JPS6366072B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to solar cell panels. [Technical Background of the Invention] As an example of a solar cell panel, an example of a superstrate type solar cell panel aiming at low cost and high reliability will be explained with reference to FIGS. 1 and 2. That is, the transparent cover glass 1 serves as a structural support for the entire panel;
One side of the filling material 2 has a string of solar cells 3 connected in series embedded therein.
is glued. This filler 2 is usually polyvinyl petitral (hereinafter referred to as PVB).
has been used a lot. A back material 4 is adhered to the back surface of the filler 2. As shown in FIG. 2, the back surface material 4 has a three-layer structure consisting of a sandwiched metal foil, such as an aluminum foil 6, in the middle and polyvinyl fluoride (hereinafter referred to as PVF) 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, in order to promote cost reduction and high reliability of solar cell panels, it has been used as filler 2.
Ethylene vinyl acetate (hereinafter referred to as EVA) has been developed to replace PVB. That is, EVA has the following advantages when compared to PVB. (1) The material cost of EVA is lower and is currently about two-thirds the price of PVB. (2) EVA is also easier when processing materials. That is, PVB is usually rolled into a roll with a heavy coating applied to its surface to prevent the PVB from adhering itself. Therefore, when used in the process of assembling solar cell panels, it is necessary to perform humidity conditioning treatment for about one day after washing with water. In contrast, EVA
The washing process can be omitted, and the humidity control process is not as strict as with PVB. (3) Since EVA lamination is formed through a crosslinking reaction, it has excellent heat resistance and reliability. On the other hand, PVB is laminated using a principle that does not involve cross-linking reactions, so its softening properties with respect to temperature are reversible, and it softens at high temperatures. In addition, reliability test items for solar cell panels have been proposed by JPL (Jet Propulsion Laboratory) and others, and are being standardized in Japan.
(Relative humidity) Temperature/humidity cycle test in an atmosphere of 90% or higher; High temperature/humidity test at 80°C, RH90% or higher; Low temperature test at -40°C; Temperature shock test at -40°C to 80°C; These include salt fog tests under 5% salt water, and the purpose is to guarantee the lifespan of solar panels, which is said to be approximately 20 years. In order to obtain highly reliable solar panels that pass these test items, lamination using EVA requires a first vacuum pumping method, unlike the usual single vacuum pumping method using a rubber bag. It is necessary to use a double vacuum system as shown in Figure 3. That is, the first chamber 11 and the second chamber 12 are surrounded by, for example, a rigid body, and a diaphragm (diaphragm)
13, each with a valve V
1, and connects to a vacuum pump (not shown) via V2. A stacked body 14 shown by diagonal lines and containing solar cells placed in this second chamber 12 is normally constructed as shown in FIG. 4. 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, and a back material 4 of the EVA 22 are laminated in this order or in the reverse order. The bonding process for manufacturing a solar cell panel is, for example, as follows. That is, the first chamber 1
1. Evacuate the second chamber 12 and remove the laminate 14.
EVA 21 and 22 are heated in a molten state at a temperature range at which no crosslinking reaction occurs, for example, at about 120°C.
Next, the first chamber 11 is returned to atmospheric pressure while the second chamber 12 is kept in vacuum. Then diaphragm 13
The laminate 14 is compressed at the center by atmospheric pressure. Next, the EVA is heated to a temperature range where a crosslinking reaction occurs. This temperature is approximately 150°C. Maintain at this temperature until the crosslinking reaction is completed, then cool,
The laminate 14 is taken out. Through the above steps, a solar cell panel using the EVA filler 2 as shown in a part of FIG. 1 is formed, and the bonding step is completed. [Problems with the background art] However, when using a laminate with the above-mentioned material structure, EVA is pressurized in a vacuum while it is in a molten state.
