Reflector panel assembly

Abstract

A reflector panel assembly for a concentrated solar system is disclosed, the assembly comprising: a reflector comprising a sheet element having a front surface and a rear surface, the reflector configured to receive and reflect electromagnetic radiation incident on the sheet element; and a substrate configured to support the reflector such that a contact surface between the rear surface and the substrate is configured to maintain a predetermined shape of the reflector. Also disclosed is a substrate configured to support a reflector for use in a concentrated solar system, the substrate constructed from a sheet material and comprising a plurality of protrusions spaced across a surface of the substrate, the plurality of protrusions extending to contact portions at peaks of the protrusions, the contact portion is configured to form a contact surface supporting the reflector.

Description

Field of the Invention

[0001] The present disclosure relates to the field of support structures for reflector panels. More particularly, the present disclosure relates to support structures for supporting reflector panels used in concentrating solar power systems. Background Art

[0002] It should be understood that if any prior art is cited herein, such citation does not constitute an admission that such prior art forms part of the common general knowledge in Australia or any other country.

[0003] Reflector panels are used in a variety of applications (such as satellite antennas, radio telescopes, concentrating solar power systems, etc.) to collect and process electromagnetic radiation. The collected electromagnetic radiation is redirected to a receiver for utilization / processing of the radiation. In a concentrating solar power system, the sunlight collected by the reflector can be used to generate heat that can be used for a variety of purposes (such as heating fluids or particles, driving thermal and chemical processes, etc.). In a concentrating photovoltaic system, the sunlight collected by the reflector can be directly converted into electricity. The ability of the reflector panel to accurately concentrate sunlight onto a desired focus or focal region has a direct impact on the design and performance of the energy collection device (i.e., the solar receiver or solar reactor). An improvement in the optical accuracy of the reflector panel can result in a smaller (and thus less costly) solar receiver and higher efficiency in collecting sunlight, and thus, accurately curved reflector panels are sometimes used. In addition, the reflector panels need to be constructed such that they maintain acceptable optical accuracy during operation under the influence of external loads (such as gravity and wind). When in the stowed position, they also need to be able to withstand the wind loads experienced during storm conditions.

[0004] One type of construction commonly used for reflector panels is the sandwich panel type construction. In this construction, a porous core material is sandwiched between two rigid panel sheets, one of the two rigid panel sheets having a reflective surface. Although such a construction provides accuracy, it has accompanying problems. For example, moisture may become trapped in the porous core, resulting in moisture damage (such as corrosion or failure of adhesives). The core may be vulnerable to ultraviolet (UV) degradation, so the use of light-blocking edges is required, which will increase the complexity and cost of manufacturing. Another construction for reflector panels is to bond a glass reflector panel sheet to a stamped steel support. Conventionally, the stamped metal support is composed of a combination of concentric ring-shaped raised features and radially ribbed raised features. The support has cutouts between these raised features to reduce the weight of the support. The contact between the support and the mirror occurs at the edges of the ring and rib features. However, this panel is constrained in its ability to achieve high shape accuracy. A third option for reflector panels is a pure glass construction, where the curvature is provided by an external support frame. This type of concentrator uses a frame assembled, welded, or joined from standard structural members (such as lightweight folding sections). The mirror is held in the desired shape using a plurality of connection elements between the frame and the mirror. The location of the connections is constrained by the geometry of the frame, which imposes limitations on the accurate shape of the mirror. The manufacture and assembly of this type of concentrator are also complex. Therefore, there is a need for a cheaper and more effective reflector panel that can maintain the accuracy of a curved mirror and can be mass-produced. SUMMARY OF THE INVENTION

[0005] In some forms, a reflector panel assembly for a concentrating solar power system is disclosed, the assembly comprising: a reflector including a panel element configured to receive and reflect electromagnetic radiation, the panel element having a front surface on which electromagnetic radiation is incident and also having a rear surface; and a substrate configured to support the reflector such that the contact surface between the rear surface and the substrate is configured to maintain a predetermined shape of the reflector.

[0006] In some forms, the substrate includes a plurality of protrusions extending from the rear substrate surface to form a contact surface spaced apart from the rear substrate surface.

[0007] In some forms, the contact surface of the substrate includes a plurality of spaced-apart contact surface portions formed at the peaks of each of at least a portion of the protrusions.

[0008] In some forms, the protrusions are generally frustoconical, extending from the substrate at the rear substrate surface to the contact surface.

