of specific situations and, upon occurrence of a specific situation, a bias operating state of the photovoltaic device (1) in which an electrical bias is applied from an energy source (121, 121') to a photoactive component (111) of the perovskite photovoltaic cell (110) is triggered for a preset period of time.

10. The method of claim 9, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

providing, by power electronics (120) of the photovoltaic device (1), a bias voltage that should be applied to the perovskite photovoltaic cell (110) in the bias operating state.

11. The method according to claim 9 or 10,

it is characterized in that the preparation method is characterized in that,

the energy source (121, 121') is an energy store from which the energy required for providing the bias voltage is extracted.

12. The method of claim 11, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

after terminating the biased operating state, at least a portion of an output voltage U1 provided by the perovskite photovoltaic cell (110) when illuminated with light L is used to recharge the energy storage (121, 121').

13. The method of any one of claims 9 to 12,

it is characterized in that the preparation method is characterized in that,

in the bias operating state, the bias voltage is applied

-is constantly applied at the perovskite photovoltaic cell (110); or

-pulsed at the perovskite photovoltaic cell (110), wherein a set of bias voltage pulses is applied such that no bias voltage is applied between two bias voltage pulses following each other, respectively, wherein a parameter representative of the instantaneous efficiency of the perovskite photovoltaic cell (110) is measured at least between some bias voltage pulses, and wherein the bias voltage operating state is terminated for the case that the measured instantaneous efficiency is greater than a preset threshold value; or

-applied such that a preset amount of charge flows into the perovskite photovoltaic cell (110).

14. The method of any one of claims 9 to 13,

it is characterized in that the preparation method is characterized in that,

the list of specific cases includes:

-the perovskite photovoltaic cell (110) is put into operation, and/or

-the perovskite photovoltaic cell (110) lacks irradiation, wherein an irradiation falling onto the perovskite photovoltaic cell (110) is measured and the corresponding irradiation measurement is compared with an irradiation threshold BS, wherein below the irradiation threshold there is a situation of the perovskite photovoltaic cell (110) lacking irradiation and/or

-a situation in which a measured variable representing the instantaneous efficiency of the perovskite photovoltaic cell (110) is below a preset efficiency threshold (EFFmin) of the perovskite photovoltaic cell (110), and/or

-a situation in which the instantaneous output voltage U1 of the perovskite photovoltaic cell (110) is below a preset minimum output voltage U1min, wherein the instantaneous output voltage is measured and the corresponding voltage measurement is compared with a voltage threshold value, wherein below the voltage threshold value there is a specific situation below the preset minimum output voltage U1, and/or

-the lapse of a preset period of time since the last occurrence of the specific situation.

15. The method of claim 14, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

in the specific case of a lack of irradiation of the perovskite photovoltaic cell (110), the bias operating state is triggered only if the irradiation measurement is above a further irradiation threshold BS' after being below the irradiation threshold BS.

Technical Field

The present invention relates to a photovoltaic device and in particular the efficiency of such a device.

Background

For example, in central europe, the share of solar power plants with Photovoltaic (PV) generation facilities in the production of electricity is increasing substantially for reasons of environmental policy and more also for economic reasons. A large number of photovoltaic installations have been installed worldwide, which are based mainly on the conventional approach with silicon-based photovoltaic cells. However, for many years the use of so-called perovskite materials, such as CH3NH3PbI3 (or more generally (CH3NH3) MX3-xYx (where M is Pb or Sn and X, Y is I, Br or Cl)) has been investigated in photovoltaic cells, which due to their optoelectronic properties can efficiently convert electromagnetic radiation energy into electrical energy. On the one hand, perovskite-based photovoltaic cells are characterized in that they are relatively inexpensive. On the other hand, perovskite photovoltaic cells are an increasingly important alternative to conventional silicon-based photovoltaic cells, since due to the advances made in recent years their efficiency is affected by the so-called "light conversion efficiency" (PCE), from a few percent to more than 20% today indicating: the efficiency or degree of effectiveness that can be achieved is substantially in excess of that achieved by conventional PV cells. It is conceivable here that the perovskite photovoltaic cells are operated individually or, however, also in tandem photovoltaic modules, for example in combination with conventional silicon photovoltaic cells. The latter is described, for example, in PCT/EP 2018/055499.

