WO2009089562A1

WO2009089562A1 - Photovoltaic module

Info

Publication number: WO2009089562A1
Application number: PCT/AU2008/000040
Authority: WO
Inventors: Igor Lvovich Skryabin; Ilya Yakupov; Jonathan Goldstein
Original assignee: 3G Solar Ltd
Priority date: 2008-01-16
Filing date: 2008-01-16
Publication date: 2009-07-23
Also published as: CA2748067A1

Abstract

The invention discloses a new method for sealing photoelectochemical devices and connecting the devices into arrays. A photoelectrochemical device of the invention comprises a dye solar cell (DSC) sandwiched between the inner faces of two panels, each having an inner face, an outer face and edges, wherein at least one pair of adjacent edges of separate panels is hermetically enclosed by a housing sealed to the outer faces and/or edges of the panel. Electrical terminals of the photoelectrochemical device are formed on the housing and are useful for interconnecting the devices to form a photoelectrochemical array.

Description

Photovoltaic Module

TECHNICAL FIELD

This invention relates to photoelectrochemical photovoltaic devices. More particularly, the invention relates to dye sensitised solar cells and modules.

BACKGROUND OF THE INVENTION

Examples of the photoelectrochemical devices are disclosed in the following patent specifications:

US4927721 , Photoelectrochemical cell; M. Graetzel et al 1990.

US5350644, Photovoltaic cells; M. Graetzel, et. al 1994.

PCT/AU2004/000689, Combined photoelectrochemical cell and capacitor, I. L. Skryabin et al, 2004

PCT/AU2005/000844, Photovoltaic module with full utilisation of surface area, I.LSkryabin et al, 2004

Dye Solar Cells, as of the type disclosed in the above patents and patent specifications, are typically fabricated in a laminate arrangement that may include one or two panels.

At least one panel is transparent to solar radiation. The panels can be made of glass, metal or plastic or a combination thereof. In some cases a metallic panel is also covered by an electrically conductive corrosion protective layer. The panels may be rigid or flexible. Dye Solar Cells (DSC) may be combined in modules, comprising a number of cells interconnected to form a single power source sandwiched between two panels. The cells can be interconnected in series or in parallel.

Each cell comprises a number of layers, including:

o dye-sensitised layer of wide band-gap semiconductor (e.g. TiO2),

o redox electrolyte,

o catalytic layer (such as Pt or carbon based catalyst).

The electrolyte may comprise liquid (e.g. organic solvent), molten salt or a polymeric hole conductor.

In all cases inadequate sealing is a major cause for degradation and insufficient durability of the DSC photoelectrochemical devices.

Prior art describes sealing techniques based on glass frit, curable polymeric materials and hot-melts, including hot-melt films backed by Al or other metallic foil.

Inadequate sealing, resulting in the fast ingress of air and humidity into a cell and/or leakage of electrolyte, is a common problem of existing sealing techniques.

Further, the connection of finished cells or modules in arrays is currently a cumbersome and time consuming process.

Subsequently, the present invention addresses the need for an adequate and cost-effective process for the sealing and arranging in arrays of Dye Solar Cells, modules and other photoelecrochemical and electrochemical devices. OBJECTIVE OF THE INVENTION

It is an object of the present invention to overcome or ameliorate at least one disadvantage of the prior art, or to provide a useful alternative.

SUMMARY OF THE INVENTION According to the first aspect of the present invention there is provided a photoelectrochemical device comprising a Dye Solar Cell (DSC) sandwiched between the inner faces of two panels, each having an inner face, an outer face and edges, wherein at least one pair of adjacent edges of the panels is hermetically enclosed by a housing sealed to the outer faces and/or the edges of the panels.

The photoelectrochemical device of the invention may comprise two or more DSCs interconnected and sandwiched between two panels.

The housing is arranged, such that adjacent edges of the panels are hermetically enclosed by the housing.

The housing is preferably made of metal, for example of Al. However, the invention provides for the utilisation of other materials such as impermeable and chemically stable plastics.

The space between the housing and the panels is preferably filled with a sealant to ensure hermetic sealing of the device. The sealant may be a hot-melt material, curable plastic material, glaze-type material, or any other suitable material that adheres both to the panels and the housing.

In one embodiment the housing comprises at least two electrical terminals for the transfer of electrical power produced by DSC to an external load.

In another embodiment the housing is electrically isolated from the electrodes of the DSCM. In this case an additional electrical means may be arranged to provide a path for electrical current generated by DSC through the housing. In one example such a path is provided through a hole made in the housing. In another example such path is provided by a pin extending through and sealed within a hole in the housing.

In yet another embodiment the housing comprises at least two electrically isolated sections each connected to a power output of a DSC. In this case the sections of the housing can be used as an external electrical terminal of the photoelectrochemical device.

In a further embodiment one section of the housing is electrically connected to a positive output of the DSC and another section of the housing is electrically connected to the negative output of the DSC. A number of the photoelectrochemical devices can be electrically configured in series, in parallel or in a combination of series/parallel by an electrical connecting means arranged between the adjacent photoelectrochemical devices. For example, when the series configuration is required, a 'positive' housing section connected to the positive output of the n-th photoelectrochemical device and a housing section connected to the negative terminal of the (n +1)th photoelectrochemical device ('negative' housing sections) are joined by an electrical connecting means. In one preferable arrangement the electrical connecting means is formed on the respective housing sections. In a further preferable arrangement the electrical connecting means is a clamping or other fastening means such that the 'positive' section (positive terminal) of the n-th photoelectrochemical device is clamped to the 'negative' section (negative terminal) of the (n+ 1)th photoelectrochemical device. In this way arrays of the photoelectrochemical devices can be formed.

The sealant is preferably a hot melt material, which is melted and adhered to the panels as well as the housing due to the heat transferred to the sealant. In some cases it is beneficial to supply heat directly to the housing; the heat is further transferred to the sealant. In the other cases, a hot sealant is delivered to a space between the housing and the panels. Special attention is given to minimise the time during which the substrates are exposed to the elevated temperature.

The invention provides for the creation and utilisation of special purpose spaces in the sealant to accommodate environment controlling agents.

In one realsisation a humidity absorbing material (e.g. - molecular sieves) is placed in these spaces to prevent the ingress of humidity into the DSC.

In another realisation these spaces are fully or partially filled with a solvent of the same chemical nature as that of the electrolyte in the DSC. This is especially useful in order to minimise long term degradation effects caused by the loss of solvent in the DSC. It may be beneficial to include in the environment controlling agent other components of the electrolyte, such that these components can be supplied to the electrolyte of the DSC to replace the degraded component of the

BRIEF DESCRIPTION OF DRAWINGS

Having broadly portrayed the nature of the present invention, embodiments thereof will now be described by way of example and illustration only. In the following description, reference will be made to the accompanying drawings in which:

Figure 1 is a cross-sectional representation of a photoelectrochemical device formed in accordance with the first example of the invention.

Figure 2a is a planar diagrammatic representation of a photoelectrochemical device formed in accordance with the second example of the invention.

Figure 2b is a planar diagrammatic representation of an array comprising photoelectrochemical devices of the second example connected in series. Figure 3 is a planar diagrammatic representation of an array comprising two photoelectrochemical devices of the third example connected in parallel.

Figure 4 is a 3D diagrammatic representation of a photoelectrochemical device formed in accordance with the 4^th example of the invention.

Figure 5 is a cross-sectional diagrammatic representation of a photoelectrochemical device formed in accordance with the fifth example of the invention.

DETAILED DESCRIPTION OF DRAWINGS

With reference to Figure 1 , a photoelectrochemical device comprises two panels 11 and 12. At least one of the panels (12) is transparent to solar light 10. A DSC 13 is formed between the panels 11 and 12. The DSC includes: dye sensitized nano-particulate titanium dioxide, an electrolyte, and a catalytic counter electrode layer. An inner surface of the panel 12 is coated with a transparent electronic conductor. An inner surface of the panel 11 is coated with a conductor. In some cases the panel 11 is an electrical conductor itself. Although not shown in the Fig.1 , the DSC may comprise a number of Dye Solar Cells formed between the panels 11 and 12 and internally connected in series, in parallel or in combination of series and parallel.

The DSC formed between the panels 11 and 12 is sealed with a primary sealant 14. A negative electrical terminal 15a (Ag coated bus-bar) is formed on the panel 11 , a positive electrical terminal 15b is formed on the panel 12.

Two prefabricated U-shaped housing sections 16a and 16b are arranged to seal the space 13 enclosed be the housing and the panels 11 and 12. The housing sections are electrically insulated and serve as external electrical terminals. The housing sections are made of Al. Electrical connectors 17 are utilized to connect the electrical terminal 16a to the positive bus-bar 15a and the element 16b to the negative bus-bar 15b. The space 18 between the housing and the panels 11 and 12 is filled with an impermeable sealant (e.g surlyn). The sealant is melted and adhered to the panels and the housing by fast heating and subsequent cooling of the housing, so that the temperature of the dye-sensitised layer of the electrolyte remains below 90 ⁰C.

With reference to Figure 2a, a photoelectrochemical device 20 is framed by a housing that comprises 4 sections: two section 26, each connected to electrical output of DSC to become external electrical terminals, and two sections 24, adopted to electrically insulate the sections 26. The housing is made relatively small, so that a sufficient area 22 of DSC is available to capture solar radiation.

An electrical terminal 27 is formed on or attached to the 'negative' housing section 26 and an electrical terminal 28 is formed on or attached to the 'positive' section 26. The shape of the electrical terminal 27 is complimentary to that of the electrical terminal 28 so that the electrical connectors of the adjacent photoelectrochemical devices (not shown) can be mechanically fastened to one another.

With reference to Figure 2b, three photoelectrochemical devices 20 each framed by a housing comprising 4 sections (2 electrically conductive sections 26 and two electrically insulated sections 24) are connected in series by means of fastening the complimentary electrical terminals 27 and 28.

With reference to Fig. 3, two photoelectrochemical devices 30, each sealed by a 4-section housing, are connected in parallel.

Each device has an area 32 available to capture solar radiation. The 4- section housing includes: a section 36b connected to the negative output of DSC , a section 36a, connected to the positive output of DSC, and 2 sections 34 electrically insulating the sections 36a and 36b. Electrical terminals 37 are formed on or attached to the 'negative' section 36b, and electrical terminals 38 are formed on/attached to the 'positive' section 36a. The electrical terminals 37 and 38 are adapted such that the terminals of two adjacent photoelectrochemical devices can be fastened together to form a mechanically sound electrical connection as schematically shown in Fig. 3.

With reference to Fig. 4 a photoelectrochemical device comprises DSC layers 43 formed between panels 41 and 42. A housing 44 forms a frame arranged at the perimeter of the panels such that all edges of the panels 41 and 42are enclosed within the housing.

A negative electrical bus-bar 45a of DSC is formed on the substrate 42 and connected to the outside of the frame by a wire 51 threaded through a hole 53a made in the housing. Similarly, a positive electrical bus-bar 45b of DSC is formed on the panel41 and connected to the outside of the housing by a wire 52 threaded through a hole 53b made in the housing.

The holes 53a and 53b are subsequently sealed.

The space between the housing and the panels is filled by a two part curable impermeable epoxy type resin.

With reference to Fig.5 a photoelectrochemical device of the fifth example comprises a DSC sandwiched between panels 61 and 62. The panel 62 is optically transparent. The inner faces of both panels are coated by a layer of electrically conductive material 63. The electrically conductive material applied to the panel 62 is optically transparent. The corners of the panels are beveled to enable the extension of the electrically conductive material from the inner surfaces of the panels to the edges of the panels. To enhance electrical conductivity of the electrically conductive material (e.g. fluorine doped tin oxide) metallic conductors in a form of bus-bars 70 are dispensed on the edges of the panels.

A DSC comprising:

o a dye sensitized layer of wide band-gap semiconductor 64 dispensed on the panel 62, o a catalytic layer 65 dispensed on the panel 61 , o a layer of electrolyte 66 dispensed between the semiconductor layer 64 and catalytic layer 65, and o Primary seal 67 formed on the periphery of the DSC layers is sandwiched between the panels 61 and 62.