[0009] In some forms, the plurality of protrusions are evenly spaced on the substrate and / or are located on the substrate in a regular pattern.

[0010] In some forms, the substrate is made of sheet metal.

[0011] In some forms, the substrate and the protrusions are formed by any sheet forming process. In some forms, the protrusions are formed by stamping sheet metal. In some forms, the protrusions are formed by turret punching. In some forms, the protrusions are formed by incremental sheet forming (ISF). In some forms, these processes provide the ability to mass-produce the substrate in an efficient and cost-effective manner.

[0012] An advantage of the assembly is that it has a substrate that provides sufficient support for the reflector to allow the accurate curvature of the reflector to be maintained, while being manufactured efficiently and inexpensively, allowing for mass production of the substrate and reflector assembly.

[0013] Also disclosed is a substrate configured to support a reflector used in a concentrating solar power system. The substrate is made of sheet material and includes a plurality of protrusions spaced apart on the surface of the substrate. The plurality of protrusions extend from the rear surface to a contact portion at the peak of the protrusion. The contact portion is configured to form a contact surface that supports the reflector in use.

[0014] In some forms, the substrate is made of sheet metal, and the protrusions are formed by a sheet metal forming process including stamping, turret punching, and incremental sheet forming.

[0015] Also disclosed is a method of manufacturing a substrate for supporting a reflector used in a concentrating solar power system. The method includes providing sheet material and forming a plurality of protrusions in the sheet material. The plurality of protrusions are spaced apart on the surface of the substrate and extend to a contact portion at the peak of each protrusion. The contact portion is configured to together form a contact surface that supports the reflector.

[0016] The use of sheet metal forming in the production of the substrate enables the use of efficient and inexpensive mass manufacturing processes, which reduces the total cost and provides consistency in production volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments will now be described by way of example only with reference to the drawings, in which:

[0018] Figure 1 a and Figure 1 b show a front perspective view and a rear perspective view of a reflector assembly according to an embodiment of the present disclosure;

[0019] Figure 2 show a side perspective view of a substrate and a reflector according to an embodiment of the present disclosure;

[0020] Figure 3 show Figure 2Side view of the base and reflector;

[0021] Figure 4 Shows Figure 2 Top view of the base and reflector;

[0022] Figure 5 Top view of the base of an embodiment of the present disclosure;

[0023] Figure 6 Top view of the base of another embodiment of the present disclosure;

[0024] Figure 7 Top view of the base of an embodiment of the present disclosure;

[0025] Figure 8 Shows Figure 7 Side perspective view of the base.

[0026] Figure 9 Perspective view of the installed solar panel reflector assembly including the base of an embodiment of the present disclosure. Detailed Description

[0027] In the following detailed description, reference is made to the accompanying drawings which form a part hereof. The illustrative embodiments described in the detailed description, depicted in the drawings, and defined in the claims are not intended to be limiting. Other embodiments may be utilized and other changes may be made without departing from the spirit or scope of the subject presented. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a variety of different configurations, all of which are contemplated within the present disclosure. In this embodiment, the concentrating solar system is a heliostat-based system that uses a reflective surface or mirror to direct light from the sun towards a solar receiver for absorption. Although the present disclosure has been described with respect to a heliostat system, it will be apparent to those skilled in the art that the components can form part of any solar system where the redirection of light requires a mirror (such as a parabolic dish system and a parabolic trough system) with an accurate and supported curvature.

[0028] Now referring to Figure 1 , a reflector panel assembly 12 used as part of a solar concentrator system 10 is disclosed.

[0029] The reflector panel assembly 12 includes a reflector in the form of a mirror 14 or a series of mirrors and a support substrate 16 that is configured to support the mirror 14 in use. In the illustrated embodiment, the support substrate is supported by a bracket 15 to position the mirror for use and to allow the mirror to move as required. The bracket includes upright columns and a base support structure coupled to the upright columns.

[0030] The mirror or reflector 14 includes a sheet element 17 that is configured to receive and reflect electromagnetic radiation incident on the sheet element. The sheet element 17 includes a front surface 18 and a rear surface 20 (as Figure 2 best illustrated therein).

[0031] In some forms, the mirror includes a sheet element. In some forms, the sheet element is a laminate. In some forms, the sheet element includes a glass layer and a reflective layer. In some forms, the glass layer forms the front surface on which electromagnetic radiation is incident. In some forms, the reflective layer includes a thin layer of metal (such as silver or aluminum) located behind the glass layer. In some forms, the sheet element also includes one or more protective layers (such as a copper layer and one or more coating layers) located behind the glass layer. In some forms, the sheet element includes a glass-metal laminate. In some forms, the sheet element includes a mirror layer and a metal sheet layer. In some forms, the sheet element includes a polished metal layer such that the front polished surface is the reflective layer. In some forms, the sheet element includes one or more protective layers that are coated or otherwise disposed on the reflective layer to protect the reflective layer from undesirable effects (such as, for example, corrosion). In some forms, the protective layer is deposited on the sheet element by chemical vapor deposition. The material, size, and type of the mirror 14 can vary. For example, for sunlight concentration, a low-iron-content silver-backed glass mirror can be employed. In alternative embodiments, any useful mirror or reflector surface can be used. For example, the mirror 14 can be a glass-metal laminate that includes a thin glass layer bonded to a thin metal layer. Another example is a front-surface polished aluminum mirror.

[0032] The support substrate 16 of the mirror 14 is configured to support the mirror 14. The contact surface of the support substrate 16 at the rear surface 20 is designed to contact the rear surface 20 to sufficiently support the mirror and maintain the predetermined shape of the reflector.

[0033] The mirror 14 is used to reflect the electromagnetic radiation falling on the slab element 17. The size of the reflector panel assembly 12 can be determined according to the requirements of the concentrating solar power system. The sunlight incident on the slab element 17 is reflected and focused onto a desired point / area. The thus concentrated electromagnetic radiation can be used to generate heat that can be used for other purposes. For example, water can be heated to turn it into steam, or molten salt can be heated to fill a thermal energy storage system. The concentrated electromagnetic radiation can also be used for other processes (such as generating electricity through photovoltaic cells or thermochemical processes).

[0034] In a preferred embodiment, the slab element 17 further comprises the following elements listed in order from the front surface to the back surface: a glass slab, a reflective silver layer or a reflective aluminum layer, a protective copper layer, and one or more protective coating layers. The glass is typically about 3 mm or 4 mm thick and protects the underlying reflective layer. The thickness is a key parameter to consider when selecting the glass. For example, simulation results (not shown here) reveal that the stress in the glass can be low enough to allow the use of 3 mm glass. Since the spacing of the glass support points is regular and close, damage caused by hail is not considered a significant risk for this design.

[0035] The reflective layer can be applied to the back surface of the glass in a wet chemical deposition process or other deposition processes (such as electroplating or vacuum deposition). The reflective layer performs the function of reflecting electromagnetic radiation. The copper and coating layers cover the back surface of the reflective layer (i.e., the surface not exposed to the incident radiation), thus protecting it from the back.

[0036] In performing the function of reflecting radiation, the mirror 14 or the reflector panel assembly 12 may have a predetermined shape. Generally, a spherical curvature, although alternative shapes are utilized in the art, this shape enables the mirror 14 to focus the reflected electromagnetic radiation at a specific or desired point or area for use. For the concentrating solar power system 10 to operate effectively, the focus / area for the reflected radiation is typically predetermined and fixed. For example, the desired point / area may be a receiver on a tower located at a certain height above the ground. The reflector panel 12 is then configured such that it can reflect as much radiation as possible towards this receiver located on the tower. The shape of the mirror 14 can be customized based on factors such as its position relative to the receiver, its position relative to other mirrors in the heliostat, or based on other factors including economic factors or the geometry of the solar tracker. Generally, the shape of the mirror is such that the radius of its spherical curvature is equal to twice the desired focal length, but sometimes other mirror shapes (e.g., parabolic or asymmetric shapes) may be desired. Thus, the shape of the mirror 14 has a direct impact on the function of the reflector panel 12 and thus on the performance of the concentrating solar power system 10. Any deviation from the predetermined shape will result in a situation where the maximum possible amount of radiation is not directed towards the receiver, thus affecting the output of the concentrating solar power system 10. For example, a lesser amount of sunlight reaching the receiver will result in a reduction in the energy in the form of heat or electricity collected by the receiver. Since the shape of the mirror 14 has a direct impact on the performance of the panel, any deviation from the expected shape can significantly affect the performance of the panel. For example, a shape with a radius of curvature greater than the expected spherical bend will cause the focus to be outside or behind the receiver, and thus in the area of the receiver, the light will be more dispersed, and some light may miss the receiver and not be collected.

