Technical field

The invention relates to a spatial structure of a photovoltaic cell or of a concentrator of solar radiation.

Background art

At present, photovoltaic cells of various types, most often silicon, are used to convert solar energy into electrical energy. These photovoltaic cells have the shape of a planar square plate, typically with dimensions of about 100 x 100 mm to about 150 x 150 mm, and their production has been standardized worldwide to a large extent and widely established. These photovoltaic cells are arranged within photovoltaic modules in regular geometric formations, most often planar, whereby they are electrically connected to each other in series (less commonly in parallel) within these modules - see, e.g., “How do PV panels or PV cells work?", National Lighting Product Informational Program, Lighting Answers, Volume 9 Issue 3, July 2006, figure 3 (available at photovoltaic-panels-work.asp) or Alternative Energy Tutorials, Solar Photovoltaic Panel dated 19.11.2014 (available at http,://www.a1te,m^ enerqy-tutorials.com/solar-power/photovoltaics.htmp. Since the method of electrical connection of individual photovoltaic cells in the module does not have a significant effect on the performance or efficiency of this module, and series connection requires less material and occupies less space, it is currently generally considered to be more advantageous.

The number of photovoltaic cells within a photovoltaic module and the resulting size of the photovoltaic module is usually determined by the location where the photovoltaic module is installed and its dispositions. At present, photovoltaic modules are usually mounted on the roofs of buildings or as autonomous assemblies for photovoltaic power plants on wide open spaces. However, photovoltaic modules assembled in this manner have numerous disadvantages. The main disadvantage is the fact that due to their structure and spatial arrangement, they are substantially able to use only direct sunlight which falls on them in case of clear sky and therefore it is necessary to install them at certain angles and orient them especially to the south. Their disadvantage is that they are not able to capture and use scattered and reflected solar radiation, which makes up most of the solar radiation even with a small degree of cloud cover. Another disadvantage is the considerable fluctuation of the electrical power supplied by them, depending not only on the current level of cloud cover, but also on the temperature and season, which causes problems with the stability of the electrical distribution network.

In addition to the above-mentioned silicon photovoltaic cells, there are also other types of photovoltaic cells, such as thin-film solar cells based on amorphous silicon or on chalcogenide compounds (CulnSe, CulnSeGa, CdTe etc.), which, due to their physical nature, achieve lower efficiencies (and thus also the amount of energy produced) than conventional silicon-based photovoltaic cells. These types of photovoltaic cells usually also have the shape of a square plate with dimensions of about 100 x 100 mm to about 150 x 150 mm.

To increase the amount of photons of solar radiation hitting a unit area of a photovoltaic cell or a module, different types of solar energy concentrators are used in practice, most often made of reflective materials (mirrors) - see, e.g., Volker Quaschning: ..Renewable energy sources", page 96 (ISBN: 9788086726489, Profipress s.r.o., 2012), or in the form of optical lenses. Even with the use of these concentrators, however, it is still true that basically only photons of direct solar radiation are utilised, which, despite light intensity increased by the concentrator, still generate disproportionately little energy in the modules. However, due to the concentrators, the photovoltaic modules overheat, which further reduces the potential energy yield. Moreover, the concentrators, e.g., in the form of mirrors, take up considerable space and increase investment costs, and can therefore be only used to a very limited extent.

Nowadays, there is no structure of a photovoltaic module or of a concentrator of solar radiation which would be able to capture and use efficiently and quantitatively direct and scattered and reflected solar radiation, which hits the photovoltaic module or concentrator of solar radiation from very different directions and at different angles already with a small degree of cloud cover.

The object of the invention is therefore to provide a spatial structure of a photovoltaic cell or of a concentrator of solar radiation which would enable this.

Principle of the invention

The object of the invention is achieved by a spatial structure of a photovoltaic cell or of a concentrator of solar radiation, whose principle consists in that it contains a base body consisting of two truncated pyramids or cones mounted on each other, whereby the area of the bottom base of the upper truncated pyramid or cone is smaller than the area of the top base of the lower truncated pyramid or cone, and the inclination angle of the lower truncated pyramid and the inclination angle of the upper truncated pyramid range from 62 to 82°. At least one pyramid or cone-shaped partial projection is mounted on the top base of the upper truncated pyramid or cone, and partial projections in the shape of a pyramid or cone are arranged on the top base of the lower truncated pyramid or cone around the circumference of the bottom base of the upper truncated pyramid or cone, whereby the inclination angle of the partial projections on the top base of the upper truncated pyramid or cone and the inclination angle of the partial projections on the top base of the lower truncated pyramid or cone range from 42 to 48°. This spatial structure is by its shape adapted to capture (in the case of a photovoltaic cell) or appropriately direct (in the case of a concentrator) the maximum possible number of photon paths of solar radiation, in any cloud cover of the sky, in particular photon paths of solar radiation which is scattered or reflected by the passage through the clouds.

In a preferred variant of embodiment, the inclination angle of the lower truncated pyramid or cone and the inclination angle of the upper truncated pyramid or cone range from 69 to 75°.

The bases of the upper truncated pyramid or cone, of the lower truncated pyramid or cone, as well as the bases of the partial projections, have preferably the shape of a regular n-sided polygon, especially with 3, 4, 6, 8, 12, 16 sides.

In a variant intended for assembly into larger units, the base body of the spatial structure is provided with at least one chamfer guided at an angle ranging from 40 to 50° along the entire height of the base body - from the bottom base of the lower truncated pyramid or cone to the centre of the top base of the upper truncated pyramid or cone, along at least a part of the length of one edge of the bottom base of the lower truncated pyramid or cone.

In a preferred variant of embodiment, the base body of the spatial structure is provided with a chamfer on two of its adjacent walls.

In another variant, at least one of the chamfers can be guided along at least a part of the length of the connecting line of two non-adjacent apexes of the bottom base of the lower truncated pyramid or cone.

If the spatial structure according to the invention constitutes a concentrator of solar radiation, it is made of an optically permeable material, or, if appropriate, it is made as a cavity in a block of an optically permeable material. In the first variant it is furthermore advantageous if at least one photovoltaic cell is provided on the bottom base of the lower truncated pyramid or cone.

If the spatial structure according to the invention constitutes a photovoltaic cell, at least one photovoltaic cell is provided on its outer or inner surface.

In any variant of embodiment, the bottom base of the lower truncated pyramid or cone may be concave or convex at least in a portion of its area to achieve the desired directing of solar radiation.

Description of the drawings

In the enclosed drawings, Fig. 1 a schematically represents typical solar photon paths for clear to partly cloudy conditions, Fig. 1 b shows typical solar photon paths for semi-clear skies to cloudiness, Fig. 1 c shows typical solar photon paths for cloudy skies to overcast skies, and Fig. 1d shows combinations of different paths of photons of solar radiation in real conditions. Fig. 2 schematically represents one variant of a structure of a photovoltaic cell or of a concentrator of solar radiation according to the invention, and Fig. 3 shows a second variant of a structure of a photovoltaic cell or of a concentrator of solar radiation according to the invention. Fig. 4 schematically shows another variant of a structure of a photovoltaic cell or of a concentrator of solar radiation according to the invention. Fig. 5 schematically shows a preferred combination of two structures of a photovoltaic cell or of a concentrator of solar radiation according to the invention in the variant according to Fig. 4, and Fig. 6 shows a more complex spatial combination of these structures. Fig. 7 is a schematic illustration of a photovoltaic cell structure using the photovoltaic cell structure according to the invention in the variant according to Fig. 2. Fig. 8 schematically shows the paths of photons of solar radiation striking the surface of the structure of a photovoltaic cell or of a concentrator of solar radiation according to the invention in the variant according to Fig. 4. Fig. 9 is a schematic cross- sectional view of a third variant of the structure of a photovoltaic cell or of a concentrator of solar radiation according to the invention.