The housing comprises two 'positive' sections 68b, two 'negative' sections 68a and two insulation sections 69. The 'positive' electrical terminals are formed on the sections 68b by connecting positive electrical outputs of DSC to each of the sections 68b using a flexible wires 73. Similarly, 'negative' sections 68a are connected via flexible wires 71 to the 'negative' bus-bars of the DSC.

The space between the housing and the panels is filled with an adhesive material 72. A part of this space is utilized for an environment controlling agent 73 to control humidity and/or vapour pressure of electrolyte solvent. In one realization the environment controlling agent comprises a solvent of the electrolyte of the DSC. In another realization the environment controlling agent comprises humidity absorbing agent, such as molecular sieves. In a further realization the environment controlling agent comprises the electrolyte of the DSC.

Arrows 75 show clamping action of the housing.

Claims

CLAIMS :

1. A photoelectrochemical device comprising a dye solar cell (DSC) sandwiched between the inner faces of two panels, each having an inner face, an outer face and edges, wherein at least one pair of adjacent edges of separate panels is hermetically enclosed by a housing sealed to the outer faces and/or edges of the panels.

2. The photoelectrochemical device of claim 1 wherein the housing comprises at least 2 electrical terminals for the transfer of electrical power produced by the DSC to an external load.

3. The photoelectrochemical device of claim 2 wherein the electrical terminals comprise a pin extending through and sealed within a hole in the housing.

4. The photoelectrochemical device of claim 2 wherein the housing comprises electrically isolated sections forming the electrical terminals.

5. The photoelectrochemical device of claim 2 wherein the electrical terminals are electrically connected to the DSC via a flexible wire.

6. The photoelectrochemical device of claim 2 wherein the electrical terminals are connected to the DSC via a spring-loaded connector.

7. The photoelectrochemical device of any one of the preceding claims wherein the electrical terminals are adapted for electrical connections between adjacent photoelectrochemical devices to form an array.

8. The photoelectrochemical device of claim 7 wherein the electrical terminals are adapted to allow secure fastening of adjacent photoelectrochemical devices.

9. The photoelectrochemical device of any one of the preceding claims, wherein the housing comprises a section adapted to provide permanent clamping action.

10. The photoelectrochemical device of any one of the preceding claims, wherein the space enclosed by the housing includes an environment controlling agent.

11. The photoelectrochemical device of claim 10, wherein the environment controlling agent controls humidity in the space enclosed by the housing.

12. The photoelectrochemical device of claim 10, wherein the environment controlling agent comprises a solvent of an electrolyte of the DSC.

13. The photoelectrochemical device of claim 10, wherein the environment controlling agent comprises an electrolyte of the DSC.

14. The photoelectrochemical device of any one of the preceding claims wherein the DSC comprises:

a dye sensitized nano-particulate layer of a wide band-gap semiconductor,

a catalyst layer, and

a layer of electrolyte sandwiched between the semiconductor layer and the catalyst layer;

and at least one of the panels is optically transparent and coated by a layer of transparent electrical conductor.

15. The photoelectrochemical device of claim 14, wherein at least one electrical terminal is connected to the transparent electrical conductor.

16. The photoelectrochemical device of claim 15 wherein the transparent electrical conductor is extended to an edge of the panel.

17. The photoelectrochemical device of claim 14 wherein the panel coated by the transparent electrical conductor further includes a metallic conductor dispensed on the inner surface of said panel and at least one of the electrical terminals is connected to said metallic conductor.

18. The photoelectrochemical device of claim 17 wherein the metallic conductor is extended to an edge of the panel.

19. The photoelectrochemical device of claim 14 wherein the catalytic layer includes carbon and the clamping action of the housing is utilized to maintain compression and high electrical conductivity of the carbon.

20. A method for manufacturing a photoelectrochemical module comprising steps of:

providing a DSC module encapsulated between two panels, and

using an adhesive material to hermetically attach a housing to the panels.

21. The method of claim 20, wherein the adhesive material is a thermoplastic.

22. The method of claim 21 , wherein the thermoplastic is injected in a liquid form into spaces enclosed by the housing.

23. The method of claim 20, wherein solid thermoplastic, dispensed between the housing and the panels, is melted by heat transferred through the body of the housing.