JPS6169179A - Manufacture of solar cell panel - Google Patents

Abstract

PURPOSE:To obtain external appearance to be satisfied and characteristics by using ethylene-vinyl-acetate as filters and specifying the maximum temperature and holding time of a processing machine in pressing lamination. CONSTITUTION:Ethylene-vinyl-acetate is employed as filters, and a maximum temperature after pressing is kept within a range of 140-155 deg.C and the holding time of the maximum temperature is kept within a range of 7-40min in a laminating process by pressing. When fillers are held at 143 deg.C or higher after pressing, a crosslinking reaction is attained at all positions of a solar cell panel in EVA, and a foaming phenomenon is not generated due to the cracked gas of EVA itself. Accordingly, a softening phenomenon is not generated out of door because EVA is not foamed on external appearance and the crosslinking reaction is also attained, and high reliability can be acquired even in a high- temperature high-humidity test and an outdoor exposure test because fillers are laminated by using a double vacuum system.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a method for manufacturing a solar cell.

[Technical Background of the Invention] As an example of a thick lJ4 battery panel, an example of a super straight type Bq H battery panel aiming at low cost and high reliability will be explained with reference to FIGS. 1 and 2.

That is, a transparent cover glass 1 provides the structural support for the entire panel, and on one side of this cover glass 1 there is a filler material embedded inside which is a string of solar cells 3 connected in series. 2 is glued. The filler 2 is usually polyvinyl butyral (hereinafter referred to as P
The engine called V8 has been widely used. Full 1. t[--face material 4 is adhered to the river surface of material 2. As shown in FIG. 2, the back surface material 4 is made of a three-layer structure consisting of gold aH, such as aluminum foil 6, sandwiched in the middle, and polyvinyl fluoride (hereinafter referred to as PVF) 5 on both sides. This aluminum foil 6 is for preventing water vapor from permeating from the outside. As shown in FIG. 1, the periphery of this solar cell panel is fixed to an alumite-treated aluminum frame 8 via 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 solar cell panels.

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

(1) The material cost of EVA is lower than that of PVB.
It is a fixed installation of 2.73.

+2) EVA is also easier for M4 material processing.

That is, PVB is usually wound into a roll with a heavy coating applied to its surface to prevent the PVB from adhering itself. Therefore, thick! ! When used in the process of manufacturing battery panels in a bright room, it is necessary to perform a humidity control process for about one day after washing with water. On the other hand, EVA can omit the water washing process, and the humidity control process can also be done using PV.
B is not too strict.

(Lamination using 31EVA is formed through a crosslinking reaction, so it has excellent heat resistance and reliability.On the other hand, PVB is laminated using a principle that does not use a crosslinking reaction, so its softening property against temperature is reversible. Yes, it softens at high temperatures.

In addition, regarding the reliability test items of solar cell panels, please refer to J.
P L (J et Propulsion l
laboratory), etc., and is being standardized in Japan, but the test items are, for example -
Temperature/humidity cycle test at 40°C to 80°C in an atmosphere of RH (relative humidity) 90% or higher; High temperature/humidity test at 80°C, R8905 or higher; Low temperature test at -40°C knee 40°C to 8
Temperature shock test at 0°C9. : Salt water fog test under 5% salt water, etc., and the purpose is to guarantee the lifespan of large round battery panels, which is said to be 20 years. In order to obtain a highly reliable solar panel that gold foils such test items, E
When laminating using VA, it is usually done.
Unlike the single vacuum evacuation method using a rubber bag, it is necessary to use a double vacuum evacuation method as shown in FIG.

That is, the first to 11 and the second to 12 are surrounded by, for example, a rigid body and separated by a diaphragm 13, and each is connected to a vacuum pump (not shown) through a valve v1゜\/2. There is.

A stacked body 14 shown by diagonal lines and containing solar cells placed in the second cell 12 is normally constructed as shown in FIG.

That is, a transparent cover glass 1 made of tempered white glass or the like, an EVA 21, a string made of solar cells 3, an EVA 22, and a backing material 4 are laminated in this order or in the reverse order.

