Photovoltaic thermal hybrid solar collector

A laminated photovoltaic thermal (PV/T) module for a PV/T hybrid solar collector comprising a cooler/absorber and a photovoltaic unit. The cooler/absorber includes at least one flat surface with raised peripheral edges and is adapted to function as a mould for a photovoltaic laminate structure. The photovoltaic unit includes a photovoltaic laminate structure including: a first layer of a first laminate material moulded on the flat surface of the cooler/absorber, wherein the first laminate material is electrically insulating and has a high thermal conductivity; a plurality of photovoltaic cells positioned on the first layer of laminate material; and a second layer of a second laminate material moulded on and substantially covering the photovoltaic cells, wherein the second laminate material is transparent and has a high heat resistance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Submission Under 35 U.S.C. § 371 for U.S. National Stage Patent Application of International Application Number: PCT/SE2015/050450, filed Apr. 20, 2015, entitled “PHOTOVOLTAIC THERMAL HYBRID SOLAR COLLECTOR,” which claims priority to Swedish Application No.: 1450519-2, filed Apr. 30, 2014, entitled “PHOTOVOLTAIC THERMAL HYBRID SOLAR COLLECTOR,” the entirety of both which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a laminated photovoltaic thermal (PV/T) module for a photovoltaic thermal hybrid solar collector, a PV/T hybrid solar collector comprising such a laminated PV/T module and a method for manufacturing such a laminated PV/T module.

TECHNICAL BACKGROUND

There exist a number of PV/T hybrid solar collector systems using PV/T modules to convert solar energy into electrical energy. The efficiency of the solar cells or photovoltaic cells keeps improving whereas costs continue to reduce, thus making solar energy an important and viable source of renewable and environment friendly energy.

Conventional PV/T modules are manufactured by encapsulating solar cells, which are very brittle, in a laminate structure to protect them from optical and mechanical damage due to continuous exposure to sunlight and the weather elements. Additionally, PV/T modules comprise a cooling/absorbing element containing fluid for carrying away the heat accumulated in the solar cells which affects the performance of the solar cell. However, in order to reach efficiency in a PV/T hybrid solar collector it is necessary to reach a certain minimum temperature of the cooling/absorbent fluid whilst at the same time the voltage output of the photovoltaic cells decreases with increasing temperature. This dual functionality places strict requirements on the materials used in the PV/T module.

Examples of such PV/T modules are disclosed in EP 2 405 489, DE 198 09 883 and WO 2011/146029, which are incorporated herein by reference. These known PV/T modules are typically manufactured with laminate layers of polymer films comprising e.g. ethylene vinyl acetate (EVA), fluoropolymers such as polyvinyl fluoride (PVF) or polyvinyl butyral (PVB) and/or silicone polymers. The polymer films are cut and placed such that the solar cells are sandwiched between two polymer layers of EVA, PVF and/or PVB and subsequently the layers are laminated together in vacuum at an appropriate temperature. The laminated solar cell structure is then afterwards integrated with the cooling/absorbing element in the form of a heat transfer plate or heat exchanger having tubes for passage of a cooling fluid.

However, because of the considerable temperature gradients across the PV/T module, especially in coolers having fluid channels interspaced by flanges such as DE 198 09 883 and WO 2011/146029, the thermal expansion experienced by the cooler and the solar cells varies and may cause damage to the solar cells and the laminate layers made from polymer films, such as deformation, cracking, delamination, separation from the cooling element etc. and also limit the efficiency of the solar cells.

Hence, there is a need to develop improved PV/T modules and manufacturing methods therefor.

SUMMARY OF THE INVENTION

The object of the present invention is to provide improved PV/T modules for PV/T hybrid solar collectors and manufacturing methods therefor.

