RU2496181C1 - Photoelectric concentrator submodule - Google Patents

Abstract

FIELD: physics.SUBSTANCE: photoelectric concentrator submodule has a front glass sheet (1), on the rear side of which there is a primary optical concentrator in form of a square-shaped lens (2) with side length W and focal distance F. In the central region of the surface of the square-shaped lens (2) there is a coaxially arranged photocell (4) with thickness z, which is in form of a square with side length dplaced on a heat-removing base (3), which is in form of a circle of diameter dor a rectangle with length of the longer side dand thickness z. On the photoactive surface of the photocell (4), coaxially with the square-shaped lens (2), there is a secondary optical concentrator in the form of, for example, a truncated glass cone (5) with height h, facing the photocell with the smaller base. A rear glass sheet (6), with a light-reflecting mirror coating (7) is mounted parallel to the front glass sheet (1). The distance from the light-reflecting mirror coating (7) to the photocell (4) is equal to L. Values of F, W, d, d, z, zhand L satisfy certain relationships.EFFECT: invention simplifies the manufacture of a photoelectric submodule while providing high accuracy of mounting the photocell and maintaining good misalignment characteristics, which increases energy efficiency and reliability, reducing material consumption by halving the thickness of the submodule also lowers the cost of manufacturing the photoelectric module.14 cl, 5 dwg

Description

The invention relates to the field of solar energy and, in particular, to solar radiation concentrators used in photovoltaic modules, used, for example, in terrestrial solar power plants intended for autonomous power supply systems.

One of the most promising methods for generating electricity from renewable sources is the photovoltaic conversion of concentrated solar radiation using expensive high-performance multi-stage solar cells. It is known that the use of optical radiation concentrators in photovoltaic modules can increase the energy efficiency of photovoltaic modules, as well as improve their energy and economic performance by repeatedly reducing the consumption of expensive semiconductor materials. So, with an increase in the degree of concentration of solar radiation on the surface of the solar cell to 1000 ^x , the area of expensive solar cells decreases by 1000 times. But the cost-effectiveness of the photovoltaic module depends on the contribution of the cost of optical concentrating systems to the total cost of the module, the degree of complexity of their manufacture and assembly of the module, and the magnitude of the lifetime.

A known photovoltaic submodule (see PCT application WO 9213362, H01L 31/00, published 06/08/1992), comprising a housing, a hub mounted in the housing and a photocell (PV) located on the rear wall of the housing. As a concentrator, a Fresnel lens can be used, and the body can take the form of a truncated cone, or a truncated pyramid.

The main disadvantage of this photovoltaic submodule with a concentrator is the complexity of manufacturing and the high cost of construction.

A known photovoltaic submodule (see patent US 6717045, IPC H01L 31/052, published April 6, 2004), consisting of a primary concentrator having a concentration of solar radiation of 5-10 times, a secondary concentrator located below the first and increasing the degree of concentration of solar radiation in 20-50 times, and a third concentrator installed in the lower plane of the secondary concentrator and focusing the radiation on the surface of the solar cell. As a primary concentrator, a Fresnel lens can be used. The secondary concentrator is a combined parabolic reflector made of glass or ceramic and having reflective and protective coatings. A glass lens serves as the third hub. A solar photocell is installed on a site having fins for heat dissipation.

The disadvantages of the known design of the photovoltaic submodule are large light losses due to reflection from the surfaces of the optical elements of a three-stage concentrator, the technical difficulties of manufacturing, mounting and aligning a large number of optical parts and, accordingly, also the high cost of the structure.

A known solar concentrator photovoltaic submodule (see application US 2007/0089778, IPC H02N 6/00, published April 26, 2007) comprising a front panel with a pair of coaxial axisymmetric curvilinear mirrors mounted on its rear side focusing solar radiation on a solar cell mounted on the back panels.

The disadvantage of the known submodule is the complexity of manufacturing two reflective optical elements with the necessary accuracy of the profile.

A known solar concentrator photovoltaic submodule (see patent US7851693, IPC H02L 31/042, published 12/14/2010) having a solid-state transparent optical hub such as Cassegrain, containing a relatively large concave reflective surface and a relatively small convex reflective surface located opposite it, focusing and directing solar radiation to the surface of a solar cell mounted on a heat sink in the central part of a concave reflective surface.

A disadvantage of the known submodule is the complexity of manufacturing optical elements of complex configuration and the high cost of construction.

A known photovoltaic submodule (see patent RU 2307294, IPC H01L 31/052, published September 27, 2007) containing a silicate glass front panel with a Fresnel lens on its rear side, as well as a solar photocell with a heat sink. The heat sink bases are located on the rear panel of silicate glass or made in the form of a tray with a flat bottom, through the central longitudinal line of the surface of which passes the optical axis of the Fresnel lens. An additional intermediate panel of silicate glass has been introduced, on the front or back of which a flat-convex lens is installed, coaxial with the Fresnel lens. The light receiving surface of the photocell is located in the focal spot of two concentrators — the Fresnel lens and the plano-convex lens. Depending on the embodiment of the submodule, the distance between the intermediate panel and the heat sink bases, the focal length of the plano-convex lens, the thickness of the photocell, the intermediate panel and the plano-convex lens are related by the ratios given in the claims.

Known photoelectric submodule provides improved misorientation characteristics of the device. However, a disadvantage of the known submodule is the high level of concentration of solar radiation on the photocell, which leads to a decrease in the efficiency of conversion of light into electricity and reduces the life of the photocell. A disadvantage of the known photovoltaic submodule is also the complexity of positioning the PV and lenses in the lens panel, as well as additional optical losses when light passes through the intermediate lens panel.

Known photoelectric concentrator submodule (see patent RU 2352023, IPC H01L 31/052, published April 10, 2009), which coincides with the claimed technical solution for the largest number of essential features and adopted for the prototype.

The photoelectric concentrator submodule contains a front panel and a back panel made of silicate glass, primary and secondary optical concentrators, and a solar cell with a heat sink. The primary optical hub is made in the form of a lens formed in the form of the back surface of the front panel by injection molding. The secondary optical hub is made in the form of a focon mounted on a smaller base on the photosensitive surface of the photocell. A solar cell with a heat sink is placed on the front surface of the rear panel coaxially with the primary optical hub. The secondary optical concentrator makes it possible to improve the disorientation characteristic of the solar photovoltaic submodule, which ensures an increase in the energy productivity of the photovoltaic module.

The disadvantages of the known photoelectric concentrator submodule prototype are the complexity of manufacturing and installation of a secondary optical concentrator on the photosensitive surface of the photocell, as well as the complexity of positioning the PE and the high statistical probability of a linear mismatch between the center of the PE and the optical center of the lens.

The problem solved by the claimed technical solution is to reduce the complexity of manufacturing a photovoltaic submodule while ensuring high accuracy of the installation of the photocell and maintaining a good disorientation characteristic, which will increase its energy productivity and reliability. Reducing the consumption of materials by halving the thickness of the submodules will also reduce the cost of manufacturing a photovoltaic module.

The problem is solved in that the photoelectric concentrator submodule includes a front glass sheet, on the back of which there is a primary optical concentrator in the form of a square lens with a side length of a square equal to W and a focal length F. In the central region of the surface of the lens is square in shape and coaxially with it installed photocell thickness z _1, configured as a square with side equal to d ₁ positioned on the heat-removing base, designed as a circle with a diameter d ₂ or squareness Single with larger side length and a thickness d ₂ z _2. A secondary optical concentrator of height h _{1 is} mounted coaxially with a square lens on the photoactive surface of the photocell. Parallel to the front glass sheet, a back glass sheet with a reflective mirror coating is installed, the distance from which to the photocell is L. The values of F, W, d ₁ , d ₂ , z ₁ , z ₂ , h ₁ and L satisfy the relations;