However, despite the promise of development, perovskite photovoltaic cells still suffer from the problem that their effective coefficient is not constant. In particular, it has been found that the perovskite photovoltaic cells exhibit what is known as start-up or switch-on behavior, which is characterized in that, for example, when the photovoltaic cell is put into operation, the efficiency does not correspond to an optimum value in the first place, but only reaches the optimum value after a certain time. The term "put into operation" is intended here to encompass not only the first time put into operation after the initial installation of the photovoltaic cell, but also, for example, switching on again after the photovoltaic cell has been deactivated during this period and, for example, in the evening after the situation in which the photovoltaic cell is not supplied with electrical energy in the absence of irradiation. In other words, putting into operation therefore generally includes a transition of the operating state of the photovoltaic cell from a deactivated state to an activated state, in which the photovoltaic cell does not provide a large amount of electrical energy. In contrast, the photovoltaic cell provides electrical energy in the activated state within a range worth mentioning due to the illumination of the photoactive component of the photovoltaic cell.

Disclosure of Invention

The effect of reaching the optimum efficiency of the respective photovoltaic cell after a certain time adversely affects the overall efficiency of the photovoltaic device. It is therefore an object of the present invention to propose a possibility to achieve a perovskite photovoltaic cell with as stable an efficiency as possible, so that the overall efficiency is improved.

This object is achieved by a photovoltaic system as described in claim 1 and by an operating method as described in claim 9. The dependent claims describe advantageous embodiments.

The corresponding photovoltaic device has a perovskite photovoltaic cell for converting light L falling onto the perovskite photovoltaic cell into an output voltage U1 which can be tapped at an electrical terminal of the perovskite photovoltaic cell. Furthermore, a control unit for operating the photovoltaic system is provided, wherein, in particular for closed-loop control of the operation of the perovskite photovoltaic cells as part of the photovoltaic system, the power electronics of the photovoltaic system, which are associated with the photovoltaic cells and which supply the voltage U1 generated by the photovoltaic cells upon irradiation, to the power electronics via corresponding electrical lines, are actually closed-loop controlled. The control unit is now set up to monitor whether the photovoltaic device exhibits a situation listed in the list of specific situations, for example is put into operation, and to operate such that upon occurrence of a specific situation within a preset time period a biased operating state of the photovoltaic device is triggered in which an electrical bias from the energy source is applied to the photoactive component of the perovskite photovoltaic cell. After terminating the bias operating state, the photovoltaic device transitions into a normal operating state in which the perovskite photovoltaic cell provides an output voltage U1.

It is known that the start-up or switch-on performance at the point of commissioning or in other equivalent specific situations appears to be linked to the regulation of the photovoltaic cells at the point of commissioning. It is therefore particularly important in which state the perovskite photovoltaic cell is, for example, in operation. Said state may be influenced according to the invention by applying an electrical bias on the perovskite photovoltaic cell or on the photoactive component thereof for a preset period of time, for example within a few seconds. This results in that the efficiency is not significantly lower than the optimum efficiency of the battery after the lapse of the preset time period. Since the optimum efficiency is not reached until after a certain period of time, typically a few seconds, the bias voltage can be switched off after the above-mentioned preset period of time after putting into operation or the like. The bias voltage may be on the order of, for example, 1.2V to 2.0V and thus relatively significantly higher than a typical operating voltage of, for example, 0.8V.

Advantageously, the power electronics of the photovoltaic device represent an energy source which, at least in the normal operating state of the photovoltaic device, converts the output voltage U1 provided by the perovskite photovoltaic cell when irradiated with light L into an output voltage U2 which can be tapped at the output of the power electronics. Thus, in other words, the power electronics that end up present provide the bias voltage to be applied to the perovskite photovoltaic cell in a manner that is operated by the control unit. No additional components are therefore required.

In particular, the energy source may be an energy store from which the energy required for providing the bias voltage is available. Alternatively, the energy source can also be realized, for example, by connection to a public or non-public power grid.