This is achieved by a laminated photovoltaic thermal (PV/T) module for a photovoltaic thermal hybrid solar collector according to claim1, comprising a cooler/absorber and a photovoltaic unit. The cooler/absorber comprises at least one flat surface with raised peripheral edges and adapted to function as a mould for a photovoltaic laminate structure. The photovoltaic unit comprises a photovoltaic laminate structure including: a first layer of a first laminate material moulded on the flat surface of the cooler/absorber, wherein the first laminate material is electrically insulating and has a high thermal conductivity; a plurality of photovoltaic cells positioned on the at least partially cured first layer of laminate material; and a second layer of a second laminate material moulded on and substantially covering the photovoltaic cells, wherein the second laminate material is transparent and has a high heat resistance, preferably up to a temperature of at least 200° C. The two layers of laminate may be of the same or of different materials.

By providing a cooler/absorber with raised peripheral edges a functional mould (a ‘bath tub’) is formed which may be used to mould a photovoltaic laminate structure using liquid laminate material through a potting process. The laminate structure thus achieved provides greater protection against damage caused by thermal expansion since the layers formed from the liquid laminate material may be applied more uniformly on the surface of the cooler/absorber and the photovoltaic cells and also provide better adhesion to each other and covering of the photovoltaic cells. Another advantage is that the photovoltaic laminate structure may be formed directly on the cooler/absorber as opposed to conventional PV/T modules wherein the laminate structure is formed separately and subsequently joined or attached to the cooling element. It has also been found that the photovoltaic laminate structure formed in accordance with the present invention provides better protection against disruptive discharge in wet conditions.

In a preferred embodiment, the PV/T module further comprises a second photovoltaic laminate structure moulded on an opposite substantially identical flat surface of the cooler/absorber, wherein the first and second photovoltaic laminate structures are substantially identical. Such a double-sided PV/T module may be used with a solar reflector in order to direct sunlight onto both sides of the PV/T module to increase the efficiency.

In an alternative embodiment, the cooler/absorber and the first laminate material comprise a transparent material such that both the front and back side of the photovoltaic cells may be illuminated by sunlight. Preferably, the transparent material comprises polyurethane or other material which is heat resistant in the range of 100-200° C. and is resistant to ultraviolet radiation above 1000 W/m2. Since the sunlight is permitted to illuminate the photovoltaic cells from both the front and back sides, the total concentration factor for the PV/T module is doubled compared with the case using two strings of photovoltaic cells on opposite sides.

In a further preferred embodiment, the first and/or second laminate material comprises siloxane or polyurethane.

Siloxanes are organosilicon compounds with elastomeric properties which provide necessary mechanical protection of the photovoltaic cells to shocks or vibration as well as ensuring excellent adhesion between the laminate layers. One example is polydimethylsiloxane (PDMS), which in liquid form is viscoelastic, meaning that at long flow times it acts like a viscous liquid to cover a surface and mould to any surface imperfections. Siloxanes also offer excellent heat resistance, up to 200° C., whilst allowing high thermal conduction as well as being electrically insulating. Compounds containing siloxane may be made transparent to optical and/or ultraviolet radiation. Furthermore, siloxane-containing compounds used in the photovoltaic laminate structure according to the present invention are cheaper and more weather resistant than conventional materials used in photovoltaic applications, such as EVA, PVF and PTFE. In highly accelerated stress tests (HAST), the photovoltaic laminate structure according to the present invention remained intact up to 300 hours, compared to 30 minutes for conventional laminate structures.

It has been found that similar laminate properties may be achieved by compounds containing polyurethane (PU).

In a preferred embodiment, the PV/T module further comprises a watertight flexible external electrical connection to the photovoltaic cells. The external electrical connections can be sheathed in a compatible material such as a silicon-based heat-shrink tubing to prevent ingress of moisture along the connection through the laminate. Such a connection may be made through a flexible coupling or flexible wire, e.g. a braided copper wire.

In an advantageous embodiment, the photovoltaic cells are arranged in strings of photovoltaic cells and the PV/T module further comprises a bypass diode connected in parallel with each string of photovoltaic cells. The bypass diodes may also be moulded into the photovoltaic laminate structure. Preferably, the bypass diodes further comprise DC/DC converters, which also may be moulded into the photovoltaic laminate structure. During morning/evening when the sun is low, the PV/T module is usually partially shaded since the sunlight reaches the module at low angles. The resulting low light intensity turns off the effect of practically all the photovoltaic cells in the module. The bypass diodes minimise the effects of shading such that the PV/T module only loses the power of the shaded strings of photovoltaic cells. Moreover, in the case where the bypass diodes and the DC/DC converters are moulded into the photovoltaic laminate structure, they will be protected and experience cooling at the same level as the photovoltaic cells.

