JPH0652801B2 - Method of manufacturing solar cell panel - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for manufacturing a solar cell panel.

[Technical Background of the Invention] As an example of a solar cell panel, an example of a super straight type solar cell panel aiming at low cost and high reliability will be described with reference to FIGS. 1 and 2.

That is, the transparent cover / glass 1 serves as a structural support for the entire panel, and one side of the cover / glass 1 is filled with a string of solar cells 3 connected in series inside thereof. 2 is glued. The filler 2 is usually poly (vinyl butyral) (hereinafter P
VB) has been widely used. A back surface material 4 is bonded to the back surface of the filling material 2. As shown in FIG. 2, the back surface material 4 is composed of a three-layer structure of a metal foil such as an aluminum foil 6 sandwiched in the middle and poly vinyl fluoride (hereinafter referred to as PVF) 5 on both sides.
This aluminum foil 6 is for preventing the permeation of water vapor from the outside. The periphery of this solar panel is the first
As shown in the figure, it is fixed to an aluminum frame 8 which has been anodized through an insulating material 7. As the insulating material 7, butyl rubber is used as a material that maintains long-term reliability and is low in cost.

However, in recent years, ethylene vinyl acetate (hereinafter referred to as EVA) has been developed as the filler 2 in place of PVB in order to promote cost reduction and high reliability of the solar cell panel.

That is, EVA has the following advantages as compared with PVB.

(1) EVA is cheaper in material cost, and is currently about 2/3 the price of PVB.

(2) EVA is also simpler when processing materials.

That is, PVB is usually wound in a roll with a heavy coating applied to the surface to prevent adhesion of PVB itself. Therefore, when it is used in the process of assembling a solar cell panel, it must be subjected to a humidity conditioning treatment for about 1 day after the water washing treatment. On the other hand, EVA can omit the water washing step, and the humidity control treatment can be PVB.
Not so strict.

(3) The bonding by EVA is excellent in heat resistance and reliability because it is formed through a crosslinking reaction. On the other hand, PVB is bonded according to the principle of not using a crosslinking reaction, so that its softening property with respect to temperature is reversible and it softens at high temperature.

For the reliability test items for solar cell panels, see J.
It is proposed by PL (Jet Propulsion Laboratory) and the like, and is being standardized in Japan, but the test items are, for example, -40 ° C to 80 ° C, RH (relative humidity) 90%.
Temperature and humidity cycle test under the above atmosphere; 80 ° C, RH
High temperature and high humidity test at 90% or higher; low temperature test at -40 ° C;
A temperature shock test at −40 ° C. to 80 ° C .; a salt fog test under 5% salt water, etc., and its purpose is to guarantee the life of the solar cell panel, which is said to be about 20 years. Unlike a single vacuum exhaust method using a rubber bag, which is usually performed to perform bonding using EVA in order to obtain a highly reliable solar cell panel that passes such a test item, It is necessary to use a double vacuum system as shown in FIG.

That is, the first chamber 11 and the second chamber 12 are surrounded by, for example, a rigid body and separated by a diaphragm (diaphragm) 13, and communicate with a vacuum pump (not shown) via valves V1 and V2, respectively.

The laminated body 14 including the solar cells to be placed in the second chamber 12 is normally constructed as shown in FIG.

That is, a transparent cover glass 1 made of a white plate glass that has been subjected to a strengthening treatment, EVA 21, a string made of solar cells 3, EVA 22, and a back surface material 4 are laminated in this order or in the reverse order.

The laminating process for manufacturing a solar cell panel is as follows, for example. That is, the first chamber 11 and the second chamber 12
Is evacuated to a vacuum, and the laminate 14 is heated to a temperature range in which the EVAs 21 and 22 are in a molten state and does not cause a crosslinking reaction. Then, the second chamber 12 is kept in vacuum and the first chamber 11 is heated. Return to atmospheric pressure. Then, the laminated body 14 is pressure-bonded through the diaphragm 13 in vacuum at atmospheric pressure. Then E
The VA is heated to a temperature range where it causes a crosslinking reaction. The temperature is maintained at this temperature until the crosslinking reaction is completed, and after cooling, the laminate 14 is taken out. Through the above steps, a solar cell panel using EVA filler 2 as shown in a part of FIG. 1 is formed, and the bonding step is completed.

