WO2018052377A2

WO2018052377A2 - A method and a system for fabricating photovoltaic devices on variably-sized substrates

Info

Publication number: WO2018052377A2
Application number: PCT/SG2017/050470
Authority: WO
Inventors: Gary FAYKOSH
Original assignee: Best Safety-Glass Manufacturing (s) Pte Ltd
Current assignee: Best Safety-Glass Manufacturing (s) Pte Ltd
Priority date: 2016-09-19
Filing date: 2017-09-19
Publication date: 2018-03-22
Anticipated expiration: 2019-03-19
Also published as: WO2018052377A3; SG10201607821WA; SG11201906667SA; CN110140224A

Abstract

An automated system for fabricating a solar energy device is described. The automated system comprises a computer for providing automated control of the system; and a substrate carrier and a vacuum chamber operationally coupled to the computer. The vacuum chamber comprises at least one heating element for uniformly heating the substrate; a coating head assembly comprising a vaporising chamber for sublimating a photovoltaic material to form a photovoltaic material vapour and an expansion chamber fluidly coupled to the vaporising chamber for receiving the photovoltaic material vapour; and a deposition chamber for uniformly depositing the photovoltaic material vapour on the substrate. The computer is configured to control the heating element, the vaporising chamber, and a speed of the substrate carrier so as to determine a position of the substrate in relation to the expansion chamber such that the photovoltaic material vapour is uniformly deposited on a predetermined portion of the substrate.

Description

A METHOD AND A SYSTEM FOR FABRICATING PHOTOVOLTAIC DEVICES ON VARIABLY-SIZED SUBSTRATES

TECHNICAL FIELD

[0001] This invention is related to a method and a system for fabricating photovoltaic devices on variably-sized substrates. More specifically, this invention is related to a method and a system for fabricating photovoltaic devices on variably-sized substrates for building- integrated photovoltaic (BIPV) applications, for example, PV integrated windows or glazing.

BACKGROUND

[0002] With the advent of solar energy, building-integrated photovoltaic (BIPV) has become one of the fastest growing industries. BIPV comprises photovoltaic materials which are used to replace conventional building materials for parts of the building envelope such as the roof, skylights or facades. Incorporating BIPV in infrastructures provides an additional source of energy to buildings, advantageously supplementing and eventually providing for all their energy needs. This is especially essential for remote buildings which have no access to an available electric power grid, for example, offshore infrastructures.

[0003] In this regard, it is important that BIPVs are made available in customized dimensions so as to suit the designs and needs of each infrastructure. Recent advances in BIPV technology have enabled incorporation of photovoltaics (PVs) to transparent substrates such as glass, paving the ways to introducing PVs into ubiquitous building components such as windows. These windows, also known as solar windows, have the advantages of minimizing space and costs of installations as compared to currently available solar panels. However, solar windows are conventionally constrained to standard dimensions. For example, the current industry standards are 65" x 40" (that is, about 1.6S metre x 1.02 metre). This constraint of current manufacturing standards means that these PV integrated glass panels will have to be made in the standard dimension initially, only to be resized into customized dimensions and designs depending on individual needs. As a result, unnecessary wastage of time, energy and materials frequently occur during the production of these BIPVs. [0004] To overcome this limitation, embodiments of the present invention disclose a method and a system to produce PV devices on variably sized and shaped substrates directed at fulfilling wide scale BIPV demands for low or net zero energy building structures. Moreover, embodiments of the present invention have the advantages of manufacturing BIPVs with increased production volume and decreased manufacturing costs, which are paramount in pushing BIPVs to become widespread commodity products.

[0005] Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.

SUMMARY

[0006] According to a first aspect of the invention, an automated system for fabricating a solar energy device is described, the automated system comprising a computer for providing automated control of the system for fabricating the solar energy device; a substrate carrier operationally coupled to the computer, the substrate carrier configured to hold a substrate onto which the solar energy device is fabricated; a vacuum chamber operationally coupled to the computer, the vacuum chamber comprising at least one heating element operationally coupled to the computer for uniformly heating at least one side of a substrate in the vacuum chamber to a predetermined temperature; a coating head assembly; and a deposition chamber for uniformly depositing the photovoltaic material vapour on the uniformly heated at least one side of the substrate. The coating head assembly comprising a vaporising chamber operationally coupled to the computer for sublimating a photovoltaic material to form a photovoltaic material vapour; and an expansion chamber fluidly coupled to the vaporising chamber for receiving the photovoltaic material vapour. The computer is configured to control the at least one heating element to determine a heating rate for uniformly heating the at least one side of the substrate to the predetermined substrate temperature, is configured to control the vaporising chamber to determine a sublimation rate of the photovoltaic material so as to determine an amount of the photovoltaic material vapour to be formed, and is configured to control a speed of the substrate carrier so as to determine a position of the substrate in relation to the expansion chamber and in response to the sublimation rate of the photovoltaic material such that the photovoltaic material vapour is uniformly deposited on a predetermined portion of the at least one side of the substrate. [0007] Preferably, the automated system further comprises at least one pump, the at least one pump being operationally coupled to the vacuum chamber and is controlled by the computer to set a pressure of the vacuum chamber to a predetermined pressure.

[0008] Preferably, the computer is further configured to control at least one throttle valve between the at least one pump and the vacuum chamber, the at least one throttle valve being configured to cooperatively control the predetermined pressure in the vacuum chamber with the at least one pump under control of the computer.

[0009] Preferably, the expansion chamber comprises at least one slit, the at least one slit is configured to fluidly couple the expansion chamber to the vaporising chamber such that the expansion chamber can receive the photovoltaic material vapour from the vaporising chamber.

[0010] Preferably, the computer is further configured to determine a predetermined chamber temperature of the vaporising chamber and a flow rate of photovoltaic material in the vaporising chamber in response to the sublimation rate of the photovoltaic material.

[001 1] Preferably, the predetermined chamber temperature of the vaporising chamber has a range of 1000 °C to 1300 °C.

[0012] Preferably, the predetermined pressure has a range of 3 to 5 Torr.

[0013] Preferably, the substrate carrier comprises substrate holding clips, the substrate holding clips being configured to keep the substrate in place.

[0014] Preferably, the expansion chamber comprises at least one opening facing in a direction towards the at least one side of the substrate, the at least one opening being configured to uniformly deposit the photovoltaic material vapour on the uniformly heated at least one side of the substrate.