For example, the jq-joint bonding process for attaching the solar cell panels to 115N is as follows. That is, the first sky 11, the second sky
The laminate 14 is heated to a temperature range where the EVA 21 and 22 are in a molten state and no crosslinking reaction occurs, and then the first is heated while the second is kept in a vacuum. Return 11 to atmospheric pressure. Then, the laminate 14 is compressed by atmospheric pressure in a vacuum via the diaphragm 13.

Next, it is heated to a temperature range in which EVA undergoes a crosslinking reaction. This temperature is maintained until the crosslinking reaction is completed, and then, after cold FA, the fl1 body 14 is taken out. Through the above steps, a large round panel using the EVA filler 2 as shown in a part of FIG. 1 is formed, and the bonding step is completed.

[Problems in the Background Art] As mentioned above, in the process of laminating solar cell panels using EVA, pressure is applied in a temperature range where EVA is not crosslinked, the laminate 14 is compressed, and then the EVA is All crosslinking temperatures and times must be kept in a closed area. However, in order to achieve the appearance and characteristics necessary for a solar cell panel product, the inventors have determined that the manufacturing conditions for the product, such as the temperature at the time of pressurization, the temperature and holding time to achieve the crosslinking reaction, are extremely narrow. It was found that E V is satisfactory only in the R range.
A remained uncrosslinked, and after being made into a Taien Yoike panel product, uncrosslinked EVA leaked out from around the panel due to temperature during high temperature and high humidity tests, temperature and humidity cycle tests, and outdoor feed tests. This phenomenon occurs. On the other hand, when the holding temperature is higher than the optimum temperature range, foaming of EVA and yellowing of EVA are observed.

Furthermore, if the temperature during pressurization is low, or if the pressurization (holding time of the yarn is long), foaming occurs.

[Objective of the Invention 1] The present invention was made in view of the above-mentioned problems, and it is possible to improve the appearance and characteristics by controlling manufacturing conditions such as temperature and time during lamination when EVA is used as a filler. The purpose is to provide a solar cell panel that satisfies both.

[Summary of the invention] r The present invention degasses a solar panel laminate in which solar cells are laminated between a cover glass and a back glass through a filler using a double vacuum method, heats it, and then pressurizes it. In the method for manufacturing solar cell panels that includes a bonding process using ethylene vinyl acetate as a filler, the bonding process uses b0 pressure, and the maximum temperature after pressurization is 1.
This method of manufacturing a solar cell panel is characterized in that the temperature is in the range of 40° C. to 155° C., and the maximum temperature is held for 7 minutes to 40 minutes.

Further, the heating of the solar cell panel In body is performed using a heating method from one direction using a hot plate, and the maximum temperature after pressurization is 140 ° C. or less at the position of the solar cell panel stack closest to the hot plate. 155℃, holding time 7 minutes to 4
0 minutes, and the maximum temperature after pressurization at the position of the solar panel stack farthest from the heating plate is 140°C to 155°C1, and the holding time is in the range of 1 minute to 32 minutes. A method for manufacturing a solar cell panel characterized by:

[Embodiments of the invention] Embodiments of the present invention will be described in detail below with reference to the drawings.

That is, the bonding apparatus is of a square vacuum type having a first column 11 and a second column 12 as shown in FIG.

Although the heating method may be one that heats the entire body, a case in which heating is performed from one direction using a hot plate 15 provided below the fJJ body 14 as shown in FIG. 5 will be described in detail.

The solar cell panel laminate 14 is, for example, as shown in FIG. 4. That is, a filler 21 made of an EVA sheet with a thickness of 0.8 seconds and a solar cell 3 are connected in series or in parallel to one side of a transparent cover glass 1 made of tempered glass with a thickness of 3 m and serving as a structural support for the whole. string,
A filler material 22 made of an EVA sheet having a thickness of 20 μm and a thickness of f7 0 of 8 tym, and a backing material 4 made of a sheet having 25 μm thick PVF on both sides with an aluminum foil sandwiched in the middle and having a thickness of 25 μm. Further, at least one layer of long glass fiber mat called microglass may be inserted between each of the transparent cover glass 1, the fillers 21 and 22, the string, and the backing material 4. In the actual manufacturing process, the fourth
The stacked body 14 may have a structure that is upside down from the one shown in the figure.