Movement of solar cells occurs. That is, even if the cells 3 are fixedly set in a desired position by soldering, after bonding, for example, as shown in FIG. 5, the two rows of cells 3 in the center come into contact with each other, and the cells 3 on both sides move outward. . In severe cases, some cells 3 may even come out to the outside of the glass plate 1. To prevent this outward movement, it is possible to tape the periphery of the laminate 14, but in this case, as shown in FIG. 6, the cells 3 in each column will move to the center and the cells 3 will A phenomenon of contact occurs. If the cells 3 come into contact with each other, not only will there be problems in appearance, but also a short circuit phenomenon will occur in which the desired electromotive force cannot be obtained as a solar cell. Furthermore, in order to prevent contact between the cells 3 due to movement,
As shown in FIG. 7, on the back side of the cells 3, in addition to the ribbon leads 25 that electrically connect the cells 3, insulating bridges 26 made of a rigid body are installed to maintain a constant distance between adjacent cells in the horizontal direction. It is conceivable to fix it to the cell 3 via an adhesive. However, the large number of bridges 26 and the adhesion work make the process complicated, and even if contact between the cells 3 can be prevented, there is a problem that the entire string moves after the bonding process. That is, this is a phenomenon in which the cells 3 move to the vicinity of the end face of the cover glass or come out to the outside of the glass plate. [Object of the Invention] The present invention was made in view of the above-mentioned problems, and it is an object of the present invention to provide a low-cost, highly reliable solar cell panel in which cell movement does not occur even when EVA is used as a filler. It is an object. [Summary of the Invention] The present invention comprises a transparent cover glass, a filler containing a string consisting of a plurality of solar cells bonded to one side of the transparent cover glass and connected in series or parallel therein; A solar cell panel having a back surface material provided on the back surface of the filler, in which a group of glass fibers is provided at least directly below or immediately below the strings in the filler, the group of glass fibers is mainly the length
In an embodiment, it is made of glass fibers of 100 mm or more, the glass fiber group is formed into a mat shape, and the filler is ethylene vinyl acetate. [Embodiment of the Invention] Next, an embodiment of the solar cell panel of the present invention will be described with reference to FIG. In the figure, the same reference numerals as in the conventional example indicate the same parts. That is, on one side of a transparent cover glass 1 made of tempered glass with a thickness of 3 mm, which serves as the overall structural support, a string in which a filler 21 made of an EVA sheet with a thickness of 0.8 mm and solar cells 3 are connected in series or in parallel is attached. For example, the product name Microglass manufactured by Nippon Sheet Glass Co., Ltd.
CFG-24 (wall thickness 0.20mm) Glass fiber group 31 made by stacking two long glass fiber mats, EVA with wall thickness 0.8mm
Filler material 22 consisting of a sheet Aluminum foil with a wall thickness of 20 μm is sandwiched in the middle and thick walls are placed on both sides.
Back material 4 consisting of a sheet with 25 μm PVF
is the laminate 14. In this case, in the actual manufacturing process, they are placed on the transparent cover glass 1 in order. In other words, it is upside down from FIG. By the way, as an example of conventional use of glass fiber in solar cell panels, the US
Department of Energy Annual Report,
“Investigation of Test Methods, Materials
Properties and Process for Solar Cell
Encapsulations” (June 1979) page 10-1,
and “Final Report on the Investigation of
Proposed Process Sequence for the Array
Automated Assembly Task (Aug・1980)
Known by page233. The main purpose of these is a. To fix the distance between the solar cell and the cover glass and relieve stress. b Maintain insulation resistance between the cell and backside material. c Serves as an air passage during evacuation. It is. The conclusion from these documents is that “Craneglass 230” is the best, and Crane and
It is said to be manufactured by Company. This Craneglass 230 is a glass nonwoven fabric made of short glass fibers with a length of several tens of mm or less as a main component and hardened with a binder of 10% or more. It is clearly distinguished from, for example, long glass fibers consisting of 2m continuous fibers. Especially for micro glass CFG-24, the length is about 2m,
Whereas groups of long glass fibers with a thickness of 10 μm intersect at an angle of approximately 120 degrees, Craneglass 230 has a
It is made of short glass fibers of 10mm or less that are randomly packed together like Japanese paper. In this example, together with Microglass CFG-24
Craneglass230 (wall thickness 0.005 inch) is also 3 in Figure 8.