[0015] Preferably, the deposition chamber further comprises at least one shutter door, the at least one shutter door being controlled by the computer and configured to isolate the deposition chamber during deposition of the photovoltaic material vapour on the at least one side of the substrate.

[0016] Preferably, the predetermined substrate temperature has a range of 550 °C to 610 °C. [0017] Preferably, the substrate comprises glass.

[0018] Preferably, the photovoltaic material comprises one or more of cadmium telluride or cadmium sulfide.

[0019] Preferably, the at least one heating element is configured to heat the substrate by infrared radiation.

[0020] Preferably, the substrate has an area of up to 1.2 metre by 2.6 metre. BRIEF DESCRIPriON OF THE DRAWINGS

[0021] The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to illustrate various embodiments, by way of example only, and to explain various principles and advantages in accordance with a present embodiment.

[0022] FIG. 1 depicts a block diagram of a system for fabricating photovoltaics on a glass substrate in accordance with a present embodiment.

[0023] FIG. 2 depicts a block diagram of a vacuum chamber, which is part of the system for fabricating photovoltaics on a glass substrate as shown in FIG. 1, in accordance with the present embodiment.

[0024] FIG. 3 depicts a block diagram of the depositing chamber, which is part of the vacuum chamber depicted in FIG. 2, comprising a coating head assembly which includes a vaporising chamber and an expansion chamber in accordance with the present embodiment. [0025] FIG. 4 depicts a block diagram of a finishing assembly line, which is part of the system for fabricating photovoltaics on a glass substrate as shown in FIG. 1, in accordance with the present embodiment.

[0026] FIG. 5 depicts a flow chart of a method for fabricating photovoltaics on a glass substrate in accordance with the present embodiment.

[0027] FIG. 6 depicts a flow diagram of a coating process in the vacuum chamber of FIG. 2 in accordance with the present embodiment.

[0028] FIG. 7 depicts a flow diagram of the coating process of FIG.6 in accordance with the present embodiment.

[0029] FIG. 8 depicts a further flow diagram of the coating process of FIG.6 in accordance with the present embodiment.

[0030] FIG. 9 depicts a graph showing relative material, processing and total (material and processing) costs for different substrate sizes (e.g. 60 cm x 120 cm and 80 cm x 160 cm) expressed in terms of cost per plate and costs per Watt in accordance with the present embodiment.

[0031] Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been depicted to scale. For example, the dimensions of some of the elements in the block diagrams or steps in the flowcharts or flow diagrams may be exaggerated in respect to other elements to help improve understanding of the present embodiment.

DETAILED DESCRIPTION

[0032] In the application, unless specified otherwise, the terms "comprising", "comprise", and grammatical variants thereof, intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, non-explicitly recited elements. [0033] The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description. It is the intent of the preferred embodiments to disclose a method and a system for fabricating photovoltaic devices on variably-sized substrates. The method in accordance with a present embodiment advantageously implements a method and a system for fabricating photovoltaic devices on variably-sized substrates for building- integrated photovoltaics (BIPV) applications. Preferably, the method and the system for fabricating photovoltaic devices on substrates for building-integrated photovoltaics allows processing of large areas of variably-sized substrates, for example, variably shaped single large pieces or multiple smaller pieces of substrates. In this way, customized BIPVs of suitable shapes and sizes can be fabricated for customized designs and needs of each infrastructure. Preferably, the method and the system for fabricating photovoltaic devices on substrates for building-integrated photovoltaics are also integrated in a complete manufacturing assembly line capable of producing such products from raw glass input to completed commercial solar windows of any desired configurations and sizes. In embodiments, the system for fabricating photovoltaic devices on substrates for building- integrated photovoltaics is capable of applying thin film coatings to a total area of a substrate of any shape or size at high throughput rates and in a single step. Preferably, the manufacturing assembly line is custom designed for producing a completed glazing product without additional process steps. Preferably, the system as well as the manufacturing assembly line delivers high speed and high volume throughput of variably sized and shaped PV glass substrates of different thicknesses for assembly into solar windows for BIPV applications.

[0034] Moreover, the method and system in accordance with the present embodiment enables alternatingly depositing desired PV materials, thereby forming desired patterns on customized BIPVs into opaque and transparent zones. In embodiments, coating of these opaque and transparent zones can be done in situ on a single substrate made in a one-step operation. In embodiments, the method and system can also be applied to low emissivity (low E) glass substrates which have the abilities to reflect infra-red (IR) and ultra-violet (UV) radiations. Windows made f om these low E glass substrates advantageously keep the interior of a building cool when its exterior is hot by reflecting infra-red radiation from the sun; and keeping the interior warm when the exterior is cold by trapping infra-red radiation within the interior. Moreover, these windows, which are capable of reflecting UV radiation, also aid in protecting interior furnishings from fading or bleaching under direct sunlight.

[0035] Furthermore, it is the intent of the present invention to blend two seemingly different industries, namely the commercial glass fabricating industry and the solar manufacturing industry. To date, the solar manufacturing industry has been focusing on power producing grid supply arrays, with standardized module size; while glass manufacturers produce glass substrates which are built to design by contractors and architects. Therefore, it is the intent of the present invention to invent a method and a system capable of combining both for the fabrication of BIPV products.