The energy store is ideally integrated into the power electronics, i.e. into the circuit of the power electronics, and is in particular designed as a capacitor, for example as a so-called "super capacitor" (Supercap), or as a battery. PCT/EP2015/061129 or also PCT/EP2015/061932, for example, show power electronics circuits together with energy stores integrated in their intermediate circuits. Power optimizers of the inverter or their integrated energy stores can also be used here.

The control unit is now set up to operate the photovoltaic device such that at least a part of the voltage U1 provided by the perovskite photovoltaic cell when irradiated with light L can be used for recharging the energy storage device at the latest after a preset time period or after termination of the bias operating state. This does not have to take place directly after a predetermined period of time, but can also be initiated only subsequently by the control unit, for example, if the energy requirement of the consumers supplied by the photovoltaic cells is lower than the electrical energy instantaneously supplied by the photovoltaic cells.

The control unit may also be designed to operate the photovoltaic device such that a bias voltage is applied to the perovskite photovoltaic cell in a constant or pulsed manner in the biased operating state, or rather a predetermined amount of charge flows into the perovskite photovoltaic cell. When the pulses are applied in a pulsed manner, a set of bias pulses is applied such that no bias voltage is applied between two subsequent bias pulses. Here, a parameter representing the instantaneous efficiency of the perovskite photovoltaic cell is measured at least between some bias pulses, i.e. during periods when no bias is applied. For the case where the measured instantaneous efficiency is greater than a preset threshold, the bias operating state is terminated and the normal operating state is triggered. This has the advantage that it is possible to make a transition into the normal operating state earlier.

The list of specific situations includes, for example, the perovskite photovoltaic cell being put into operation and/or the perovskite photovoltaic cell being out of irradiation, wherein a light sensor for measuring the irradiation falling onto the perovskite photovoltaic cell is provided, wherein the light sensor is connected to the control unit in order to transmit sensor data to the control unit, and the control unit is configured to evaluate the sensor data and compare it with an irradiation threshold value, wherein below the irradiation threshold value there is a preset situation of the perovskite photovoltaic cell being out of irradiation. Further, the list may include the following: wherein the measured variable representing the instantaneous efficiency of the perovskite photovoltaic cell is below a preset efficiency threshold (EFFmin) of the perovskite photovoltaic cell. Such a representative measured variable may be, for example, the so-called "maximum power point" of the instantaneous current-voltage characteristic of the photovoltaic cell, or may nevertheless be an actual efficiency which can be ascertained on the basis of a comparison of the radiant power falling onto the perovskite photovoltaic cell with the power which is provided by the photovoltaic cell in accordance therewith. Furthermore, the list may comprise a situation in which the instantaneous output voltage U1 of the perovskite photovoltaic cell is below a preset minimum output voltage U1min, wherein a voltage meter is provided for measuring the output voltage U1 of the perovskite photovoltaic cell, wherein the voltage meter is connected with the control unit in order to transmit voltage measurement data for the control unit, and the control unit is set up to evaluate the voltage measurement data and compare with a voltage threshold value, wherein below the voltage threshold value there is a preset situation below the preset minimum output voltage U1. Another particular situation that may be considered may be the elapse of a preset time period since the last occurrence of the preset situation, i.e. in principle the bias voltage is applied regularly or periodically. In particular, the particular situation which is taken into operation and has elapsed a predetermined time period since the last occurrence of the particular situation can be monitored by the control unit without special additional auxiliary means in that: the control unit is provided with corresponding open-loop/closed-loop control software, which registers this situation.

In a method for operating such a photovoltaic system, the photovoltaic system is monitored with regard to the occurrence of a situation from a list of specific situations. Upon occurrence of one of the particular conditions, a bias operating state of the photovoltaic device is triggered for a preset period of time, wherein an electrical bias is applied from an energy source to a photoactive component of the perovskite photovoltaic cell.

The bias voltage to be applied to the perovskite photovoltaic cell in the bias operating state is advantageously provided by the power electronics of the photovoltaic device, so that the power electronics therefore represent an energy source, which at least in the normal operating state of the photovoltaic device originally converts the output voltage U1 provided by the perovskite photovoltaic cell when irradiated with light L into an output voltage U2 which can be tapped at the output of the power electronics. The actual energy source is in particular an energy store, for example a battery or a capacitor, which is integrated into the power electronics. In general, the energy source may be an energy store from which the energy required to provide the bias voltage is extracted.

At least a portion of the output voltage U1 provided by the perovskite photovoltaic cell when illuminated with light L is used to recharge the energy storage after a preset period of time or after terminating the bias operating state.

The operating method provides that, in the biased operating state, a bias voltage is applied to the perovskite photovoltaic cell, as already mentioned, either constantly or in a pulsed manner or in such a way that a predetermined amount of charge flows into the perovskite photovoltaic cell. For the case of pulsed application, a set of bias pulses is applied such that no bias voltage is respectively applied between two bias pulses following one another, wherein a parameter representing the instantaneous efficiency of the perovskite photovoltaic cell is measured at least between some of the bias pulses, i.e. during the absence of bias voltage. For the case where the measured instantaneous efficiency is greater than a preset threshold, the bias operating state is terminated and the normal operating state is triggered.

The operating method further provides that the list of specific situations at least comprises: putting the perovskite photovoltaic cell into operation; the perovskite photovoltaic cell lacks irradiation; a situation in which the measured variable representing the instantaneous efficiency of the perovskite photovoltaic cell is below a preset efficiency threshold (EFFmin) of the perovskite photovoltaic cell; the situation that the instantaneous output voltage U1 of the perovskite photovoltaic cell is lower than the preset minimum output voltage U1 min; and/or the elapse of a preset period of time since the last occurrence of the particular situation.

In particular in the case of the occurrence of a particular situation in which the perovskite photovoltaic cell is short of irradiation, the bias operating state is only triggered when the irradiation measurement is above a further irradiation threshold BS' after being below the irradiation threshold BS. Here, the BS and the BS' may be the same. It is thereby ensured that the bias operating state is only triggered if it is foreseen that the irradiation is sufficient for the normal operation of the perovskite photovoltaic cell.

Further advantages and embodiments emerge from the figures and the corresponding description.

In connection with the expression "for operating a photovoltaic installation" or "the control unit is set up to operate a photovoltaic installation", etc., i.e. the expression that the control unit should "operate" a photovoltaic installation or one of its components, it is to be noted that the respective operation is, depending on the situation and need, a closed-loop control or an open-loop control of the respectively operating components. It is assumed that the control unit in the respective case for example performs a closed-loop control or an open-loop control, as is clear to the person skilled in the art in the light of the situation and needs.

Drawings

The invention and exemplary embodiments are explained in detail below with reference to the drawings. Where like components in different figures are denoted by like reference numerals. It is therefore possible that specific reference numerals which have already been set forth in connection with the further first drawing are not set forth in detail in the description of the second drawing. In this case, in the embodiment of the second drawing it can be assumed that the components denoted there by this reference numeral also have the same characteristics and functions as those explained in connection with the first drawing without being explained in detail in connection with the second drawing. Furthermore, for the sake of overview, not all reference numerals are partially shown in all the figures, but only the reference numerals referred to in describing the respective figures are shown.

Description of the drawings:

figure 1 shows a perovskite photovoltaic cell which is,

fig. 2 shows a photovoltaic device.

Detailed Description

To explain the terms explained in advance, terms such as "above", "below", "above", "upper", "lower" and the like refer in the respective context to a coordinate system in which the source of the light to be converted into voltage by the photovoltaic cell, i.e. for example the sun, is located "above" or "above" the photovoltaic cell.