A similar experiment was conducted using the same method as No. 1. The laminate 14 set as shown in FIG. 8 is pasted together using a double vacuum type pasting apparatus shown in FIG. 3 in the same manner as in the prior art. A typical schedule in the bonding process is shown in FIG. That is, first, preliminary evacuation is performed for 10 minutes, for example. This allows the degree of vacuum before heating to be, for example,
It will be about 0.05Torr. Next, start heating. The temperature increase gradient is, for example, 4° C./min. The temperature at which EVA melts is approximately 85°C, and the crosslinking reaction begins at 130°C. When the temperature of the laminate 14 reaches 120°C, the first chamber 11 is returned to atmospheric pressure and the laminate 14
Crimp in vacuum. Next, the temperature is increased until it reaches 150°C, and after reaching 150°C, it is held for 20 minutes, for example, to allow the crosslinking reaction to occur sufficiently.
Next, after cooling the laminate 14 to a temperature of, for example, 50° C. or lower, the second chamber 12 is returned to atmospheric pressure.
In this case, microglass CFG-24 and
Crameglass 230 suppresses the movement of the solar cell 3 and is also compatible with EVA, allowing the string to be bonded without causing bubble defects. The bonding process is completed as described above, but in order to complete the solar cell panel, as shown in FIG. 1, a frame is formed using an aluminum frame 8 and an insulating material 7, for example, butyl rubber. Table 1 shows the results of a high temperature and high humidity test conducted as a reliability test for solar cell panels using Microglass CFG-24 and Craneglass 230. The conditions were 80°C and RH90%, and the test was carried out for up to 500 hours.

[Table] In other words, when microglass is used, it performs well in high temperature and high humidity tests, whereas
When Craneglass 230 was used, discoloration of Craneglass occurred after 168 hours. Next, microglass CFG-24 and
Table 2 shows the relationship between the maximum temperature during lamination and the appearance as an initial appearance test before conducting the reliability test when Craneglass 230 is used. The maximum temperature was maintained for 20 minutes.

[Table] In other words, when using microglass, 145
Appearance is good over a temperature range of ℃ to 160℃, whereas when Craneglass is used, the temperature is about 155℃
Craneglass begins to discolor. Next, microglass CFG-24 and
Table 3 shows the firing experiment of Craneglass 230 itself in the atmosphere, that is, the relationship between firing temperature and appearance. However, the holding time is 30 minutes.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a low-cost, high-quality, highly reliable solar cell panel in which cell movement does not occur even when inexpensive EVA is used as a filler.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the solar panel, Figure 2 is a schematic cross-sectional view of the back material, Figure 3 is a schematic illustration of a double vacuum laminating device, and Figure 4 is a conventional lamination of solar panels. 5 and 6 are explanatory diagrams illustrating defects in the arrangement of different cells that occur during the manufacturing process of solar cell panels, and Figure 7 is a cross-sectional view showing the body.
The figure is a back view showing an example of a structure that eliminates defects in cell arrangement, Figure 8 is a sectional view showing a laminate of an embodiment of the solar cell panel of the present invention, and Figure 9 is a typical lamination process. Schedule diagram, Figure 10 is
FIG. 11 is an explanatory diagram showing the cell arrangement when using Craneglass, and FIG. 11 is an explanatory diagram showing the cell arrangement when using microglass. 1... Cover glass, 2, 21, 22... Filler,
3... Solar cell, 4... Back material, 11... First chamber, 12... Second chamber, 13... Diaphragm, 14
... Laminate, 26... Bridge, 31... Long glass fiber group.

Claims (1)

[Claims] 1. A cover glass, a backing material, and a string consisting of a plurality of solar cells arranged in between and connected in series or in parallel,
In a solar cell panel having a filler made of ethylene vinyl acetate, a group of glass fibers mainly made of long glass fibers with a length of 100 mm or more is provided at least immediately below or directly above the string in the filler material. A solar panel featuring: