Batteries: thermoelectric and photoelectric – Photoelectric – Panel or array
Reexamination Certificate
2002-08-28
2004-11-02
Diamond, Alan (Department: 1753)
Batteries: thermoelectric and photoelectric
Photoelectric
Panel or array
C136S291000, C136S293000, C323S906000, C363S056030, C361S049000, C361S042000
Reexamination Certificate
active
06812396
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photovoltaic power generation system that has an exposed electroactive portion.
2. Related Background Art
In recent years, awareness of ecological problems has been raised worldwide. Among others, the global warming resulting from CO
2
emission is a serious concern, and clean energy has been desired increasingly. In such a circumstance, a solar battery shows great promise to serve as a source of clean energy in terms of its safety and operability.
The solar battery includes a photoelectric conversion layer for converting light into electricity, typical materials of which include single-crystal silicon semiconductor, polycrystalline silicon semiconductor, amorphous silicon-based semiconductor, groups III-V compound semiconductor, groups II-VI compound semiconductor and groups I-III-VI
2
compound semiconductor.
An example of a typical solar cell module is shown in
FIGS. 6A and 6B
. In these figures,
FIG. 6A
is an outside view of a solar cell module
601
, and
FIG. 6B
is a sectional view taken in the line
6
B—
6
B of FIG.
6
A. As shown in
FIG. 6B
, the solar cell module
601
consists of a photovoltaic element
602
that converts received light into electricity, a solar cell envelope, and an output cable
605
for taking out an output, in rough classification. Then, the solar cell envelope comprises a front cover
603
that is made of a glass plate, a light-transmissive resin, or the like and is arranged in the side of a light-receiving surface of a photovoltaic element, a back cover
604
that is made of a glass plate, a resin, a metal plate, or the like and is arranged in the side of a non-light-receiving surface, a frame member
607
to reinforce and fix the solar cell module, and an adhesive
606
to bond the frame member.
In addition, so as to mutually connect solar cell modules in series or parallel, a cable such as an IV wire, a CV cable, or the like that is coated with insulating coating is used.
Then, since a solar cell array that uses these members is strictly given insulation measures to the solar cell modules and wiring members, a DC output generated by the solar cell array hardly flows to the ground as a leakage current Ir even in a moist state like fair weather after rainfall. Therefore, a leakage current from the solar cell array is smaller than a set current of a ground-fault interrupter (earth leakage breaker) in a receiving terminal.
A photovoltaic power generation system utilizing such a solar cell exists in a wide variety of scales from several watts to several thousands kilowatts. For example, a photovoltaic power generation system using a battery to store energy generated by the solar cell, or a photovoltaic power generation system using a DC-AC converter to supply output energy of the solar cell to a commercial electric power system (simply referred to as “system (power system)” hereinafter).
FIG. 2
is a block diagram of a typical photovoltaic power generation system disclosed in Japanese Patent Application Laid-Open No. 2000-207662. In this photovoltaic power generation system, four solar cell strings
204
to
207
are connected in parallel to constitute a solar cell array
201
, each of the solar cell strings being composed of a plurality of solar cell modules connected in series. An output of the solar cell array
201
is led to a power conditioner
202
having a controller for controlling a maximum output, for example, and then supplied to a load
203
. The load
203
may be a system, and such a system of flowing the power of the solar cell back to the system is referred to as “system-interconnecting system (utility connected system)”.
The typical structure of these system-interconnecting systems will be explained below.
FIG. 4
shows a schematic diagram of a solar cell array that uses a power conditioner without an insulating transformer. Here, reference numeral
401
denotes a solar cell array,
402
does an inverter,
403
does a differential current sensor,
404
does a switchboard,
405
does a system (power system),
406
does a load,
407
does a current I
1
that flows from a positive electrode terminal of the solar cell array,
408
does a current I
2
that flows into a negative electrode terminal of the solar cell array, and
409
does a ground-fault interrupter.
A DC—DC converter boosts an output from the solar cell array
401
, and the inverter
402
converts it into an alternating current at the commercial frequency. In the case of a single-phase three-wire system, electric power is supplied to a 200-V circuit in a single phase, and only a system-interconnecting apparatus detects three lines in a single phase. Since being small, light, and low-cost, and also reliable, this system becomes a main stream in the present power conditioners. Nevertheless, it is known that there is a demerit that, since this system is not isolated from the power conditioner, it is necessary to ground a conductive part of an envelope of a solar battery in preparation for the case where a flaw etc. arises in the envelope of the solar battery, and hence, the construction of the solar cell array becomes complicated.
In this solar cell array without an insulating transformer, it is possible to detect a ground-fault from the solar cell array
401
by the following system.
That is, when the ground-fault arises in the solar cell array
401
, a ground-fault current flows in a circuit of (solar cell array)→(ground)→(system (power system))→(power conditioner)→(solar cell array), and hence, the relation between the current
407
and current
408
that are shown in
FIG. 4
becomes off balance. The ground-fault can be detected by detecting a differential current between them.
When being connected to the system, these system-interconnecting systems are connected via each receiving terminal. In addition, other loads used are connected in these receiving terminals.
FIG. 5
shows the relation between the ground-fault interrupter
409
and load
406
that are installed in the receiving terminal.
The ground-fault interrupter comprises a zero-phase-sequence current transformer
501
, a sensitivity-switching device
502
, an amplifier
503
, a coil
504
, an opening and closing mechanism
505
, a test button
506
, and a leak display panel
507
. Reference numeral
508
denotes a system (power system),
509
denotes a load,
510
denotes a power conditioner, and
511
denotes a solar cell array.
The zero-phase-sequence current transformer
501
detects a differential current between an outgoing current from the system side and a returning current from the load. When the leak arises, that is, the differential current is a set current or more, a circuit breaker interrupts a line. In general, in such a ground-fault interrupter, it is possible to set a sensitivity current and detection time with respect to leak.
Then, it is usual that the power conditioner
510
is connected to this load
509
in parallel.
Therefore, as for a set current value of the ground-fault detector incorporated in the power conditioner
510
of the solar cell array using the conventional solar cell module, which is strictly insulated and the wiring members, and a set current value of the ground-fault interrupter installed in the receiving terminal, the set current value of the ground-fault interrupter is set larger than the set current value of the ground-fault detector. This is because it becomes almost meaningless to provide the ground-fault detector since the ground-fault interrupter unintentionally operates before the ground-fault detector operates if the set current value of the ground-fault interrupter is smaller than the set current value of the ground-fault detector.
On one side, in the power conditioners with each insulating transformer, there are two types depending on the type of a transformer.
One type of power conditioner uses a commercial-frequency transformer, and is a system to perform the insulation and voltage conversion with the commercial-frequency transformer after converti
Itoyama Shigenori
Makita Hidehisa
Matsushita Masaaki
Mimura Toshihiko
Mukai Takaaki
LandOfFree
Photovoltaic power generation system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Photovoltaic power generation system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photovoltaic power generation system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3303925