[Problems of the Background Art] As described above, in the process of laminating a solar cell panel using EVA, EVA is pressed in a temperature range where crosslinking is not carried out, the laminate 14 is pressure-bonded, and then EVA is completely removed. It must be kept in the temperature and time domain for crosslinking. However, in order to obtain the appearance and characteristics required for a solar cell panel product, the present inventor has an extremely narrow range with respect to the temperature at the time of pressurization, the temperature at which the crosslinking reaction is achieved, and the holding time, which are the production conditions. I found that I was only satisfied. That is,
When the holding temperature is lower than the optimum temperature range, EVA remains uncrosslinked, and after being made into a solar cell panel product, uncrosslinked in a high temperature and high humidity test, a temperature and humidity cycle test, and an outdoor feed test. A phenomenon occurs in which EVA flows out from the periphery of the panel depending on the temperature. On the other hand, when the holding temperature is higher than the optimum temperature range, EVA foaming and EVA
Yellowing phenomenon is seen.

Further, when the temperature during pressurization is low, or when the holding time after pressurization is long, a foaming phenomenon occurs.

[Object of the Invention] The present invention has been made in view of the above problems, and when EVA is used as a filler, the appearance and characteristics can be controlled by controlling the manufacturing conditions such as temperature and time during bonding. The object is to provide a solar cell panel that satisfies both requirements.

[Summary of the Invention] A method of manufacturing a solar cell panel according to the present invention is a method of degassing a solar cell panel laminate in which solar cells are laminated between a cover glass and a back surface material via a filler by a double vacuum method. Then, in the method for manufacturing a solar cell panel having a laminating step by applying pressure after heating, ethylene vinyl acetate is used as the filler, and the hot plate is provided on one side of the double vacuum chamber and the hot plate is placed on the hot plate. After arranging the solar cell panel laminate and using the heating method from one direction by the hot plate, in the laminating step by pressurization, at the position of the solar cell panel laminate closest to the hot plate, after applying pressure. Has a maximum temperature in the range of 140 ° C to 155 ° C, a maximum temperature holding time in the range of 7 minutes to 40 minutes, and is pressed at the position of the solar cell panel laminate farthest from the hot plate. The maximum temperature of The temperature is in the range of 140 ° C. to 155 ° C., and the holding time is in the range of 1 minute to 32 minutes.

Embodiments of the Invention Embodiments of the present invention will be described in detail below with reference to the drawings.
That is, the laminating apparatus is of a double vacuum type having a first chamber 11 and a second chamber 12 as shown in FIG.
The heating method will be described in detail with reference to the case of heating from one direction by the heating plate 15 provided below the laminated body 14 shown in FIG.

The laminated body 14 of the solar cell panel is, for example, as shown in FIG. That is, a filler 21 made of EVA sheet having a thickness of 0.8 mm and solar cells 3 are connected in series or in parallel on one surface of a transparent cover glass 1 made of tempered glass having a thickness of 3 mm, which is a structural support for the entire structure. String,
Filler 22 made of EVA sheet with wall thickness 0.8 mm, wall thickness 2
It consists of a backside material 4 consisting of a sheet of 0 μm aluminum foil sandwiched in the middle with a PVF thickness of 25 μm on each side. Also, the transparent cover glass 1 and the filler 2
At least one mat of long glass fibers called microglass is provided between each of the 1, 2, 22, the string and the back surface material 4.
Layers may be inserted. In the actual manufacturing process, the laminated body 14 may have a structure in which the transparent cover glass 1 is placed in order, that is, a structure in which an up-and-down reaction is performed as in FIG.

A typical profile in the laminating process is shown in FIG.
That is, first, as indicated by a curve 31 representing the degree of vacuum, preliminary vacuum evacuation is performed for 20 minutes by, for example, an oil rotary pump. As a result, both the first chamber 11 and the second chamber 12 have a degree of vacuum before heating of, for example, 0.3 Torr.
Next, heating is started in the step of FIG. Laminate 14
The temperature is measured experimentally by the thermocouple 16 shown in FIG. 5 at the position closest to the hot plate 15 and by the thermocouple 17 at the position farthest from the hot plate 15. The temperature rising gradient at the time of heating is, for example, 4 ° C./minute at the position of the thermocouple 16. A temperature rising curve at the position of the thermocouple 16 is shown in a curve 34 representing temperature in FIG. 6, and a temperature rising curve at the position of the thermocouple 17 is shown in a curve 35 representing temperature in FIG. Generally, the temperature at which EVA melts is about 85 ° C., and the temperature at which the crosslinking reaction starts is 1
It is 30 ° C. When 140 ° C. is reached at the position of the thermocouple 16 as in the step, the first chamber 11 is returned to the atmospheric pressure as shown by the curve 32 representing the degree of vacuum, and the laminated body 14 is vacuum-pressed. At this time, as shown by the curve 35, the temperature of the thermocouple 17 farthest from the heating plate 15 is not sufficiently raised. Therefore, the temperature is raised so that EVA crosslinks even at the position of the thermocouple 17. After the pressure bonding, the thermocouple 16 and the thermocouple 17 have almost the same temperature except the heat insulation by the vacuum.
Next, as in the step, after reaching 148 ° C. at the position of the thermocouple 16, for example, 25 minutes at the position of the thermocouple 16 and 25 minutes at the position of the corresponding thermocouple 17 in order to cause the crosslinking reaction to the entire laminate 14. Hold at maximum temperature for 17 minutes. Then, as in step, the hot plate is cooled by an air cooling tube, and after a while, the hot plate is cooled by a water cooling tube as in step.
After the temperature of the laminated body 14 is cooled to, for example, 50 ° C. or lower as in the step, the second chamber 12 is returned to the atmospheric pressure as shown by the curve 33 representing the degree of vacuum. With the above, the laminating step is completed.

However, the appearance as a solar cell panel or EVA
From the viewpoint of achieving the crosslinking reaction of, the temperature during the bonding process, the maximum temperature holding time, and the timing of pressure bonding should be
The inventor has found that only a very small area is satisfied. That is, for example, as shown in FIG.
When the maximum temperature was maintained at the position of 25 minutes for 25 minutes, when the maximum temperature was 141 ° C. or less, the gel fraction, which represents the ratio of crosslinking, was 50% or less. At 143 ° C, the gel fraction reached 90%. That is, if the temperature is maintained at 143 ° C. or higher after the pressurization, EVA allows the crosslinking reaction to be achieved at all positions of the solar cell panel. The method for measuring the gel fraction is as follows: Springborn Labo-ratories, Inc .: “Crosslinkable
Ethy-lene / Vinyl Acetate Coppolymer, Formula A99
18 "Technical Information Pack-et-System and Pro
cess (1980), p. Compliant with 7. When the gel fraction is 70% or more, the crosslinking reaction is considered to be achieved in practice. When the maximum temperature was 154 ° C. or higher for the same holding time as above, a foaming phenomenon caused by the decomposition gas of EVA itself occurred. When the maximum temperature becomes higher, along with the foaming phenomenon,
Yellowing of EVA occurred. As described above, even if the maximum temperature holding time at the position of the thermocouple 16 is limited to 25 minutes, the optimum maximum temperature is 1
It is in a narrow temperature range of 43 ° C to 154 ° C. Also, when the holding time was lengthened, for example, when the maximum temperature was held at 147 ° C. for 40 minutes at the position of the thermocouple 16, generation of small bubbles due to foaming of EVA itself was observed.

To summarize the above-mentioned experimental results, after applying pressure by the double vacuum system, it is sufficient to bond at the maximum temperature and the holding time in the "optimal region" shown in FIG. That is, the maximum temperature of the thermocouple 16, which is the position of the laminated body 14 closest to the heating plate 15, is 140 ° C. to 155 ° C., and the holding time is 7 minutes to 4 minutes.
Laminated body 1 with 0 minutes in the range and farthest from the hot plate 15
With the thermocouple 17 at the position 4, the maximum temperature may be 140 ° C. to 155 ° C., and the holding time may be 1 minute to 32 minutes. In addition, it is considered that the crosslinking reaction has been achieved, 7
The 0% crosslink line is between the 50% and 90% lines. When pasted in the "optimal area", EVA achieves a crosslinking reaction,
It does not cause a softening phenomenon when the temperature changes outdoors.

As described above, in the present embodiment, the case where the temperature is raised and the bonding is performed by the heating method from one direction from the hot plate has been described in detail. However, in the case of heating the solar cell panel laminate as a whole, The thermocouples 16 and 17 have almost the same temperature, but EVA is uncrosslinked when the maximum temperature is 140 ° C. or lower, and EVA foams when the maximum temperature is 155 ° C. or higher. Also, when the maximum temperature holding time reaches 40 minutes or more, small bubbles are generated. When the maximum temperature retention time is 7 minutes or less, EVA is uncrosslinked. Since the present invention uses the heating method from one direction, it is superior in energy saving to the heating method over the whole area. Further, since the hot plate and the solar cell panel laminated body are arranged on one of the double vacuum chambers, the thermal efficiency is improved as compared with the case where the heat source is placed outside the vacuum chamber.

[Advantages of the Invention] When the method for manufacturing a solar cell panel according to the present invention is used, EVA does not foam externally and the crosslinking reaction is achieved, so that the softening phenomenon does not occur outdoors. In addition, since they are laminated using the double vacuum method, high reliability can be obtained even in high temperature and high humidity tests and outdoor exposure tests.

[Brief description of drawings]

1 is a cross-sectional view of a solar cell panel, FIG. 2 is a schematic cross-sectional view of a back surface material, FIG. 3 is a schematic explanatory view of a double-vacuum bonding apparatus, and FIG. 4 is a laminated body of a solar cell panel. FIG. 5 is a schematic view of a double-vacuum type laminating apparatus by a heating method from one direction, and FIG. 6 is a profile showing the relationship between temperature, vacuum degree (pressure) and time according to the present invention. Fig. 7 is a characteristic diagram showing an example. Fig. 7 shows EV depending on the maximum temperature and holding time.
It is a state diagram of A, and is a figure showing the highest area | region. 1 ... Cover glass, 2, 21, 22 ... Filler material, 3 ... Solar cell, 4 ... Back surface material, 11 ... 1st chamber, 12 ... 2nd
Chamber, 13 ... diaphragm, 14 ... laminated body, 15 ... hot plate, 16, 17 ... thermocouple, 31, 32, 33 ... curve showing vacuum degree, 34, 35 ... curve showing temperature.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-59-22978 (JP, A) JP-A-59-16388 (JP, A) JP-A-58-17685 (JP, A)

Claims (1)

[Claims] 1. A solar cell panel laminated body in which solar cells are laminated between a cover glass and a back surface material with a filler interposed therebetween is degassed by a double vacuum method, and a laminating step is performed by applying pressure after heating. In the method for manufacturing a solar cell panel having, ethylene / vinyl acetate is used as the filler, and a hot plate on one side of a double vacuum chamber and the solar cell panel laminate is arranged on the hot plate, A heating method from one direction using a plate is used, and in the laminating step by pressing, the maximum temperature after pressing is in the range of 140 ° C to 155 ° C at the position of the solar cell panel laminate closest to the hot plate. And the maximum temperature holding time is in the range of 7 minutes to 40 minutes, and the maximum temperature after pressing is 140 ° C. to 15 ° C. at the position of the solar cell panel laminate most distant from the hot plate.
A method for manufacturing a solar cell panel, wherein the temperature is in the range of 5 ° C. and the holding time is in the range of 1 minute to 32 minutes.