A concentrated photovoltaic cell module and its preparation method

Abstract

This invention discloses a concentrated photovoltaic (CPV) module and its fabrication method, comprising a concentrated gallium arsenide (GaAs) solar cell, a buffer layer, a first silver-gold plating layer, a front copper foil, a substrate, a back copper foil, a nickel plating layer, a palladium plating layer, and a gold plating layer. The front and back copper foils are respectively disposed on the front and back sides of the substrate. The back side of the back copper foil is sequentially plated with a nickel plating layer, a palladium plating layer, and a gold plating layer. The front side of the front copper foil is plated with the first silver-gold plating layer, and a pre-defined battery fixing area is located on its front side. The back side of the CPV solar cell is plated with a buffer layer, which is either a second silver-gold plating layer or a gold-tin plating layer. The CPV solar cell is placed in the battery fixing area, and the positive electrode of the CPV solar cell is connected to the positive electrode of the front copper foil. The negative electrode of the CPV solar cell and the negative electrode of the front copper foil are connected by resistance welding. This invention effectively solves the problem of poor heat dissipation of CPV solar cells in high-concentration applications.

Description

Technical Field

[0001] This invention relates to the technical field of space power solar power generation, and in particular to a concentrated photovoltaic cell module and its preparation method. Background Technology

[0002] With the development of my country's aerospace industry, the functions of spacecraft are constantly expanding, creating an urgent need for ultra-high conversion efficiency solar cell technology that is efficient, lightweight, compact, portable, and easy to replace. In recent years, concentrated gallium arsenide (GaAs) solar cells, exhibiting high conversion efficiency under high-concentration light, have emerged as a promising technology. However, under high-concentration light applications, the operating temperature of GaAs solar cells increases significantly. Solar arrays constructed by bonding GaAs solar cells to flexible polyimide films or rigid aluminum honeycomb substrates using traditional adhesive bonding processes suffer from poor heat dissipation at high temperatures, compromising the performance and reliability of the solar arrays in space applications. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a concentrating cell module that can effectively solve the problem of poor heat dissipation of concentrating gallium arsenide solar cells in high-concentration applications.

[0004] Another object of the present invention is to provide a method for preparing a concentrated photovoltaic cell module.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A concentrated photovoltaic (CPV) module includes a concentrated gallium arsenide (GaAs) solar cell, a buffer layer, a first silver-gold plating layer, a front copper foil, a substrate, a back copper foil, a nickel plating layer, a palladium plating layer, and a gold plating layer. The front and back copper foils are respectively deposited on the front and back sides of the substrate using DPC or AMB processes. The back side of the back copper foil is sequentially plated with a nickel plating layer, a palladium plating layer, and a gold plating layer. The front side of the front copper foil is plated with a first silver-gold plating layer, and a pre-defined battery fixing area is located on its front side. The back side of the concentrated GaAs solar cell is plated with a buffer layer, which is either a second silver-gold plating layer or a gold-tin plating layer. The concentrated GaAs solar cell is placed in the battery fixing area. The positive electrode of the concentrated GaAs solar cell is connected to the positive electrode of the front copper foil using a reflow soldering process or a eutectic soldering process. The negative electrode of the concentrated GaAs solar cell and the negative electrode of the front copper foil are connected by resistance soldering. The contact thermal resistance between the concentrated GaAs solar cell and the substrate is not greater than 0.3°C / W.

[0007] Furthermore, the substrate is an aluminum nitride substrate or a silicon carbide substrate.

[0008] Furthermore, the substrate has a thermal conductivity of 170–230 W / m·K and a coefficient of thermal expansion of 4.5–5.5 × 10⁻⁶ W / m·K over a temperature range from room temperature to 300°C. -6 / K; the thermal conductivity of the solder paste is 50 W / m·K, and the coefficient of thermal expansion is 24~25×10⁻⁶ in the temperature range of room temperature to 100℃. -6 / K.

[0009] Furthermore, the concentrated gallium arsenide solar cell has a coefficient of thermal expansion of 5.7 to 6.0 × 10⁻⁶ in the temperature range of room temperature to 300°C. -6 / K; The coefficient of thermal expansion of the front copper foil and the back copper foil is 17~18×10 in the temperature range of room temperature to 300℃. -6 / K.

[0010] Furthermore, stress-reducing holes for exposing the substrate are provided at the edges of both the front and back copper foils.

[0011] Furthermore, the front side of the concentrated gallium arsenide solar cell is provided with an anti-radiation glass cover and a bypass diode.

[0012] Furthermore, the concentrated solar cell module is welded to the rigid solar array of the spacecraft via a high thermal conductivity material, which is solder paste, silver paste, or thermally and electrically conductive adhesive with a thermal conductivity greater than or equal to 30 W / m·K.