In another preferred embodiment, the strings of photovoltaic cells are connected in series to form at least one series circuit. Preferably, the strings of photovoltaic cells are connected to form at least two series circuits connected in parallel. This parallel connection of the strings of photovoltaic cells makes it possible to reduce the partial shading to below 50% of the aperture surface of the PV/T module, i.e. at least 50% of the PV/T module is operational, for increased efficiency in shaded conditions. The shading effect decreases with increasing number of strings and parallel circuits, thus ensuring that the performance of the PV/T module is maintained at a high level.

In an alternative embodiment, the cooler/absorber comprises a plurality of longitudinal fluid channels adapted to give an evenly distributed flow of fluid. Preferably, the fluid channels have a substantially elliptic or circular cross-sectional shape. Tests have shown that by adapting the cross-sectional shape and size of the fluid channels, it is possible to achieve an evenly distributed flow of fluid which gives excellent cooling effect and near isothermal temperature distribution across the cooler/absorber.

In a preferred embodiment, the fluid channels comprise a honeycomb or rhombic structure on the surface which facilitates longitudinal movement of the fluid in the fluid channels. Preferably, the system of fluid channels is created by extrusion of a metal alloy, such as aluminium or similar, or a polymer, preferably polyurethane (PU), and the fluid channels are adapted to tolerate hydraulic pressures in the range 1-25 bar.

In an advantageous embodiment, the PV/T module further comprises at least one pipe connector having a first distribution section connected to the fluid channels of the cooler/absorber and a second section with an adaptable inlet opening in fluid communication with the first section. The distribution section may possess a plurality of openings adapted for connection to the fluid channels. The pipe connector may be made from moulding of metal or polymer material and is adapted to evenly distribute the flow of fluid into and out of the fluid channels through pressure drop or decompression distribution. The inlet opening may be in the form of a nozzle with inwardly projecting flanges which may be milled down to desired size and shape to regulate or equalise fluid flow.

In a preferred embodiment, the pipe connector is designed such that it may be connected to a fluid hose/pipe with a quick-connect function, e.g. for trapezoid-shaped metal hoses or pipe parts with O-ring sealing, or another quick-connect methodology.

In a second aspect of the present invention, there is provided a method for manufacturing a laminated PV/T module for a PV/T hybrid solar collector, comprising the steps:

providing a cooler/absorber having at least one flat surface with raised peripheral edges and adapted to function as a mould for a photovoltaic laminate structure;

pouring a first layer of a first laminate material in liquid form onto the flat surface of the cooler/absorber, wherein the first laminate material is electrically insulating and has a high thermal conductivity;

at least partially curing the first layer of the first laminate material;

positioning a plurality of photovoltaic cells on the at least partially cured first layer of laminate material;

pouring a second layer of a second laminate material in liquid form onto the photovoltaic cells such that they are substantially covered by the second laminate material, wherein the second laminate material is transparent and has a high heat resistance;

curing the second layer of the second laminate material and the at least partially cured first layer of the first laminate material.

In a preferred embodiment, the method further comprises the steps of moulding a second photovoltaic laminate structure onto an opposite substantially identical flat surface of the cooler/absorber, wherein the first and second photovoltaic laminate structures are substantially identical.

In an alternative embodiment, the cooler/absorber and the first laminate material comprise a transparent material such that both the front and back side of the photovoltaic cells may be illuminated by sunlight. Preferably, the first and/or second laminate material comprises siloxane or polyurethane.

In an advantageous embodiment, the method further comprises arranging the photovoltaic cells in strings and connecting a bypass diode in parallel with each string of photovoltaic cells before pouring of the second layer of the second laminate material.

In a preferred embodiment, the method further comprises providing a DC/DC converter in conjunction with the bypass diode before pouring of the second layer of the second laminate material.

In an alternative embodiment, the method further comprises connecting the strings of photovoltaic cells in series to form at least one series circuit.

In an advantageous embodiment, the method further comprises connecting the strings of photovoltaic cells to form at least two series circuits connected in parallel.

In an alternative embodiment, the method further comprises providing a watertight flexible electrical connection including a sheath chemically compatible with the laminate material to the photovoltaic cells in order to prevent ingress of moisture along the connection through the laminate.

In a preferred embodiment, the method further comprises wetting the sheath of the electrical connection with the second laminate material thereby creating a watertight joint. The step of wetting the electrical connection ensures a tight bond between the electrical connection and the laminate which is resistant to moderate relative movement.

In an advantageous embodiment, the cooler/absorber comprises a plurality of longitudinal fluid channels adapted to give an evenly distributed flow of fluid, the method further comprising directing a heated fluid through the fluid channels in order to cure the first and/or second laminate material.

In an alternative embodiment, the fluid channels have a substantially elliptic or circular cross-sectional shape. Preferably, the fluid channels comprise a honeycomb or rhombic structure on the surface. The shape and surface structure of the fluid channels are adapted to optimise distribution of fluid to give an evenly distributed fluid flow.

In a preferred embodiment, the fluid channels are formed by extrusion of a metal alloy, preferably aluminium, or a polymer, preferably polyurethane (PU). By extrusion it is possible to create fluid channels of any desired cross-section with an excellent surface finish.

In an advantageous embodiment, the method further comprises accelerating the curing process by subjecting the laminate to UV light, infrared heat, humidity and/or by adding a catalyst. Alternatively, the curing process may be allowed to take its time by letting the laminate material sit without external influence.

In an alternative embodiment, the method further comprises providing at least one pipe connector having a first distribution section with a plurality of openings adapted to be connected to the fluid channels and a second section with an adaptable inlet opening in fluid communication with the first section.

In a preferred embodiment, the method further comprises arranging a transparent convection barrier above the photovoltaic cells.

DETAILED DESCRIPTION OF THE INVENTION

Below, the laminated PV/T module10and the method of manufacturing thereof will be described more in detail, reference being made to the figures. However, the invention should not be considered limited to the embodiment or embodiments shown in the figures and described below, but may be varied within the scope of the claims.

InFIG. 1, there is shown a laminated PV/T module10according to the present invention in an elevated side view.FIG. 2shows the separate laminate layers31,32and the photovoltaic cells33in an exploded view for easier understanding of the invention. The PV/T module10comprises a cooler/absorber20and a photovoltaic unit30having a plurality of photovoltaic or solar cells33encapsulated in a laminate structure for protection. The advantages with the PV/T module10will now be explained.

Contrary to conventional PV/T modules having laminated solar cells, the present invention discloses a construction wherein the photovoltaic laminate structure30is produced or manufactured directly on the surface21of the cooler/absorber20, instead of being produced separately and later joined or integrated with the cooler/absorber20.

As seen inFIG. 2, the cooler/absorber20has raised edges22at least along the longitudinal sides thereof resulting in a functional mould. The raised edges22create an enclosure allowing liquid to be contained therein, which is advantageous when pouring and moulding the laminate layers31,32. The cooler/absorber20is shown to have raised peripheral edges22on both sides, the top side and underside. This is to allow for moulding of photovoltaic laminate structures30,35both on the top side and the underside to increase efficiency and use of space.

Positioned nearest to the flat top surface21of the cooler/absorber20is an electrically insulating first layer31of a first laminate material which has been moulded in liquid form and subsequently at least partially cured by application of heat. The first laminate layer31is 0.2 to 2 mm thick and has a high thermal conductivity, in the range of 0.1-10 Wm−1K−1to carry away heat generated in the photovoltaic cells33. This is to ensure that the photovoltaic cells33do not exceed their stagnation temperature, which can cause efficiency reduction. The first laminate material is adapted to be heat resistant to temperatures above 150° C., preferably at least 200° C. The required insulation effect provided by the first laminate layer31is at least 10 GΩ at 5 kV. The dielectric strength is at least 18 kV/mm.

