Field of the Invention
The present invention relates to an electric power
management system that performs an electric power management
by associating an electric power generation apparatus, such
as a photovoltaic power generation apparatus, with the
electric power system of a commercial power source.
Background of the Invention
Recently, the number of houses and offices equipped
with a photovoltaic power generation apparatus (or solar
cells) tends to increase. Power generation of the solar
cell may be characterized that an increased amount of
electric power is generated as the illuminance of sunlight
grows higher, while a reduced amount of electric power is
generated as the illuminance of sunlight becomes lower due
to the rainy weather or other causes and no power is
generated during the nighttime when there is no sunlight.
For that reason, the power generation pattern thereof is not
consistent with the power consumption pattern in houses or
other places for many cases. Further, it is often the case
that the generated power amount becomes excessively smaller
than the consumed power amount. Accordingly, even if a

house is equipped with a solar cell, the house is usually
connected to an electric power system of a commercial power
source so that, when the generated power amount is
insufficient, the deficient electric power can be supplied
(bought) from the commercial power source, and when surplus
electric power is generated, the surplus electric power is
reversely supplied (sold) to the commercial power source.
The electric power generated by the solar cell differs
in nature from the electric power of the commercial power
source. In light of this, the electric power generated by
the solar cell is converted, by a power conditioner
including an inverter and the like, to an electric power
having the same nature as that of the alternating current
power of the commercial power source and is used in
association with the electric power system of the commercial
power source. This makes it possible to use, in
combination, the electric power generated by the solar cell
in a house or other places and the electric power of the
commercial power source. That is, the power conditioner is
a device for converting the electric power generated by the
solar cells so as to be made consistent with the electric
power of the commercial power source in a voltage, a
frequency and a phase, and an example thereof is described
in Patent document 1.
The power conditioner described in Patent document 1
is configured to boost the voltage of a DC power generated

by solar cells by using a step-up chopper, to convert the DC
power into an AC power by using an inverter, and to output
the AC power. An electric appliance and the electric power
system of a commercial power source are connected to the
output of the power conditioner. As described above, the
power conditioner makes the power generated by the solar
cells consistent to be associated with the electric power
system of the commercial power source. The power
conditioner converts the voltage of the power generated by
the solar cells into a voltage higher than the voltage of
the electric power system of the commercial power source and
outputs the high voltage. Then, the power conditioner
supplies the output power to the electric appliance, and
reversely supplies (sells) surplus power, which is not
consumed by the electric appliance, to the electric power
system of the commercial power source.
Patent document 1: Japanese Patent Application
Publication No. 2007-97310
When the surplus power is reversely supplied (output)
to the commercial power source, the power conditioner
increases the voltage of the output power to a voltage
higher than the voltage of the electric power system of the
commercial power source. However, if high-voltage powers
are simultaneously outputted from multiple houses, the
voltage of the electric power system of the commercial power
source may be considerably increased. Furthermore, the

increase in voltage may cause a variation, exceeding an
allowable value, in the power of the electric power system
of the commercial power source, and reduces the voltage
difference between the voltage of the output power of the
power conditioner and the voltage of the electric power
system of the commercial power source, thereby reducing the
amount of power outputted (sold) from the power conditioner
to the electric power system of the commercial power source.
Summary of the Invention
In view of the above, the present invention provides
an electric power management system capable of stabilizing
the quality of electric power to the electric power system
of the commercial power source even when multiple power
generation apparatuses, such as solar cells, are connected
thereto.
In accordance with an embodiment of the present
invention, there is provided an electric power management
system for coordinating and managing an amount of electric
power outputted from a power generation apparatus for
generating the electric power to an electric power system of
a commercial power source, the electric power management
system including: a power meter for receiving grid-connected
information, which is information related to stabilization
of electric power of an electric power system from a

management center for managing the electric power of the
electric power system; and a power conditioner for
outputting the electric power generated by the power
generation apparatus to the electric power system based on
the grid-connected information.
Further, the power meter is connected to the electric
power system and configured to detect an amount of electric
power inputted from the electric power system and an amount
of electric power outputted to the electric power system.
The power meter receives the grid-connected information from
the management center through a first communications unit.
The power conditioner is connected to the power generation
apparatus and the electric appliance through respective
power lines and acquires the grid-connected information from
the power meter through a second communications unit. The
power conditioner outputs the electric power generated by
the power generation apparatus to the electric power system
based on the grid-connected information.
The AC power quality (frequency, voltage, and the
like) of the electric power system of the commercial power
source is stabilized in a predetermined state, and the
electric power from an power generation apparatus, such as
an independent power generation apparatus (photovoltaic
power generation apparatus), is outputted to the electric
power system of the commercial power source to be connected
to the power generation apparatus after grid-connection is

achieved. In other words, the quality of the power from the
power generation apparatus is adjusted to be consistent with
that of the AC power of the electric power system of the
commercial power source, and the adjusted power is outputted
to the electric power system of the commercial power source
after the voltage of the power is adjusted to a voltage that
is higher than a voltage of the electric power system of the
commercial power source.
In this case, when the supply of power to the electric
power system of the commercial power source is performed by
multiple power generation apparatuses, the voltage of the
electric power system of the commercial power source may be
increased. Furthermore, the increase in the voltage of the
electric power system of the commercial power source may
cause the problem of reducing the difference between the
output voltage of each of the power generation apparatuses
and the voltage of the electric power system of the
commercial power source, which results in reduction of the
amount of power to be outputted to the electric power system
of the commercial power source.
However, with such configuration, the grid-connected
information, which is information related to the electric
power stabilization of the electric power system of the
commercial power source that the power meter is received
from a management center, is also shared to the power
conditioner, and the electric power is outputted to the

electric power system of the commercial power source from
the power conditioner based on the grid-connected
information. Since the grid-connected information is
information related to the power stabilization of the
electric power system of the commercial power source, the
appropriate electric power based on the grid-connected
information can be outputted to the electric power system of
the commercial power source by the power conditioner.
Further, the power conditioner can output the electric power
to the electric power system of the commercial power source
at an appropriate timing based on the grid-connected
information. Accordingly, in accordance with the electric
power management system, the quality of electric power can
be stabilized by suppressing an increase in the voltage of
the electric power system of the commercial power source and
the like.
Further, grid-connected information is reliably and
accurately transmitted to the power meter from the
management center through the first communications unit
managed same as the electric power system of the commercial
power source. Accordingly, since such grid-connected
information is used by the power conditioner, the grid
connection of output power therefrom can. be achieved more
accurately, so that the stabilization of the power quality
of the electric power system of the commercial power source
can be maintained.