Examples of embodiment

Based on the research of the inventors, completely new, hitherto unsuspected paths of photons of solar radiation for various degrees of cloud cover were discovered using real experimental photovoltaic cells and modules and with the support of modern optical and electrical devices. It is a grouping of photon paths into specific cones a, b, c which are formed by a complex network of straight photon paths and which end in specific foci V with specific dimensions and energy intensities. Depending on the degree of cloud cover, and thus also on the resulting type of solar radiation, these cones a, b, c differ from each other in the width and size of the apex angle. Cones a formed by the paths of photons of direct solar radiation have the smallest apex angles, whereas the paths of photons of the scattered and reflected solar radiation have the largest apex angles. The smaller the apex angle of the cone a, b, c of paths of the photons, the tighter and denser this network structure, and the more concentrated the energy of the photons at its apex V - see Fig. 1 a, which schematically shows typical cones a of the paths of photons of solar radiation for the case of clear to almost clear sky (i.e., the fraction of the sky covered with clouds is not more than 2/8), typically having an apex angle of about 20°, Fig. 1 b, which schematically shows typical cones b of the paths of photons of solar radiation for the case of small cloudy sky (i.e., the fraction of the sky covered with clouds is 3/8) to half cloudy sky (i.e., the fraction of the sky covered with clouds is 4/8), which, due to scattering when passing through clouds, usually have an apex angle of about 40°, and Fig. 1c, which schematically represents typical cones c of the paths of solar radiation photons for the case of cloudy sky (i.e., the fraction of the sky covered with clouds is 5/8) to an overcast sky (i.e., the fraction of the sky covered with clouds is 8/8), which, due to a larger degree of scattering when passing through clouds, typically have an apex angle of about 60°C. With all these types of cloud cover, solar radiation creates realtime, every day, and anywhere in the Earth's atmosphere geometrically accurate all-spatial network structures of the same shape formed by cones a, b, c of photons which concentrate in the apexes V of these cones a, b, c and which due to different lengths of the photon paths contain different energy intensities. When conditions change, the directional character of solar radiation striking the Earth's surface also changes. For example, in the case of partly cloudy sky, a combination of two or more types of photon paths with greater and lesser intensity may occur, where part of the radiant flux comes in the form of direct radiation and part in the form of scattered and/or reflected radiation - see Fig. 1d. Under these conditions, these networks intermingle and, thanks to the same basic shapes, form a spectral, quantum and all-space network of cones a, b, c and their apexes V.

All these photon paths meet at the apexes V of the cones a, b, c and then leave them to meet again at the apexes V of the cones a, b, c arising in the lower part of the atmosphere into which cones a, b, c of photons can flow on the way to the Earth's surface with a larger or even smaller apex angle.

The spatial structure 1 of a photovoltaic cell or of a concentrator of solar radiation according to the invention, which is represented schematically in five variants in Fig. 2, Fig. 3, Fig. 4, Fig. 7 and Fig. 9, corresponds to this theory and is adapted by its shape to capture (in the case of a photovoltaic cell) or to direct in a suitable manner (in the case of a concentrator) the maximum possible number of the paths of photons of solar radiation, with any cloud covering of the sky. Each of the variants of this structure 1 described below can be used either alone or in combination with the same or similar structures as part of a larger unit within which the individual structures 1 can be arranged on a planar base or in any spatial arrangement.

The spatial structure 1 of a photovoltaic cell or of a concentrator of solar radiation according to the invention contains a base body 2 consisting of two truncated pyramids 20 and 21, mounted on each other. The upper truncated pyramid 21 is mounted by its bottom base 210 in the centre of the top base 201 of the lower truncated pyramid 20, whereby the area of the bottom base 210 of the upper truncated pyramid 21 is smaller than the area of the top base 201 of the lower truncated pyramid 20. The inclination angle ago of the lower truncated pyramid 20, i.e., the angle between its bottom base 200 and its side walls 2000, and the inclination angle g _2i of the upper truncated pyramid 21 range from 62 to 82°, preferably from 69 to 75°. In a preferred variant of embodiment, the inclination angles ago and g _2i of the two truncated pyramids 20, 21 are identical.

