JUNCTION BOX FOR SOLAR CELL

Abstract

The present invention discloses a junction box for a solar cell. The junction box includes a box body, wherein the box body is provided with a plurality of conducting pieces for connecting solar cell pieces; two adjacent conducting pieces are connected by a diode; the conducting pieces at both ends are connected to the outside parts via a guide line respectively; and the forward dissipation power of the diode in the middle is less than that of the diodes at both sides. According to the invention, the diode with lower forward dissipation power is employed in parts where the temperature rise is easily produced to reduce the temperature rise; while the diode with higher forward dissipation power is employed in parts where the temperature rise is not easily produced to control cost.

Claims

1. A junction box for a solar cell, comprising a box body, wherein the box body is provided with a plurality of conducting pieces for connecting solar cell pieces; two adjacent conducting pieces are connected by a diode; the conducting pieces at both ends are connected to outside parts via a guide line respectively; characterized in that the forward dissipation power of a diode in the middle is less than that of diodes at both sides.

2. The junction box for the solar cell according to claim 1, wherein the box body is provided with N+1 conducting pieces connected by N diodes and the power dissipation of each diode satisfies the following conditions: when N is an even number, formula I is satisfied if counting from any direction; when N is an odd number, formula II is satisfied if counting from any direction;
P.sub.N/2≦P.sub.N/2−1≦ . . . <P.sub.1  Formula I
P.sub.(N+1)/2≦P.sub.(N+1)/2−1≦ . . . <P.sub.1  Formula II wherein: P is the forward dissipation power, and subscript represents the sequence of the diodes.

3. The junction box for the solar cell according to claim 1, wherein the box body is provided with four conducting pieces connected by three diodes, wherein the forward dissipation power of the diode in the middle is less than that of the diodes at both ends.

4. The junction box for the solar cell according to claim 1, wherein the difference of the forward dissipation power of the diodes is realized by employing different models of diodes.

5. The junction box for the solar cell according to claim 1, wherein the difference of the forward dissipation power of the diodes is realized by setting different number of diodes that are parallelly connected.

6. The junction box for the solar cell according to claim 1, wherein the difference of the forward dissipation power of the diodes is realized by changing the process so that the positive power dissipation is reduced by.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention is further described in details hereinafter by reference to the drawings and the exemplary embodiments of the present invention.

[0016] FIG. 1 is a structural schematic diagram of a junction box in the prior art.

[0017] FIG. 2 is a structural schematic diagram of the first embodiment of the present invention.

[0018] FIG. 3 is a structural schematic diagram of the second embodiment of the present invention.

[0019] FIG. 4 is a structural schematic diagram of the third embodiment of the present invention.

[0020] FIG. 5 is a side view of a middle diode chip of the third embodiment of the present invention.

[0021] Reference numerals in figures: conducting piece 1, diode 2, middle diode 21, two-end diode 22, first chip 31, second chip 32, third chip 33, trench/groove 34.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Referring to the drawings, the junction box described in the embodiment comprises a box body, wherein the box body is provided with a plurality of conducting pieces 1 for connecting solar cell pieces; two adjacent conducting pieces 1 are connected by a diode 2; the conducting pieces 1 at both ends are connected to the outside via a busbar respectively; as illustrated in FIG. 1, in the prior art, the box body is provided with four conducting pieces 1 connected by three diodes 2, and the forward dissipation power of a first chip 31 on all the diode 2 is the same. It does not seem desirable as the cost is increased greatly once the forward dissipation power of the diode is reduced.

[0023] As the temperature rise of the diode in the middle is greater than that of the diodes at both sides, the method employed in the embodiment is that the forward dissipation power of the diode in the middle is reduced so as to be less than that of the chip of the diodes at both sides.

First Embodiment

[0024] As illustrated in FIG. 2, the box body of the embodiment is provided with four conducting pieces 1 for connecting solar cell pieces; two adjacent conducting pieces 1 are connected by a diode; the conducting pieces 1 at both ends are connected to the outside via a busbar respectively; wherein the model of a second chip 32 of the middle diode 21 is different from that of the first chip 31 of two-end diodes 22. The forward dissipation power is that galvanization I=15 A at the temperature of 25° C., the voltage drops V of the three diode chips are 0.5V, 0.4V and 0.5V respectively, and the forward dissipation powers of the three diode chips are P1=V*I=0.5*15=7.5 W, P2=V*I=0.4*15=6 W and P3=V*I=0.5*15=7.5 W. The forward dissipation power of the second chip 32 on the middle diode 21 is less than that of the first chip 31 on the two-end diode 22. Thus, the cost increase is controlled due to the decrease in heating.

Second Embodiment

[0025] As illustrated in FIG. 3, the box body of the embodiment is provided with four conducting pieces 1 for connecting solar cell pieces; two adjacent conducting pieces 1 are connected by a total of three diodes; the conducting pieces 1 at both ends are connected to the outside parts via a busbar respectively; wherein the middle diode 21 is connected parallelly with two first chips 31 respectively so that the forward dissipation power of the two first chips 31 on the middle diode 21 is less than that of the two-end diode 22. Thus, the cost increase is controlled due to the decrease in heating.

Third Embodiment

[0026] As illustrated in FIG. 4, the box body of the embodiment is provided with four conducting pieces 1 for connecting solar cell pieces; two adjacent conducting pieces 1 are connected by a total of three diodes; the conducting pieces 1 at both ends are connected to the outside parts via a busbar respectively; wherein the surface of a third chip 33 on the middle diode 21 is provided with a trench or groove 34, the forward dissipation power of the third chip 33 is reduced by the trench/groove 34 so as to be less than that of the first chip 31 on the two-end diode 22. Thus, the cost increase is controlled due to the decrease in heating.