JP2011060835A - Solar cell module - Google Patents

Abstract

A solar cell module capable of reducing refracted light generated when sunlight is incident is provided.
SOLUTION: A solar cell module 1 includes a single-sided light receiving solar cell element 2, a front plate 3 disposed on the front side of the solar cell element 2, and a back plate disposed on the back side of the solar cell element 2. 4 is provided. The back plate 4 has a V-shaped light reflection plate portion 7 that reflects sunlight incident from the front plate 3 toward the front plate 3. Here, when the inclination angle of the inclined surfaces 7a and 7b forming the light reflecting plate portion 7 is θa, the apex angle of the inclined surfaces 7a and 7b is θb, and the absolute refractive index of the front plate 3 is Nb, the light reflecting plate The shape of the part 7 is set to satisfy sin ⁻¹ (1 / Nb) −2 ° ≦ θb−2θa ≦ sin ⁻¹ (1 / Nb) + 10 °.
[Selection] Figure 4

Description

  The present invention relates to a solar cell module having a single-sided light receiving solar cell element.

  As a conventional solar cell module, for example, as described in Patent Document 1, it is arranged between a plurality of single-sided light-receiving solar cell elements and two adjacent solar cell elements, and is incident from the module light-receiving surface. What is provided with the V-shaped light reflection surface which reflects sunlight toward a module light-receiving surface is known.

JP 2000-101124 A

  However, in the above prior art, depending on the shape (angle) of the V-shaped light reflecting surface, the light reflected by the light reflecting surface is refracted by the module light receiving surface and flows out to the outside. In this case, since the light reflected by the module light receiving surface and incident on the solar cell element is reduced, the power generation efficiency is lowered.

  The objective of this invention is providing the solar cell module which can reduce the refracted light which generate | occur | produces when sunlight injects.

  As a result of intensive studies on a solar cell module including a single-sided light-receiving solar cell element and a V-shaped light reflecting plate, the present inventors have found that the shape of the V-shaped light reflecting plate (inclination angle and peak By optimizing the angle, it was found that the light refracted at the interface between the front plate and the air layer can be reduced when sunlight incident from the front plate is reflected by the light reflecting plate, and the present invention is completed. I came to let you.

That is, the solar cell module of the present invention includes a single-sided light receiving solar cell element, a front plate disposed on the front side of the solar cell element, a solar cell element disposed on the back side of the solar cell element, and incident from the front plate. A V-shaped light reflecting plate that reflects light toward the front plate, when the inclination angle of the light reflecting plate is θa, the apex angle of the light reflecting plate is θb, and the refractive index of the front plate is Nb, sin ⁻¹ (1 / Nb) −2 ° ≦ θb−2θa ≦ sin ⁻¹ (1 / Nb) + 10 ° is satisfied.

  In such a solar cell module, when sunlight enters from the front plate and is reflected by the light reflecting plate, the reflected light is reflected at the interface between the front plate and the air layer and enters the solar cell element. At this time, by setting the shape of the light reflecting plate so as to satisfy the above relational expression, the reflectance of light at the interface between the front plate and the air layer is increased, and is generated at the interface between the front plate and the air layer. Refracted light is reduced.

  According to the present invention, it is possible to reduce refracted light generated when sunlight is incident. Thereby, since the light which injects into a solar cell element increases, it becomes possible to improve electric power generation efficiency.

It is sectional drawing which shows one Embodiment of the solar cell module concerning this invention. It is sectional drawing which shows the structural example of the backplate shown in FIG. It is a figure which shows the shaping | molding method of the backplate shown in FIG. It is the schematic which shows a mode when sunlight injects into the solar cell module shown in FIG. It is a figure which shows a mode when light injects into the medium from which a relative refractive index differs. It is a graph which shows the relationship between a front plate incident angle and light utilization factor at the time of using a front plate with a refractive index of 1.53.

  Hereinafter, preferred embodiments of a solar cell module according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an embodiment of a solar cell module according to the present invention. In the figure, a solar cell module 1 of the present embodiment includes a plurality of single-sided light receiving solar cell elements 2, a front plate 3 disposed on the front side of the solar cell element 2, and a back side of the solar cell element 2. The rear plate 4 is disposed, and the resin portion 5 is provided between the front plate 3 and the rear plate 4 and made of a sealing resin for fixing each solar cell element 2.