[0036] Referring to FIG. 1 , a block diagram of a system 100 for fabricating photovoltaics on a glass substrate in accordance with a present embodiment is depicted. In embodiments, the system 100 comprises a substrate carrier 102, a thin film coating system including a vacuum load lock 104, a vacuum chamber 106, an exit load lock 108 and a pump 110, and a finishing assembly line 112. This entire system 100 is also operationally connected to a computer 114, giving users precise controls of various process parameters. The computer 114 thus provides automated control of the system 100 for fabricating solar energy device, for example photovoltaics, on the glass substrate. In embodiments, this system 100 is fully automated so that raw materials such as unprocessed glass substrates can be made to BIPV products once these raw materials are loaded onto substrate carriers 102 and are conveyed throughout the system 100 in a flexible and cost effective manner. In embodiments, the substrate carriers 102 are operationally coupled to the computer 114, the substrate carriers are configured to hold a substrate onto which the solar energy device is fabricated. In embodiments, the vacuum load lock 104, the vacuum chamber 106 and the exit load lock 108 are operationally connected to the pump 110. Preferably, the pump 1 10 is configured to set a pressure in the vacuum load lock 104, the vacuum chamber 106 and the exit load lock 108 separately. Preferably, the pump 110 is controlled by the computer to set and maintain a process chamber pressure in the vacuum chamber 106 to a predetermined pressure. Preferably, the pressure in the vacuum chamber 106 is set to a predetermined pressure in the range of 3 to 5 Torn Preferably, the process chamber pressure is controlled by pressure transducers which provide feedback to a proportional controller that modulates throttle valves leading to the pump 110. Preferably, the proportional controller is controlled by the computer 114. In embodiments, the pump 110 can includes more than one pump. In embodiments, the computer 114 also controls at least one throttle valve between the at least one pump 110 and the vacuum chamber 106, where the at least one throttle valve is configured to cooperatively control the predetermined pressure in the vacuum chamber 106 with the at least one pump 110 under control of the computer 114. Preferably, any background normal leaks in the vacuum chamber 106 can be regulated by this feedback mechanism, in embodiments, the vacuum chamber 106 is designed such that it is capable of heating and coating, in the same chamber. In embodiments, a constant speed transport conveyance works in synergy with the vacuum chamber 106 so as to transport substrates to appropriate sections of the vacuum chamber 106 for different processes. In embodiments, the constant speed transport conveyance is capable of transporting loaded substrate carriers 102 carrying substrates of glass or other materials of random sizes and shapes. In embodiments, these substrates of different materials can be batch processed simultaneously, which is accomplished by presenting the substrates to appropriate processes in the heating and coating regions of the vacuum chamber 106. In embodiments, a substrate carrier 102 is a shuttle plate that comprises the mechanisms for holding pieces of different substrates. In embodiments, the substrate carrier 102 is configured to hold the substrate during processing. In embodiments, the substrate carrier 102 is driven by a chain drive extending throughout the entire vacuum chamber. In embodiments, the substrate carrier 102 is designed such that substrate holding clips or fixtures of the substrate carrier 102 can be easily placed on the desire substrates of different shapes and sizes during the loading process outside the vacuum chamber 106. In embodiments, these substrate holding clips or fixtures help to secure the substrates or keep them in place during the entire fabrication process. Preferably, a complete finishing assembly line 112 for processing the photovoltaic material coated substrates into finished BIPV products is operationally connected to the exit load lock 108 of the thin film coating system to complete the entire manufacturing process. Preferably, these finished BIPV products are in a state ready for installation.

[0037] Referring to FIG. 2, a block diagram 200 of a vacuum chamber 106, which is part of the system for fabricating photovoltaics on substrates as shown in FIG. 1, comprising a coating head assembly 202, a deposition chamber 204 and a heating chamber 206 are depicted. Preferably, the vacuum chamber 106 is a single large multi-zone vacuum chamber. Preferably, the vacuum chamber 106 is designed to accomplish all tasks to make a complete semiconductor product. In embodiments, the vacuum chamber 106 is designed to include at least one heating chamber 206 and at least one deposition chamber 204. In embodiments, the vacuum chamber can include more than one deposition chamber 204, where each deposition chamber is configured to uniformly deposit at least one type of photovoltaic material vapour on at least one side of a substrate. Preferably, the deposition chamber is configured to uniformly deposit at least one type of photovoltaic material vapour on at least one side of a substrate when the at least one side of the substrate is uniformly heated to a desired temperature. In embodiments, the deposition chamber 204 is connected to the heating chamber 206 by means of a shutter door, where the shutter door being controlled by the computer 208 and is configured to compartmentalize the individual chambers such that for example, the deposition chamber 204 and the heating chamber 206 are temporarily decoupled when the shutter door is closed. The In embodiments, the more than one deposition chambers can also be connected in the same manner with at least one shutter door, where the at least one shutter door is configured to separate the deposition chambers such that for example, a first deposition chamber and a second deposition chamber are temporarily decoupled when the shutter door is closed. In embodiments, the at least one shutter door being controlled by the computer is thus configured to isolate the deposition chamber during deposition of the photovoltaic material vapour on the at least one side of the substrate. In embodiments, the at least one deposition chamber 204 includes at least one coating head assembly 202 within the at least one deposition chamber 204. In embodiments, more than one coating head assemblies 202 dispensing the same photovoltaic material are included in the same deposition chamber 204. In embodiments, the at least one coating head assembly 202 is configured to sublimate and deposit the photovoltaic material onto the at least one surface of the substrates. In embodiments, each coating head assembly 202 is configured to deposit one type of photovoltaic material (e.g. P-type or N-type photovoltaic material) only, to prevent cross- contamination of different types of photovoltaic material. In embodiments, the heating chamber 206 comprises at least one heating element configured to heat the glass substrates. In embodiments, the at least one heating element of the heating chamber 206 is configured to uniformly heat the at least one side of the substrate to a predetermined substrate temperature of 550 °C to 610 °C. In embodiments, a heating control of a heater connected to the at least one heating element is set to a temperature of 550 °C to 750 °C. Preferably, the at least one hearing elements in the heating chamber 206 are perfectly coupled to heat only the glass substrates and not the surroundings. Preferably, the uniformly heating of the at least one side of the substrate in the heating chamber 206 is by infra-red radiation. Preferably, the vacuum chamber 106 is also computerized and fully automated such that it works in synergy with the substrate carriers 102 and the conveyer to have the capability to track the exact position of the substrate carriers 102 and activate a photovoltaic material feed to the coating head assembly 202, so as to control the photovoltaic material vapour output to be deposited on selected portions of the substrates where photovoltaic material coating is desired. Preferably, the deposition of photovoltaic material vapour on the selected portions of the substrates is achieved with discrete control of the presence of the photovoltaic material vapour with respect to the substrates positions in relation to the coating head assembly 202. Preferably, this high precision of patterning is achieved by high speed servo position control of the substrate carrier 102, the photovoltaic material feed, carrier gas pressures, carrier gas flow rates and background pressure in the vacuum chamber 106. Preferably, all these parameters are coordinated by custom software installed in the computer 208 which is operationally connected to the vacuum chamber 106. In embodiments, the computer 208 may also be connected to the computer 1 14 so that the computers can work in synergy in operating the processes in the thin film coating system 100.

[0038] Referring to FIG. 3, a block diagram 300 of the depositing chamber 204, which is part of the vacuum chamber 106 depicted in FIG. 2, comprising a coating head assembly 202 which includes a vaporising chamber 302 and an expansion chamber 304 in accordance with the present embodiment is depicted. In embodiments, the coating head assembly 202 is capable of creating vapour out and off near instantaneously. This is accomplished by customized design and methods of photovoltaic material feed, carrier gas control, and pressure relief in the vaporising chamber 302. In embodiments, the vaporising chamber 302 is fluidly coupled to the expansion chamber 304. In embodiments, the vaporising chamber 302 is configured to sublimate photovoltaic materials, such as cadmium telluride and cadmium sulfide, into a photovoltaic material vapour, followed by passing the photovoltaic material vapour through a ceramic frit (not shown) to remove any non-evaporated material, before delivering the photovoltaic material vapour to the expansion chamber 304. Preferably, the amount of the photovoltaic material vapour to be formed comprises setting a predetermined chamber temperature of the vaporising chamber 302 and/or determining an amount of photovoltaic material to be sublimated in the vaporising chamber 302. In embodiments, the amount of the photovoltaic material vapour to be formed can be determined by setting the predetermined chamber temperature of the vaporising chamber 302 and/or the amount of photovoltaic material to be sublimated in the vaporising chamber 302 by the computer 208. The computer 208 is further configured to determine the predetermined chamber temperature of the vaporising chamber and a flow rate of photovoltaic material in the vaporising chamber in response to a sublimation rate of the photovoltaic material. In embodiments, the predetermined chamber temperature of the vaporising chamber has a range of 1000 °C to 1300 °C. Preferably, the predetermined chamber temperature of the vaporising chamber has a range of 1050 °C to 1250 °C. In embodiments, the amount of photovoltaic material to be sublimated in the vaporising chamber 302 is provided by a commercially available powder feeder (not shown), used in plasma or powder coating applications, but modified / customized for vacuum use. In embodiments, the modified powder feeder comprises components to pick up a predetermined volume of the photovoltaic material. In embodiments, carrier gas supply is also provided to the vaporising chamber 302. In embodiments, both the photovoltaic material and the carrier gas may be fed into the vaporising chamber 302 through means external to the deposition chamber 204 or the vacuum chamber 106. In embodiments, the photovoltaic materials can be any suitable semiconductor materials of N-type or P-type. In embodiments, the expansion chamber 304 is a box with at least one slit 308 and at least one opening 310, is heated to a very high temperature, and allows the photovoltaic material vapour to spread out evenly over a long distance. In embodiments, the at least one slit 308 is configured to fluidly couple the expansion chamber 304 to the vaporizing chamber 302 such that the expansion chamber 304 can receive the photovoltaic material vapour from the vaporising chamber 302. Preferably, the at least one opening 310 faces in a direction towards the at least one side of the substrate, the at least one opening being configured to uniformly deposit the photovoltaic material vapour on the uniformly heated at least one side of the substrates 306 as the substrates 306 move in and out of the deposition chamber 204 during the step of depositing the photovoltaic material vapour on the uniformly heated at least one side of the substrates. In some embodiments, the photovoltaic material vapour is deposited onto at least one side of the substrates 306 in the expansion chamber 304. Preferably, the expansion chamber 304 is designed to be able to coat a large web area and load substrates with sizes of up to 1.2 metre x 2.6 metre as compared to present systems which are confined to a width of only 60 cm or less. In embodiments, the expansion chamber 304 can be designed to coat substrates 306 of any dimensions as desired. In embodiments, the deposition chamber 204 is designed to deposit the photovoltaic material vapour in a vertical transport deposition (VTD) technique. In some embodiments, the VTD technique is a vertical coating process. In embodiments, the deposition chamber 204, comprising at least the vaporising chamber 302 and the expansion chamber 304, is connected to the computer 208, which is configured to determine an amount of the photovoltaic material vapour to be formed and/or to determine a position of the substrate in relation to the expansion chamber 304 and/or to determine a size of the substrate such that the photovoltaic material vapour is deposited on a predetermined portion of the at least one side of the substrate. In the present embodiment, the expansion chamber 304 preferably coats substrate sizes of up to 1.2 metre x 2.6 metre due to consideration of market demands as well as the weight and ease of handling substrates of large sizes. It is noted that manufacturing costs double above substrate sizes of up to 1.2 metre x 2.6 metre. Moreover, substrates such as glass or PV panels become exponentially more difficult and expensive to handle as their sizes increases above 1.2 metre x 2.6 metre. Furthermore, the weight of such large substrates will also become a major consideration for installers. In other embodiments, the expansion chamber 304 can be designed to load and coat substrates sizes of more than 1.2 metre x 2.6 metre. Preferably, the expansion chamber 304 can be designed to scale up to customized dimensions (e.g. 4 or 5 metres in length and width) should the market exists and warrants for such a large system.

[0039] Referring to FIGs. 1 to 3, it is therefore clear that the computer 1 14, 208 which is operationally coupled to the automated system 100 including the substrate carrier 102, the pump 110, and the vacuum chamber 106 comprising the heating chamber 206, the deposition chamber 204 and the coating head assembly 202 (which includes the vaporizing chamber 302 and expansion chamber 304) enables automated and efficient processing for fabricating solar energy devices (e.g. photovoltaics for B1PV applications). In embodiments, the computer 114, 208 is configured to control the at least one heating element to determine a heating rate for uniformly heating the at least one side of the substrate to the predetermined substrate temperature. In an embodiment, the computer 114, 208 is configured to control the vaporising chamber 302 to determine a sublimation rate of the photovoltaic material so as to determine an amount of the photovoltaic material vapour to be formed. In an embodiment, the computer 114, 208 is configured to control a speed of the substrate carrier 102 so as to determine a position of the substrate in relation to the expansion chamber 304 and in response to the sublimation rate of the photovoltaic material such that the photovoltaic material vapour is uniformly deposited on a predetermined portion of the at least one side of the substrate. Preferably, the computer 114, 208 is able to perform all of the functions discussed above.

