TECHNICAL FIELD
This disclosure relates to the field of renewable solar energies and concerns a device with self-repairing multi-junction solar cells and a method for self-repair of such a device, making it possible to produce a new architecture of multi-junction solar generation units. In the case of thin-film multi-junction solar cells, in particular film layers based on perovskite materials, these layers may undergo reversible degradation and therefore are able to allow self-repair of these layers and therefore of the cells.
BACKGROUND
Silicon solar cells degrade slowly but irreversibly and their average production life cycle is on the order of 40 years (considering a degradation of 0.5% per year and an end of life at 80% of the nominal power). The novel perovskite cell technologies, which will be used in perovskite/silicon multi-junction modules to limit thermalization losses and thus increase efficiency, undergo a more significant degradation according to ongoing studies which varies with the technologies analyzed (on the order of 0.05% to 0.5% per day, for example). However, some of this degradation, linked among other things to the electronic and ionic nature of the charges in perovskite materials, is reversible, which makes it possible to consider a self-repairing of the perovskite layers of multi-junction cells.
The reversible degradation of perovskite layers is linked in particular to the movement of ions within the structure of these layers. Unlike the reference case of silicon, transient phenomena are observed under real conditions, for example in day-night cycles, and one can take advantage of these phenomena to reduce degradation and regain optimal cell performance. Currently, self-repairing in the case of reversible degradation is limited to recovery during night periods, this recovery being similar to resting the cell.
Self-repair, which is limited to the duration of night periods and which in particular is not controlled by an algorithm, may not take into account all of the needs for self-repair created by the cells' use, is not optimized, and in particular does not allow searching for and providing the regeneration optimum required in order to return to the initial performance point of the cells at each cycle/day.
DETAILED DESCRIPTION
In view of this situation, the objective of the present disclosure is, on the one hand, to propose cells that allow optimizing their self-repair and to produce photovoltaic modules provided with such cells, and, on the other hand, to provide methods and algorithms for controlling such photovoltaic modules in order to control and maximize the self-repair of said cells. To do so, the invention is based on photovoltaic assemblies configured to allow the use of first photovoltaic stacks as a power generator while a second photovoltaic stack undergoes a self-repair process during the day.
More specifically, this disclosure proposes a photovoltaic assembly comprising, from a first face of the assembly to a second face of the assembly:
- a first electrode for connecting a first transparent electrical contact layer to at least a first selective charge extraction layer of a first photovoltaic stack,
- the first photovoltaic stack,
- a second electrode for connecting a second transparent electrical contact layer to at least a second selective charge extraction layer of said first photovoltaic stack,
- a first transparent insulating layer,
- a third electrode for connecting a first transparent electrical contact layer to at least a second selective charge extraction layer of a second photovoltaic stack,
- the second photovoltaic stack,
- a fourth electrode for connecting a second transparent electrical contact layer to at least a first selective charge extraction layer of said second photovoltaic stack,
- a second transparent insulating layer,
- a fifth electrode for connecting a first transparent electrical contact layer to at least a first selective charge extraction layer of a third photovoltaic stack,
- the third photovoltaic stack,
- a sixth electrode for connecting a second transparent electrical contact layer to at least a second selective charge extraction layer of said third photovoltaic stack,
- a seventh electrode for connecting a first transparent electrical contact layer to at least a first selective charge extraction layer of a fourth photovoltaic stack,
- said fourth photovoltaic stack,
- an eighth electrode for connecting a second transparent electrical contact layer to at least a second selective charge extraction layer of said fourth photovoltaic stack, said fourth photovoltaic stack being arranged between the second photovoltaic stack and the third photovoltaic stack, said fourth photovoltaic stack being a stack in which the absorber material has a lower band gap than that of the third stack, in particular an absorber of silicon, another perovskite, a thin-film absorber, or some other material, said electrodes of said fourth stack being independent of the electrodes of the first, second, and third stacks, and wherein:
- the first photovoltaic stack and the third photovoltaic stack are photovoltaic stacks with perovskite absorber,
- the second photovoltaic stack is a photovoltaic stack in which the absorber material has a lower band gap than that of the first stack, in particular an absorber of silicon, another perovskite, a thin-film absorber, or some other material,
- the fourth photovoltaic stack is a photovoltaic stack in which the absorber material has a lower band gap than that of the third stack, in particular an absorber of silicon, another perovskite, a thin-film absorber, or some other material,
- said electrodes connecting said transparent electrical contact layers are independent of each other.
The first and third photovoltaic stacks of the assembly may each comprise:
- one or more first protection and passivation layers for said absorbers, between said first selective charge extraction layers and said perovskite absorber,
- said perovskite type of absorber,
- one or more second protection and passivation layers for said absorbers, between said one or more second selective charge extraction layers and said perovskite type of absorber.
This disclosure further proposes a photovoltaic device comprising a panel provided with photovoltaic assemblies as described above and further comprising an electrical connection device configured for:
- connecting the first electrode and third electrode, and connecting the second electrode and fourth electrode, of said assemblies and forming first parallel bi-junction solar cells by means of the first and second assemblies on a first side of the panel,
- connecting the fifth electrode and the seventh electrode, and connecting the sixth electrode and the eighth electrode, and forming second parallel bi-junction solar cells by means of the third and fourth assemblies on a second side of the panel.
The device may be such that, when the first face of the panel is arranged on the sunlight side and the second face of the panel on the shadow side, said first solar cells form a first current/voltage generator and said second solar cells are in a self-repair mode, and such that, when the device is turned over with the second face on the sunlight side and the first face on the shadow side, said second solar cells form a second voltage/current generator and said first solar cells are in a self-repair mode.
This disclosure further proposes a photovoltaic system comprising at least:
- a photovoltaic device as described above,
- a frame provided with turning means for turning the panel,
- a converter module with MPPT regulation, and
- a regeneration module for regenerating said perovskite absorbers,
- wherein the converter module comprises means for monitoring the irradiance detected by the panel and means for monitoring weather data, means for monitoring the degradation of the absorbers, for example perovskite type absorbers, and means for controlling said turning means which are configured to turn said panel over in the event of a degradation exceeding a defined threshold in those among said first or third photovoltaic stacks with perovskite absorber that are positioned on the sunlight side in order to position them on the shadow side and to position the others among said first and third photovoltaic stacks with perovskite absorber on the sunlight side, the connection device being configured to disconnect those among said first and third photovoltaic stacks that are positioned on the shadow side of the converter module and to connect it to the regeneration module.
The system may be such that the regeneration module comprises at least one of:
- a device for short-circuiting the electrodes of a photovoltaic stack with perovskite absorber that is connected to it,
- a device for open-circuiting the electrodes of said photovoltaic stack with perovskite absorber that is connected to it,
- a device for generating voltage pulses towards the photovoltaic stack with perovskite absorber that is connected to it, and may comprise means for measuring the current/voltage, in darkness, of said photovoltaic stacks with perovskite absorber that are connected to it.
This disclosure also proposes a method comprising a sequence of:
- one or more measurements of the detected irradiance and the temperature at said at least one panel, and measurements of weather data;
- a detection of whether it is a day or night situation;
- if night is detected:
- one or more recordings and analyses of the regeneration of the first and third photovoltaic stacks with perovskite absorber, estimation of the time required for maximum regeneration of said stacks, and implementation of regeneration processes for said first and third photovoltaic stacks with perovskite absorber of said panel (160);
- if day is detected:
- one or more sequences comprising: regeneration (120) of the shadow-side photovoltaic stacks with perovskite absorber; estimation of the expected performances of the sunlight-side photovoltaic stacks with perovskite absorber; measurement of the degradation of the sunlight-side photovoltaic stacks with perovskite absorber relative to said expected performances; and estimation of the regeneration rate of the shadow-side photovoltaic stacks with perovskite absorber of said panel relative to said expected performances in order to detect a regeneration rate giving a higher performance of the shadow-side photovoltaic stacks with absorber than the performance of the sunlight-side photovoltaic stacks with perovskite absorber after degradation; and a detection such that:
- if the regeneration of the shadow-side photovoltaic stacks with perovskite absorber corresponds to a higher performance than the performance of the sunlight-side photovoltaic stacks with perovskite absorber after degradation, said panel is turned over by controlling said turning means;
- if the regeneration of the shadow-side photovoltaic stacks with perovskite absorber remains lower than the performance of the degraded sunlight-side photovoltaic stacks with perovskite absorber, the panel is maintained in its position.
The method may be such that the estimation of the regeneration rate of the shadow-side photovoltaic stacks with perovskite absorber of said panel comprises current/voltage measurements in shadow/in darkness.
The regeneration steps may comprise at least one of the following operations:
- one or more applications of voltage pulses across the photovoltaic stacks with perovskite absorber,
- short-circuiting said photovoltaic stacks with perovskite absorber, one or more times, and
- open-circuiting said photovoltaic stacks with perovskite absorber, one or more times.
Said sequence may be repeated throughout the operation of said panels.
The photovoltaic system advantageously comprises a processor associated with a program memory containing a program provided with instructions for implementing the above method.
This disclosure further provides a computer-readable non-transitory storage medium on which said program is stored.
BRIEF DESCRIPTION OF DRAWINGS
Other features, details and advantages of the invention will become apparent upon reading the detailed description below of some non-limiting exemplary embodiments, and upon analyzing the appended drawings, in which:
FIG. 1 shows a schematic cross-section view of a photovoltaic assembly;
FIG. 2A shows a schematic view of a use of the assembly of FIG. 1;
FIG. 2B shows a schematic view of a use of the assembly of FIG. 1;
FIG. 3 shows an example of a flowchart of a method for controlling a solar panel;
FIG. 4 shows a schematic view of a use of a panel provided with the assembly, at night.
DETAILED DESCRIPTION
The drawings and the following description contain elements which may not only serve to provide a better understanding of the invention, but where appropriate may also contribute to its definition.
Reference is now made to FIG. 1 which shows a photovoltaic assembly of this disclosure which comprises, from a first face 1 of the assembly to a second face 2 of the assembly:
- a first electrode c1 which is connected to a first transparent electrical contact layer 32a, for example a contact grid or a conductive layer, in order to connect at least a first transparent charge extraction layer 33a of a first photovoltaic stack 3,
- first photovoltaic stack 3,
- a second electrode c2 which is connected to a second transparent electrical contact layer 32b, for example a contact grid or a conductive layer, in order to connect at least a second transparent charge extraction layer 33b of first photovoltaic stack 3,
- a first transparent insulating layer 61,
- a third electrode c3 connected to a first transparent electrical contact layer 52a in order to connect at least a first transparent charge extraction layer 53a of a second photovoltaic stack,
- second photovoltaic stack 5,
- a fourth electrode c4 connected to a second transparent electrical contact layer 52b in order to connect at least a second transparent charge extraction layer 53b of second photovoltaic stack 5,
- a second transparent insulating layer 62,
- a fifth electrode c5 which is connected to a first transparent electrical contact layer 42a in order to connect at least a first transparent charge extraction layer 43a of a third photovoltaic stack 4,
- third photovoltaic stack 4,
- a sixth electrode c6 which is connected to a second transparent electrical contact layer 42b in order to connect at least a second transparent charge extraction layer 43b of said third photovoltaic stack,
wherein:
- first photovoltaic stack 3 and third photovoltaic stack 4 are photovoltaic stacks with perovskite absorber 31, 41,
- second photovoltaic stack 5 is a photovoltaic stack with silicon absorber 51,
- electrodes c1, c2, c3, c4, c5, c6 for connecting extraction layers 33a, 33b, 43a, 43b, 53a, 53b through conductive layers 32a, 32b, 42a, 42b, 52a, 52b are independent of each other,
- the assembly comprises a fourth photovoltaic stack 6 with silicon absorber between the second photovoltaic stack with silicon absorber 51′ and the third photovoltaic stack 4 with perovskite absorber 41. Fourth photovoltaic stack 6 comprises its own electrodes c3′ and c4′.
In this configuration of two multi-junction cells, the assemblies forming cells 3 and 5 and the assemblies forming cells 4 and 6 are back to back and are used in alternation by turning over the panel comprising them. These two assemblies are separated by an electrically insulating layer 55 which may or may not be a transparent layer.
The first photovoltaic stack and the third photovoltaic stack each comprise one or more first protection and passivation layers 34a, 44a, 33b, 44b for said absorbers, between the selective charge extraction layers 33a, 43a, 33b, 43b on each side of perovskite absorber 31, 41.
The selective charge extraction layers may in particular be layers known by the abbreviations ETL or HTL (“electron transport layer” or “hole transport layer”).
The electrically insulating and optically transparent layers 61, 62 are for example films known in the field by the acronym EVA.
The assemblies shown are component elements of solar panels P, schematically represented in FIG. 2A in a first position and in FIG. 2B in a position that is turned over relative to the first position as seen above. In these figures, two series of assemblies are shown in order to simplify the drawing, but the panel may comprise a large number of assemblies in an x, y matrix. The assemblies are chosen according to the desired voltage and current to be output from the device, according to the electrical system downstream. In the context of this disclosure, the electrodes of first stacks 3, 3′ . . . are connected in parallel, the electrodes of second stacks 5, 5′ . . . are connected in parallel, the electrodes of third stacks 4, 4′, . . . are connected in parallel, and the electrodes of stacks 6, 6′, . . . are connected in parallel.
For this configuration, the stacks with perovskite absorber located on the light side 10 and the stacks with silicon absorber which are beneath them, are receiving light and can operate as a generator, while the stacks with silicon absorber and the stacks with perovskite absorber located under the panel receive practically no light, the stacks with perovskite absorber that are under the panel being able to be placed in a regeneration configuration even during the day.
To do so, a connection device 7 is configured to allow the electrodes of the photovoltaic stacks with perovskite absorber that are under the panel to be disconnected from the electrodes of the upper ones which are connected in parallel. This makes it possible to connect the electrodes of the stacks with perovskite absorber that are under the panel to a regeneration module 9, while the electrodes of the light-side stacks 10 with perovskite absorbers and the first stacks with silicon absorbers are connected to an MPPT converter module 8, MPPT being the acronym for “Maximum power point tracking”.
The electrical connection device may comprise two contact carrier plates adapted to rotate relative to each other as occurs in a rotary connector, or may be an electronic device with electronic switches, for example based on IGBT (insulated gate bipolar transistor) or MOSFET (metal-oxide gate field effect transistor) transistors which are configured to distribute the electrodes between MPPT converter module 8 and regeneration module 9 and are controlled by the position of the panel.
The assemblies of the panel are such that a first multi-junction cell based on first stack 3 with perovskite absorber 31 and first stack 5 with silicon absorber 51, and a second multi-junction cell implemented based on second stack 4 with perovskite absorber 41 and second stack 6 with silicon absorber 51, are created. According to FIG. 2A, it is the electrodes of second photovoltaic stacks 4, 4′ which are located under the panel in the shadow 11 of the panel when face 1a of the panel is on the light side and face 2a of the panel is on the shadow side. The electrodes of second stacks 4, 4′ with perovskite absorbers are then connected through electrical connection device 7 to the regeneration module, while, in the diagram shown, the electrodes of second stacks 6, 6′ are left disconnected. In this case, first stacks 3, 3′ with light-side perovskite absorbers 11 and stacks 5, 5′ with silicon absorbers are connected together and are connected to MPPT converter module 8 through electrical connection device 7.
When the panel is turned over according to FIG. 2B, first stacks 3, 3′ with perovskite absorbers are then located under the shadow side 11 of the panel and are then connected to regeneration module 9, while first stacks 5, 5′ with silicon absorbers are disconnected. On the sunlight side 10, the second stacks with perovskite absorbers and second silicon stacks 6, 6′ are connected in parallel and linked to MPPT converter module 8.
This system therefore allows performing sequences of self-repair or regeneration of the stacks with perovskite absorbers which are located under the panel during the day, while the panel is supplying electricity by means of the multi-junction cells formed by the stacks with perovskite and silicon absorbers on the light side on the upper face.
To allow panels P, P′ to operate as explained above, the panels are integrated into a photovoltaic system comprising: said panels mounted in frames equipped with turning means 12 for turning the panels; electrical connection devices 7 associated with the panels, preferably one per panel or one per group of assemblies in a distribution of assemblies by row or by column on the panel; one or more converter modules 8 with MPPT regulation; and one or more regeneration modules 9 for regenerating said perovskite absorbers.
The converter module(s) are connected to the panel outputs in a conventional manner. These converter modules preferably comprise means for monitoring the irradiance detected by the panel and means for monitoring weather data.
According to this disclosure, the converter modules or the monitoring modules associated with them are provided with means for monitoring the degradation of perovskite absorbers 31, 41 and means for controlling turning means 12 which are configured to turn over the panels associated therewith in the event of a degradation exceeding a defined threshold of the ones among said photovoltaic stacks 3, 4 with perovskite absorbers of the panel that are positioned on the sunlight side 10 in order to position them on the shadow side and position on the sunlight side the photovoltaic stacks 4, 3 with perovskite absorbers of the panel that were previously on the shadow side.
In parallel, when turning panels over, connection device 7 of the panels is configured to disconnect those among said first and third photovoltaic stacks that are positioned on the shadow side of converter module 8 and to connect them to regeneration modules 9 associated with the rotated panels.
For the regeneration of perovskite absorbers that is related to the movement of ions and their distribution, the regeneration modules comprise at least one among a device 91 for short-circuiting the electrodes of a photovoltaic stack with perovskite absorber that is connected to it, a device 92 for open-circuiting the electrodes of said photovoltaic stack with perovskite absorber that is connected to it, and a device 93 for generating voltage pulses towards the photovoltaic stack with perovskite absorber that is connected to it.
To measure the degradation and regeneration of the stacks, regeneration module 9 comprises means 94 for measuring the current/voltage of said photovoltaic stacks with perovskite absorber, in darkness.
These devices are used based on the degradation of said stacks in order to reposition the ions according to determined sequences comprising for example regeneration modes comprising in particular a short-circuiting of the stacks, an open-circuiting of the stacks, and/or a generation of voltage pulses across the stacks, the system being configured to evaluate autonomously whether the treatment is effective or whether to switch to another mode.
It should be noted that, during the day, the stacks located under the panels are regenerated, while at night the stacks with perovskite absorbers on both sides of the panel are regenerated. To do this, the connection device may, as shown in FIG. 4 where the connections of assemblies 5 and 6 are not shown for simplicity, comprise two groups of additional switches 71, 72 controlled by the converter module and by the means for day/night detection for example coming from means for monitoring the weather, these groups of additional switches 71, 72 making it possible to connect all the stacks with perovskite absorber to regeneration device 9 and to disconnect them from converter module 8. Again according to FIG. 4, switch device 7, converter module 8, and the regeneration module are grouped together in a solar panel monitoring or management device 20.
A method for controlling a photovoltaic system as described in FIG. 3 may in particular comprise a sequence of:
- one or more measurements of the detected irradiance and the temperature at said at least one panel, and measurements of weather data;
- a detection 110 of whether it is a day or night situation;
- if night is detected:
- one or more recordings and analyses of the regeneration of the first and third photovoltaic stacks with perovskite absorber, estimation of the time required for maximum regeneration of said stacks, and implementation of regeneration processes for said photovoltaic stacks with perovskite absorber of panel 160;
- if day is detected:
- one or more sequences comprising: regeneration 120 of the shadow-side photovoltaic stacks with perovskite absorber; estimation of the expected performances of the sunlight-side photovoltaic stacks with perovskite absorber; measurement of the degradation of the sunlight-side photovoltaic stacks with perovskite absorber relative to said expected performances; and estimation of the regeneration rate of the shadow-side photovoltaic stacks with perovskite absorber of said panel relative to said expected performances in order to detect a regeneration rate giving a higher performance of the shadow-side stacks with absorber photovoltaic than the performance of the sunlight-side photovoltaic stacks with perovskite absorber after degradation 130; and a detection 140 such that:
- if the regeneration of the shadow-side photovoltaic stacks with perovskite absorber corresponds to a higher performance than the performance of the sunlight-side photovoltaic stacks with perovskite absorber after degradation, said panel is turned over 150 by controlling turning means 12;
- if the regeneration of the shadow-side photovoltaic stacks with perovskite absorber remains lower than the performance of the degraded sunlight-side photovoltaic stacks with perovskite absorber, the panel is maintained in its position.
Estimation of the regeneration rate of shadow-side photovoltaic stacks with perovskite absorber of said panel comprises current/voltage measurements in shadow.
The regeneration steps comprise at least one of the following operations:
- a. one or more applications of voltage pulses across the photovoltaic stacks with perovskite absorber,
- b. short-circuiting said photovoltaic stacks with perovskite absorber, one or more times, and
- c. open-circuiting said photovoltaic stacks with perovskite absorber, one or more times.
Said sequence is in particular repeated throughout the operation of said panels and the life of the system.
The invention is not limited to the examples described above solely as examples, but encompasses all variants conceivable to a person skilled in the art in the context of the protection sought. In particular, the converter module, connection device, and regeneration module may be separate elements or may be grouped wholly or in part in a controller device, and the method may be integrated into a method for managing a fleet of solar panels or groups of panels.
Patent Application
20250169198