In the electric power management system, the power
generation apparatus may be provided in plural numbers, and
electric power generated by one of the power generation
apparatuses may be stored in a battery device storing
electric power, the battery device being another one of the
power generation apparatuses.
With such configuration, since the electric power
generated by the power generation apparatus can be stored in
the battery device, the electric power generated by the
power generation apparatus can be supplied to the electric
power system of the commercial power source at an
appropriate timing based on the grid-connected information.
That is, the electric power to be consumed soon after
generation is temporarily stored, and therefore the electric
power can be efficiently outputted to the electric power
system of the commercial power source based on the grid-
connected information regardless of the timing of the
generation, so that the electric power quality of the
electric power system of the commercial power source is
stabilized. Furthermore, the power generation apparatus can
output a greater amount of electric power to the electric
power system of the commercial power source.
Further, if it is determined based on the grid-
connected information that the electric power generated by
said one of the power generation apparatuses cannot be
outputted to the electric power system of the commercial

power source, the power conditioner may store the electric
power, which is not consumed by the electric appliance, in
the battery device.
With such configuration, in case where the electric
power generated by the power generation apparatus cannot be
outputted to the electric power system of the commercial
power source in accordance with the determination based on
the grid-connected information, the electric power, which is
not consumed, is stored, thereby minimizing the waste of the
generated electric power.
Further, if it is determined based on the grid-
connected information that the electric power generated by
said one of the power generation apparatuses can be
outputted to the electric power system of the commercial
power source, the power conditioner may output the electric
power, which is generated by said one of the power
generation apparatuses and stores in the battery device,
from the corresponding battery device to the electric power
system of the commercial power source.
With such configuration, in case where the electric
power generated by the power generation apparatus can be
outputted to the electric power system of the commercial
power source in accordance with the determination based on
the grid-connected information, the electric power generated
by the power generation apparatus and temporarily stored in
the battery device can be outputted to the electric power

system of the commercial power source based on the preferred
conditions, and therefore an increase in the amount of
output power can be expected. Accordingly, when power is
output to the electric power system of the commercial power
source, the electric power can be efficiently outputted to
the electric power system of the commercial power source and
there is no concern about the output power making the power
quality of the electric power system of the commercial power
source unstable.
Further, the management center may acquire, as the
grid-connected information, status information of the power
generation apparatus from the power meter through the first
communications unit, the status information being acquired
by the power meter from the power conditioner corresponding
to the power meter connected to the electric power system of
the commercial power source through the second
communications unit, and the management center may generate,
based on the acquired information, grid-connected
information including conditions for output power under
which electric power is outputted to the electric power
system of the commercial power source by the power
conditioner.
With such configuration, the power conditioner is
controlled by the management center such that the electric
power is outputted to the electric power system of the
commercial power source by the power conditioner based on

the conditions for power output included in the grid-
connected information, which is produced based on the
contexts of the power generation apparatus, and therefore
the power quality of the electric power system of the
commercial power source is further improved.
Further, the power generation apparatus may further
include a photovoltaic power generation apparatus. The
status information of the power generation apparatus may
include generation information indicative of an amount of
electric power generated by the photovoltaic power
generation apparatus, and illuminance information indicative
of illuminance of light irradiating the photovoltaic power
generation apparatus, which serves as environmental
information indicative of surrounding environmental status
of the photovoltaic power generation apparatus. Further,
the management center may generate the conditions for output
power included in the grid-connected information based on
the amount of electric power generated by the photovoltaic
power generation apparatus, the amount of the electric power
being obtained based on the illuminance information and the
generation information of the photovoltaic power generation
apparatus.
With such configuration, since the conditions for
power output included in the grid-connected information are
generated based the amount of electric power generated by
the photovoltaic power generation apparatus obtained based

on generation information and illuminance information, which
serves as environmental information, the electric power
generated by the photovoltaic power generation apparatus can
be efficiently outputted to the electric power system.
Accordingly, more appropriate conditions for power output
can be provided to the power generation apparatus, so that
the stabilization of the electric power system of the
commercial power source and the efficient use of the power
generated by the power generation apparatus are further
promoted.
Further, the power meter may be provided in plural
numbers and the power meters may be connected to the
electric power system of the commercial power source. The
management center may estimate a change in illuminance of
the photovoltaic power generation apparatus corresponding to
each of the power meters, based on the illuminance
information inputted through each of the power meters and
location information indicative of a location of each of the
power meters that outputs the illuminance information, and
the management center may generate the grid-connected
information based on the estimated change in illuminance.
With such configuration, the actually measured
illuminance is collected through each power meter whose
location is individually designated based on location
information, and a change in the illuminance of the
photovoltaic power generation apparatus corresponding to

each power meter is estimated based on the distribution of
the illuminance information. Accordingly, the accuracy of
the estimation of the power generation amount of the
photovoltaic power generation apparatus is improved, and the
stabilization of the electric power system of the commercial
power source can be improved using the grid-connected
information generated based on the above estimation.
Further, the power conditioner may function as a
estimation control unit for measuring and storing past power
management data and producing estimated power consumption
information indicative of an amount of electric power
currently consumed, based on the stored power management
data, and the management center may generate the grid-
connected information by referring to the estimated power
consumption information acquired from the power conditioner.
With such configuration, since the management center
can perform the high-precision estimation of the power
consumption amount of the power conditioner, the
stabilization of the electric power system of the commercial
power source can be performed in a planned manner.
Further, the management center and the power meter may
perform relay communications through a base unit provided on
a pole, and, among the communications between the management
center and the base unit and the communications between the
base unit and the power meter, the first communications unit
may be configured such that the communications between the

base unit and the power meter is wireless or wired
communications.
With such configuration, the communications between
the power meter and the base unit is performed in a wireless
manner, the power meter does not require wiring installation
for communications, and the time and space required for the
wiring installation of a communications line to the power
meter are eliminated. When the communications between the
power meter and the base unit is performed in a wired
manner, communications equipment is simplified and stable
communications is ensured. For example, when power line
communications is used as the wired communications, the
wired communications between the power meter and the base
unit can be performed without requiring new wiring
installation for communications, thereby saving on wiring in
the electric power management system.
Brief Description of the Drawings
The objects and features of the present invention will
be apparent from the following description of preferred
embodiments which is given in conjunction with the
accompanying drawings, in which:
Fig. 1 is a functional block diagram illustrating a
schematic configuration of a power supply system which forms
a part of an electric power management system in accordance

with a first embodiment of the present invention;
Figs. 2A and 2B show a specific configuration of the
power management system of the first embodiment;
Fig. 3 schematically shows a connection for
communications between a power meter and a power conditioner
in the electric power management system of the first
embodiment;
Fig. 4 schematically shows a connection for
communications between a grid-connected server and the power
conditioner of the first embodiment;
Fig. 5 illustrates relationships between devices
during the power selling process of the power conditioner of
the first embodiment;
Fig. 6 schematically illustrates relationships among
multiple power supply systems associated with the power
management system of the first embodiment;
Fig. 7 schematically illustrates a case where
communications between a power meter and a power conditioner
is performed through an external network in an electric
power management system in accordance with a second
embodiment of the present invention;
Fig. 8 schematically illustrates a case where
communications between a power meter and a power conditioner
xs performed through the server of an external
communications network in an electric power management
system in accordance with a third embodiment of the present

invention;
Fig. 9 schematically illustrates a case where
communications between a power meter and a power conditioner
is performed through an electric power company connected to
an external network in the power management system in
accordance with a fourth embodiment of the present
invention;
Figs. 10A and 10B illustrate examples of the
communications of each of the first to fourth embodiments,
wherein Fig. 10A illustrates an example in which
communications between a base unit and a power meter is
wireless communications, and Fig. 10B illustrates an example
in which communications between a power meter and a power
conditioner is wireless communications;
Fig. 11 illustrates an example in which communications
between a power meter and a power conditioner is power line
communications (PLC) in each of the first to fourth
embodiments ;
Fig. 12 illustrates an example in which a power is
supplied to the power meter from a battery when the electric
power system is subjected to power failure in each of the
first to fourth embodiments;
Fig. 13 illustrates an example of the power meter of
each of the first to fourth embodiments; and
Fig. 14 is a perspective view illustrating an example
in which a camera has been provided in the power meter of

each of the first to fourth embodiments.
Detailed Description of the Preferred Embodiments
Hereinafter, embodiments of the present invention will
be described with reference to the accompanying drawings
which form a part hereof. Throughout the drawings, like
reference numerals will be given to like parts, and
redundant description thereof will be omitted.
(First embodiment)
An electric power management system in accordance with
a first embodiment of the present invention will be
described in detail. Fig. 1 is a functional block diagram
showing a schematic configuration of a power supply system 1
which forms a part of the electric power management system.
As shown in Fig. 1, a house is provided with the power
supply system 1 for supplying an electric power to a variety
of home appliances (such as an illuminating device, an air
conditioner, an electrical device and an audiovisual
device). In the following description, a single house will
be taken as an example of the building to which the present
invention is applied. However, it is not limited thereto.
For example, the present invention may also be applied to
building or collective housings such as an office, a
shopping arcade and a factory. The power supply system 1
supplies the electric power of a home-use commercial AC

source (or a commercial power source) 2 and further supplies
the electric power from a solar cell 3 generating electric
power with the sunlight to operate various kinds of
appliances. The power supply system 1 supplies the electric
power to not only DC appliances 5 operated with the DC power
inputted from a DC power supply but also an AC appliance 6
operated with the AC power inputted from an AC power supply
2 .
The power supply system 1 is provided with a power
conditioner 50 including a controller 7 and a DC
distribution board (in which a DC breaker is arranged) 8.
The power supply system 1 is further provided with a control
unit 9 and a relay unit 10 for controlling operations of the
DC appliances 5 installed in the house.
An AC distribution board 11 for dividing the AC power
is connected to the controller 7 through an AC power line
12. The controller 7 is connected to the commercial AC
power source 2 via the AC distribution board 11 and is
connected to the solar cell 3 via a DC power line 13. The
controller 7 receives AC power from the AC distribution
board 11 and receives DC power from the solar cell 3. The
controller 7 converts the AC power and the DC power to a
specified DC power to be used as the source power of the
appliances. The controller 7 outputs the converted DC power
to the DC distribution board 8 through a DC power line 14 or
to a battery 16 through a DC power line 15 to thereby store

the DC power in the battery 16. Not only does the
controller 7 receive the AC power from the AC distribution
board 11 but also the controller 7 can convert the electric
power from the solar cell 3 or the battery 16 to an AC power
and supply the AC power to the AC distribution board 11.
The controller 7 "exchanges data with the DC distribution
board 8 through a signal line 17. An illuminometer 42 for
measuring the illuminance of the light irradiated on the
solar cell 3 is connected to the controller 7. Illuminance
information as environmental information such as an
illuminance value is transmitted from the illuminometer 42
to the controller 7.
The DC distribution board 8 is a kind of breaker for
the DC power. The DC distribution board 8 divides the DC
power inputted from the controller 7 and outputs the divided
DC power to the control unit 9 through a DC power line 18 or
to the relay unit 10 through a DC power line 19. The DC
distribution board 8 exchanges data with the control unit 9
through a signal line 20 or with the relay unit 10 through a
signal line 21.
In the power supply system 1, the power conditioner 50
for coordinating power management in the power supply system
1 is configured in such a fashion as to include the
controller 7 and the DC distribution board 8. In other
words, the power conditioner 50 is connected to the AC
distribution board 11, the solar cell 3, the battery 16 and

the DC appliances 5 through individual power lines. Based on
this, the power conditioner 50 is configured to measure the
power information on the AC power supplied or reversely
supplied (inputted or outputted) to or from the AC power
source 2 and to measure the power information (power
generation information) on the electric power generated by
the solar cell 3 and the power information on the DC power
consumed in the DC appliances 5.
Examples of the power information on the AC power
include a voltage, a current, an electric power amount, a
frequency and a phase. Examples of the power information on
the DC power include a voltage, a current and an electric
power amount. The power information selected from them is
measured in the power conditioner 50. In the power
conditioner 50, the power information on the AC power source
2 and the power information of the solar cell 3 and the DC
appliances 5 thus measured are collected.
A plurality of DC appliances 5 is connected to the
control unit 9. The DC appliances 5 are connected to the
control unit 9 through respective DC supply lines 22 through
which both DC power and data can be transmitted by using the
same wiring. Communications signals for transmitting data
with a high-frequency carrier wave are overlapped with the
DC power to be supplied to the DC appliances 5 and are
transmitted through the respective DC supply lines 22. For
example, both the electric power and the data are

transmitted to each of the DC appliances 5 by using a pair
of lines. The control unit 9 receives the DC power for the
DC appliances 5 through a DC power line 18 and determines
how to control which of the DC appliances 5 based on an
operation instruction obtained from the DC distribution
board 8 through a signal line 20. Then, the control unit 9
outputs the DC power and the operation instruction to the
designated DC appliances 5 through the corresponding DC
supply lines 22, thereby controlling the operations of the
DC appliances 5.
Switches 23 that are manipulated when the operations
of the DC appliances 5 are switched over are connected to
the control unit 9 through a DC supply line 22. In
addition, a sensor 24 for detecting radio waves transmitted
from, e.g., an infrared remote controller is connected to
the control unit 9 through the DC supply line 22.
Accordingly, the DC appliances 5 are controlled by
transmitting communications signals through the DC supply
lines 22 in response not only to the operation instruction
from the DC distribution board 8 but also to the
manipulation of the switches 23 and the detection in the
sensor 24.
Further, the control unit 9 can transfer the power
information on the electric power amounts consumed by the
respective DC appliances 5 and the like to the power
conditioner 50 (or the DC distribution board 8) through a

signal line 20. As a result, the power information of the
respective DC appliances 5 connected to the control unit 9
is collected in the power conditioner 50. Alternatively,
the DC appliances 5 connected to the control unit 9 through
the respective DC supply lines 22 can transfer the power
information on the electric power amounts detected by
themselves and the like to the power conditioner 50 through
the control unit 9 so that the information can be collected
in the power conditioner 50.
A plurality of DC appliances 5 is connected to the
relay unit 10 through individual DC power lines 25. The
relay unit 10 obtains the DC power for the DC appliances 5
through a DC power line 19, and determines which of the DC
appliances 5 is to be operated based on an operation
instruction obtained from the DC distribution board 8
through the signal line 21.
Further, the relay unit 10 controls the operations of
the DC appliances 5 determined to be operated in such a way
that relays built therein turn on and off the supply of
powers through the DC power lines 25. A plurality of
switches 26 for manually operating the DC appliances 5 is
connected to the relay unit 10. The DC appliances 5 are
controlled by manually manipulating the switches 2 6 to cause
the relays to turn on and off the supply of powers to the DC
power lines 25. The relay unit 10 can transfer the power
information on the electric power amounts consumed by the

respective DC appliances 5 and the like to the power
conditioner 50 (or the DC distribution board 8) through the
signal line 21. As a result, the power information of the
respective DC appliances 5 connected to the relay unit 10 is
collected in the power conditioner 50.
In other words, various kinds of power information of
the power supply system 1 such as the power information
measured by the power conditioner 50 itself and the power
information detected by the control unit 9 and the relay
unit 10 are collected in the power conditioner 50. These
types of power information can be utilized as power
management data in the power supply system 1. Furthermore,
the power conditioner 50 can generate estimated consumption
information indicating the current power consumption amount
based on the power management data obtainable from the power
information. That is, the power conditioner 50 also has a
function of an estimation control unit for producing
estimated power consumption information. Furthermore, the
power conditioner 50 may generate grid-connected information
based on power information measured by the power conditioner
50 itself, power information detected by the control unit 9
or relay unit 10, or power information received from the
power conditioner of some other power supply system.
DC 'sockets 27 installed in the house in the form of,
e.g., a wall socket or a floor socket, are connected to the
DC distribution board 8 through a DC power line 28. If the

plugs (not shown) of the DC appliances 5 are inserted into
the DC sockets 27, it is possible to directly supply the DC
power to the DC appliances 5.
A power meter 29 capable of remotely measuring the
amount of the power used by the commercial AC power source 2
is connected between the commercial AC power source 2 and
the AC distribution board 11. The power meter 29 is
equipped with not only a function of remotely measuring an
amount of power used by the commercial AC power source 2 but
also, e.g., a power line communications (PLC) function and a
wireless communications function. The power meter 29
transmits measurement results to an electric power company
or the like through power line communications or wireless
communications.
In the present embodiment, the communications between
the power meter 29 which transfers the measurement results
to the electric 'power company and the power company is
performed as follows. Communications is performed between
the power company and an electric pole through a well-known
communications line. Moreover, communications is performed
between the communications line and the power meter 29 by
virtue of power line communications in which a lead-in power
line 2A connected to a step-down transformer TR (see Figs.
2A and 2B) is used as a communications medium.
The power supply system 1 is provided with a network
system 30 that makes it possible to control various kinds of