[0037] In use, for a variety of reasons, the shape of the mirror 14 may deviate from the target shape. For example, during fabrication, due to the nature of the materials used in the panel assembly 12, there may be a springback effect from the molding. Thus, due to this springback effect, the finished reflector panel assembly 12 may have a curvature slightly greater than desired. During operation, the external force due to wind hitting the panel 12 may cause the panel to deform, affecting its shape. The gravity acting on the panel may cause the panel to sag, affecting the shape of the mirror 14. Since the solar panel changes its orientation according to the sun's position, the effect of gravity sag will vary at different times of the day.

[0038] It is desirable for the reflector panel 12 to have high stiffness. Among various factors, the stiffness of the reflector panel 12 depends particularly on the distribution of materials in the structure. To increase the stiffness, it is desirable to have a high second moment of area around the neutral axis of the bend. Two parameters in the protrusion design that affect the second moment of area are the area ratio of the support surface and the aspect ratio of the protrusion. The area ratio is defined as the rectangular area of the support structure divided by the area of the surface of the protrusion that contacts the mirror. A larger value indicates that more material is distributed from the metal support substrate to the glass reflector sheet, which increases the stiffness of the panel, all other conditions being equal. The aspect ratio of the protrusion, which is the ratio of the height of the protrusion to its base diameter, gives a dimensionless indication of how slender the protrusion is. A larger value indicates a slender protrusion shape and thus more efficient use of material to separate the ends of the reflector panel, thus increasing the second moment of area and increasing the stiffness.

[0039] Now referring to Figures 2 to 4 , the support substrate 16 in the illustrated form includes a panel consisting of a series of protrusions 22 that extend from the rear substrate surface 23 to the contact substrate surface 24. The contact substrate surface 24 is configured to contact and support the mirror 14 in use.

[0040] In the illustrated embodiment, each protrusion 22 of the support substrate 16 is in the form of a frustum of a cone that protrudes from the rear substrate surface 23. The contact substrate surface 24 is formed at the truncated peak of the frustum of the cone of the protrusion 22 and includes a plurality of spaced circular contact surface segments. It will be clear to those skilled in the art that other shapes of the protrusion also fall within the scope of the present disclosure. For example, the cross-section of the protrusion can be circular / square / rectangular or any other suitable shape.

[0041] As Figures 2 to 4 shown, each protrusion 22 includes a contact portion 22a and a curved outer conical surface 22b. The contact portion 22a defines and forms the contact substrate surface 24, and the outer conical surface 22b extends from the rear substrate surface 23 to the contact substrate surface 24. The outer surface 22b of the protrusion supports the contact substrate surface 24 away from the rear substrate surface 23. The length of the outer surface 22b can be varied to adjust the spacing between the rear substrate surface 23 and the sheet element 17, which, in structural engineering terms, increases the second moment of area. In other words, increasing this spacing allows the cross-sectional area associated with the sheet element 17 and the rear substrate surface 23 to be located further away from the neutral bending axis, which helps to minimize the deflection associated with the bending moment caused by loads such as wind and gravity. Minimizing the deflection from the desired shape improves the optical performance of the mirror panel.

[0042] The rear surface 20 of the mirror 14 contacts the contact base surface 24 of the base 16. This contact serves to support the mirror 14.

[0043] The contact base surface 24 consists of a plurality of contact portions 22a of a plurality of protrusions 22. Each of the contact portions 22a contacts the rear surface 20 of the mirror 14. In the illustrated form, each contact portion 22a of the cut-off portion of the formed frustum-shaped protrusion is circular. In an alternative embodiment not shown, the contact portions 22a may include other shapes.

[0044] By providing such a configuration, the base 16 supports the mirror 14 at a plurality of contact portions spaced apart over a wide area. The base provides a plurality of support contacts between the mirror 14 and the base 16, each contact portion providing support over the entire surface, and the respective contact portions work together to support the sheet member. Thus, the mirror 14 is supported at a plurality of points spaced apart at intervals across its surface to maintain a desired accurate or consistent shape. The contact portions 22a also facilitate the bonding between the support base 16 and the mirror 14. For example, an adhesive may be applied to the contact base surface 24 before the contact base surface 24 contacts the rear surface 20 of the sheet element 17.