[0040] Referring to FIG. 4, block diagrams 400 of the finishing assembly line 1 12, which is part of the system 100 for fabricating photovoltaics on a glass substrate as shown in FIG. 1, comprising an activation furnace 402, a single side etch 404, laser scribe systems 406, a photoresist station and developer 408, a back metal contact sputter chamber 410, an inline sealing press 412 and a batch autoclave 414 are depicted. Preferably, selected components or equipment of the finishing assembly line 112 are modified from standard available equipment in use by current semiconductor PV industry. Preferably, the equipment are modified and assembled in such a way to be suitable for processing thin film photovoltaic material-based devices, for example cadmium sulfide and cadmium telluride based devices. Preferably, the equipment of the finishing assembly line 1 12 are modified and assembled in such a way to accommodate different shapes and sizes requirements of the customized BIPV products, while retaining the automation necessary to keep the entire fabrication process cost competitive. In embodiments, a commercially available activation furnace 402 customized for semiconductor coated glass plates of up to 2.6 metre x 2.6 metre forms part of the finishing assembly line 112. In embodiments, a custom-design single-side etch 404 for sunny side cleaning of overspray is deployed as part of the finishing assembly line 1 12. In embodiments, the custom-design single side etch 404 can accommodate substrates of at least up to 1.2 metre x 2.6 metre. In embodiments, the laser scribe systems 406 must be reconfigured to match the specific cell structure for photovoltaic material-based devices, particularly for cadmium telluride (CdTc) devices. Preferably, this will require not only reprogramming of the laser scribe systems 406, but also modifications to the mechanics of the substrates handling. Preferably, the laser scribe systems 406 are designed to process substrates of up to 2.6 metre x 2.6 metre. In other embodiments, the photoresist station and developer 408 used can accommodate substrates of various shapes for up to 1.2 metre x 2.6 metre. Preferably, wet chemistry involved in the manufacturing processes is modified to achieve the desired result without any waste of the photovoltaic material and substrates. In embodiments, a commercially-available back metal contact sputter chamber 410 forms part of the finishing assembly line 112. Preferably, the back metal contact sputter chamber 410 can accommodate substrates of various shapes for up to 1.2 metre x 2.6 metre. In embodiments, selected BIPV products can be laminated by the inline sealing press 412 and finally batch autoclaved 414 depending on the desired applications of the BIPV products. Preferably, the final BIPV products comprise electrical connections of a different type of configuration depending on their applications. Preferably, these final BIPV products do not use soldered wires to complete the electrical connections. In embodiments, the electrical connections are configured to feed out from the edges of the BIPV products (e.g. PV integrated windows / glazing) and are placed out of sight. In embodiments, the BIPV products are also designed to output in the range of 24 V to 48 V which is deemed non-lethal on contact. [0041] Referring to FIG. 5, a flow chart of a method for fabricating pholovoltaics on a glass substrate in accordance with a present embodiment is depicted. In the present embodiment, glass substrates are used though substrates of other materials can also be used. In embodiments, at step 502, the glass type to be coated is first selected. In embodiments, the different glass types correspond to glass substrates with different thicknesses. Preferably, this is determined by the contractors and customers. In an embodiment, the glass substrates can have a thickness of 3.2 mm. Preferably, this thickness of 3.2 mm provides desirable physical characteristics which allow the glass substrates to pass quality assessment tests such as load tests, hail ball impact tests and thermal stress resistance tests. Preferably, this glass substrate's thickness is also thin enough to avoid trapping visible light transmission energy. In other embodiments, the thickness of glass substrates can be 4, 5, or 6 mm depending on their BIPV applications. Preferably at these glass substrates' thicknesses, power production of BIPV products made from these glass substrates will not be appreciably compromised. In embodiments, at step 504, the desired glass substrates are loaded onto a holding apparatus. Preferably, the glass substrates are manually loaded onto the holding apparatus. Preferably, the holding apparatus is the substrate carrier as mentioned previously of FIG. 1. Preferably, before the glass substrates are loaded onto the holding apparatus, the glass substrates are cut, seamed, followed by washed through a glass washer, before they are transferred to an auto tilt station. Preferably, the holding apparatus holding the glass substrates are then placed on a conveyor belt and are released to the computer control of the chamber main computer 1 14. In embodiments, at step 506, the glass substrates supported by the substrate carrier(s) are transported into the vacuum load lock. Preferably, the glass substrates are transported by the conveyor belt automatically. In embodiments, at step 508, the vacuum load lock 104 is pumped down to match a predetermined process chamber pressure of the vacuum chamber 106. Preferably, the process chamber pressure is in the range of 3 - 5 Torr (e.g. 6 millibar). Preferably, this is the optimum pressure for the processes in the vacuum chamber 106, and has die advantage of not causing the photovoltaic material film formed on the glass substrates to thin out, or has a poorly formed crystalline structure. In embodiments, at step 510, the glass substrates are transported into the vacuum chamber 106. In embodiments, at step 512, the glass substrates are uniformly heated to a desired surface temperature on at least one side of the glass substrates. Preferably, the desired surface temperature can be verified by scanning the surface of the glass substrates with a thermal image. Preferably, a Landscan Ametek thermal imaging system is used to scan the surfaces of the glass substrates just prior to coating. Preferably, a result of the scan is displayed on a terminal screen of the computer 208. Preferably, the scan reads out information such as temperature, profile curve, and a color display of the suiface of the glass substrates in real time. Preferably, the information obtained is used to maintain the perfect coating temperature. Preferably, the at least one heating element can be trimmed in all zones to achieve this temperature uniformly on the surfaces of the glass substrates. Preferably, the glass substrates are heated by infra-red (IR) radiation alone. Preferably, a heating time is adjusted in response to different sizes and thicknesses of the glass substrates. Preferably the heating time is controlled by a set of rule, where the rule of setting the heating time is 40 seconds per mm of glass substrate's thickness. In embodiments, the glass substrate used is of the low E type where one side of the glass substrate is coated by a transparent conducting oxide (TCO) that rejects IR radiation. Preferably, the heating of the clear side (high absorption of IR) and the heating on the TCO side is balanced in such a way as to keep the glass flat and not excessively warped when the low E glass substrates are heated. Preferably, the heating of the low E glass substrate is done uniformly from the clear side. Preferably, the desired surface temperature of the glass substrates is achieved prior to the coating process. Preferably, the computer 208 controlling the vacuum chamber 106 comprises at least one set of control algorithm to achieve the desired surface temperature of the glass substrates. In embodiments, at step 514, a solid photovoltaic material is sublimated in the vaporizing chamber 302 to form a photovoltaic material vapour. Preferably, sublimation allows direct conversion of the solid photovoltaic material to form the photovoltaic vapour without going through a liquid stage. In embodiments, the solid photovoltaic material can be in its powdered form. Preferably, the sublimation process done in vacuum allows a much lower temperature needed to vaporize the photovoltaic material than at atmospheric pressure or in an inert gas environment. In embodiments, the sublimation process for the photovoltaic material, for example CdS or CdTe, is done under a pressure of less than 50 mbar. Preferably, the sublimation process offers better material utilization, and hence lower manufacturing cost. Preferably, the sublimation process also has the capability to achieve film thicknesses at higher speeds far beyond other deposition techniques, for example electrochemical and plasma sputtering methods. In embodiments, plasma sputter methods may require minutes to deposit a layer of three microns-thick photovoltaic material film, whereas photovoltaic material vapour deposition by sublimation in vacuum takes only seconds to achieve the same. In embodiments, at step 516, the photovoltaic material vapour formed in the vaporising chamber 302 is received in the expansion chamber 304. In embodiments, the expansion chamber 304 is configured to spread the photovoltaic material vapour out evenly for deposition of the photovoltaic material vapour onto at least one side of the glass substrates in the deposition chamber 204 at step 518. In embodiments, at step 518, the photovoltaic material vapour is deposited on at least one side of the glass substrates in at least one deposition chamber 204. Preferably, step 518 comprises controlling deposition of the photovoltaic material vapour such that the photovoltaic material vapour is deposited on a predetermined portion of the at least one side of the substrate. Preferably, the step 518 which comprise controlling deposition of the photovoltaic material vapour such that the photovoltaic material vapour is deposited on a predetermined portion of the at least one side of the substrate, further comprises determining an amount of the photovoltaic material vapour to be formed and/or determining a position of the substrate in relation to an expansion chamber and/or determining a size of the substrate; and controlling the deposition of the photovoltaic material vapour in response to the determination. Preferably, the photovoltaic material vapour is deposited by a vapour transport deposition (VTD) technique. Preferably, the VTD employed is a vertical coating process. Preferably, the glass surface is at 550 °C to 610 °C, but preferably at 550 °C, before the vertical VTD coating takes place. Preferably, the computer control of the vacuum chamber allows users to select type and thickness of coatings. Preferably, an area of the glass substrates to be coated is also programmed and controlled by the computer. Preferably, the area of the glass substrates to be coated can be a total area, a partial area, or a specific area of the glass substrates predetermined by the users. Preferably, at step 518, the conveyor belt holding the glass substrates runs at a constant speed, generally, 28 mm/second while the deposition takes place. In embodiments, the first layer of photovoltaic material vapour deposited in a first deposition chamber 204 is from sublimation of a N-type semiconductor, such as cadmium sulfide (CdS). Preferably, the first layer of N-type semiconductor deposited is less than 60 nm. Preferably, after the deposition of the first layer of N-type semiconductor, the glass substrates are transported to a second deposition chamber 204, for the P-type semiconductor. Preferably, the P-type semiconductor is cadmium telluride. Preferably, the P-type semiconductor deposited has a thickness of 30,000 nm. Preferably, both the N-type and P-type semiconductor layers are selectively controlled for thickness and uniformity. In other embodiments, the P-type semiconductor has a thickness of less than 5000 nm for near transparent B1PV applications. Preferably, the computerized controlled vacuum chamber 106 provides users with complete control of the deposition thickness of the PV materials and the desired portions of the substrates to be coated. In embodiments, the computerized control allows users to coat at least a first portion of the glass substrates on the conveyor belt, while leaving at least a second portion of the glass substrates uncoated. Preferably, the ability to selectively coat the glass substrates is provided by the computerized position tracking of the glass substrates, the coating head assembly 202 control of vapour timing for deposition of the photovoltaic material vapour and the computerized control of the materia] feed through the customized powder feeder. In embodiments, the computerized position tracking of the glass substrates is identified by a visual system that transfers the graphics data to the computer 114. In embodiments, this is accomplished with some off the shelf items and software. In other embodiments, this may be achieved by customised software for tracking and coating the glass substrates. In embodiments, at step 520, the glass substrates are unloaded from the vacuum chamber 106 through an exit load lock 108. In embodiments, at step 522, the glass substrates are transported to the finishing assembly line 112 for further processing. In embodiments, the entire fabrication method from step 502 to step 522 as described in FIG. 5 is fully automated. Preferably, this leads to the lowest energy cost per watt of the BIPV products produced.