The bases 200, 201, 210, 211 of both truncated pyramids 20, 21 may generally have the shape of an n-sided polygon, including a star polygon, preferably regular, whereby n is equal to 3 to oo, preferably especially 3, 4, 6, 8, 12, 16, most preferably 4. In a preferred variant of embodiment, both bases 200, 201 , 210, 211 of the two truncated pyramids 20, 21 have the same shape.

According to the requirements and intended application, the bottom base 200 of the lower truncated pyramid 20 is planar or is spatially shaped in at least a part of its surface - preferably continuously, e.g., as a convex or concave surface. A preferred variant with the bottom base 200 of the lower truncated pyramid 20 being concave in its entire area is shown in Fig. 3. This shaping of the bottom base 200 enhances to direct the solar radiation more optimally towards the unillustrated photovoltaic cell/cells located below the bottom base 200. Analogous concave shape of the bottom base 200 of the lower truncated pyramid 20 may be formed in any of the described variants of the spatial structure 1 of a photovoltaic cell or a concentrator of solar radiation according to the invention. The radius (preferably greater than the diameter of the bottom base 200 of the lower truncated cone 20) and location of this curve are determined by the specific dimensions of the spatial structure 1 and conditions in the specific location. The inclination angle g ₂ o of the lower truncated pyramid 20 in this variant, as well as in the variants of different shaping of the bottom base 200 of the lower truncated pyramid, is measured from a plane interposed by all points on the circumference of the bottom base 200 of the lower truncated pyramid 20. In an unillustrated variant of embodiment, at least one of the truncated pyramids 20, 21 is formed by a truncated cone, i.e., both its bases 200, 201 , 210, 211 are formed by an n-sided polygon, wherein n is equal to oo. However, the principle of the invention will be further explained with reference to an embodiment with truncated pyramids 20, 21 having square bases 200, 201, 210, for a different shape of the bases 200, 201 , 210, 211 , all the information below applies analogously.

On the top base 201 of the lower truncated pyramid 20, upwardly oriented pyramid-shaped partial projections 3 are evenly arranged around the circumference of the bottom base 210 of the upper truncated pyramid 21. The height of these partial projections 3 is in this case equal to or smaller than the height of the upper truncated pyramid 21 of the base body 2. In a preferred variant of embodiment, shown in Fig. 2, there are 16 partial projections 3.

On the top base 211 of the upper truncated pyramid 21 , four mutually identical upwardly oriented pyramid-shaped partial projections 4 are arranged next to one another in a 2 x 2 matrix. Preferably, the bases 41 of these partial projections 4 cover the entire area of the top base 211 of the upper truncated pyramid 21.

The inclination angle 03, 04 of the pyramid of the partial projections 3, 4 on the top base 201 of the lower truncated pyramid 20, as well as on the top base 211 of the upper truncated pyramid 21, i.e., the angle between the base 30 or 40 of these projections and their side walls 31 , 41 , ranges from 42 to 48°. The base 30, 40 of the partial projections 3, 4 may generally have the shape of an n-sided polygon, including a star polygon, preferably regular, where n is 3 to 00, preferably especially 3, 4, 6, 8, 12, 16, most preferably 4, or 00. In a preferred variant of embodiment, the partial projections 3, 4 have a base 30 or 40 of the same shape as the lower truncated pyramid 2 and/or the upper truncated pyramid 21 of the base body 2.

Any of the partial projections 3, 4 can end in a sharp point or can be rounded.

In the most preferred variant, all the partial projections 3, 4 are mutually identical.