$$0.5F<W<F,\mathrm{from}m;(\mathrm{one})$$

$$0.01F<d_{\mathrm{one}}<\mathrm{0,03}F,\mathrm{from}m;(2)$$

$$0.15W<{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="00000011.png,00000012.png"\; state="\{\{state\}\}">d</figure-callout>}}_2<0.3W,\mathrm{from}m;(3)$$

$$L=\frac{F-z_{\mathrm{one}}-{\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="00000011.png,00000012.png"\; state="\{\{state\}\}">z</figure-callout>}}_2+h_{\mathrm{one}}\left(\mathrm{one}-\frac{2F}{\sqrt{\mathrm{four}{n}_{\mathrm{one}}^2{\mathrm{<figure-callout\; id="2"\; label="F"\; filenames="00000011.png,00000012.png"\; state="\{\{state\}\}">F</figure-callout>}}^2+W^2\left(n_{\mathrm{one}}^2-\mathrm{one}\right)}}\right)}{2},\mathrm{from}m;(\mathrm{four})$$

where n ₁ is the refractive index of the material of the secondary optical hub.

New in this photovoltaic concentrator submodule is the installation in the central region of the lens surface of a square shape and coaxially with it a photocell of thickness z ₁ made in the form of a square with a side equal to d ₁ placed on a heat sink made in the form of a circle of diameter d ₂ or a rectangle greater side length and a thickness d ₂ z _2, installing parallel to the frontal glass sheet of the rear glass sheet with a reflective mirror coating, whose distance from the photocell Rav of L, and finding the relationship between the values F, W, d _1, d _2, z _1, z _2, h ₁ and L.

Installing the photocell in the central region of the square-shaped lens surface and aligned with it on the back side of the front glass sheet increases the accuracy of mounting the elements and allows you to get a complete assembly unit in the manufacture of photovoltaic modules. The installation of a rear glass sheet parallel to the front glass sheet with a reflective mirror coating, the distance from which to the photocell is equal to L, allows focusing solar radiation on the photodetector surface of the photocell and eliminates the positioning error that occurs when installing primary optical concentrator lenses and photocells on different surfaces. In addition, the installation of a rear glass sheet with a reflective mirror coating parallel to the front glass sheet allows to reduce the thickness of the submodules by 2 times, which leads to a reduction in the consumption of materials and a decrease in the cost of manufacturing a photovoltaic module.

The primary optical hub can be made in the form of a Fresnel lens or in the form of a flat-convex lens.

The heat sink base can be in the form of a bypass diode made of a silicon wafer with a pn junction, the polarity of which is opposite to the polarity of the pn junction of the photocell, or can be made of copper.

A reflective mirror coating may be located on the front side of the back glass sheet. When this reflective mirror coating can be made in the form of a circle with a diameter of D ₁ coaxial with the lens of the primary optical hub, the diameter of the circle D ₁ satisfies the ratio:

$$\frac{LW}{F}<D_{\mathrm{one}}<W,\mathrm{from}m.(5)$$

A reflective mirror coating can also be installed on the back of the back glass sheet and coated with a protective material that is resistant to environmental influences. In this case, the reflective mirror coating can be made in the form of a circle with a diameter of D ₂ coaxial with the lens of the primary optical hub, while the diameter of the circle D ₂ satisfies the ratio:

$$2W\left(\frac{L-{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="00000011.png,00000012.png"\; state="\{\{state\}\}">h</figure-callout>}}_2}{2F}+\frac{h_2}{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="00000011.png,00000012.png"\; state="\{\{state\}\}">n</figure-callout>}}_2\sqrt{\mathrm{four}{\mathrm{<figure-callout\; id="2"\; label="F"\; filenames="00000011.png,00000012.png"\; state="\{\{state\}\}">F</figure-callout>}}^2+\left(\mathrm{one}-\raisebox{1ex}{$\mathrm{one}$}\!\left/ \!\raisebox{-1ex}{$n_2$}\right.\right)\cdot W^2}}\right)<{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="00000011.png,00000012.png"\; state="\{\{state\}\}">D</figure-callout>}}_2<W,\mathrm{from}m,(6)$$

where n ₂ is the refractive index of the back glass sheet,

h ₂ - the thickness of the back glass sheet, see

The secondary optical hub can be made in the form of a truncated glass cone, facing the smaller photocell, with a diameter of a smaller base equal to or less than d ₁ , or in the form of a glass cylinder with a diameter of the base equal to or less than d ₁ , or in the form of a truncated glass pyramid with square bases, the smaller base facing the photocell, with a side length of a smaller base equal to or less _than d ₁ , or in the form of a glass plate with square bases and a side length of a square equal to or m smaller d ₁ , or in the form of a short-focus plano-convex lens. The diameters of the bases of the glass cylinder or the truncated glass cone, as well as the lengths of the sides of the bases of the truncated glass pyramid or glass plate with square bases facing the photocell, are selected equal to d ₁ if the size of the photoactive surface of the photocell coincides with the size of the photocell. In the case when the photoactive surface of the photocell is smaller than the size of the photocell, the corresponding sizes of the bases of the secondary optical concentrators facing the photocell are selected equal to the size of the photoactive surface of the photocell.

The choice of the optimal size range of the primary optical concentrator in the form of a lens, given by the ratio 0.5F <W <F, is determined by the need to obtain the maximum energy multiplicity of concentration of solar radiation on the surface of the solar cell. For this, the ratio of the area of the lens to the area of the light spot on the surface of the photocell should be as large as possible while maintaining a high optical efficiency of the lens. It is known that the diameter of the light spot focused by the lens is strictly determined by the angular size of the solar disk and the focal length of the lens, and is equal to 0.01F. With an increase in the size of the lens W greater than F, its optical efficiency decreases, since in this case the peripheral regions operate at large refraction angles, which increases the reflection of the rays from the refractive surface of the lens until the condition of total internal reflection is reached. However, for lens sizes W smaller than 0.5F, the concentration ratio of solar radiation is already significantly reduced.

The size of the photocell d ₁ is chosen so that the focused light spot completely falls on the photoactive surface of the photocell and has the ability to move with an angular mismatch in the orientation of the submodule. Since the diameter of the light spot focused by the lens is 0.01 F, the minimum size of the photocell d ₁ must be no less than this value. The size of the photocell d ₁ = 0.03F ensures that the light spot hits the photoactive surface of the photocell during misorientation of the submodule ± 30 '. Increasing the size of d ₁ more than this value is impractical due to the high cost of solar cells.

To ensure heat dissipation from the photocell, the diameter d _{2 of the} round heat sink base or the dimensions of the sides d _{2 of the} rectangular heat sink base must be at least 0.15W. An increase in the size of the heat-removing base leads to an increase in the area of shadowing of radiation focused by the primary optical concentrator and to a decrease in the focusing efficiency. The maximum dimension value d _{2 of the} heat sink base must not exceed 0.3W, while the optical loss does not exceed 10%.

The distance L from the back glass sheet with a reflective mirror coating to the photocell is calculated by the formula (4) and is determined by the focal length of the lens F, reduced by the total thickness of the heat sink base and the photocell z ₁ + z ₂ and increased by the difference in the path of the rays resulting from refraction light in a secondary optical concentrator of height h ₁ .

A reflective mirror coating on the back glass sheet can be applied both to the front and back sides of the glass sheet as a continuous layer. However, in order to save material, the reflective mirror coating can be made in the form of a circle coaxial with the lens of the primary optical hub. In this case, the minimum values of the diameters of the circles D ₁ and D _{2 are} limited by the geometric path of the rays in the optical system and can be calculated by formulas (5) and (6). Increasing the diameters of circles D ₁ and D ₂ more than the size W of the lens of the primary optical hub is impractical.

The present photoelectric concentrator submodule is illustrated by drawings, where:

figure 1 shows a side view in section in a variant embodiment of the present photovoltaic concentrator submodule;

figure 2 shows a side view in section in another embodiment of the present photoelectric concentrator submodule;

figure 3 shows a side view in section in a third embodiment of the present photoelectric concentrator submodule;

figure 4 shows a side view in section in a fourth embodiment of the present photovoltaic concentrator submodule;

5 is a sectional side view of a fifth embodiment of the present photovoltaic concentrator submodule.

The present photoelectric concentrator submodule (see FIG. 1) contains a front glass sheet 1, on the back of which there is a primary optical hub in the form of a square lens 2 with a square side length equal to W and focal length F. In the central region of the surface of the lens 2 a square shape and coaxially mounted with it, a photocell 4 of thickness z ₁ made in the form of a square with a side equal to d ₁ placed on a heat sink 3 made in the form, for example, of a circle with a diameter of d ₂ and a thickness of z ₂ . On the photoactive surface of the photocell 4 coaxially with the square-shaped lens 2, a secondary optical concentrator is installed in the form of, for example, a truncated glass cone 5, height h ₁ , facing the smaller photocell with a base diameter equal to d ₁ . In parallel with the front glass sheet 1, a rear glass sheet 6 with a reflective mirror coating 7 is installed. The distance from the reflective mirror coating 7 to the photocell 4 is L. The values F, W, d ₁ , d ₂ , z ₁ , z ₂ h ₁ and L satisfy the above above relations (1) - (4).

The secondary optical hub can be made (see figure 2) in the form of a glass cylinder 8 with a diameter of the base less than d ₁ if the size of the photoactive surface of the photocell is smaller than the size of the photocell. The secondary optical hub can be made (see Fig. 3) in the form of a truncated glass pyramid 9 with square bases, facing the smaller base to the photocell, with a side length of the smaller base less than d ₁ if the size of the photoactive surface of the photocell is smaller than the size of the photocell. The secondary optical hub can be made (see figure 4) in the form of a glass plate 10 with square bases and a side length of the square equal to d ₁ if the size of the photoactive surface of the photocell coincides with the size of the photocell. The secondary optical hub can be made (see figure 5) in the form of a short-focus plane-convex lens 11.

When a real photoelectric concentrator submodule with a photocell 4 is oriented perpendicularly to the sun's rays, the solar radiation incident on the input aperture of the primary optical concentrator in the form of a square lens 2 is refracted by it and, after the mirror coating 7 is reflected by the back glass sheet 6, focuses on a larger base secondary optical hub in the form of a truncated glass cone 5. After refraction at the input surface of the truncated glass cone, a partial reflection from the lateral surface of the truncated glass cone, the light beam through the smaller base of the truncated glass cone 5 hits the photoactive surface of the photocell 4. In this case, the disorientation characteristic of the photoelectric concentrator submodule, determined by the ratio of the sizes of the photoactive surface of the photocell 4 and the diameter of the focal spot, remains higher than in photovoltaic modules without a secondary optical hub; the distribution of the concentration of solar radiation on the photoactive surface of the photocell 4 is more uniform than in the focal spot of the primary concentrator. A more uniform distribution of the concentration of solar radiation on the surface of the solar cell 4 leads to a decrease in local overheating of the solar cell 4, increase the reliability of its operation and increase the efficiency of conversion of solar radiation into electrical energy. The coaxial placement of the lens 2 of the primary optical concentrator and the photocell 4 on the rear side of the front glass sheet 1 provides high accuracy of the mutual arrangement of structural elements, and light reflection with a reflective mirror coating 7 of the rear glass sheet 6 allows reducing the thickness of the submodule by almost 2 times compared to the focal length F. lenses

The use of the proposed photoelectric concentrator submodule gives a great economic effect, due to the fact that the concentrator submodule is simple in design, technologically advanced during assembly, has high photoelectric characteristics, and ensures reliable and long-term operation.

Claims (14)

1. Photoelectric concentrator submodule, including a front glass sheet, on the back of which there is a primary optical concentrator in the form of a square lens with a side length of a square equal to W and a focal length F, a photocell is installed in the central region of the surface of the square lens and coaxially with it thickness z _1, configured as a square with side equal to d ₁ positioned on the heat-removing base, designed as a circle with a diameter d ₂ or greater with a rectangle side length d ₂ and t lschinoy z _2, on the photoactive surface photocell coaxially with lens square shape mounted secondary optical concentrator height h ₁ parallel to the frontal glass sheet is set back sheet of glass with a reflective mirror coating, whose distance from the photocell is equal to L, wherein the values of F, W, d ₁ , d ₂ , z ₁ , z ₂ , h ₁ and L, expressed in cm, satisfy the relations
0.5F <W <F, cm;
0.01 F <d ₁ <0.03 F, cm;
0.15W <d ₂ <0.3W, cm;
$$L=\frac{F-z_{\mathrm{one}}-z_2+h_{\mathrm{one}}\left(\mathrm{one}-\frac{2F}{\sqrt{\mathrm{four}{n}_{\mathrm{one}}^2{F}^2+W^2\left(n_{\mathrm{one}}^2-\mathrm{one}\right)}}\right)}{2},\mathrm{from}m;$$

where n ₁ is the refractive index of the material of the secondary optical hub. 2. The submodule according to claim 1, characterized in that the primary optical hub is made in the form of a Fresnel lens. 3. The submodule according to claim 1, characterized in that the primary optical hub is made in the form of a flat convex lens. 4. The submodule according to claim 1, characterized in that the heat sink base is made in the form of a bypass diode made of a silicon wafer with a pn junction, the polarity of which is opposite to the polarity of the pn junction of the photocell. 5. The submodule according to claim 1, characterized in that the heat sink base is made of copper. 6. The submodule according to claim 1, characterized in that the reflective mirror coating is located on the front side of the back glass sheet. 7. The submodule according to claim 6, characterized in that the reflective mirror coating is made in the form of a circle with a diameter D ₁ coaxial with a Fresnel lens, while the diameter of the circle D ₁ satisfies the ratio
$$\frac{LW}{F}<D_{\mathrm{one}}<W,\mathrm{from}m.$$

8. The submodule according to claim 1, characterized in that the reflective mirror coating is installed on the back side of the back glass sheet and is coated with a protective material that is resistant to environmental influences. 9. The submodule of claim 8, wherein the reflective mirror coating is made in the form of a circle with a diameter of D ₂ coaxial with the Fresnel lens, while the diameter of the circle D ₂ satisfies the ratio
$$2W\left(\frac{L-h_2}{2F}+\frac{h_2}{n_2\sqrt{\mathrm{four}{F}^2+\left(\mathrm{one}-\raisebox{1ex}{$\mathrm{one}$}\!\left/ \!\raisebox{-1ex}{$n_2$}\right.\right)\cdot W^2}}\right)<D_2<W,\mathrm{from}m,$$

where n ₂ is the refractive index of the back glass sheet,
h ₂ - the thickness of the back glass sheet, see 10. The submodule according to claim 1, characterized in that the secondary optical hub is made in the form of a truncated glass cone, facing a smaller base to the solar cell, with a diameter of a smaller base equal to or less than d ₁ . 11. The submodule according to claim 1, characterized in that the secondary optical hub is made in the form of a glass cylinder with a base diameter equal to or less than d ₁ . 12. The submodule according to claim 1, characterized in that the secondary optical hub is made in the form of a truncated glass pyramid with square bases, facing a smaller base to the photocell, with a side length of a smaller base equal to or less _than d ₁ . 13. The submodule according to claim 1, characterized in that the secondary optical hub is made in the form of a glass plate with square bases and a side length of a square equal to or less _than d ₁ . 14. The submodule according to claim 1, characterized in that the secondary optical hub is made in the form of a short-focus plano-convex lens.

Images