[0042] Referring to FIG. 6, a flow chart 600 of the fabrication process in the vacuum chamber 106 from step 502 to step 520 of FIG. 5 are depicted. FIG. 6 shows further processing details in the vacuum chamber 106. In embodiments, the vacuum chamber 106 is further sectioned into different regions, namely, Buffer 1 608, Heat 1 610, Heat 2 612, Heat 3 614, Deposition A 616, Deposition B 618 and Buffer 2 620. In embodiments, sections Heat 1 610, Heat 2 612 and Heat 3 614 are part of the heating chamber 206 of the vacuum chamber 106, and sections Deposition A 616 and Deposition B 618 are comprised in two different deposition chambers, for example deposition chamber A and deposition chamber B respectively, of the vacuum chamber 106 as described in FIG. 2. The processes which take place in each of the sections are further discussed in detail. In embodiments, the glass substrates with the substrate carriers 102 (thereafter 'glass substrates') are transported from a loading area and enter the vacuum load lock 604 through an opened Door 1 602. In embodiments, when Door 1 602 closes, the pump 110 evacuates the vacuum load lock 104 to match a desired process chamber pressure of 3 to 10 Torr of the vacuum chamber 106. Preferably, the pump 110 evacuates the vacuum load lock 104 to match a desired process chamber pressure of 3 to 5 Torr of the vacuum chamber 106. Preferably, when the pressure in the vacuum load lock 104 matched the desired process chamber pressure, Door 2 606 is opened so that the glass substrates are transferred to section Buffer 1 608 for preheating. Preferably, the glass substrates are then transported through sections Heat 1 610, Heat 2 612, and Heat 3 614 respectively after being preheated in Buffer 1 608. Preferably, the glass substrates are heated to 710 °C in section Heat 1 610, 680 °C in section Heat 2 612 and 680 °C in section Heat 3 614 respectively. Preferably, the glass substrates are transported in a continuous motion at a speed of 30 mm/sec. Preferably, the glass substrates are then transported to section Deposition A 616 for deposition of a first layer of N-type semiconductor material. Preferably, the N-type semiconductor material is cadmium sulfide (CdS). Preferably, the glass substrates are then transported to section Deposition B 618 after the first deposition of the N-type semiconductor material. Preferably, deposition of a P- type semiconductor material occurs in section Deposition B 618. Preferably, the P-type semiconductor material is cadmium telluride (CdTe). Preferably, thicknesses and areas of the semiconductor materials to be deposited are dependent upon the desired type of BIPV products to be fabricated. Preferably, the glass substrates are then briefly cooled in section Buffer 2 620 before it exits the vacuum chamber 106 through Door 3 622. In embodiments, the exit load lock 108 is pumped down to 10 Ton^* before the glass substrates exits the vacuum chamber 106 through Door 3 622. Preferably, the exit load lock 108 is then filled with an inert gas to bring its chamber pressure up from 10 Torr to the atmospheric pressure. Preferably, the glass substrates are then transported out of the exit load lock 108 through Door 4 626 to be further processed by the finishing assembly line 112.