Next in the direction from the surface21of the cooler/absorber20there is positioned on top of the electrically insulating first laminate layer31a plurality of photovoltaic cells33in strings, and additional wiring necessary to create the electrical circuits and connections. Any commercially available photovoltaic cells33with high efficiency and short distance between the contact fingers may be used. As an example, it is suggested to use photovoltaic cells from Hitachi with high fill factor and transparent front side contact. The PV/T module10may have at least 2 strings of photovoltaic cells33, each string36comprising a number of photovoltaic cells33to attain sufficient output voltage, typically 34 photovoltaic cells or more. The photovoltaic cells33are shaped like thin strips and placed perpendicular to the longitudinal direction of the cooler/absorber20with a length adapted to the width of the cooler/absorber20. This leads to a highly reduced thermal load on the photovoltaic cells33and helps avoid damage. In one embodiment, the width of the photovoltaic cells33is 26.6 mm.

The wires running the length of the cooler/absorber20are provided with a stress-relief jog in the centre of their span. This protects the electrical system against strain caused by longitudinal expansion of the cooler/absorber20. The external electrical connections to the photovoltaic cells are made with a flexible electrical wire72, as shown inFIG. 8, and sheathed with an insulating sleeve or sheath (not shown). In a preferred embodiment, this flexible electrical wire72is of braided tinned copper wire, and the sheath is of a silicone-based heat-shrink tube compatible with the laminate material to promote chemical bonding between the sheath and the laminate material and thereby create a watertight joint71around the connection point between the flexible electrical wire72and the photovoltaic cells33. However the particular materials are not significant; it is proposed within the scope of this invention to use a flexible electrical wire with any sheath material chemically compatible with the chosen laminate.

Finally, furthest away from the surface21of the cooler/absorber20there is provided a second covering layer32of a transparent second laminate material to cover and protect the photovoltaic cells33. The covering layer32is poured and moulded on top of the photovoltaic cells33and has the advantage of filling in small recesses between and around the photovoltaic cells33to give a substantially plane and uniform top layer contrary to the case with laminate structures created from polymer films stretching over the solar cells. Furthermore, the covering layer32is heat resistant to a temperature of at least 200° C.

The materials chosen for the first and second laminate layers31,32preferably comprise siloxanes and/or polyurethane (PU). Siloxanes are a functional group in organosilicon chemistry with an Si—O—Si linkage, i.e. each pair of silicon centres is separated by one oxygen atom. The siloxane-containing compounds tested and used in the present invention, although being an organic material, does not act as such. Firstly, siloxane-containing laminate layers exhibit negligible reactions after prolonged exposure to ultraviolet radiation, as opposed to conventional EVA laminates, which start to dry and turn yellow. Siloxane-containing laminates have a higher transmittance within the spectrum of relevant wavelengths, roughly 93-96% transmittance from about 300 nm to about 1200 nm, and no considerable dips or spikes, as opposed to EVA, which has a transmittance of about 90% and considerable dips when nearing the infrared region. The proposed siloxane-containing compounds have a short curing time, when heated or exposed to UV light to trigger the chemical curing process. Finally, siloxane-containing compounds exhibit high electrical resistance, 2×1015Ω, and dielectric strength, 18.3 kV/mm.

InFIG. 3, a cooler/absorber20according to an embodiment of the present invention is illustrated in cross-section. The peripheral side edges22are shown as well as the system of fluid channels23formed in the cooler/absorber20. The cross-sectional shape of the fluid channels23has been adapted to give an evenly distributed fluid dynamic flow through the fluid channels23. Tests have shown that in order to achieve optimal cooling/absorption of heat from the photovoltaic cells33, the fluid channels23should have a substantially elliptic cross-section giving excellent cooling characteristics and close to isothermal surface temperatures. As opposed to fluid channels23with rectangular or quadratic cross-section, there is no movement or deformation observed of the cooler/absorber20at the high hydraulic pressure of the cooling/absorbent fluid used in the PV/T hybrid application. Therefore, there is no mechanical stress propagated to the photovoltaic cells33, which otherwise would cause considerable damage. Circular cross-sections also protect against deformation of the cooler/absorber20. However, an elliptic cross-section is preferred since this shape enables thinner coolers/absorbers with equal cross-sectional area compared to circular fluid channels23, thus requiring less material. Thereby, the temperature gradient across the PV/T module10is minimised which reduces thermal load and stress on the photovoltaic cells33and allows the photovoltaic cells33to operate at ideal conditions at full efficiency.

The surface of the fluid channels23may be shaped in order to optimise fluid flow and heat transfer, e.g. by providing a honeycomb or rhombic structure. This surface structure may then be coated with a suitable material to reduce friction, such as polytetrafluoroethylene (PTFE).

Since the pressure of the fluid passing through the fluid channels23may be elevated, the fluid channels23are adapted to withstand a hydraulic pressure of between 1 and 25 bar.

The cooler/absorber20including the system of fluid channels23is created through extrusion of a metal alloy, e.g. aluminium, or a polymer, e.g. polyurethane (PU), in applications where the cooler/absorber20is made transparent for double sided illumination by sunlight.

In order to connect the PV/T module10to a closed or open loop of cooling/absorbent fluid, there is provided a pipe connector50adapted to be attached to the end surfaces of the cooler/absorber20. The pipe connector50as illustrated inFIG. 4comprises a distribution section51having substantially the same width as the cooler/absorber20and a plurality of openings53adapted to the fluid channels23. The fluid flow through the distribution section51is evenly distributed through pressure drop or decompression distribution.

In fluid communication with the distribution section51is a second inlet/outlet section52which may have an adaptable inlet/outlet opening54to regulate or equalise the fluid flow there through. The inlet/outlet opening54may take the form of a nozzle having inwardly projecting flanges55which may be milled down to the desired dimension, or may also take the form of mechanical modifications to the shape of the end of the PV/T module10.

FIG. 5shows the PV/T module10connected at its end sections to pipe connectors50. The inlet/outlet opening54may be seen, as well as the flanges55.

The pipe connector50is designed to be attached to fluid pipes or hoses through a quick-connect function, e.g. trapezoid-shaped metal hoses or pipe details for quick connection with an O-ring sealing, as is known in the art.

InFIG. 6there is shown a transparent convection barrier60arranged above the PV/T module10. The convection barrier60is shaped with a plurality of partially cylindrical elements or half-tubes61arranged perpendicular to the longitudinal direction of the PV/T module10. The partially cylindrical elements61are connected along their respective valley regions62. The purpose of the convection barrier60is to reduce convective thermal losses from the cooler/absorber at high temperatures such that the heat is transferred to the cooling/absorbent fluid instead of the air in the hybrid solar collector. The convection barrier60is adapted to be attached to the edge profile of the cooler/absorber20, e.g. in a groove, above the photovoltaic laminate structure30.

InFIG. 7a connection diagram for the strings36of photovoltaic cells33is shown. The PV/T module10shown has 8 cell strings36with 38 photovoltaic cells each, internally connected in parallel. Each string section36has a bypass diode40located in the end sections of the PV/T module10. Each photovoltaic cell is connected by means of soldering at two spots on the top or bottom side, respectively, thereby relieving all stress on the photovoltaic cells33.

Now, the lamination procedure will be described in further detail. Contrary to conventional lamination using polymer films, the present invention relies on potting to encapsulate the photovoltaic cells33and create a protective laminate structure30. In the potting procedure the photovoltaic assembly is filled with a solid or gelatinous compound for resistance to shock and vibration, and for exclusion of moisture and corrosive agents.

First, the cooler/absorber20is prepared for lamination by subjecting the flat surface21to be coated to cleaning with a damp wipe of a solvent such as isopropanol or ultrasonic cleaning in order to remove any foreign particles, and subsequently priming the flat surface21through applying a coating of a primer solution suitable for the laminate material, e.g. propanol with optional additives, or through plasma treatment of the flat surface21. The cooler/absorber20is allowed to cool to the ambient temperature, preferably below 30° C.

Now, the first layer31of the first laminate material is formed on the pretreated surface21of the cooler/absorber20by pouring an electrically insulating polymer material in liquid form onto the surface21. The peripheral edges22of the cooler/absorber20retain the liquid first laminate material in the mould thus created to give an electrically insulating layer31of uniform thickness in the range of 0.2 to 2 mm. Since the first layer31is also intended to carry away heat from the photovoltaic cells33, it is desirable to use a material which has a high thermal conductivity, preferably in the range of 0.1-10 Wm−1K−1. Preferably, the first laminate material comprises a siloxane in liquid form. A protective lid is placed above the first layer31and negative pressure is applied by a vacuum pump. The vacuum process is an option al step of this production method which may increase repeatability and enhance quality control.

When substantially all gas has been evacuated from the liquid material and the space above, the first laminate material31is at least partially cured, either through applied heat in the temperature range of 60-140° C., UV light, or any other appropriate method. By leaving the first layer31partially cured before moulding of the second laminate layer32, the two laminate layers31,32will adhere even better to each other. Of course, it is also proposed within the scope of the present invention to fully cure the first layer31to achieve a material in solid form and having a Shore A durometer in the range 30-80, preferably 45-65. Advantageously, curing time may be accelerated by applying UV light, or heat by infrared light or passing a heated fluid through the fluid channels23of the cooler/absorber20) or some other method, enabling short production times.

After the curing process of the first layer31is completed, the lid is opened and a string36of photovoltaic cells33is placed on the at least partially cured first layer31which now constitutes an electrical insulator for the photovoltaic cells33. The string36is connected at its respective ends to circuit boards protection circuits, connection wires and/or contacts.

At this point, the second layer32of the second laminate material is formed on top of the string36of photovoltaic cells33positioned on the at least partially cured first layer31by pouring a polymer material in liquid form onto the photovoltaic cells33and the underlying electrical insulation layer31until the photovoltaic cells33are at least substantially covered. The height of the peripheral edges22of the cooler/absorber20is adapted to the thickness of the photovoltaic laminate structure30such that the liquid second laminate material is also retained in the mould, even under vacuum conditions wherein the fluids may occupy a greater volume as dissolved gases are removed.

Preferably, the dispensing of the liquid second laminate material is carried out by pouring the whole volume of liquid over the string36of photovoltaic cells33in a rapid movement along the centre line of the photovoltaic cells33in a longitudinal direction of the PV/T module10. This rapid placement of the liquid second laminate material, which may be carried out by means of a robot arm, creates a mound or wall of liquid which flows towards the side edges22such that all the air is evacuated towards the side edges22.

Additional processes may be used such as vacuum, agitation, and mechanical pressure to ensure that all dissolved gases and bubbles in the laminate materials31,32are removed. One important point of this process is to ensure a tight bond between the electrical connections and the laminate which is resistant to moderate relative movement. In one embodiment, this is achieved by wetting one to two centimetres of the sheath of the flexible electrical wire72with the second laminate material while the material is being dispensed into the cooler/absorber10over the photovoltaic cells33. This will create a watertight joint71around the connection point between the flexible electrical wire72and the photovoltaic cells33, as shown inFIG. 8.

The steps for curing the first laminate material are then repeated by replacing the protective lid over the second layer32and applying a negative pressure by means of the vacuum pump. Subsequently, the curing reaction may be accelerated as before by the application of UV light or heat in order to cure the second layer32to a material in solid form having a Shore A durometer in the range 30-80, preferably 45-65. Alternatively, heat may be applied by passing a heated liquid through the fluid channels23of the cooler/absorber20.

When the final heating step is completed and the second laminate material in the second layer32and the at least partially cured first layer31of the first laminate material has been cured, the cooler/absorber20including the laminated photovoltaic structure30may be moved to the next process step of the manufacturing procedure.