Fig. 1 shows a photovoltaic cell 110 by way of example and in a simplified manner. The photovoltaic cell 110 has a photosensitive element 111, which is embedded in a carrier 112, for example glass. The photoactive component 111, which provides the voltage U1 when irradiated with light L, i.e. converts the light L falling onto the perovskite photovoltaic cell 110 into the output voltage U1, is substantially composed of a perovskite material as already described at the outset, so that the photovoltaic cell 110 is also referred to below as a "perovskite photovoltaic cell". In practice, the photoactive component 111 is composed of a plurality of layers, in particular comprising a main layer composed of a perovskite material, wherein, however, in the context discussed here, the precise layer structure of the photovoltaic cell 110 is not important and is accordingly not explained in detail. The general mode of operation of photovoltaic cells and in particular of photoactive components is furthermore sufficiently known and is likewise not explained in detail below. It is mentioned only that the output voltage U1 generated in the photosensitive component 111 as a result of the illumination with light L can be tapped at the electrodes 113, 114 of the photovoltaic cells. The electrodes 113, 114 in practice typically extend over the entire upper or lower surface 111o, 111u of the photosensitive element 111. Here, the electrode 113 on the surface 111o of the light-sensitive component 111 facing the light L or a corresponding, not expressly shown, light source is transparent at least for the part of the spectrum of the light L for which the light-sensitive component 111 has its maximum efficiency. The material, which is thus partially transparent, may be, for example, Li-TFSI doped Spiro-OMeTAD. Conversely, the electrode 114 on the lower surface 111u of the photosensitive member 111 does not have to be transparent and may be made of gold, for example. The perovskite photovoltaic cell 110 furthermore has an electrical terminal with leads 115-1, 115-2, by means of which the photovoltaic cell 110 can be connected to the power electronics 120, as is illustrated in fig. 2, in order to provide the power electronics 120 with a voltage U1 generated upon irradiation. The power electronics 120 are typically configured as an inverter which converts the direct voltage U1 provided by the perovskite photovoltaic cell 110 into an alternating voltage U2 suitable for the consumer 2.

Fig. 2 shows, by way of example and in a simplified manner, a photovoltaic device 1 having a perovskite photovoltaic cell 110 as illustrated in fig. 1 and having the already mentioned power electronics 120. The photovoltaic system 1 also comprises a control unit 130, which is designed to operate the photovoltaic system 1 according to a desired or required operating mode. In this case, in particular for the closed-loop control of the operation of the perovskite photovoltaic cell 110 as part of the photovoltaic device 1, the power electronics 120 are actually closed-loop controlled, which are connected on the one hand to the control unit 130 via a data connection 131. On the other hand, the power electronics 120 are associated with the photovoltaic cell 110 and deliver the voltage U1 generated by the photovoltaic cell 110 upon irradiation to the power electronics 120 via an electrical lead or terminal 115.

The control unit 130 is particularly in a normal operating state or "normal operation" and biasedAnd distinguishing between pressure running states. In normal operation of the photovoltaic device 1, the perovskite photovoltaic cell 110 is illuminated with light L and generates an output voltage U1. The output voltage is supplied to the power electronics 120 and is converted there, as required and in a manner operated by the control unit 130, into a voltage U2, which is ultimately supplied to the electrical load 2. During normal operation, the photovoltaic device 1 and in particular the perovskite photovoltaic cells 110 are at a normal efficiency EFF (t) ═ EFF_normOperating, the normal efficiency ideally corresponds to the maximum achievable efficiency EFFmax. However, as already explained in the introduction, after a period of no irradiation or at most very weak irradiation, for example after the photovoltaic cell 110 has been put into operation at the time point T0, a certain period of time first has to elapse until the efficiency EFF reaches the normal efficiency EFF at the time point T1_norm. Thus, basically EFF (t')<EFF_normFor the time period T0 ≦ T' ≦ T1, and for T>T1 applies to EFF (T) ═ EFF_norm。

Thus, in other words and in particular in general terms, the efficiency EFF of the perovskite photovoltaic cell 110 is, in the example mentioned, at commissioning when a specific situation arises, and is then also expected in a certain period of time than in normal operation_normAnd is smaller.

The control unit 130 is now set up to monitor whether such a specific situation occurs in the photovoltaic arrangement 1 and to operate such that the bias operating state of the photovoltaic arrangement 1 is triggered within a preset time period dT, which typically lasts for a few seconds, when the specific situation occurs. In the bias operating state, an electrical bias in the order of, for example, 1.2V to 2.0V is applied from the energy source 121 onto the perovskite photovoltaic cell 110 or onto the photoactive component 111 thereof and in particular via the electrodes 113, 114. The bias induces ion migration within the photosensitive element 111, which causes a resulting electric field that advantageously acts on the efficiency EFF (t), particularly when the normal efficiency EFF has not been reached_normThis is the case.

The bias operating state is also terminated by switching off the bias voltage and the photovoltaic system 1 is converted into normal operation, in which the perovskite photovoltaic cells 110 provide an output voltage U1 which is output in a known manner to the power electronics 120 for further processing and in which the photovoltaic system 1 operates, in particular, with a normal efficiency EFFnorm and with a normal efficiency.

The energy source 121 is ideally integrated into the power electronics 120 which are present anyway. The expression "integrated" is understood here to mean that the energy source 121 is not merely arranged, for example, in a housing of the power electronics 120. Rather, "integrated" means that the energy source 121, which is in this case in particular designed as a battery or as a capacitor, is integrated into the circuit of the power electronics 120 in terms of circuitry. Particularly advantageously, the energy source 121 may be a component which is provided in the circuit of the power electronics 120. As already mentioned hereinbefore, PCT/EP2015/061129 and also PCT/EP2015/061932 show a power electronics circuit together with an energy storage integrated in its intermediate circuit.

As an alternative to integration into the power electronics 120, the energy source 121 can of course also be a separate energy source 121' arranged outside the power electronics 120 and independently of the power electronics 120, for example a battery or also a terminal to a public or non-public electrical network. This is indicated in fig. 2 by an energy source 121' indicated with dashed lines, which may be connected to the photosensitive element 111, for example, via electrical connection means or terminals 115 and the respective electrodes 113, 114. Alternatively, the energy source 121' can of course also be connected to the electrodes 113, 114 of the photosensitive element 111 via separate, additional connections. However, this is less advantageous insofar as additional effort is required in the case of corresponding wiring and contacting. Depending on the type of the individual energy source 121 ', an electronic device 122 ' may be required, which converts an alternating voltage, for example provided by the grid 121 ', into the required bias voltage. In the case described, the electronics 122' embodied as a rectifier is operated accordingly by the control unit 130.

The integration of the energy source 121 into the power electronics 120 however brings about the major advantage over the use of a separate energy source 121' that an always present data connection 131 between the control unit 130 and the power electronics 120 can be used in order to directly operate the energy source 121 in the power electronics 120 such that it provides the required bias voltage in the particular case. It is particularly advantageous to use an energy source that is already present in the electronic circuit of the power electronics 120. Such modern power electronics 120 are usually connected to or comprise a so-called "power optimizer", which is electrically coupled to the inverter 120 and has components available as energy sources or can itself serve as such components. The described components of the electronic circuit of the power electronics 120 can be used in the application described here as a source 121 of electrical energy for supplying a bias voltage to the electrodes 113, 114, wherein a correspondingly required closed-loop or open-loop control is provided in the control unit 130. In the described case, the power electronics 120 thus do not have to be changed, but rather utilize the available electronic circuits.

In operation of the photovoltaic system 1, the control unit 130 is operated such that it places the photovoltaic system 1 at the latest after a predetermined period of time dT in the normal operating state again such that the photovoltaic system operates in normal operation, in which the photovoltaic system 1 is in the biased operating state. Advantageously, now in normal operation at least a portion of the output voltage U1 generated by the perovskite photovoltaic cell 110 in normal operation is used to recharge the energy storage 121. This does not have to take place directly after the preset time period dT, but is initiated only subsequently by the control unit 130, for example when the energy demand of the consumers 2 supplied by the photovoltaic device 1 is lower than the electrical energy instantaneously supplied by the photovoltaic cells 110.

The control unit 130 is also designed to operate the photovoltaic system 1 and, in particular, the power electronics 120, if the energy source 121 is integrated into the power electronics 120, such that the bias voltage is constantly applied to the photoactive component 111 of the perovskite photovoltaic cell 110 or to the respective electrode 113, 114 during a predetermined time period dT.

In a first alternative thereto, the control unit 130 can also be operated such that the bias voltage is applied in pulses. Here, bias pulses are appliedIs applied to the electrodes 113, 114, wherein no voltage is applied to the electrodes 113, 114 between two pulses following each other. In this case, it is possible to make a measurement between two bias pulses, respectively, of, for example, the effective coefficient or the current-voltage characteristic curve or another variable representing the instantaneous efficiency of the perovskite photovoltaic cell 110. If the measurement yields that the measured efficiency EFF (t) reaches, for example, an efficiency EFF which substantially corresponds to the normal efficiency_normThe bias operating state may be terminated early, i.e., before the preset time period dT has elapsed.

In a second alternative, a bias voltage is applied such that a predetermined amount of charge flows into the perovskite photovoltaic cell 110 or the photoactive assembly 111. Since it is assumed, as mentioned in the introduction, that the ion transport in the photosensitive element 111 is important initially in the case of reduced efficiency and in the case of a favorable action of the bias voltage, the control of the charge flowing into the photosensitive element 111 in the biased operating state allows the operating conditions of the photovoltaic cell 110 to be set more accurately than in the case of a constant bias voltage being applied.

In the example mentioned above, the particular situation, which is a prerequisite for the triggering of the bias operating state of the photovoltaic device 1, which occurs, as it has been defined in the introduction, is the commissioning of the photovoltaic device 1. In the case of such a commissioning, the control unit 130 is typically directly involved, since the commissioning is usually triggered via the control unit 130 itself. Accordingly, the monitoring of whether a particular situation occurs and the possible subsequent action of applying a bias voltage is less complex and can be implemented in the simplest case by a pure software solution of the operating software of the control unit 130.

The particular situation of commissioning is not, however, the only situation in which the photovoltaic device 1 is transitioned into the biased operating state such that an electrical bias is applied to the perovskite photovoltaic cells 110. The specific situation as a precondition for its occurrence being the triggering of a biased operating state of the photovoltaic device 1 may also be taken into account in a first modification of the lack of irradiation of the perovskite photovoltaic cell 110, for example due to cloudiness or in the case of dawn or dusk or the like. In order to monitor the occurrence of this particular situation of lack of illumination of the photovoltaic device 1, the photovoltaic device 1 has a light sensor 116 which is arranged as close as possible to the photoactive component 111 of the perovskite photovoltaic cell 110 and which is also connected to the control unit 130 in order to transmit sensor data for the control unit 130. The sensor data are quantities representing the intensity of the irradiation of the perovskite photovoltaic cell 110, and the control unit 130 is set up to evaluate the sensor data and compare them with an irradiation threshold BS. Below the irradiation threshold BS it may be assumed that there is a specific situation where the perovskite photovoltaic cell 110 is lacking irradiation and the control unit 130 may trigger the bias operating state in the time period dT as in the case of commissioning. However, in an advantageous further development, the triggering of the bias operating state takes place in particular when the instantaneous illumination measured by the light sensor 116 exceeds a predetermined illumination threshold BS', since the illumination would otherwise be insufficient for normal operation and the application of the bias would be superfluous, since the perovskite photovoltaic cell 110 would not always operate effectively. Here, BS ═ BS' may be applied as necessary. Thus, in the specific case of lack of illumination, two points in time TS1, TS2 are ideally observed, namely a point in time TS1 below the illumination threshold BS and a point in time TS2 above the illumination threshold BS'. Upon determining that the first illumination threshold BS is undershot, the control unit 130 can first switch to standby operation and only then switch from standby operation to bias operation state when the illumination threshold BS' is exceeded. If the bias operating state is triggered, the method proceeds further, as already described above, i.e. the bias and the bias operating state with the bias are terminated after a time period dT, or in the case of a pulsed application of the bias, possibly only when the measured efficiency eff (t) reaches a predefinable threshold value.

As a special case of the premise that its occurrence is the triggering of the bias operating state of the photovoltaic device 1, a lower than preset minimum efficiency EFFmin of the perovskite photovoltaic device 110 can also be considered in the second modification. Here, a measured variable representing the instantaneous efficiency of the perovskite photovoltaic cell 110 is ascertained and compared to an efficiency threshold. The possibilities for measuring such a measurement variable representing the instantaneous efficiency are given below. Similarly to the first modification, the control unit 130 is also used in the second modification in order to monitor the instantaneous efficiency or a corresponding representative measured variable. Below the efficiency threshold it is assumed that there is a particular situation where the instantaneous efficiency of the perovskite photovoltaic cell 110 is too small, and the control unit 130 triggers the bias operating state for a time period dT. If the bias operating state is triggered, a further method is carried out, as already described above.