[0043] Referring to FIG. 7, a flow chart 700 comprising further details of the heating process in the hearing chamber 206 are depicted. Preferably, the glass substrates are heated by the at least one heating element in section Heat 1 610 of the heating chamber 206 to a temperature range of 685 °C to 750 °C with a background pressure of 3 to 5 Torr. Preferably, the glass substrates are then transported to section Heat 2 612 after being heated in section Heat 1 610. Preferably, the glass substrates are heated by the at least one heating element in section Heat 2 612 of the heating chamber 206 to a temperature range of 685 °C to 750 °C with a background pressure of 3 to 5 Torr. Preferably, the glass substrates are then transported to section Heat 3 614 after being heated in section Heat 2 612. Preferably, the glass substrates are heated by the at least one heating element in section Heat 3 614 of the heating chamber 206 to a temperature range of 650 °C to 700 °C with a background pressure of 3 to 5 Torr. Preferably, the heating processes on the glass substrates in the heating chamber 206 of the vacuum chamber 106 bring the surfaces of the glass substrate to an ideal temperature for the following deposition processes. Preferably, these sections 610, 612, 614 of the heating chamber 206 also control warp and cure of the glass substrates for absolute flatness, which is necessary for later processing. In embodiments, glass substrates of various shapes can be transported via the conveyor belt and carrier system at a desired speed. Preferably, the desired speed at which the glass substrates are transported is substantially at 30 mm/sec. Preferably, the glass substrates have an area from a range of 600 mm x 1200 mm to 1200 mm x 2600 mm.

[0044] Referring to FIG. 8, a flow chart 800 comprising further details of the deposition process in the deposition chamber A and the deposition chamber B are depicted. Preferably, a photovoltaic material, such as a N-type semiconductor material, for example CdS, is vaporised in the vaporising chamber 302 at 1150 °C to a vapour form to be deposited in section Deposition A 616 in deposition chamber A. Preferably, the CdS vapour is carried by a carrier gas, such as helium or nitrogen. Preferably, the carrier gas is flowing at a rate of 2-4 litres per minute. Preferably, the carrier gas carries the CdS vapour to section Deposition A 616 of the deposition chamber A where it is heated to a temperature substantially at 850 °C. Preferably, the CdS vapour is carried by the carrier gas to the glass substrates through a slit 308 of the expansion chamber 304, where the slit 308 operationally connects the vaporising chamber 302 to the expansion chamber 304. Preferably, the CdS vapour carried by the carrier gas condenses on the glass substrates at a location 25 mm from an opening 310 of the expansion chamber to form a CdS film. Preferably, the thickness of the CdS film formed is controlled by the feeding rate of the CdS material to the vaporising chamber 302 and the flow rate of the carrier gas transporting the CdS vapour. Preferably, the deposition process is carried out at a background pressure of 3 to 5 Torn In embodiments, a shutter door between deposition chamber A and the heating chamber 202, as well as a shutter door between deposition chamber A and deposition chamber B are both closed to isolate deposition chamber A when deposition of the photovoltaic material vapour takes place in deposition chamber A. The glass substrates with the first deposited CdS layer are then transported to section Deposition B 618 of deposition chamber B where a second photovoltaic material can be deposited. Preferably, the second photovoltaic material layer comprises a P-type semiconductor material. Preferably, the P-type semiconductor material is CdTe and is vapourised in a second vaporising chamber 302 at 1150 °C to a vapour form to be deposited in section Deposition B 618. Preferably, the CdTe vapour is carried by a carrier gas, such as helium or nitrogen. Preferably, the carrier gas is flowing at a rate of 2-4 litres per minute. Preferably, the carrier gas carries the CdTe vapour to section Deposition B 618 of the deposition chamber B where it is heated to a temperature substantially at 1050 °C. Preferably, the CdTe vapour is carried by the carrier gas to the glass substrates through a second slit 308 of a second expansion chamber 304, where the second slit 308 also operationally connects the second vaporizing chamber 302 to the second expansion chamber 304. Preferably, the CdTe vapour carried by the carrier gas condenses on the glass substrates at a location 25 mm from a second opening 310 of the second expansion chamber 304 to form a CdTe film on the CdS film. Preferably, the thickness of the CdTe film formed is also controlled by the feeding rate of the CdTe material to the second vaporising chamber 302 and the flow rate of the carrier gas transporting the CdTe vapour. Preferably, the deposition of CdTe is carried out at a background pressure of 3 to 5 Torr. In embodiments, a shutter door between deposition chamber A and deposition chamber B, as well as a shutter door between deposition chamber B and section Buffer 2 620 of the vacuum chamber 106 are both closed to isolate deposition chamber A when deposition of the photovoltaic material vapour takes place in deposition chamber B. Preferably at the end of the deposition step in section Deposition B 618 of the deposition chamber B, the glass substrates are transported to section Buffer 2 620 of the vacuum chamber 106. Preferably, the glass substrates with the deposited photovoltaic material layers are cooled to 400 °C in section Buffer 2 620 before being returned to atmosphere and transported further to the exit load lock 108. In embodiments, glass substrates of various shapes can be transported via the conveyor and carrier system at a desired speed. Preferably, the desired speed at which the glass substrates are transported is substantially at 30 mm/sec.