A typical profile during the lamination process is shown in FIG.

That is, first, as shown in a curve 131 representing the degree of vacuum, partial evacuation is performed for 20 minutes using, for example, an oil rotary pump. As a result, the vacuum degree of both the first chamber 11 and the second chamber 12 before heating becomes, for example, 0.3 Torr.

Next, heating is started in step (2) in FIG. Laminated body 14
The temperature is experimentally measured at a position closest to the hot plate 15 using a thermal lightning pair 16 shown in FIG. 5, and at a position farthest from the hot plate 15 using a thermal lightning pair 17. The temperature increase gradient at the thermocouple 16 is, for example, 4° C./min. The temperature increase curve at the location of the thermocouple 16 is shown as a temperature curve 34 in FIG. 6, and the temperature increase curve at the location of the thermoelectric lightning pair 17 is shown as a temperature curve 35 in FIG. Generally, the temperature at which EVA melts is about 85°C and the temperature at which the crosslinking reaction begins is 130°C. Step ■ bo < , thermocouple 1
When the temperature reaches 140℃ at position 6, song 1 represents the degree of vacuum.
As shown in i132, the first Wll is returned to atmospheric pressure and the laminate 14 is vacuum-pressed. At this time, as shown by a curve 35, the temperature at the position of the thermal lightning pair 17 farthest from the hot plate 15 is not sufficiently increased. Therefore, even at the location of thermal lightning pair 17, EVA
Raise the temperature so that it crosslinks. After crimping, the positions of thermocouple 16 and thermocouple 17 exhibit almost the same temperature since the vacuum insulation is removed. Next, as in step (2), after the temperature reaches 148°C at the position of the thermocouple 16, in order to cause the crosslinking reaction to occur throughout the laminate 14, for example, the thermocouple is heated at the position of the thermocouple 16 for 25 minutes. Hold at maximum temperature for 17 minutes at position 17. Next, as in step (2), the hot plate is cooled by an air cooling tube, and after a while, as in step (2), the hot plate is cooled by a water cooling tube. After the temperature of the laminate 14 is cooled down to, for example, 50° C. or lower as in step (2), the song I! representing the degree of vacuum is played.
As shown at 33, the second chamber 12 is returned to atmospheric pressure. The bonding process is thus completed.

However, there are some limitations in terms of appearance as a solar panel.
The present inventor found that from the viewpoint of achieving the crosslinking reaction of EVA, only a narrow range of 111 was satisfied between the temperature in the lamination process, the maximum holding time of 3 degrees, and the timing of pressure bonding. Ta. That is, for example, as shown in FIG. 7, when the maximum temperature is maintained at the position of the thermocouple 16 for 25 minutes, when the maximum temperature is 141° C. or lower, the gel fraction, which represents the percentage of crosslinking, will be 50%. It became the following. Further, at 143°C, the gel fraction reached 90%. That is, if the temperature is maintained at 143° C. or higher after pressurization, EVA will achieve the chestnut reaction at all locations in the solar cell panel.

The method for measuring the gel fraction is S Dringborn.
l aho-ratories, Inc.: ℃r
osslinkable Ethy-lene/V
1nyl A cetate Copolyme
r, Formula A9918″ Technic
al 1 rrrormation Pack-
et-8system and Process (19
80), in accordance with 7. In addition, the gel fraction is 7o%
If the above is achieved, it is assumed that the crosslinking reaction has been practically achieved. When the maximum temperature reached 154° C. or higher under the same holding time as described above, a foaming phenomenon occurred due to the decomposition gas of EVA itself.

As the maximum temperature rises further, along with the foaming phenomenon, EVA
yellowing occurred. As mentioned above, even if the maximum temperature holding time at the position of thermocouple 16 is limited to 25 minutes, the optimal maximum temperature is 143°
It has a narrow temperature range of 154°C to 154°C. Further, when the holding time was increased, for example, when the maximum temperature was held at 147° C. for 40 minutes at the position of the thermal lightning pair 16, small bubbles were observed due to foaming of the EVA itself.