Similarly, in a third modification, a preset minimum output voltage U1min below the perovskite photovoltaic cell 110 may be considered as a specific situation on the premise that its occurrence is a trigger for the bias operating state of the photovoltaic device 1. The instantaneous output voltage U1 of the perovskite photovoltaic cell 110 is applied across the power electronics 120 and it may be assumed that a voltage U1 is also present for the control unit 130. In general this may be expressed as the photovoltaic device 1 having a voltmeter for measuring the output voltage U1 of the perovskite photovoltaic device 110, wherein the voltmeter is actually realized by the power electronics 120 in combination with the control unit 130. The voltage meter 120 is connected to the control unit 130 in order to transmit voltage measurement data, which represent the instantaneous output voltage U1, and the control unit 130 is designed to evaluate the voltage measurement data and to compare them to a voltage threshold value. Below the voltage threshold there is a specific situation below a preset minimum output voltage U1min and the control unit 130 triggers the bias operating state. If the bias operating state is triggered, a further method is carried out, as already described above.

In a fourth refinement, the elapse of a predetermined time period since the last occurrence of the specific situation can again be regarded as a specific situation, i.e. the specific situation and its accompanying bias operating state occur in principle regularly or periodically. If the bias operating state is triggered, a further method is carried out, as already described above. In particular, a specific situation that has elapsed a preset period of time since the last occurrence of the specific situation can be monitored by the control unit 130 without special additional assistance, as can the specific situation put into operation, by: the control unit is provided with a corresponding software solution running software, which records this situation.

Finally, it is proposed that the way for measuring the instantaneous efficiency of the perovskite photovoltaic cell 110 or for ascertaining a measurement variable representing the instantaneous efficiency is to measure the amount of light or the intensity of the illumination falling onto the photovoltaic cell 110 in the form of a corresponding power and to compare this power with the power generated by the photovoltaic cell 110 as a result of the illumination. Another possibility for determining the measured variable representing the instantaneous efficiency of the perovskite photovoltaic cell 110 is to determine an instantaneous, so-called "maximum power point" (MPP) of the current-voltage characteristic of the perovskite photovoltaic cell 110, which maximum power point describes the point on the current-voltage characteristic at which the photovoltaic cell 110 delivers the maximum possible power under the respectively given environmental conditions. Thus, for example, an instantaneous current-voltage characteristic can be recorded at time Tx and the instantaneous mpp (Tx) can be determined therein, which is then a quantity representing the instantaneous efficiency. When the mpp (tx) is less than the mpp (norm) assumed to be known, it must be assumed that the instantaneous efficiency is less than the efficiency common or possible in normal operation, where mpp (norm) describes the maximum possible power in a normal or optimally operating photovoltaic cell 110. The absolute value mpp (tx) is therefore not critical here, but a comparison with a reference value, for example mpp (norm), is critical.

It is further noted that the "photon conversion efficiency" PCE of the photoactive component 111 of the perovskite photovoltaic cell 110 may be assumed hereinabove to represent a magnitude of the efficiency or effective coefficient of the perovskite photovoltaic cell 110, even if it is assumed that the efficiency of the photovoltaic cell 110 is not only related to the PCE, but also to other partially fixed parameters, such as the type or material of the electrodes 113, 114, the arrangement of the electrodes 113, 114 and possibly other layers of the photoactive component 111 not mentioned herein. However, it is also assumed that the bias applied here substantially acts on the PCE and does not act on other efficiency affecting parameters. Therefore, it is reasonable here to have a way to represent the efficiency substantially by the PCE.

List of reference numerals

1 photovoltaic device

110 perovskite photovoltaic cell

111 photosensitive component

111o upper surface

Lower surface of 111u

112 bearing part

113 electrode

114 electrode

115 electrical terminal, connecting device

115-1 electric lead

115-2 electrical lead

116 light sensor

120 power electronic device

121 energy source, battery, capacitor, super capacitor

121' energy source, electric network

122' electronic device

130 control unit

131 data connecting device