[0045] Referring to FIG. 9, a graph 900 showing relative material, processing and total (material and processing) costs for different substrate sizes (e.g. 60 cm x 120 cm and 80 cm x 160 cm) expressed in terms of cost per plate and cost per Watt in accordance with the present embodiment is depicted. The purpose of FIG. 9 is to demonstrate the benefits of the present B1PV manufacturing method over standard size BIPV manufacturing. Specifically, computer control of different parameters in the present automated system 100 enables sublimated PV material to be uniformly deposited across a wide-web substrate (e.g. substrate size of 80 cm x 160 cm). For examples, the computer 1 14, 208 operationally connected to the automated system 100 is configured to control the at least one heating element to determine a hearing rate for uniformly heating the at least one side of the substrate to the predetermined substrate temperature, is configured to control the vaporising chamber 302 to determine a sublimation rate of the photovoltaic material so as to determine an amount of the photovoltaic material vapour to be formed, and is configured to control a speed of the substrate carrier 102 so as to determine a position of the substrate in relation to the expansion chamber 304 and in response to the sublimation rate of the photovoltaic material such that the photovoltaic material vapour is uniformly deposited on a predetermined portion of the at least one side of the substrate. This eases BIPV manufacturing on wide-web substrates, thereby providing the advantages of reducing cost and increasing yield as compared to those of standard size BIPV manufacturing (e.g. substrate size of 60 cm x 120 cm). In particular, the graph 900 shows that normalised substrate and normalised processing (e.g. finishing) costs per plate for substrates with a substrate size of 80 cm * 160 cm is higher than that of a substrate size of 60 cm * 120 cm. This can be understood as the inherent higher costs require to manufacture larger substrates, where more materials would be required in both fabricating the larger substrates and processing the larger substrates. This is shown in the first three bar charts on the left of FIG. 9, where it is shown that the normalised substrate cost per plate for substrate size 80 cm * 160 cm is about 1.06 times higher than that of substrate size 60 cm x 120 cm considering 90% yield during fabrication of the substrates, and the normalized finishing cost per plate for substrate size 80 cm x 160 cm is about 1.27 times higher than that of substrate size 60 cm x 120 cm. This results in an overall normalized cost per substrate for substrate size 80 cm x 160 cm to be about 1.19 times higher than that of substrate size 60 cm x 120 cm. In these estimations, the costs of labour, material and energy consumed in fabrication the substrates have been taken into account. However, it may be appreciated that a larger PV substrate is also expected to provide more power than a smaller substrate. For example, a wide-web PV substrate of size 80 cm x 160 cm is expected to produce 150 W as compared to the 80 W produced by a standard PV substrate of size 60 cm x 120 cm. Considering the modest increase in the costs for materials and processing (e.g. finishing) with a much larger increase in power output, it is shown that the cost per Watt produced by the wide-web PV substrate is lower than that of the standard PV substrate. It is estimated that the cost per Watt for the wide-web PV substrate is 0.63 times that of the standard PV substrate. That is, for every $0.63 spent in getting 1 Watt from the wide-web PV substrate, $1 is required in getting the same 1 Watt from the standard PV substrate. Therefore, the automated system 100 of the present invention advantageously enables manufacturing of wide-web PV substrates for BIPV applications, thereby reducing cost of energy production compared to that of the currently available standard PV substrates.

[0046] In the application, unless specified otherwise, the terms "comprising", "comprise", and grammatical variants thereof, intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, non-explicitly recited elements. [0047] It will be apparent that various other modifications and adaptations of the application will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the application and it is intended that all such modifications and adaptations come within the scope of the appended claims.

Claims

WHAT IS CLAIMED:

1. An automated system for fabricating a solar energy device, the automated system comprising:

a computer for providing automated control of the system for fabricating the solar energy device;

a substrate carrier operationally coupled to the computer, the substrate carrier configured to hold a substrate onto which the solar energy device is fabricated;

a vacuum chamber operationally coupled to the computer, the vacuum chamber comprising:

at least one heating element operationally coupled to the computer for uniformly heating at least one side of the substrate in the vacuum chamber to a predetermined substrate temperature;

a coating head assembly, the coating head assembly comprising:

a vaporising chamber operationally coupled to the computer for sublimating a photovoltaic material to form a photovoltaic material vapour; and

an expansion chamber fluidly coupled to the vaporising chamber for receiving the photovoltaic material vapour;

a deposition chamber for uniformly depositing the photovoltaic material vapour on the uniformly heated at least one side of the substrate; and

wherein the computer is configured to control the at least one heating element to determine a heating rate for uniformly heating the at least one side of the substrate to the predetermined substrate temperature, is configured to control the vaporising chamber to determine a sublimation rate of the photovoltaic material so as to determine an amount of the photovoltaic material vapour to be formed, and is configured to control a speed of the substrate carrier so as to determine a position of the substrate in relation to the expansion chamber and in response to the sublimation rate of the photovoltaic material such that the photovoltaic material vapour is uniformly deposited on a predetermined portion of the at least one side of the substrate.

2. The automated system according to claim 1, further comprising:

at least one pump, the at least one pump being operationally coupled to the vacuum chamber and is controlled by the computer to set a pressure of the vacuum chamber to a predetermined pressure.

3. The automated system according to claim 2, wherein the computer is further configured to control at least one throttle valve between the at least one pump and the vacuum chamber, the at least one throttle valve being configured to cooperatively control the predetermined pressure in the vacuum chamber with the at least one pump under control of the computer.

4. The automated system according to any one of claims 1 to 3, wherein the expansion chamber comprises at least one slit, the at least one slit is configured to fluidly couple the expansion chamber to the vaporising chamber such that the expansion chamber can receive the photovoltaic material vapour from the vaporising chamber.

5. The automated system according to any one of claims 1 to 4, wherein the computer is further configured to determine a predetermined chamber temperature of the vaporising chamber and a flow rate of photovoltaic material in the vaporising chamber in response to the sublimation rate of the photovoltaic material.

6. The automated system according to claim 5, wherein the predetermined chamber temperature of the vaporising chamber has a range of 1000 °C to 1300 °C.

7. The automated system according to any one of claims 2 and 3 wherein the predetermined pressure has a range of 3 to 5 Torr.

8. The automated system according to any of the preceding claims, wherein the substrate carrier comprises substrate holding clips, the substrate holding clips being configured to keep the substrate in place.

9. The automated system according to any of the preceding claims, wherein the expansion chamber comprises at least one opening facing in a direction towards the at least one side of the substrate, the at least one opening being configured to uniformly deposit the photovoltaic material vapour on the uniformly heated at least one side of the substrate.

10. The automated system according to any of the preceding claims, wherein the deposition chamber further comprises at least one shutter door, the at least one shutter door being controlled by the computer and configured to isolate the deposition chamber during deposition of the photovoltaic material vapour on the at least one side of the substrate.

11. The automated system according to any of the preceding claims wherein the predetermined substrate temperature has a range of 550 °C to 610 °C.

12. The automated system according to any of the preceding claims wherein the substrate comprises glass.

13. The automated system according to any of the preceding claims wherein the photovoltaic material comprises one or more of cadmium telluride or cadmium sulfide.

14. The automated system according to any of the preceding claims wherein the at least one heating element in the vacuum chamber is configured to heat the substrate by infra-red radiation.

15. The automated system according to any of the preceding claims wherein the substrate has an area of up to 1.2 metre by 2.6 metre.