home appliances through network communications. The network
system 30 includes a home server 31 that functions as a
control unit thereof. The home server 31 is connected to an
outdoor management server 32 through an external
communications network N such as the Internet and is also
connected to home appliances 34 through a signal line, 33.
The home server 31 is operated by the DC power supplied from
the DC distribution board 8 through a DC power line 35.
A control box 36 for managing the operations of
various kinds of home appliances controlled through network
communications is connected to the home server 31 through a
signal line 37. The control box 36 is connected to the
controller 7 and the DC distribution board 8 through a
signal line 17. The control box 36 is capable of directly
controlling the DC appliances 5 through a DC supply line 38.
A gas/tap water meter 39 capable of remotely measuring,
e.g., the amounts of gas and tap water used, is connected to
the control box 36. The control box 36 is connected to an
operation panel 40 of the network system 30. A monitoring
device 41 formed of, e.g., a door phone extension unit, a
sensor or a camera, is connected to the operation panel 40.
If an operation instruction to operate the various
kinds of home appliances is inputted through the external
communications network NT, the home server 31 notifies the
control box 36 of the operation instruction and operates the
control box 36 so that the home appliances can be operated

based on the operation instruction. Moreover, the home
server 31 can provide various kinds of information obtained
from the gas/tap water meter 39 to the management server 32
through the external communications network N. If an
abnormality detected by the monitoring device 41 is notified
to the home server 31 through the operation panel 40, the
home server 31 provides the information on the detected
abnormality to the management server 32 through the external
communications network N.
Next, the specific configuration of the electric power
management system in accordance with the present embodiment
will be described with reference to Figs. 2 to 4. Figs. 2A
and 2B specifically show the configuration of the electric
power management system. Fig. 3 schematically shows the
configuration of a communications line between the power
meter 2 9 and the power conditioner 50, and Fig. 4
schematically illustrates a communications line between the
power conditioner 50 and a grid-connected server 61.
Although, in Fig. 3, Figs. 7 to 9 and Figs. 11 to 13, the
power meter 2 9 and the power conditioner 50 are connected to
each other by way" of the AC distribution board 11, this is
illustrated by a dotted line 2B for simplicity of
illustration.
As shown in Figs. 2A and 2B, the power supply system 1
provided in a house or other places is connected through the
power meter 29 to an electric power system of the AC power

source 2 managed by an electric power company 60. That is,
a plurality of power meters 29 is connected to the electric
power system of the AC power source 2 through individual
lead-in power lines 2A from a step-down transformer TR.
Furthermore, the power meters 29 are provided with extension
units 68 having the function of making power line
communications with a base unit 66 disposed on an electric
pole, and the base unit 66 on the electric pole and the
extension unit 68 of each of the power meters 29 are
connected to each other through the power signal line 67 and
the lead-in power line 2A with the step-down transformer TR
interposed therebetween. That is, the lead-in power line 2A
transmits AC power between the electric power system and the
power meter 29, and serves as a communications medium
through which a power line communications signal is
transmitted between the base unit 66 and the extension unit
68 of each of the power meter 29.
The electric power company 60 has a dedicated
communications line 64 used in remotely reading the amount
of power measured by the power meter 29. The communications
line 64 is similar in form to the wiring line of the
electric power system of the AC power source 2. The base
unit 66 is communicatively connected to the communications
line 64 through a communications line 65 and a media
converter 63. That is, the base unit 66 enables
communications signals to be exchanged between the

communications line 64 and the power signal line 67 and
converts the type of received signals into the type of
transmitted signals and vice versa. Furthermore, a meter
reading server (not shown) of the electric power company 60
is communicatively connected to the communications line 64.
Accordingly, the meter reading server can perform a so-
called remote reading that acquires the amount of power (the
meter reading results) measured by each of the power meters
29 communicatively connected through the communications line
64 and records the amount of power thus acquired.
Furthermore, the electric power company 60 has a grid-
connected server (management center) 61 for managing
information used to stabilize AC power flowing through the
power system of the commercial power source, and the grid-
connected server 61 is communicatively connected to the
communications line 64 through the communications line 62
and the media converter 63. Accordingly, the grid-connected
server 61 of the electric power company 60 is
communicatively connected to the power meters 29, connected
to the communications line 64, through the communications
line 64.
For example, the grid-connected server 61 generates
and stores grid-connected information, that is, information
for use in stabilizing the AC power of the electric power
system managed by the electric power company 60, based on
pieces of power information such as the power generation

amounts of the respective power plants held by the electric
power company 60, the power consumption amounts of the
respective electric power systems distinguished for
respective areas, and the power amounts reversely supplied
to the electric power system from the solar cells 3 or the
like. That is, each of the power meters 29 communicatively
connected to the grid-connected server 61 is configured to
obtain grid-connected information for use in stabilizing the
above-described electric power system from the grid-
connected server 61.
Further, the grid-connected server 61 generates grid-
connected information that determines an electric power to
be outputted from each of the power plants or each group of
solar cells 3 to the electric power system of the commercial
power source such that the appropriate power is supplied to
the electric power system of the corresponding commercial
power source, based on an estimation on the power
consumption amount of the electric power system of
commercial power source obtained mainly from the past
records.
Therefore, the accuracy of the grid-connected
information is improved by generating the grid-connected
information based on a more accurate estimation on the power
consumption amounts obtained by using the power information
having the estimated power consumption information and the
like, information on the power generation amounts of the

solar cells 3 and the like, in addition to the past records
of the electric power company.
Furthermore, in the present embodiment, the
communications between the grid-connected server 61 and the
power meter 2 9 is performed by the first communications
unit. That is, the first communications unit includes the
communications line 64, the base unit 66, the lead-in power
line 2A, and the extension unit 68 of the power meter 29
that communicatively connect the grid-connected server 61
and the power meter 2 9 to each other. Furthermore, the
first communications unit, as described above, performs
communications between the electric power company 60 and the
base unit 66 on the electric pole and communications between
the base unit 66 on the electric pole and the power meter
29.
As shown in Fig. 3, the power conditioner 50 is
provided with a subordinate extension unit 70 having the
function of making communications with the extension unit 68
of the power meter 29. The extension unit 68 of the power
meter 29 and the subordinate extension unit 70 of the power
conditioner 50 perform wired communications through a
dedicated communications line 69 connecting them.
Accordingly, the power meter 29 and the power conditioner 50
transfer AC power through the power line 2B, and transmit
communications signals through the dedicated communications
line 69. However, the communications between the extension

unit 68 of the power meter 29 and the subordinate extension
unit 70 of the power conditioner 50 is not limited to the
wired communications performed through the dedicated
communications line 69. In the present embodiment, a second
communications unit is configured to communicatively connect
the power meter 29 and the power conditioner 50 to each
other. That is, the second communications unit includes the
extension unit 68 of the power meter 29, the subordinate
extension unit 70 of the power conditioner 50, and the
dedicated communications line 69.
As shown in Fig. 4, the power meter 29 is provided
with a memory device 29DB, and power information 29J,
including the current, voltage, amount of power and the like
measured by the power meter 29 with respect to AC power
supplied and reversely supplied via the power meter 29, is
stored in the memory device 29DB. Furthermore, the power
conditioner 50 is provided with a memory device 50DB, and
power information 50J, including the various types of power
information collected in the power conditioner 50 or the
estimated power consumption information, is stored in the
memory device 50DB. Furthermore, the grid-connected server
61 is provided with a memory device 61DB, and various types
of power information 61J, including the power generation
amount of each power plant, the power consumption amount of
each electric power system, and the amount of power
reversely supplied to the electric power system, are stored

in the memory device 61DB.
Furthermore, since the power meter 29 and the power
conditioner 50 are communicatively connected to each other,
the power meter 29 may acquire the power information 50J of
the power conditioner 50 and store it in the memory device
29DB as the power information 29J. On the contrary, the
power conditioner 50 may acquire the power information 29J
of the power meter 29 and store it in the memory device 50DB
as the power information 50J.
Furthermore, since the grid-connected server 61 and
the power meter 29 are communicatively connected to each
other, the grid-connected server 61 may acquire the power
information 29J of the power meter 29 and store it in the
memory device 61DB as the power information 61J. On the
contrary, the power meter 29 may acquire the power
information 61J of the grid-connected server 61 and store it
in the memory device 29DB as the power information 29J.
Accordingly, the grid-connected server 61 and the power
conditioner 50 can transfer information to each other via
the power meter 29, the grid-connected server 61 may acquire
the power information 50J of the power conditioner 50 via
the memory device 29DB of the power meter 29 and store it in
the memory device 61DB as the power information 61J. On the
contrary, the power conditioner 50 may acquire the power
information 61J of the grid-connected server 61 via the
memory device 29DB of the power meter 29 and store it in the

memory device 50DB as the power information 50J.
Furthermore, the grid-connected information 61K
generated to stabilize the electric power system of the
commercial power source is also stored in the grid-connected
server 61 of the memory device 61DB. That is, similar to
the power information 61J of the grid-connected server 61,
this grid-connected information 61K can be acquired by the
power meter 29 and be stored in the memory device 29DB as
the grid-connected information 29K and may be acquired by
the power conditioner 50 and stored in the memory device
50DB as the grid-connected information 50K. That is, the
power conditioner. 50 can share various types of power
information 50J or grid-connected information 50K not only
with the power meter 29 but also with the grid-connected
server 61.
Next, the stabilization of the electric power system
of the commercial power source based on the grid-connected
information will be described with reference to Figs. 5 and
6. Fig. 5 shows a sequence of information processing in the
power management system when the power conditioner 50
outputs power generated by the solar cells 3 to the electric
power system of the commercial power source, and Fig. 6 is a
schematic view of the electric power system of the AC power
source 2 and the communications line 64 connected to the
grid-connected server 61.
Generally, the AC power quality (frequency, voltage.

and the like) of the electric power system of the AC power
source 2 is stabilized in a predetermined state, and the
power from an power generation apparatus, such as the solar
cells 3, is adjusted to be consistent with the quality of
the AC power of the electric power system of the commercial
power source to be connected to the power generation
apparatus. After such grid-connection is achieved, the
adjusted power is outputted to the electric power system of
the commercial power source. In other words, the quality of
the power of the solar cells 3 is adjusted to be consistent
with that of the AC power of the electric power system of
the commercial power source by the power conditioner 50, and
the adjusted power is outputted to the electric power system
of the commercial power source after the voltage of the
power is adjusted to a voltage that is higher than a voltage
of the electric power system of the commercial power source.
In this case, when the reverse supply (output) of
power to the electric power system of the commercial power
source is performed by a plurality of solar cells 3 (power
conditioners 50) , the voltage of the electric power system
of the commercial power source may be increased.
Furthermore, the increase in the voltage of the electric
power system of the commercial power source may cause the
problem of reducing the difference between the output
voltage of the power conditioner 50 (solar cells 3) and the
voltage of the electric power system of the commercial power

source, resulting in reduction of the amount of power
outputted from each power conditioner 50 (solar cells 3) to
the electric power system.
Accordingly, in the present embodiment, the power
conditioner 50 outputs the power of the solar cells 3 to the
electric power system of the commercial power source based
on the grid-connected information 50K acquired from the
grid-connected server 61. Specifically, as shown in Fig. 5,
when surplus power that is not consumed by electric
appliances is produced in the power generated by the solar
cells 3 (step S10), the power conditioner 50 transmits power
selling request information Jl requesting permission to the
grid-connected, server to output (sell) the corresponding
surplus power from the power conditioner 50 to the electric
power system of the commercial power source. The power
selling request information Jl is transmitted to the grid-
connected server 61 from the subordinate extension unit 70
of the power conditioner 50 through the extension unit 68 of
the power meter 29 and the base unit 66 on the electric pole
in such a way that the power information 50J of the power
conditioner 50 is acquired by the grid-connected server 61.
When the grid-connected server 61 receives the power
selling request information Jl from the power conditioner
50, the conditions for the power output permitted to the
corresponding power conditioner 50, that is, the power
buying conditions of the electric power company 60 are set