[0013] Another objective of this invention is achieved through the following technical solution:

[0014] A method for fabricating a concentrated photovoltaic cell module includes the following steps:

[0015] S1. Design the shape and internal circuit layers of the substrate according to actual needs, and set the front copper foil and back copper foil on the front and back of the substrate respectively through DPC process or AMB process.

[0016] S2. A first silver-gold plating layer is plated on the front side of the front copper foil, and a nickel plating layer, a palladium plating layer, and a gold plating layer are plated sequentially on the back side of the back copper foil. Then, stress-reducing holes for exposing the front and back sides of the substrate are processed on the edges of the front copper foil and the back copper foil, respectively.

[0017] S3. Using a soldering machine, apply solder paste to the pre-set battery fixing area on the front copper foil. Place the concentrated gallium arsenide solar cell with a second silver-plated gold layer on the back into the pre-set battery fixing area. Use a vacuum eutectic soldering machine to apply reflow soldering to bond the positive electrode of the concentrated gallium arsenide solar cell to the positive electrode of the front copper foil. Alternatively, use a dispensing machine to apply flux to the pre-set battery fixing area on the front copper foil. Place the concentrated gallium arsenide solar cell with a gold-plated tin layer on the back into the pre-set battery fixing area. Use a vacuum eutectic soldering machine to apply eutectic soldering to bond the positive electrode of the concentrated gallium arsenide solar cell to the positive electrode of the front copper foil.

[0018] S4. Using silver or Kovar silver interconnects, the negative electrode of the concentrated gallium arsenide solar cell and the negative electrode of the front copper foil are connected by resistance welding, and then an anti-radiation glass cover is set on the front of the concentrated gallium arsenide solar cell.

[0019] S5. Finally, a bypass diode is installed on the substrate to complete the fabrication.

[0020] Furthermore, the bonding force between the front and back copper foils and the substrate is not less than 2 N / mm. 2 The peel strength of any coating shall not be less than 3.4 N / cm.

[0021] Furthermore, the thrust between the concentrated gallium arsenide solar cell and the substrate is not less than 6 N / mm. 2 The void ratio is no more than 10%.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] 1. The theoretical contact thermal resistance of the concentrating cell module of the present invention when welded to the rigid solar fin is 0.008℃ / W, which is much lower than that of the substrate adhesive bonding process (the theoretical contact thermal resistance of the traditional gallium arsenide solar cell substrate adhesive to the rigid solar fin is 0.494℃ / W). This can meet the heat conduction requirements of the concentrating gallium arsenide solar cell after the high temperature is generated in the high-concentration application in space, effectively ensuring the reliability of the concentrating gallium arsenide solar cell in the high-concentration environment of space and improving the service life of the product.

[0024] 2. Due to the differences in the coefficients of thermal expansion of different materials, this invention can effectively match the differences in the coefficients of thermal expansion of the substrate, copper foil, and solar cell by plating nickel, palladium, gold, and silver-gold layers on the surface of conductive and thermally conductive copper foil, and designing stress-reducing holes at the edges. A silver-gold layer or a gold-tin layer is also plated on the back of the concentrated gallium arsenide solar cell as a buffer layer. This can reduce thermal stress. Attached Figure Description

[0025] Figure 1 This is a plan view of the photovoltaic cell module of the present invention.

[0026] Figure 2 This is a cross-sectional view of the photovoltaic cell module of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] Example 1:

[0029] like Figures 1 to 2 As shown, this embodiment provides a concentrated photovoltaic cell module, including a concentrated gallium arsenide solar cell 1, a buffer layer, a first silver-gold plating layer 4, a front copper foil 5, a substrate 6, a back copper foil 7, a nickel plating layer 8, a palladium plating layer 9, and a gold plating layer 10. The front and back copper foils are respectively disposed on the front and back sides of the substrate using DPC or AMB processes. The back side of the back copper foil is sequentially plated with a nickel plating layer, a palladium plating layer, and a gold plating layer. The front side of the front copper foil is plated with a first silver-gold plating layer, and its front side has a pre-set battery fixing area. The fixing area can be made by etching grooves using a copper plating layer or by adding solder resist ink. Stress-reducing holes 11 are provided at the edges of both the positive and negative copper foils to expose the substrate. The back side of the concentrated gallium arsenide solar cell is plated with a buffer layer, which is a second silver-gold plating layer. 2. A silver-gold layer or a gold-plated tin layer is used as the buffer layer. When the buffer layer is a second silver-gold layer, solder paste 3 is applied to the battery fixing area. The concentrated gallium arsenide solar cell is placed in the battery fixing area, and the positive electrode of the concentrated gallium arsenide solar cell is connected to the positive electrode 501 of the front copper foil using a reflow soldering process. When the buffer layer is a gold-plated tin layer, flux is added to the battery fixing area, and the concentrated gallium arsenide solar cell is placed in the battery fixing area. The positive electrode of the concentrated gallium arsenide solar cell is connected to the positive electrode 501 of the front copper foil using a eutectic soldering process. Then, silver or Kovar silver interconnects are used to achieve conductivity between the negative electrode of the concentrated gallium arsenide solar cell and the negative electrode 502 of the front copper foil through resistance soldering. The contact thermal resistance between the concentrated gallium arsenide solar cell and the substrate is not greater than 0.3℃ / W.

[0030] The substrate is made of a high thermal conductivity material such as aluminum nitride or silicon carbide, with a thermal conductivity of 170–220 W / m·K and a coefficient of thermal expansion of 4.5–5.5 × 10⁻⁶ W / m·K over a temperature range from room temperature to 300°C. -6 / K; The thermal conductivity of the solder paste is 50 W / m·K, and its coefficient of thermal expansion is 24~25×10⁻⁶ in the temperature range from room temperature to 100℃. -6 / K; The coefficient of thermal expansion of concentrated gallium arsenide solar cells is 5.7~6.0×10⁻⁶ in the temperature range from room temperature to 300℃. -6 / K; The coefficient of thermal expansion of the front and back copper foils is 17~18×10 in the temperature range from room temperature to 300℃. -6 / K.

[0031] The concentrated solar cell module is welded to the rigid solar array of the spacecraft using a high thermal conductivity material, such as solder paste, silver paste, or thermally and electrically conductive adhesive, with a thermal conductivity greater than or equal to 30 W / m·K.

[0032] The front side of the concentrated gallium arsenide solar cell is equipped with a radiation-resistant glass cover and a bypass diode.

[0033] Example 2:

[0034] This embodiment provides a method for preparing a concentrated photovoltaic module, including the following steps:

[0035] S1. Design the shape and internal circuit layers of the substrate according to actual needs, and set the front copper foil and back copper foil on the front and back of the substrate respectively through DPC process or AMB process.

[0036] S2. A first silver-gold plating layer is plated on the front side of the front copper foil, and a nickel plating layer, a palladium plating layer, and a gold plating layer are sequentially plated on the back side of the back copper foil. Then, stress-reducing holes are machined on the edges of the front and back copper foils to expose the front and back sides of the substrate, respectively. The adhesion force between the front and back copper foils and the substrate is not less than 2 N / mm. 2 The peel strength of any coating layer shall not be less than 3.4 N / cm;

[0037] S3. Using a soldering machine, apply solder paste to the pre-designated battery mounting area on the front copper foil. Place the concentrated gallium arsenide solar cell with a second silver-plated gold layer on the back into the pre-designated battery mounting area. Use a vacuum eutectic soldering machine to bond the positive electrode of the concentrated gallium arsenide solar cell to the positive electrode of the front copper foil using a reflow soldering process. Alternatively, use a dispensing machine to apply flux to the pre-designated battery mounting area on the front copper foil. Place the concentrated gallium arsenide solar cell with a gold-plated tin layer on the back into the pre-designated battery mounting area. Use a vacuum eutectic soldering machine to bond the positive electrode of the concentrated gallium arsenide solar cell to the positive electrode of the front copper foil using a eutectic soldering process. The thrust between the concentrated gallium arsenide solar cell and the substrate should be no less than 6 N / mm. 2 The void ratio is no more than 10%;

[0038] S4. Following the traditional solar cell encapsulation process, silver or Kovar silver interconnects are used to connect the negative electrode of the concentrated gallium arsenide solar cell to the negative electrode of the front copper foil through resistance welding, and then an anti-radiation glass cover is set on the front of the concentrated gallium arsenide solar cell.

[0039] S5. Finally, a bypass diode is installed on the substrate to complete the fabrication.

[0040] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A photovoltaic cell module, characterized in that: The system comprises a concentrated gallium arsenide (GaAs) solar cell, a buffer layer, a first silver-gold plating layer, a front copper foil, a substrate, a back copper foil, a nickel plating layer, a palladium plating layer, and a gold plating layer. The front and back copper foils are respectively deposited on the front and back sides of the substrate using DPC or AMB processes. The back side of the back copper foil is sequentially plated with a nickel plating layer, a palladium plating layer, and a gold plating layer. The front side of the front copper foil is plated with a first silver-gold plating layer, and its front side has a pre-defined battery fixing area. The battery fixing area is formed by etching grooves using a copper plating layer or by adding solder resist ink. Stress-reducing holes are provided at the edges of both the positive and negative copper foils to expose the substrate. The back side of the concentrated gallium arsenide solar cell is plated with a buffer layer, which is a second plating layer. The buffer layer consists of a silver-gold layer or a gold-plated tin layer. When the buffer layer is a second silver-gold layer, solder paste is applied to the battery fixing area, and the concentrated gallium arsenide solar cell is placed in the battery fixing area. The positive electrode of the concentrated gallium arsenide solar cell is connected to the positive electrode of the front copper foil using a reflow soldering process. When the buffer layer is a gold-plated tin layer, flux is added to the battery fixing area, and the concentrated gallium arsenide solar cell is placed in the battery fixing area. The positive electrode of the concentrated gallium arsenide solar cell is connected to the positive electrode of the front copper foil using a eutectic soldering process. The negative electrode of the concentrated gallium arsenide solar cell and the negative electrode of the front copper foil are connected by resistance soldering. The contact thermal resistance between the concentrated gallium arsenide solar cell and the substrate is not greater than 0.3℃ / W.

2. The concentrated solar cell module according to claim 1, characterized in that: The substrate is an aluminum nitride substrate or a silicon carbide substrate.

3. The concentrating solar cell module according to claim 1, characterized in that: The substrate has a thermal conductivity of 170–230 W / m·K and a coefficient of thermal expansion of 4.5–5.5 × 10⁻⁶ W / m·K over a temperature range from room temperature to 300°C. -6 / K; the thermal conductivity of the solder paste is 50 W / m·K, and the coefficient of thermal expansion is 24~25×10⁻⁶ in the temperature range of room temperature to 100°C. -6 / K.

4. The concentrating cell module according to claim 1, characterized in that: The concentrated gallium arsenide solar cell has a coefficient of thermal expansion of 5.7 to 6.0 × 10⁻⁶ in the temperature range of room temperature to 300°C. -6 / K; The coefficient of thermal expansion of the front copper foil and the back copper foil is 17~18×10 in the temperature range from room temperature to 300°C. -6 / K.

5. The concentrating photovoltaic module according to claim 1, characterized in that: Both the front and back copper foils have stress-reducing holes at their edges to expose the substrate.

6. The concentrated solar cell module according to claim 1, characterized in that: The front side of the concentrated gallium arsenide solar cell is provided with an anti-radiation glass cover and a bypass diode.

7. The concentrator module according to claim 1, characterized in that: The concentrated solar cell module is welded to the rigid solar array of the spacecraft via a high thermal conductivity material, which is a solder paste, silver paste, or thermally and electrically conductive adhesive with a thermal conductivity greater than or equal to 30 W / m·K.

8. A method for preparing a concentrated photovoltaic cell module according to any one of claims 1 to 7, characterized in that, Including steps, S1. Design the shape and internal circuit layers of the substrate according to actual needs, and set the front copper foil and back copper foil on the front and back of the substrate respectively through DPC process or AMB process. S2. A first silver-gold plating layer is plated on the front side of the front copper foil, and a nickel plating layer, a palladium plating layer, and a gold plating layer are plated sequentially on the back side of the back copper foil. Then, stress-reducing holes for exposing the front and back sides of the substrate are processed on the edges of the front copper foil and the back copper foil, respectively. S3. Using a soldering machine, apply solder paste to the pre-set battery fixing area on the front copper foil. Place the concentrated gallium arsenide solar cell with a second silver-plated gold layer on the back into the pre-set battery fixing area. Use a vacuum eutectic soldering machine to apply reflow soldering to bond the positive electrode of the concentrated gallium arsenide solar cell to the positive electrode of the front copper foil. Alternatively, use a dispensing machine to apply flux to the pre-set battery fixing area on the front copper foil. Place the concentrated gallium arsenide solar cell with a gold-plated tin layer on the back into the pre-set battery fixing area. Use a vacuum eutectic soldering machine to apply eutectic soldering to bond the positive electrode of the concentrated gallium arsenide solar cell to the positive electrode of the front copper foil. S4. Using silver or Kovar silver interconnects, the negative electrode of the concentrated gallium arsenide solar cell and the negative electrode of the front copper foil are connected by resistance welding, and then an anti-radiation glass cover is set on the front of the concentrated gallium arsenide solar cell. S5. Finally, a bypass diode is installed on the substrate to complete the fabrication.

9. The method for preparing a concentrated photovoltaic module according to claim 8, characterized in that, The bonding force between the front and back copper foils and the substrate is not less than 2 N / mm. 2 The peel strength of any coating shall not be less than 3.4 N / cm.

10. The method for preparing a concentrated photovoltaic module according to claim 8, characterized in that, The thrust between the concentrated gallium arsenide solar cell and the substrate is not less than 6 N / mm. 2 The void ratio is no more than 10%.

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