In the variant of embodiment shown in Fig. 4, which, on the basis of the experiments performed, appears to be more advantageous for practical use, the base body 2 of the structure 1 according to Fig. 2 is provided with a chamfer 5 guided at an angle a§ ranging from 40 to 50° along the entire height of the body 2 - from the bottom base 200 of the lower truncated pyramid 2 to the centre of the top base 211 of the upper truncated pyramid 21 , along at least a part of the length, preferably along the entire length of an edge of the bottom base 200 of the lower truncated pyramid 20. Especially if the bottom base 200 of the lower pyramid 20 has more than 4 edges, the base body 2 of the structure 1 of a photovoltaic cell or a concentrator of solar radiation may be provided with more partial chamfers 5, each of them being guided along at least a part of the length of one edge of the bottom base 200 of the lower truncated pyramid 20. In a preferred variant of embodiment, these chamfers 5 are immediately adjacent to each other. In another variant of embodiment, the chamfer 5, or at least one of the chamfers 5, is guided along at least a part of the length of the connecting line of two non-adjacent apexes of the bottom base 200 of the lower pyramid 20. Due to this chamfer/these chamfers 5 a smaller number of the partial projections 3 or 4 are arranged on the top base 211 of the upper truncated pyramid 21 and on the top base 201 of the lower truncated pyramid 20 - in the variant shown in Fig. 4 there are 2 partial projections 4 (in a view of Fig. 4 arranged one behind the other) on the top base 211 of the upper truncated pyramid 21 and 11 partial projections 3 on the top base 201 of the lower truncated pyramid 20. In any case, at least one partial projection 4 is arranged on the top base 211 of the upper truncated pyramid 21.

In the case of a combination of more spatial structures 1 according to the invention in the variant shown in Fig. 4, these structures 1 are preferably facing each other with their chamfers 5, thus preventing their mutual shielding - see Fig. 5 and Fig. 6. Fig. 6 shows a more complex spatial construction 10, which combines the structures 1 of a photovoltaic cell or a concentrator of solar radiation according to the invention in the variant according to Fig. 4 and which itself corresponds by its shape to the structure 1 of a photovoltaic cell or a concentrator of solar radiation according to Fig. 2. The structures 1 are provided with a chamfer 5 oriented towards the opposite structure 1, the corner structures 1 are provided with two chamfers 5 - each oriented towards one of the adjacent structures 1. In an unillustrated variant of embodiment, this spatial construction 10 as a whole can also be provided with a chamfer which corresponds to the chamfer 5 of the structure 1 according to Fig. 4 - see the indication by the dashed lines. In addition, these constructions 10 are in an analogous manner further combined into other more complex spatial structures.

The structure 1 of a photovoltaic cell or a concentrator of solar radiation according to the invention is preferably monolithic.

The structure 1 of a photovoltaic cell or a concentrator of solar radiation according to the invention serves either as a carrier for the photovoltaic cell/cells 7, which is/are mounted on its outer surface, when in combination with it/them it constitutes a spatially shaped photovoltaic cell - see Fig. 7, or it is made of an optically permeable material, such as glass, transparent plastics, etc., and serves as a concentrator of solar radiation directing the solar radiation to the photovoltaic cell/module mounted below it. If it serves as a carrier for the photovoltaic cell/cells 7, its shape ensures that solar radiation, whether direct or scattered, or reflected, hits the photovoltaic cell/cells always at a suitable angle for maximum use. If it serves as a concentrator of solar radiation, its shape ensures that solar radiation, whether direct, scattered or reflected, hitting any part of its surface will be always directed at a suitable angle towards the surface of a photovoltaic cell/cells (not shown), arranged under the structure 1, or of a module, even in the case of an impact at a very small angle - see Fig. 8.

In the variant of the embodiment shown in Fig. 9, the structure 1 of the photovoltaic module or the concentrator of solar radiation is formed inversely, i.e., as a cavity 60 in a block 6 of an optically permeable material. This optically permeable material serves as a concentrator of solar radiation towards the photovoltaic cell/cells 7 located in the cavity 60 or below it, or towards the photovoltaic cell/cells 7 located on the inner walls of the cavity 60. In the variant of embodiment shown, the cathode matrix of the photovoltaic cell 7 is applied to the walls of the cavity 60; in a variant of embodiment not shown, the cavity 60 can be completely or at least partially filled with the cathode matrix of the photovoltaic cell 7.

Example 1

Real measurements of the output of a standard 100 x 100 mm silicon photovoltaic cell were performed. The first series of measurements were performed with a separate photovoltaic cell. The second series of measurements were performed with a photovoltaic cell supplemented by a concentrator of solar radiation according to US2015285959, consisting of a group of 16 spatial elements in the shape of a hollow truncated pyramid oriented upwards with its larger base and closed by a solid pyramid. The third series of measurements were performed with a photovoltaic cell to which was assigned one concentrator of solar radiation in the embodiment according to Fig. 4 having an area of the bottom base 200 equal to the area of the photovoltaic cell, the inclination angles ago and g i of 72°, inclination angles 03, c<4 of 45° and chamfer angle of 45°. The fourth group of measurements were performed with a photovoltaic cell to which were assigned 16 concentrator of solar radiation in a 4 x 4 matrix, in the embodiment according to Fig. 4, each having an area of the bottom base of the lower pyramid 25 x 25 mm and the above-described geometry. All the measurements were conducted under the same conditions and the same cloudy conditions.

During these measurements, it was found that the increase in the output of the photovoltaic cell when using the concentrator of solar radiation according to US2015285959 was about 5 to 10 %, whereas, when using the concentrator of solar radiation according to the invention, the increase in the output of the photovoltaic cell was due to the contribution of indirect solar radiation in both variants about 15 %. Example 2

In the same manner and under the same conditions as in Example 1 , the output of a 100 x 100 mm silicon photovoltaic cell was measured, to which one concentrator of solar radiation was assigned in the embodiment according to Fig. 2 with the bottom base 200 having an area equal to the area of the photovoltaic cell, with inclination angles ago and g _2i of 72°, inclination angles 03, 04 of 45°. Furthermore, the output of a 100 x 100 mm silicon photovoltaic cell was measured, to which were assigned 16 concentrator of solar radiation in a 4 x 4 matrix in the embodiment according to Fig. 2, each having an area of the bottom base 25 x 25 mm and the above-described geometry. All the measurements were conducted under the same conditions and the same cloudiness.

During these measurements, it was found that the increase in the output of the photovoltaic cell, when using the concentrator of solar radiation according to the invention in both variants, was due to the contribution of indirect solar radiation about 20 %.

Example 3

In the same manner as in Examples 1 and 2 and under the same conditions, the output of a 100 x 100 mm silicon photovoltaic cell was measured, to which was assigned a concentrator of solar radiation in the embodiment according to Fig. 6, which was formed by the spatial construction 10 made of an optically permeable material. This construction 10 was provided with a total of 20 structures 1 in the embodiment according to Fig. 4 with inclination angles g ₂₀ and g _2i of 72°, inclination angles 03, 04 of 45° and a chamfer angle g§ of 45°. Each of the structures 1 on the top base 100 of the construction 10 and the structures 1 located in the corners of the middle base 1000 of the constructions 10 was provided with two chamfers 5, each being oriented towards one of the adjacent structures 1. The other structures 1 were each provided with one chamfer oriented towards the opposite structure 1.

During these measurements, it was found that the increase in the output of the photovoltaic cell when using this variant of the concentrator of solar radiation according to the invention was due to the increased contribution of indirect solar radiation in the range from about 20 to 25 %.

List of references

1 spatial structure of a photovoltaic cell or of a concentrator of solar radiation

10 spatial construction combining the structure of a photovoltaic cell or a concentrator of solar radiation

100 top base of the spatial construction

1000 middle base of the spatial construction

2 base body of the structure

20 lower truncated pyramid

200 bottom base of the lower truncated pyramid

201 top base of the lower truncated pyramid

2000 wall of the lower truncated pyramid

21 upper truncated pyramid

210 bottom base of the upper truncated pyramid

211 top base of the upper truncated pyramid

3 partial projection

30 base of the partial projection

31 wall of the partial projection

4 partial projection

40 base of the partial projection

41 wall of the partial projection

5 chamfer

6 block of an optically permeable material

60 cavity in a block of an optically permeable material

7 photovoltaic cell c(2o inclination angle of the lower truncated pyramid a _2i inclination angle of the upper truncated pyramid a ₃ inclination angle of the partial projection

Ou inclination angle of the partial projection a ₅ chamfer angle