as the grid-connected information 61K generated based on
various types of power information 61J (step S20) .
Furthermore, the grid-connected server 61 transmits to the
corresponding power conditioner 50 the grid-connected
information 61K in which the corresponding conditions for
power output (the power buying conditions) are set. The
grid-connected information 61K transmitted by the grid-
connected server 61 is transferred to the power conditioner
50 through the base unit 66 on the electric pole, the
extension unit 68 of the power meter 29, and the subordinate
extension unit 70 of the power conditioner 50 in sequence.
When the grid-connected information 61K is
transferred, the power conditioner 50 performs a power
selling control for outputting (selling) an electric power
to the electric power system of the commercial power source
based on the conditions for power output (the power buying
conditions) included in the corresponding grid-connected
information 61K (step S30). The voltage outputted from the
power conditioner 50 is increased by the power selling
control, and therefore the electric power is outputted from
the power conditioner 50 to the electric power system of the
commercial power source.
Furthermore, the amount of power sold by the power
conditioner 50 as power selling information J3 is
transmitted to the grid-connected server 61. Accordingly,
the power selling information J3 is transferred to the grid-

connected server 61 through the subordinate extension unit
70 of the power conditioner 50, the extension unit 68 of the
power meter 29, and the base unit 66 on the electric pole in
sequence in such a way that the power information 50J of the
power conditioner 50 is acquired by the grid-connected
server 61. Accordingly, the grid-connected server 61 can
check the power selling status of the power conditioner 50,
and can stabilize the amount of output power from the power
conditioner 50 and the electric power system of the
commercial power source.
As shown in Fig. 6, a plurality of houses having
respective power supply systems 1 are connected to the
electric power system of the commercial power source.
Specifically, the communications line 64 disposed along the
electric power system of the commercial power source is
communicatively connected to the multiple power supply
systems 1 through respective base units 66A to 66G adjacent
to the step-down transformers individually provided on the
electric power system of the commercial power source.
That is, each of multiple power supply systems 1AA,
1AB, 1AC, and 1AD connected to the base unit 66A is
communicatively connected to the grid-connected server 61
and the other power supply systems through the base unit 66A
and the communications line 64. In the same manner, each of
multiple power supply systems 1BA, 1BB, and 1BC connected to
the base unit 66B is communicatively connected to the grid-

connected server 61 and the other power supply systems
through the base unit 66B and the communications line 64.
Furthermore, in the same manner, each of multiple power
supply systems 1CA, 1CB, 1CC and 1CD connected to the base
unit 66C and each of multiple power supply systems 1DA, 1DB,
1DC and 1DD connected to the main unit 66D are
communicatively connected to the grid-connected server 61
and the other power supply systems through the corresponding
base units 66C and 66D and the communications line 64.
Furthermore, in the same manner, each of multiple
power supply systems 1EA, 1EB, 1EC and 1ED connected to the
base unit 66E and each of multiple power supply systems 1FA,
1FB, 1FC and 1FD connected to the base unit 66F are
communicatively connected to the grid-connected server 61
and the other power supply systems via the corresponding
base units 66E and 66F and the communications line 64.
Furthermore, each of multiple power supply systems 1GA, 1GB,
1GC and 1GD connected to the base unit 66G is
communicatively connected to the grid-connected server 61
and the other power supply systems via the base unit 66G and
the communications line 64.
In the meantime, if the multiple power supply systems
connected to the electric power system of the commercial
power source as described above perform initiation and
termination of power selling based on their individual
determinations, power selling initiation or termination

timings may be overlapped with each other. When the power
selling initiation or termination timings are overlapped
with each other, the voltages of the commercial power source
may be changed, thereby resulting in an undesirable
influence on the stabilization of the electric power in the
electric power system of the commercial power source.
Specifically, the high voltages simultaneously
outputted from multiple power conditioners 50 may increase
the voltage of the electric power system of the commercial
power source. Further, the simultaneous termination of the
outputs of multiple power conditioners 50 may reduce the
voltage of the electric power system of the commercial power
source.
In order to overcome the above problems, in the
present embodiment, each of the power conditioners 50
supplies an electric power based on the grid-connected
information, and, if the grid-connected information has not
been received, the electric power is outputted based on a
value arbitrarily and appropriately generated by a power
generation apparatus to the electric power system.
Specifically, when the power supply system 1 desires
to sell the electric power, the power supply system 1
transmits power selling request information Jl to the grid-
connected server 61. When the grid-connected server 61
receives pieces of power selling request information Jl from
the respective power supply systems 1, the grid-connected

server 61 coordinates the pieces of power selling request
information Jl so as not to harm the stabilization of the
electric power of the electric power system of the
commercial power source, and generates grid-connected
information 50K in which the coordinated results are set as
the power buying conditions with respect to each power
supply system 1. The grid-connected server 61 transfers the
generated grid-connected information 50K to the
corresponding power supply system 1. The power supply
system 1 that has received the grid-connected information
50K outputs (sells) power from the power conditioner 50
based on the power buying conditions set by the grid-
connected server 61, thereby maintaining the stabilization
of the power of the electric power system of the commercial
power source.
For example, when the grid-connected server 61
receives pieces of power selling request information Jl from
the multiple power supply systems 1AA, 1BA, 1CA, 1DA, 1EA,
1FA, and 1GA, respectively, the grid-connected server 61
determines whether or not the stabilization of the power of
the electric power system of the commercial power source can
be harmed if the powers from all of the power supply systems
are outputted to the electric power system of the commercial
power source.
If it is determined that the stabilization of the
power of the electric power system of the commercial power

source can be harmed, the periods for which electric power
is outputted from each of the power supply systems are
coordinated. Specifically, with respect to each of the
power supply systems 1AA, 1BA and 1CA, the power buying
condition is set such that electric power can be outputted
only for a predetermined period, and with respect to each of
the power supply systems 1DA, 1EA, 1FA and 1GA, the power
buying condition is set such that electric power can be
outputted after the predetermined period. Further, in view
of the power buying conditions, the grid-connected server 61
determines whether or not each of the power conditioners 50
can output electric power to the electric power system of
the commercial power source, and such determination is also
used to control the electric power outputted from each of
the power conditioners 50. Accordingly, the output of the
electric power to the electric power system of the
commercial power source from the power supply systems is
distributed over time, so that the stabilization of the
power of the electric power system of the commercial power
source can be achieved.
Meanwhile, when electric power cannot be outputted to
the electric power system of the commercial power source,
the power conditioner 50 stores the electric power desired
to be outputted therefrom, in, e.g., a battery 16, and
outputs the corresponding electric power stored in the
battery 16 when the electric power can be outputted.

