JPS6155271B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solar cell device in which thin film semiconductor solar cell elements provided on a substrate are connected in series.

A solar cell is a semiconductor thin film made of silicon, which has a junction such as a pn junction or a Schottky barrier as a photoelectric conversion active region, and is arranged on a substrate with electrodes on both sides. Attention has been paid. However, since this solar cell generates a low electromotive force, multiple elements must be connected in series in order to use it as a power source. When one or more of these solar cell elements connected in series does not generate an electromotive force due to shadows, etc., that element will be in a reverse bias state due to the electromotive force of the other elements, which may lead to destruction of the element. It may come to that. In order to prevent this, it is necessary to connect an anti-parallel diode 2 to each solar cell element 1 as shown in Fig. 1 so that no reverse bias is applied to the element 1, or as shown in Fig. 2, one of the elements The number of elements connected in series is 1 so that it will not be destroyed by reverse bias even if it is in the shadow.
One diode 2 is connected in antiparallel to each other, and such elements are further connected in series. This diode 2 reduces the probability that a reverse bias will be applied even when noise is applied between both ends of the series-connected elements, thereby improving reliability. However, for this purpose, it is necessary to prepare the diode 2 separately and to wire it at the time of assembling the solar cell device.

It is an object of the present invention to eliminate this drawback and provide a solar cell device with a reverse bias blocking function that can be manufactured by a simple method.

The purpose of this is to arrange a plurality of solar cell elements formed by stacking a first conductive film, a semiconductor film having a bond, and a second conductive film in order from the substrate side on the same substrate with gaps between the substrate and the first conductive film. Either the film or the second conductive film is made of a material that transmits light, and the plurality of elements are connected in series by sequentially connecting the first conductive film to the second conductive film of an adjacent element. connected, the first conductive film of the element at one end and the second conductive film at the other end are connected to one terminal, and the second conductive film of the element passing through a predetermined ordinal number from either end is connected to another terminal. This is achieved by being connected to a terminal.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 3, a transparent conductive film 5 made of, for example, ITO (indium tin oxide) is provided on a glass plate 3 serving as a substrate with a small gap 4 in between by sputtering or the like. Next, an amorphous silicon film 6 that fills this gap 4 and covers the transparent conductive film 5 is formed by plasma depositing, for example, by decomposing monosilane in a glow discharge.
It is provided through a small gap 7 by the CVD method. Furthermore, this gap 7 is filled and the silicon film 6 is covered. For example, a metal film 8 such as an aluminum vapor-deposited film is provided with a gap therebetween. Although not shown, the amorphous silicon film 6 is made up of three layers, a p layer, an i layer, and an n layer, deposited sequentially from the substrate 3 side. As is well known, such a film 6 is formed by the decomposition of monosilane (SiH ₄ ) by glow discharge, and diborane (B ₂ H ₆ ) is used to form a P-type film, and phosphine (SiH 4 ) is used to form an N-type film. PH ₃ ) into the monosilane. When light enters through the substrate 3 and the transparent conductive film 5, photoelectric conversion of the solar cell is performed by this pin junction. By configuring as shown in FIG. 3, each solar cell element 9 is connected in series.
The transparent conductive film 51 of the element 91 at one end and the metal film 82 of the element 92 at the other end are connected to the common terminal A, and the transparent conductive film 52 of the element 92, that is, the element 93 next to it, When connected to another terminal B, the connection corresponds to the equivalent diagram shown in FIG. 4. That is, another solar cell element 92 is connected in antiparallel to the series-connected solar cells from element 91 to element 93. However, since the pin junction that acts as a photoelectric conversion active region in a solar cell element also has a rectifying function, the solar cell element 9
2 acts as a diode, and the connection is exactly the same as that shown in FIG. Therefore, the number of elements 9 connected in series (eight in the case of Figures 3 and 4) is selected so as to withstand the reverse bias caused by the electromotive force of the remaining elements 9 when one of them becomes a shadow. If this is done, even when solar cell modules and arrays are created by connecting such solar cell device units in series, the reverse bias applied by other units will be bypassed by the element 92, so that the shadowed element will be cannot be destroyed.

When the amorphous silicon film 6 in FIG. 3 consists of an n layer, an i layer, and a p layer deposited sequentially from the substrate 3 side, the connection corresponds to the equivalent circuit shown in FIG. 5.

Since the element 92 has a function as a solar cell, it generates an electromotive force when light enters it, and since the polarity of the electromotive force is opposite to that of the series-connected elements, it is effective to shield this element from light.

The element 92 may be replaced by a plurality of elements connected in series. In this case, the terminal B is led out from the connection between the corresponding ordinal element and the adjacent electrode. This increases the reverse bias voltage that can be blocked by the anti-parallel connected diodes, and accordingly increases the number of solar cell elements connected in series for photoelectric conversion.

In FIG. 3, a glass plate is used as the substrate 3,
Light passes through the glass plate 3 and the transparent conductive film 5 and enters the silicon thin film 6, but a metal plate such as a stainless steel plate is used as the substrate and serves as one electrode, and a transparent conductive film is used as the counter electrode. The same method can be applied to a solar cell in which light enters through a transparent conductive film from the side opposite to the substrate.

Although the above embodiment describes a solar cell using amorphous silicon, the present invention is not limited to amorphous silicon, and can be similarly implemented in a solar cell using a polycrystalline silicon thin film deposited on a substrate. Moreover, a Schottky barrier may be formed instead of a pin junction or a pn junction, and its rectification property may be utilized.

As described above, the solar cell device according to the present invention utilizes the solar cell element itself as an anti-parallel connected diode for blocking reverse bias. Since it can be built into the top, almost no extra cost or effort is required, making it extremely economical.

[Brief explanation of the drawing]

Figures 1 and 2 are circuit diagrams of a solar cell connected with a reverse bias blocking diode, Figure 3 is a sectional view showing an embodiment of the present invention, and Figures 4 and 5 are equivalent circuit diagrams. be. 3: Substrate (glass plate), 5, 51, 52: Transparent conductive film, 6: Amorphous silicon film, 8, 82, 8
3: Metal film, 9, 91, 92, 93: Solar cell element.

Claims (1)

[Claims] 1 A plurality of solar cell elements formed by laminating a first conductive film, a semiconductor film having a junction, and a second conductive film in order from the substrate side are arranged on the same substrate with gaps between them, and the substrate, the first conductive film, and the second conductive film Any one of the two conductive films is made of a material that transmits light, and all of the plurality of elements are connected in series by sequentially connecting the first conductive film to the second conductive film of an adjacent element. , the first conductive film of the element at one end and the second conductive film at the other end are connected to one terminal, and the second conductive film of the element that has passed through a predetermined ordinal number from either end is connected to another terminal. A solar cell device characterized in that: