Solar roof panel and solar roof system

Abstract

The present invention relates to a solar roof panel (1) comprising - a base structure (2), - photovoltaic cells (3) provided in top of base structure (2), - a wiring (4) of photovoltaic cells (3), - connection points (5) comprising electrically conductive bolts (6), - a protective layer (7) provided on top of the photovoltaic cells (3) wherein the solar roof panel (1) is a self supporting structure, suitable as a roof covering The present invention further relates to solar roof system comprising at least two solar roof panels (1)

Description

[0001] Solar Roof Panel and Solar Roof System

[0002] The present invention relates to a solar roof system comprising solar roof panels that unite a classic roofing with additionally mounted solar panels to a single solar roof system to maximize the efficiency of energy generation from sunlight while considering aesthetic and structural aspects.

[0003] Solar panels on roofs are commonly known. They are mounted additionally, often subsequently on top of existing roof structures, since decentralized energy production is one of the major elements of sustainable energy production.

[0004] By means of photovoltaic cells, sun light is converted to electricity, whereby direct current (DC) is produced. Since public power grid is alternating power (AC) grid, a DC / AC converter is needed to supply the generated electricity to the grid. A number of photovoltaic cells placed on a supporting structure is called solar panel, whereby also the term solar cell is used for photovoltaic cell synonymously.

[0005] Solar panels have been used for harvesting energy for a long time. Most common are solar panels with the seize of about one square meter, that are mounted on top of existing roofing.

[0006] Yet, there are also other systems with overlapping solar panels, as shown for example in DE 44 38 858 A1 . The electrical connection to a conductor rail is done with a clipsystem. Roof tiles are mounted overlapping.

[0007] In EP 2 061 091 B1 a roofing orfagade system is described where there are liquid or gas filled pipes in a solar roof panel, embedded on the panel by a foaming process to use the solar panel for heat exchange. A wire mesh is needed for stability reasons.

[0008] Although each known solution is described as advantageous in itself, there are disadvantages with common solar roof panels concerning the efficiency of energy generation from sunlight while also considering aesthetic and structural aspects. Conventional photovoltaic roof panels and solar roofing systems have complex installation procedures and at least the most common ones are mounted on top of existing roofing systems, which is highly cost intensive. Consequently, there is a need for a new type of solar roofing that overcomes these disadvantages and is based on the task that except for a clear appearance when uniting roofing with photovoltaic elements more energy output for the same area of photovoltaic elements, more energy than conventional systems can be produced, using a newly designed wiring on the solar roof panels.

[0009] The aforementioned task is solved in a first aspect of the present invention by a solar roof panel (1) comprising a base structure (2), photovoltaic cells (3) provided in top of base structure (2), a wiring (4) of photovoltaic cells (3), connection points (5) comprising electrically conductive bolts (6), a protective layer (7) provided on top of the photovoltaic cells (3) wherein the solar roof panel (1) is a self supporting structure, suitable as a roof covering.

[0010] According to the invention, the base structure (2) is made from polyvinyl chloride (PVC) to which a variety of additives can be add. Those additives can be chosen from the following list:

[0011] - High-Impact Modifiers: These modifiers improve the impact resistance of ridged PVC. Acrylic-based modifiers, often referred to as impact modifiers, are commonly used. They improve the material's toughness and ability to withstand sudden impacts without breaking.

[0012] - Plasticizers: Plasticizers are essential to make PVC flexible and pliable. Phthalate-free plasticizers like adipates, taramellites, or bio-based plasticizers are preferred, especially in applications where human contact is involved, due to health and environmental concerns associated with certain phthalates.

[0013] - Stabilizers: Heat and UV stabilizers are added to protect PVC from degradation caused by high temperatures and ultraviolet (UV) light exposure. Calciumbased or mixed metal stabilizers are commonly used. - Fillers: Fillers like calcium carbonate may be added to improve the material's stiffness and impact resistance. In shock-proof applications, the balance between flexibility and stiffness is crucial.

[0014] - Processing Aids: These aids help in the manufacturing process, improving the flow and processing of the PVC material. They ensure that the material can be properly formed and molded into the desired shape.

[0015] - Lubricants: Lubricants are used to reduce friction and improve the flow properties of PVC during processing.

[0016] - Impact Resistance Testing: PVC formulations for shock-proof applications often undergo specific impact resistance testing to ensure they meet the required standards and can withstand impacts without shattering.

[0017] Photovoltaic cells (3) are well known from literature. As for the invention it is crucial, that the photovoltaic cells (3) are glued onto the base structure (2). The wiring (4) of the single photovoltaic cells (3) happens to be done with standard electrical wires, as mostly supplied by the manufacturer of photovoltaic cells (3). These standard photovoltaic cells

[0018] (3) are then connected to the copper wiring (4) characterizing the invention. No external cables or conductor lines are needed for wiring.

[0019] Different solar roof panels (1) can be connected on certain connection points (5a and 5b). Depending on their design, there are holes with treads for connecting the solar panels to a supporting roof structure (5b) and through holes (5a) for interconnecting solar panels (1). The holes (5a and 5b) comprise a thread positioned on a characteristic wiring

[0020] (4) of the solar roof panel (1). For interconnection of solar panels (1), electrically conductive bolts, preferably copper bolts (6) are used to maintain energy flow.

[0021] A final protective layer (7) provided on top of the photovoltaic cells (3) and the characteristic wiring (4).

[0022] The mounting of solar roof panels is (1) especially advantageous, since mounting time is reduced drastically, as the panels function as roof covering, too. The self-supporting structures are from light-weight material and can therefore be carried by one person, which reduced costs, e.g. for a special lifting tools. No special tools are needed for mounting, as there are electrically conductive bolts, preferably copper bolts (6) for aligning the panels together. The panels can also be mounted on animal shelters and so be used for a second income.

[0023] A special embodiment of the solar roof panel (1) is that there are three separate areas of photovoltaic cells (3) on the panel. In one central area (3a) of the panel, the single photovoltaic cells (3) are connected in a parallel electrical connection among each other. The main advantage is, to raise up amperage while keeping voltage low with the parallel connection of the cells. Photovoltaic cells are designed for producing direct current. All positive terminals of the single solar cell, the anodes, are all connected among each other, as well as the negative terminals, the cathodes. That results in a parallel connection of all photovoltaic cells (3) in the central area.

[0024] A special embodiment of the solar roof panel (1) is, as well that there are two areas (3b) with photovoltaic cells (3) located near the edges of the panel (1), besides the centered area photovoltaic cells (3). In this particular embodiment the single photovoltaic cells (3) being connected in serial electrical connection, meaning an anode of one cell is tapped to the cathode of the next cell, due to wiring, a ring of serial photovoltaic cells (3) is formed. In a series circuit, voltages across individual components add up. This allows for the convenient use of multiple voltage sources to achieve a higher total voltage. The same current flows through all components in a series circuit. This ensures uniformity of current throughout the circuit, simplifying current measurements and analysis. In serial connection, components can be controlled sequentially, meaning that one photovoltaic cell (3) must be powered before the next one.

[0025] Another further development of the solar roof panel (1) is a centralized electrical wiring (4). Therefore, there are two wires directly included on the solar roof panel (1). These can be formed as a copper band, a bus system, or a ribbon wire positioned on the solar roof panel (1). Since there are two main wires on the solar roof panel (1), those can be seen as a bus system, collecting all energy from the photovoltaic cells (3).

[0026] To the first of the two strings all anodes of the centered area are connected. All cathods of the centered area (3a) are connected to the second string.

[0027] From the series circuit of photovoltaic cells from the edged area (3b) of the plate, one anode is connected to first string; a cathode is connected to the second string. That way all energy can be bundled and due the combination of series and parallel connection a maximum of energy is produced.

[0028] One embodiment of the solar roof panel (1), especially the described wiring (4) above, is the diameter of the wiring (4). It is in the range of 0,8 mm up to 14 mm. Since wiring (4) is directly included on the panel itself that factor is crucial for the thickness of the panel, besides aspects of stability. Therefore the range of thickness is 20 mm to 40 mm, preferably 30 mm, including the base structure (2), wiring (4) and the protective layer (7) protecting the photovoltaic cells (3).

[0029] In a preferred embodiment the protective layer (7) is made from Epoxy is characterized by the following advantages

[0030] - Sunlight (UV Exposure): Epoxy resins are susceptible to yellowing and degradation when exposed to prolonged sunlight. UV-resistant epoxy formulations are available to overcome that challenge, or epoxy surfaces can be coated with UV-resistant finishes for outdoor applications.

[0031] - Temperature Extremes: Epoxy resins can handle a wide range of temperatures. They remain stable and maintain their mechanical properties in both high and low- temperature environments. However, extreme heat might cause some epoxies to soften, so it is essential to choose the right formulation for specific temperature requirements.

[0032] - Moisture and Rain: Epoxy is generally resistant to moisture. It does not absorb water easily, making it suitable for outdoor applications. However, prolonged exposure to water can weaken the epoxy bond over time, especially if the surface preparation and application were not done correctly.

[0033] - Freezing Temperatures: Epoxy can withstand freezing temperatures without significant degradation. It does not become brittle when exposed to cold, making it suitable for applications in cold climates. - Chemical Resistance: Epoxy is resistant to many chemicals, including acids, bases, and solvents. This resistance makes it suitable for outdoor applications where exposure to various chemicals is a concern.

[0034] - Saltwater Exposure: Epoxy resins have excellent resistance to saltwater, making them suitable for marine applications. So there will not much difficult in apply near sea area.

[0035] A special embodiment of the solar roof panels (1) is, that they are designed in a way that overlapped mounting is possible. Regular solar panels available on the market have gaps between the single solar panels which is why an extra normal roof coverage is essential. Pouring water will result either in water on the ground, when the solar panel is just mounted on a field for a second income, or with a force to have a roof covering besides the solar panel to avoid water in the building.

[0036] Due to the overlapping structure of the inventive solar roof panels (1), a potential rubber isolation as between conventional solar panels can be omitted. Rubber isolation is often used with conventional panels between the panels to gain additional water protection. Due to gravity water will simply flow downwards with the new invention with no need for additional rubber isolation.

[0037] A further embodiment of the solar roof panel (1) is that due to designated mounting points it is not only possible to mount the solar roof panels (1) directly to a supporting roof structure, but also an overlapping mounting from roof rigde downwards as well as sideways is possible. Therefore, high wind loads as well as high amounts of rain can be dealt with. Additionally these mounting points are designed in a way, that not only a mechanical connection can be realized, but also the electrical connection between the panels is made. To obtain this, a special embodiment is to use a electrically conductive bolt (6), preferably a copper bolt for connecting the panels. The mounting points are placed in the central wiring (4) of the solar roof panels (1). There are four mounting points on each panel, two located on the top, two at the bottom, each placed on one of the ventral wiring (4) strings. There is a thread provided in the central wiring (4) at the mounting points such as due to the contact when screwing the electrically conductive bolt (6) an electrical connection between the panels is made. For the solar roof panel (1) mounted closest to the roof ridge only the mounting points at the bottom of the solar roof panel (1) are through-holed with threads (5b). The mounting points at the top of that special panel just show a hole with thread up to the centralized wiring (4) strings from the back of the solar roof panel (1). The regular solar roof panels (1) show four through holes with thread to allow interconnection of overlapping solar roof panels (1). As a special design an overlap of 250 mm should be realized in the top to bottom overlapping process in a way that the solar roof panel (1) on top overlaps the bottom one by 250 mm.

[0038] It is important to note, that even though the overlapping is claimed from top to bottom and also sideways, the electrical connection between the solar roof panels (1) is only to be done by connecting the solar roof panels (1) in a row from the roof ridge facing downwards. So there is no mechanical connection with bolts or certain clamps to secure overlapping sideways.

[0039] A special embodiment of the overlapping panels is that there will be an element for distance (12), preferably made from an isolating plastic, e.g. rubber or foam having a hole with the diameter of the electrically conductive bolt (6) to obtain a certain distance between the solar roof panels (1) for the overlapping mounting. That is advantageous concerning mounting procedure and to prevent scratches or demolition of the solar roof panels (1). Furthermore, oxidation of the electrically conductive bolts due to moisture in the air can be minimized by the distance element as well.

[0040] A further embodiment of the solar roof panel (1) is that each row the of solar roof panels (1) from the roof ridge downwards is connected to an individual DC / AC Converter. As a big advantage that means that each row of solar roof panels (1) can be monitored separately and therefor also maintained separately. A failure of one panel does not mean that there is no more power production all over the roof, even during the repair or replacement process. So, energy harvesting can be maximized.

[0041] Further objectives, features and possible applications are shown in the following description of non-limiting embodiments of the invention with reference to the figures. All the features described and / or illustrated form the object of the invention either individually or in any combination. The figures show

[0042] Fig. 1 a schematic illustration of the solar roof panel 1 according to the invention in a preferred embodiment showing the designated areas for the photovoltaic cells 3, Fig. 2 a schematic illustration of more than one solar roof panel 1 according to the invention mounted overlapping on a supporting roof structure,

[0043] Fig 3 a schematic partial sectional view (A-A) of the solar roof panel 1 according to the invention, as drawn in Fig. 1 ,

[0044] Fig. 4a a schematic sectional view B-B, showing detail c (one of the connection points 5b) of the solar roof panel 1 according to the invention Fig. 1

[0045] Fig. 4b a schematic sectional view B-B, showing detail b (one of the connection points 5a) of the solar roof panel 1 according to the invention Fig. 1

[0046] Fig. 5 a schematic view of the connections of the DC / AC converter

[0047] Fig. 6 a schematic illustration of the area 3a with photovoltaic cells 3 mounted in parallel circuit in the solar roof panel 1 according to the invention

[0048] Fig. 7 a schematic illustration of the areas 3b with photovoltaic cells 3 mounted in serial circuit in the solar roof panel 1 according to the invention

[0049] Fig. 8 a schematic illustration of joining two solar roof panels 1 by one electrically conductive bolt 6

[0050] Identical parts have the same reference signs in all figures, but for reasons of clarity not all parts are labelled with reference signs in all figures.

[0051] In Figure 1 the solar roof panel 1 is shown schematically as it will be designed for the mounting position on the roof ridge. The areas 3a and 3b for photovoltaic cells 3 are marked. There is a central area 3a for the photovoltaic cells 3 being in parallel circuit connection and two areas 3b for photovoltaic cells 3 at the edge of a solar roof panel 1. Positions of cross sections, shown in later figures are marked. There are 4 mounting points marked at the solar roof panel 1. Two mounting points at the top of the solar roof panel 1 are mounting points comprising a through hole with a thread 5a; further two mounting points 5b at the bottom of the solar roof panel 1are only accessible from the back of the solar roof panel 1 , since they do not comprise a through hole, but a thread for connection with other solar roof panel 1 via electrically conductive bolt 6.

[0052] Solar roof panels 1 , mounted on a roof support structure 8 are shown in Figure 2. The overlapping of the roof panels is demonstrated. Due to the overlapping no water can reach the attic of housing. By overlapping, preferably with a 250 mm overlap, the roofing is formed. A first solar roof panel 1 is mounted on a supporting roof structure 8 using the connection point with the through hole 5a and an electrically conductive bolt 6. Alternatively any the bolt, bearing the load can be used, since no electrical connection is made. A second solar roof panel 1 is then mounted at the bottom and from the back of the first solar roof panel 1 , in such way, that electrically conductive bolts 6 are inserted through the connection points with through holes 5a in the second solar roof panel 1 into the connection points 5b at the bottom the first solar roof panel 1. Mechanical support can be done, by also tightening the electrically conductive bolt 6 into a roof supporting structure 8, as can be seen in Figure 9.

[0053] Figure 3 shows a cross section (A-A) through a solar roof panel 1 as indicated in Figure 1 . The layered structure, consisting of the base structure 2 and the protective layer 7 can be clearly seen. Since the wiring 4 is embedded, the copper wires, which can also be in the form of a copper bus system, can be clearly seen. In the cross section the designated areas for photovoltaic cells 3, located at the edges 3b and the center 3a of a solar roof panel 1 are shown, where it is important to know, that is just a schematic view, and not the single photovoltaic cell 3 is shown.

[0054] Going back to figure 1 there are, 4 mounting points all together. The mounting points at the top of the solar roof panel 1 differ from those at the bottom of the panel. Figure 4a shows the mounting point 5b in detail c (indicated on Figure 1). The layered structure, consisting of the wiring 4, the base structure 2 and the protective layer 7 of the solar roof panel 1 can be seen. The connection point 5b is realized by a hole through the base structure 2 into the wiring 4 from the back of the solar roof panel 1 , comprising a thread.

[0055] In contrast there are through holes in the solar roof panel 1 , positions also exactly on one of the wiring strings 4 on the solar roof panel 1 . Those through holes with thread are shown in figure 4b and are positioned at the top of a solar roof panel 1 as shown in Figure 1 as detail b. A thread in the hole is completely cut through all layers, allowing an electrically conductive bolt 6 to be screwed.

[0056] Figure 5 shows the DC / AC converter with the possible connections. Receiving the cathodic and the anodic wiring 4 from solar roof panels 1 of a row a dataline can be used to monitor the current state of the DC / AC converter. So energy production or system failures can be detected at an early stage. To alternating current converted energy can be used in one of the following ways: a) for homeappliance, b) to be fed into the power grid or c) to be stored in a battery possibly using another SC / DC converter. So, energy, even though produced during bright, sunny hours of the day, can be used at night. Figure 6 shows an example of a possible arrangement of single photovoltaic cells 3 in the designated area 3a for photovoltaic cells 3 in parallel circuit. Each single cathode part of a photovoltaic cell is connected to the neighbouring cathode part of a photovoltaic cell and each single anode part of a photovoltaic cell 3 is connected to the neighbouring anode part of a photovoltaic cell 3 resulting in a perfect parallel circuit of all photovoltaic cells 3 in the designated area. The end of the cathode connection is soldered to one of the wirings 4 whereas the end of the cathode connection is soldered to the other wiring 4 string. In a preferred embodiment a soldering point is set close to the top left connection point 5a for one connection, eg, the cathode connection and the other soldering point, for the anode-connection is placed close to the bottom right connection point (5b).

[0057] Figure 7 shows an exemplary arrangement of photovoltaic cells 3 in serial connection in the designated areas 3b on a solar roof panel 1. The cathode part of a single photovoltaic cell 3 is connected to an anode part of a neighbored photovoltaic cell 3. So, a seriesconnection is established. Near the connection points 5a at the top right corner and the bottom left corner a connection 5b to the main wire 4 is established each, preferably connecting an anode to the main anode-wire 4 and a cathode of the photovoltaic cells 3 to the cathode- wire 4.

[0058] Figure 8 shows the mounting situation of two overlapping solar roof panels 1. An electrically conductive bolt 6 is screwed through the roof supporting structure 8, a second solar roof panel 1 using the connection point with a through hole 5a and into the back of a first solar roof panel 1 using the connection point 5b. There is a distance element, preferably out of rubber or foam material between the solar roof panels 1 , surrounding also the electrically conductive bolt 6. That rubber ring / foam material 12 not only prevents scratches, keeps the distance between the solar roof panels 1 , but also, what actually is the main function, prevents moisture from the surrounding getting to the electrically conductive bolt 6 preventing a possible oxidation process and therefore a loss in electrical conductivity. Reference symbols

[0059] I solar roof panel 2 base structure

[0060] 3 photovoltaic / solar cells

[0061] 3a center area for photovoltaic cell

[0062] 3b edged region for photovoltaic cells

[0063] 4 wiring of solar roof panel 1 5a connection point with through hole and thread

[0064] 5b connection point with thread

[0065] 6 electrically conductive bolt

[0066] 7 protective layer

[0067] 8 supporting roof structure 9 DC / AC converter

[0068] 10 wiring for photovoltaic cells

[0069] I I area of overlapping / underlapping

[0070] 12 element for distance

Claims

I Claim:1 . Solar roof panel (1) comprising a base structure (2), photovoltaic cells (3) provided in top of base structure (2), a wiring (4) of photovoltaic cells (3), connection points (5) comprising electrically conductive bolts (6), a protective layer (7) provided on top of the photovoltaic cells (3) wherein the solar roof panel (1) is a self supporting structure, suitable as a roof covering.

2. A solar roof panel (1) according to claim 1 , wherein there are three separate areas of photovoltaic cells (3) on the panel of which one area with separate photovoltaic cells (3a) is centered on the solar roof panel (1), wherein that area is characterized by the single photovoltaic cells (3) being connected in a parallel electrical connection among each other.

3. A solar roof panel (1) according to claim 1 or 2 wherein there are three separate areas of photovoltaic cells (3) on the solar roof panel (1) of which two areas (3b), each containing more than one single photovoltaic cell (3), are located near the edges of the solar roof panel (1), besides the centered area of single photovoltaic elements (3), and are characterized by these single photovoltaic cells (3) being connected in serial electrical connection in the electric circuit of the solar roof panel (1).

4. A solar roof panel (1) according to any of the claims 1 to 3, wherein the wiring (4) is included on the solar roof panel (1) itself in the form a copper band, a bus system, or a ribbon wire positioned on the solar roof panel (1) to connect single photovoltaic elements, and whereby the copper wire is placed on the solar roof panel (1) in a way that as much energy as possible can be distributed.

5. A solar roof panel (1) according to any of the claims 1 to 4, wherein the wiring (4) has a diameter of 0.8 mm to 14 mm, the thickness of the panel (1) is 20 mm to 40 mm, preferably 30 mm.

6. A solar roof panel (1) according to any of the claims 1 to 5, wherein the protective layer (7) is made of epoxy resin.

7. Solar roof system comprising at least two solar roof panels (1) according to any of claims 1 to 6, wherein the solar roof panel (1) are designed to be partially mounted overlapping on a support structure (8) provided on a building, wherein on sloped roofs the mounting is done in the way, that the first solar roof panel (1) on the roof ridge is overlapping a second solar roof panel (1) in direction facing downwards as well as in direction of the length of the roof ridge.

8. The system according to claim 7, wherein the at least two solar roof panels (1) are mechanically and electrically connected to each other via electrically conductive bolts (6) on certain designated connection points (5), in a way that an overlap of 250 mm will be realized.

9. The system according to claim 7 or 8, wherein the at solar roof panels (1) are kept in correct distance to each other when overlapping by a distance element.

10. The system according to any of the claims 7 to 9, wherein each row of solar roof panels (1), starting from the roof ridge down to the end of the roof its separate DC / AC converter (9).

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