  The front plate 3 is made of, for example, white plate tempered glass. As the sealing resin for forming the resin portion 5, for example, ethylene vinyl acetate copolymer resin (EVA resin) or the like is used.

  The back plate 4 is provided on both sides of each of the flat plate portions 6 on which the solar cell elements 2 are placed, and reflects the sunlight incident from the front plate 3 toward the front plate 3. It comprises a plurality of V-shaped light reflecting plate portions (light collecting portions) 7 to be made.

  As shown in FIG. 2, the back plate 4 has a metal substrate 8, and a PET layer 9, an Ag film layer 10, and an EVA film layer 11 are sequentially laminated on the surface of the metal substrate 8 via an adhesive layer 12. ing. A PET layer 13 is formed on the back surface of the metal substrate 8 via an adhesive layer 12, and a fluorine coating layer 14 is formed on the back surface of the PET layer 13.

  The molding method of the back plate 4 is shown in FIG. In the molding method shown in FIG. 3A, after the roll-shaped base material 4a is unwound and cut, the base material 4a is pressed by a press 15 to obtain the back plate 4 which is an uneven molded product. . In the molding method shown in FIG. 3 (b), after the roll-shaped 4 a base material is fed out, the base material 4 a is gear-rolled by a pair of gears 16 and cut to obtain the back plate 4. In the molding method shown in FIG. 3 (c), the cut plate-like base material 4 b is bendered by the press brake 17 to obtain the back plate 4.

  In the solar cell module 1 as described above, as shown in FIGS. 1 and 4, when sunlight enters from the front plate 3 and is reflected by the light reflecting plate portion 7 of the back plate 4, the reflected light is the front Reflected at the interface 3a between the face plate 3 and the air layer. Then, the light reflected by the interface 3 a is incident on the front surface of the solar cell element 2, and power is generated by the solar cell element 2.

  However, since a refractive index difference occurs at the interface 3a between the front plate 3 and the air layer, refracted light may be generated in addition to reflected light. This refracted light is light that leaks outside the module. For this reason, when refracted light is generated, optical loss increases, and light incident on the solar cell element 2 decreases, resulting in a decrease in light utilization rate.

  Therefore, in order to reduce the refracted light generated at the interface 3a between the front plate 3 and the air layer as much as possible and to allow a large amount of reflected light to enter the solar cell element 2, the shape of the V-shaped light reflecting plate portion 7 ( Angle) needs to be optimized. At this time, the maximum output is obtained when sunlight enters in parallel from a direction perpendicular to the front plate 3. Therefore, it is important to optically design the shape of the light reflecting plate portion 7 in consideration of the case where sunlight is incident in parallel from a direction perpendicular to the front plate 3.

Specifically, as shown in FIG. 4, the inclination angles (inclination angles with respect to the front surfaces of the solar cell element 2 and the front plate 3) of the inclined surfaces 7a and 7b forming the V-shaped light reflecting plate portion 7 are set to θa, When the apex angle of the inclined surfaces 7a and 7b (the angle between the inclined surfaces 7a and 7b) is θb, and the absolute refractive index of the front plate 3 is Nb, the shape of the light reflecting plate portion 7 is
sin ⁻¹ (1 / Nb) −2 ° ≦ θb−2θa ≦ sin ⁻¹ (1 / Nb) + 10 °
Is set to satisfy. Hereinafter, the reason why the above relational expression is set will be described.

  In FIG. 4, sunlight is incident in parallel from a direction perpendicular to the front plate 3, and the incident light is sequentially reflected by the inclined surfaces 7 a and 7 b of the light reflecting plate portion 7, and the front plate 3, the air layer, The state when reaching the interface 3a is shown.

  In the same figure, when the inclination angle of the inclined surfaces 7a and 7b is θa and the apex angle of the inclined surfaces 7a and 7b is θb as described above, the angle θc formed between the light reflected by the inclined surface 7a and the inclined surface 7b is 90 ° + θa−θb. Further, the angle θd formed by the inclined surface 7b and the surface in the direction perpendicular to the front plate 3 is 90 ° + θa. Furthermore, the angle θe formed by the light reflected by the inclined surface 7b and the surface in the direction perpendicular to the front plate 3 is θb−2θa. That is, the incident angle of the reflected light incident on the front plate 3 (front plate incident angle) is θb−2θa.

FIG. 5 shows a state in which light enters a medium having a different relative refractive index. In this case, the relative refractive index of the medium A is Na, the relative refractive index of the medium B is Nb, the incident angle of light incident on the interface between the media A and B is θ _b , and the light refracted at the interface between the media A and B is and the refractive angle is theta _a, generally following expression is established.
Na × sin θ _a = Nb × sin θ _b (A)

At this time, when the medium A, the incident angle theta _b of light incident on the interface B is increased constant or eliminates the refraction phenomenon, so the total reflection phenomenon occurs. If the incident angle θ _b when this total reflection phenomenon occurs is the critical angle θ _m , the following conditional expression can be obtained from the above equation (A). However, since the medium A here is an air layer, the relative refractive index Na is 1.0.
1.0 × sin 90 ° = Nb × sin θ _m (B)

Then, the critical angle θ _m is calculated by modifying the above equation (B).
sin θ _m = 1 / Nb
θ _m = sin ⁻¹ (1 / Nb) (C)

From the above formula (C), for example, when a glass material having an absolute refractive index Nb of 1.53 is used as the front plate 3, the critical angle θ _m = 40.8 ° is a condition for causing the total reflection phenomenon. Therefore, from the following formula, the inclination angle θa of the inclined surfaces 7a and 7b of the light reflecting plate portion 7 is determined to be 34.8 °, and the apex angle θb of the inclined surfaces 7a and 7b of the light reflecting plate portion 7 is determined to be 110.4 °. The
θb-2θa = 40.8 °
θa + θb / 2 = 90 °

  Here, FIG. 6 shows the relationship between the front plate incident angle (θb−2θa) and the light utilization factor when the material of the front plate 3 has an absolute refractive index Nb of 1.53. As can be seen from the figure, when the front plate incident angle is 40.8 ° (total reflection establishment condition), the light utilization rate is maximum at 90.8%, and even when the front plate incident angle is 50 °, The light utilization rate is 90.0%. In addition, when the front plate incident angle is 50 °, the light utilization decreasing rate with respect to the total reflection establishment condition is 0.88%. As the deviation of the front plate incident angle from the total reflection establishment condition increases, the light utilization rate decreases.

From the graph shown in FIG. 6, the inclination angle θa of the inclined surfaces 7a and 7b of the light reflecting plate portion 7 and the apex angle θb of the inclined surfaces 7a and 7b of the light reflecting plate portion 7 are numerical values that satisfy the following relational expression. Set to range. This numerical range is set so that the light utilization rate is approximately 90% or more and the light utilization decrease rate with respect to the total reflection establishment condition is approximately 1% or less.
sin ⁻¹ (1 / Nb) −2 ° ≦ θb−2θa ≦ sin ⁻¹ (1 / Nb) + 10 °

  Since the shape of the V-shaped light reflector 7 is optimized so as to satisfy such a relational expression, the light refracted at the interface 3a between the front plate 3 and the air layer is reduced, and the front plate is correspondingly reduced. The light reflected from the interface 3a between the air layer 3 and the air layer increases. For this reason, the quantity of light incident on the solar cell element 2 increases, and the light utilization rate by the solar cell element 2 increases. Thereby, power generation efficiency (module efficiency) can be made high.

DESCRIPTION OF SYMBOLS 1 ... Solar cell module, 2 ... Solar cell element, 3 ... Front plate, 7 ... Light reflection board part (light reflection board).

Claims (1)

A single-sided light receiving solar cell element;
A front plate disposed on the front side of the solar cell element;
A V-shaped light reflecting plate that is disposed on the back side of the solar cell element and reflects sunlight incident from the front plate toward the front plate;
When the inclination angle of the light reflecting plate is θa, the apex angle of the light reflecting plate is θb, and the refractive index of the front plate is Nb,
sin ⁻¹ (1 / Nb) −2 ° ≦ θb−2θa ≦ sin ⁻¹ (1 / Nb) + 10 °
A solar cell module characterized by satisfying

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