Summarizing the above experimental results, it is sufficient to apply pressure using a double vacuum system and then bond at the maximum temperature and holding time in the "optimum range" shown in factor 7.

That is, the maximum temperature at the thermocouple 16 at the position of the 8I layer 14 closest to the hot plate 15 is 140°C to 155'C1, and the holding time is within the range of 7 minutes to 40 minutes,
At the thermal lightning pair 17 at the farthest position of the stack 14,
The bonding may be carried out at a maximum temperature of 140° C. to 155° C. and a holding time of 1 minute to 32 minutes. Note that the 70% crosslinking line, which is considered to be the completion of the crosslinking reaction, is between the 50% and 90% lines.

When laminated in the "optimal wA range", EVA undergoes a crosslinking reaction and does not soften due to outdoor temperature changes.

In this example, we have described in detail the case in which the temperature is raised and bonded using the heating method from one direction from the hot plate, but in the case where the entire solar cell panel @layer is heated The present invention is also applicable to In this case, thermocouple 16 and thermocouple 17 show almost the same temperature, but the maximum iai temperature is 1
At temperatures below 40°C, EVA is uncrosslinked, and at temperatures above 155°C, EVA foams. Moreover, when the maximum temperature holding time reaches 40 minutes or more, small bubbles start to appear.

Note that when the maximum temperature holding time is 7 minutes or less, EVA is not crosslinked. In either heating method, lamination can be carried out in the ``most area'', but in terms of energy saving, heating from one direction is preferred.

[Effects of the Invention] If the method for manufacturing a solar cell panel according to the present invention is used, there is no foaming of EVA in appearance, and the crosslinking reaction is also achieved, so that the softening phenomenon does not occur outdoors. In addition, since it is laminated using a double vacuum method, high reliability can be obtained even in high temperature and high humidity tests and outdoor exposure test roasting.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a large circular battery panel, Fig. 2 is a schematic cross-sectional view of the back material, Fig. 3 is a schematic illustration of a double vacuum laminating device, and Fig. 4 is a stack of solar cell panels. 5 is a schematic diagram of a laminating apparatus using a double vacuum method using a heating method from one direction. FIG. ? Figure 7 shows the EVA characteristics according to maximum temperature and holding time.
FIG. 2 is a diagram showing the highest region in the state diagram of FIG. 1... Cover glass, 2.21.22... Filler,
3... Solar battery cell, 4... Back material, 11...
First chamber, 12... Second chamber, 13... Diaphragm, 14... Reconnaissance body, 15... Hot plate, 16.17.
...Thermocouple, 31.32.33...Curve representing degree of vacuum, 34°35...Curve representing temperature. Patent Attorney Patent Attorney Takehiko Suzue Figure 1 Figure 2 /4 Figure 3 Figure 4 214 Figure 5 Figure 6 Time (Extra) Figure 7

Claims (2)

[Claims] (1) A solar cell panel laminate in which solar cells are laminated between a cover glass and a back glass through a filler is degassed using a double vacuum method, and then bonded by heating and pressurizing. In the manufacturing method of battery panels, ethylene vinyl acetate is used as the filler, and in the bonding process by pressurization, the maximum temperature after pressurization is 140 ° C.
It is in the range of 55℃, and the maximum temperature holding time is 7 minutes to 4
A method for manufacturing a solar cell panel, characterized in that the solar cell panel is within a range of 0 minutes. (2) The solar panel laminate is heated by a heating method from one direction using a hot plate, and the maximum temperature after pressurization is 140°C at the position of the solar panel laminate closest to the hot plate. 155℃, holding time 7 minutes to 40℃
The maximum temperature after pressurization is between 140°C and 100°C at the position of the solar panel stack farthest from the heating plate.
The method for manufacturing a solar cell panel according to claim 1, wherein the temperature is 55° C. and the holding time thereof is in the range of 1 minute to 32 minutes.