[0045] Alternative embodiments can be obtained, in which the shape and size of the protrusions form the configuration and layout of the contact surface. Changes in the configuration and layout of the contact surface between the base 16 and the mirror 14 result in changes in the support of the sheet element. The spacing of the protrusions on the contact surface results in various patterns, configurations, and layouts of the contact surface. In some forms, the protrusions may be regularly spaced.

[0046] Reference Figure 5 and Figure 6 , the pattern of the protrusions can be changed to obtain different configurations of the base 16. In one embodiment ( Figure 5 shown in), the protrusions 22 may be arranged in a repeating circular pattern (indicated by overlapping concentric circles A, B, C, which are not part of the protrusions). It can be seen that the concentric circles of the protrusions 22 can be formed on the base 16, radiating outward from the central section. This provides a regular pattern of support protrusions 22.

[0047] In another embodiment, as Figure 6 best shown in, the protrusions 22 may be arranged in a repeating honeycomb or hexagonal pattern (indicated by overlapping hexagons A, B, C, which are not part of the protrusions). The protrusions are arranged in offset rows over the entire surface of the base.

[0048] Alternative embodiments are also contemplated. By varying the pattern, the number of protrusions that can be placed in a given area can be varied and the support provided to different segments of the mirror can be varied. This will again result in a change in the contact surface between the substrate 16 and the mirror 14.

[0049] The substrate 16 serves to prevent / minimize such deviations in the shape of the mirror 14. The contact substrate surface 24, which consists of a plurality of spaced-apart contact portions 22a of the substrate 16, allows significant support to be provided across the entire extent of the rear surface 20 of the mirror 14. Because an enhanced anchoring effect is achieved by spacing the protrusions 22 in this way, the forces acting locally on a segment of the mirror 14 will be able to be limited to avoid deflecting this segment of the mirror from its original position. Thus, the resulting reflector assembly 12 can resist shape deviations caused by forces acting on the mirror.

[0050] Reference Figure 7 and Figure 8 and, show additional views of the substrate 16 including the rear substrate surface 23 and the contact substrate surface 24 defined by the contact portions 22a of the plurality of protrusions 22. The substrate is formed from sheet metal material. In the illustrated embodiment, the substrate 16 includes a plurality of identical or similar protrusions 22 spaced across its surface. The position and shape of the protrusions can be pre-planned or designed on the sheet. The substrate is formed from a suitable sheet and the protrusions are formed on the sheet by sheet metal forming operations such as stamping, turret punching or incremental sheet forming (ISF). Using a sheet metal stamping operation enables the substrate 16 to be fabricated in a process that is well-suited for mass manufacturing. The protrusions can be formed in a single-step process such as stamping, formed by a multi-step process such as using a turret punch press, or formed by an incremental process (i.e., deformation that occurs in a plurality of small steps) such as ISF (where the form of ISF involves single-head or multi-head) to ensure that the protrusions maintain precise accuracy. Using a sheet metal forming process in the production of the substrate allows for production in an efficient and inexpensive mass production, which reduces the overall cost and provides production consistency.

[0051] Materials for the substrate 16

[0052] In some forms, the substrate is formed from a suitable sheet material.

[0053] The key criteria for selecting a suitable sheet material for the substrate 16 are formability, suitability for external exposure in a solar site, compatibility with adhesives, and cost. In some forms, since the stresses generated in use, as determined by finite element analysis, are relatively low (~50 MPa) compared to the tensile strength of the material, the strength requirements for the support structure are not high. Weight may also be a consideration in determining the material, but weight is not a key criterion.

[0054] In the illustrated embodiment, the sheet material is Al-Zn alloy coated structural steel (Bluescope Zincalume G300). In another embodiment, the sheet material is galvanized commercial forming steel (Bluescope Galvabond G2). In other embodiments, stainless steel and other structural steels, draw steel and forming grade steels can be used.

[0055] Corrosion resistant coating

[0056] In some embodiments, a coating can be applied to the material of the substrate 16 to provide suitable corrosion resistance. In some forms, the coating can be zinc or an aluminum-zinc alloy.

[0057] Manufacturing techniques

[0058] In some forms, the protrusions are formed by stamping, turret punching, rolling, incremental sheet forming (ISF) or other alternative forming methods. In some forms, the substrate is formed in any way as long as the protrusions are formed of the sheet material. In some forms, the forming method is suitable for mass production.

[0059] The manufacturing method can advantageously have the following characteristics:

[0060] - High rate of production of large amounts of material

[0061] - Flexibility in producing finished products of different sizes

[0062] - Suitability for on-site production by simplifying the tools and machines used

[0063] In this regard, stamping may be a potential manufacturing method but requires a large capital investment to set up. There are also other manufacturing methods with lower capital intensity, although the production rate is usually lower. In some forms, these manufacturing methods can be any of the following:

[0064] - Incremental sheet forming (ISF) with single or multiple heads on a CNC router

[0065] - Cluster type tools equipped with multiple forming tool heads

[0066] - Needle forming of materials

[0067] - Embossing or turret punching

[0068] Although not explicitly disclosed, it will be understood that different equipment may be used for the above process. For example, mechanical presses / hydraulic presses of different tonnages may be utilized for stamping. The press line may feed directly from a coil of steel or load pre-cut blanks. Multiple stamping stages / operations may be used for blanking, punching, forming (including several step-forming stages), and trimming. The increase in the number of operations increases the tool and production costs, and thus efforts are made to minimize the operations. Loading and unloading may be fully automated.

[0069] In an alternative embodiment not shown, over the entire substrate, the shape and size of the protrusions 22 may vary, or the protrusions 22 may be positioned at regular or irregular intervals over the entire surface of the substrate to provide the necessary support.

[0070] Simulation of the manufacturing process

[0071] In some forms, simulations may be performed to determine the suitability of other manufacturing processes for fabrication. Such simulations may be performed using software specifically designed for stamping (e.g., Autoform, EasyBlank, Altair Inspire Form, etc.). These simulations may provide useful information regarding whether the manufacturing process is suitable for forming a particular design of the substrate 16. For example, it may be estimated whether stamping can be used to form protrusions 22 having a particular depth and a particular substrate diameter.

[0072] Similarly, the simulations may also assist in deciding which is the best geometry to utilize from a forming perspective and which is the best initial geometry for a given forming process. For example, different-shaped protrusions may be tested to evaluate which gives the best formability and reduces the press tonnage and which is the most ideal initial geometry, etc.

[0073] Adhesives and their selection

[0074] In some forms, to produce the curved reflector 12, an adhesive is applied to contact the substrate surface 24, and the mirror 14 and the substrate 16 are elastically deformed and held together on a curved mold until the adhesive cures and is strong enough to resist the resilience force and hold the shape of the reflector. During this curing period, the mirror and the substrate may be held together by weights, presses, vacuum bag systems, or other means.

[0075] Given that other components of the panel have a long lifespan, it may be advantageous to select an adhesive that has a comparable lifespan when exposed to these elements. For example, the design lifespan of the device is typically 25 years. Thus, it may be advantageous to have a panel 12 that can last for the duration of the device lifespan.

[0076] The adhesive can advantageously be suitable for rapid assembly during high-volume manufacturing. The assembly process requires a balance of open time, working time, and curing time. The adhesive needs to be applied over a significant surface area before the support structure is maneuvered into place and lowered onto the mirror. Thus, the working time can advantageously be on the order of several minutes. After the support is placed on the mirror, pressure is applied to cause the assembly to take the shape of the mold. During this process, it is advantageous for the adhesive to be able to move freely and be molded into shape. The molding time may only require a few seconds. Finally, rapid curing may be advantageous so that the mirror can be produced at an acceptable rate. A longer curing time would result in a need for more molds to maintain the production rate and this could increase costs and may affect the accuracy of the molds. A solution to the long curing time problem may be that, due to low bonding stress, full curing is not required. The adhesive can be tested to determine how long it needs to cure before the reflector 12 can be safely handled. As an example, the open time can advantageously be about 5 minutes or longer, the working time can be at least a few seconds, and the controlled curing time can be approximately 15 minutes.

[0077] Given that the panel is located outdoors, the adhesive also needs to withstand a range of operating temperatures. In some forms, it may be advantageous to have an adhesive that can withstand operating temperatures in the range of at least -10°C to 90°C. When determining the temperature range, the diurnal temperature variations that occur can be considered, along with the temperatures that may be experienced due to light being reflected from one mirror to an adjacent neighboring mirror. It will be apparent to those skilled in the art that there is no upper or lower limit to the temperature range as long as other functional requirements are met (such as maintaining bond integrity, ease of assembly, etc.). For example, the lower limit of the operating temperature can be -20°C or -30°C or lower. Similarly, the upper limit of the operating temperature can be 110°C or 120°C or higher.

[0078] The bond formed by the adhesive should be able to withstand the stresses generated during use. Without being bound by theory, simulations considering various factors can be performed to estimate such stresses. For example, these factors can include the external loads (wind, snow, earthquake, etc.) that the mirror panel is subjected to during operation, the springback effects from the manufacturing process, the weight of the components (gravity loads), and the thermal expansion / contraction loads caused by temperature changes due to sunlight and environmental condition variations are some of the factors that can be used in the simulation. The bond formed by the adhesive can also advantageously withstand creep or other instability mechanisms that occur when the material is placed under stress for a long period of time.

[0079] The adhesive can advantageously be able to withstand weathering by exposure to thermal cycling, humidity cycling, long-term exposure to moisture, and exposure to UV light. Since the contact points are mostly shielded by the mirror and the support structure, medium UV light resistance can provide sufficient protection.

[0080] Adhesives that can meet some or all of the requirements listed above are two-component acrylic adhesives. These two-component adhesives have excellent bonding strength and durability. Because they cure quickly and have high tolerance to oily or unprepared bonding surfaces, they are easy to use in many applications and manufacturing processes.

[0081] In other embodiments, other types of adhesives that meet the above functional requirements can also be selected. For example, the adhesive can be selected from epoxy resins, silicones, and / or pressure-sensitive adhesives.

[0082] Example

[0083] The following examples illustrate the fabrication and testing of a solar panel reflector assembly according to the present invention.

[0084] Example 1 - Prototyping of Small-Scale Mirror Panels

[0085] This example illustrates the development and prototyping of two small-sized mirror panels (Mirror A and Mirror B). The physical properties of these panels are shown in Table 1 below.

[0086] Table 1. Physical Properties of Two Small-Scale Reflector Panel Assemblies

[0087] Glass length (mm) 1130 Glass width (mm) 1070 Glass thickness (mm) 3 Top diameter of protrusion (mm) 20 Base diameter of protrusion (mm) 45.2 Draft angle (degrees) 50 Protrusion pitch (mm) 50 Area ratio 0.34 Length-width ratio 0.33

[0088] The mirrors are made of solar reflector glass obtained from commercially available suppliers. The reflector glass is supplied in the required dimensions and has its edges ground into a rounded shape and has a coating applied to the edges of the glass. The silver-plated mirror coating is applied to the glass through a process involving cleaning, sensitization, immersion in a silver-plating bath, rinsing, application of a protective coating, and drying. The silver-plating bath typically contains silver nitrate and a reducing agent to deposit the reflective silver layer, and a protective paint coating is added to preserve the integrity of the mirror.

[0089] The substrate 16 is fabricated by incremental sheet forming using a medium-density fiberboard sheet (MDF) mold as the base plate on a CNC router. The material selected is a 0.4 mm thick G300 Zincalume steel sheet.

[0090] An acrylic adhesive is used. It has a moderate working time and is more suitable for the manual assembly process used during the prototyping process.

[0091] Assemble the mirror panel on a suitable convex mold, with the glass side facing down and laid on the convex mold. Apply a pea-sized amount of adhesive to each protrusion. Then place the support on the glass and cover it with a plastic sheet for vacuum forming. Then evacuate the air and control it to approximately -15 kPa. This process is completed within a few minutes to avoid the adhesive from solidifying before the desired vacuum is reached.

[0092] The on-site test panel is coated with a white washable paint and placed on a bracket, supported by one edge of the panel. Project the images of multiple points onto the coated surface and take photos from multiple angles for photogrammetric analysis.

[0093] The results show that the mirror has some springback from the shape of the mold, but has a very low slope error, indicating a mirror panel of high optical quality (Table 2).

[0094] Table 2. Slope error and radius of curvature (ROC) results.

[0095]

[0096] Example 2 - Prototyping of large-scale mirror panels

[0097] This example illustrates the development of a prototype large-scale mirror panel, which is more representative of the scale commonly found in heliostats.

[0098] The backing support structure is made using the single point incremental forming (SPIF) process, and thus the size of the panel is roughly determined by the maximum size that can be formed on the CNC router at the Australian National University, i.e., approximately 2.8 m x 1.4 m. The material selected for the substrate 16 is a G2 grade galvanized formed steel with a thickness of 0.6 mm, which is inexpensive and readily available.

[0099] Select acrylic adhesive as the adhesive for assembling the prototype.

[0100] A hexagonal-shaped protrusion pattern is laid on the sheet, which is suitable for the maximum size of the router table. Since the protrusions taper inwards, the glass is slightly smaller than the support, and the resulting glass size is 2840 mm × 1400 mm.

[0101] The glass is obtained from a commercially available supplier. The thickness is selected by comparing costs and confirming its suitability using finite element analysis.

[0102] The dimensions of the prototype large-scale reflector panel are shown in Table 4 below.

[0103] Table 4. Physical properties of the large reflector panel assembly

[0104] Glass length (mm) 2840 Glass width (mm) 1400 Glass thickness (mm)3 3 Top diameter of protrusion (mm) 34.3 Base diameter of protrusion (mm) 134.1 Draft angle (degrees) 52.5 Protrusion pitch (mm) 156 Radius of curvature (m) 120 Area ratio 0.37 Length-width ratio 0.48

[0105] The SPIF process is used to form the shape of the protrusions, again using the MDF backing structure.

[0106] The glass is laid face down on a convex mold made of MDF, and then a support structure is laid. The backing structure is held to the mold by applying a combined tension and downward pull to the edges. To simplify the operation, in this case, the adhesive is applied by injecting the adhesive through a through-hole drilled at the center of each protrusion until the adhesive starts to flow out of the gap, which indicates that the gap is filled with the adhesive. The completed mirror panel 24 (as Figure 9 shown) is mounted on the H-shaped frame 26 and installed in the heliostat field. Refer to Figure 9 , Figure 9 shows the heliostat on site (the completed mirror panel 24, mounted on the H-shaped frame 26) and an image 28 of the reflection from this heliostat on the flux target.

[0107] Variations and modifications may be made to the previously described portions without departing from the spirit or scope of the present disclosure.

[0108] In the following claims and in the foregoing description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations thereof (such as "comprises" or "comprising") is used in an inclusive sense, i.e., specifying the presence of the feature but not excluding the presence or addition of other features in various embodiments of the invention.

Claims

1. A reflector panel assembly for a concentrated solar power system, the assembly include: a reflector comprising a plate element configured to receive and reflect electromagnetic radiation, the plate element having a front surface and a rear surface, the electromagnetic radiation being incident on the front surface; A substrate is configured to support the reflector so that a contact surface between the rear surface and the substrate is configured to maintain a predetermined shape of the reflector.

2. The assembly of claim 1, wherein the substrate includes a plurality of protrusions extending from a rear substrate surface to form the contact surface, the contact surface being spaced apart from the rear substrate surface. 3 . The assembly of claim 1 , wherein the contact surface of the substrate includes a plurality of spaced-apart contact surface portions formed at a peak of each of at least a portion of the protrusions.

4. An assembly according to claim 2 or 3, wherein the protrusion is frustoconical in shape, the protrusion extending from the base at the rear base surface to the contact surface.

5. The assembly of any one of claims 2 to 4, wherein the plurality of protrusions are evenly spaced apart on the substrate.

6. An assembly according to any one of claims 2 to 5, wherein the protrusions are located in a regular pattern on the substrate.

7. An assembly according to any one of the preceding claims, wherein the substrate consists of sheet metal.

8. An assembly according to claim 7 when dependent on any one of claims 2 to 6, wherein the projection is manufactured by sheet metal forming.

9. The assembly of claim 8, wherein the protrusion is manufactured by sheet metal stamping, turret stamping, or incremental sheet forming.

10. A substrate configured to support a reflector used in a concentrated solar energy system, the substrate being formed of a panel material and comprising a plurality of protrusions spaced apart on a surface of the substrate, the plurality of protrusions extending from a rear surface to contact portions at peaks of the protrusions, the contact portions being configured to form a contact surface that supports the reflector during use.

11. The substrate of claim 10, wherein the substrate is comprised of sheet metal and the projections are formed by forming the sheet metal.

12. The substrate of claim 11, wherein the sheet metal forming comprises stamping, turret stamping, or incremental sheet metal forming.

13. A method for manufacturing a substrate for supporting a reflector used in a concentrated solar energy system, the method comprising providing a panel material and forming a plurality of protrusions in the panel material, the plurality of protrusions being spaced apart on the surface of the substrate and extending to a contact portion at a peak of each protrusion, the contact portions being configured to together form a contact surface for supporting the reflector.

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