Therefore, it is possible to effectively use electric power
generated by the solar cells 3.
Further, for example, the amount of electric power
generated by the solar cells 3 provided in the power supply
system 1 varies considerably depending on the received
illuminance of sunlight. This variation in the amount of
power generation considerably varies the amount of power
that each power supply system receives from the electric
power system of the commercial power source or that each
power supply system outputs to the electric power system of
the commercial power source. That is, if there is
simultaneous variation in the amounts of electric power that
the multiple power supply systems 1 receive from the
electric power system of the commercial power source or the
amounts of electric power that the multiple power supply
systems output to the electric power system of the
commercial power -source, the variation in the amount of
power of each power supply system 1 may harm the
stabilization of the electric power system of the commercial
power source.
However, the variation in the illuminance of sunlight
is influenced by the movement of the clouds and, thus, based
on illuminance variations in time, which can be obtained by
acquiring a wide range of illuminance information, it is
possible to estimate illuminance variations at each point in
the corresponding information range. Further, it is

possible to estimate the variation in the amount of power
generation from the solar cells 3 based on the estimated
illuminance variations.
Accordingly, the illuminance information acquired from
the power conditioner 50 of each of the power supply systems
1AA to 1GD through each power meter is collected in the
grid-connected server 61, and the grid-connected server 61
estimates the illuminance variation of each of the power
supply systems 1AA to 1GD in accordance with the movement of
the clouds based on the collected illuminance information
and the location of each of the power supply systems 1AA to
1GD corresponding to each piece of the illuminance
information and sets the power buying conditions based on
the corresponding estimation.
Accordingly, it is possible to estimate the variation
in the amount of power generation in the solar cells 3
caused by the illuminance variations in accordance with the
movement of the clouds, and the stabilization of the power
of the electric power system of the commercial power source
can be maintained by setting the conditions of selling power
that do not harm the stabilization of the power of the
electric power system of the commercial power source for
each of the power supply systems 1AA to 1GD in advance.
Furthermore, the approximate location of each power supply
system 1 may be determined based on the location of a
corresponding step-down transformer or each base unit, and

the precise location thereof may be determined based on an
address registered for the power meter 2 9 managed by the
electric power company 60.
When the illuminance information of the power supply
system 1 is utilized as described above, the illuminance can
be estimated with high precision based on the acquisition of
information about the movement of the clouds at intervals
shorter than the intervals of normally provided weather
information, so that the amount of power generated by the
solar cells 3 can also be estimated with high precision, and
therefore the stabilization of the electric power system of
the commercial power source can be maintained at a higher
level. That is, in regard to the estimation of illuminance,
when the decreases in illuminance in the sequence of the
power supply systems 1AD, 1AC, 1AB and 1AA on the left side
of Fig. 6 are measured, it is estimated that the illuminance
of the power supply systems 1BA to 1BC connected to the base
unit 66B sequentially decreases and thereafter the
illuminance of the power supply systems 1CA to 1CD connected
to the base unit 66C sequentially decreases. Furthermore,
commonly provided weather information may also be used as
additional means for estimation of illuminance. For
example, referring to the direction of the wind for moving
the clouds included in the weather information, if a
decrease in the illuminance of the power supply system 1AD
is measured when the wind blows from the base unit 66A to

the base unit 66C, the illuminance of each power supply
system 1 is estimated to decrease as well. In all cases,
the conditions of selling power are set based on the above
estimations, or the amount of power supplied to the electric
power system of the commercial power source varies to deal
with the estimated increase and decrease in the amount of
power consumed, so that the stabilization of the power of
the electric power system of the commercial power source can
be appropriately maintained.
As described above, the electric power management
system in accordance with the present embodiment can provide
the following effects.
(1) Grid-connected information 61K, which is
information related to the power stabilization of the
electric power system that the power meter 29 received from
the grid-connected server 61, is also shared to the power
conditioner 50, and the electric power is outputted to the
electric power system of the commercial power source from
the power conditioner 50 based on the grid-connected
information. Since the grid-connected information is
information related to the power stabilization of the
electric power system of the commercial power source, the
appropriate electric power based on the grid-connected
information can be outputted to the electric power system of
the commercial power source by the power conditioner 50.
Further, the electric power can be outputted to the electric

power system of the commercial power source at an
appropriate timing based on the grid-connected information.
Accordingly, with such electric power management system, the
quality of the electric power can be stabilized by
suppressing an increase in the voltage of the electric power
system of the commercial power source and the like.
(2) Grid-connected information is reliably and
accurately transmitted to the power meter 29 from the grid-
connected server 61 through the communications line 64
managed same as the electric power system of the commercial
power source. Accordingly, since such grid-connected
information is used by the power conditioner 50, the grid
connection of output power therefrom can be achieved more
accurately, so that the stabilization of the electric power
quality of the electric power system of the commercial power
source can be maintained.
(3) The applicability of the electric power management
system can be increased by using the solar cells 3
(photovoltaic power generation apparatus) generally used in
recent years.
(4) Since the electric power generated by the solar
cells 3 can be stored in the battery, the electric power
generated by the solar cells 3 can be supplied to the
electric power system of the commercial power source at an
appropriate timing based on the grid-connected information.
That is, the electric power to be consumed soon after

generation is temporarily stored, and therefore, regardless
of the timing of the generation, the electric power can be
efficiently outputted to the electric power system of the
commercial power source based on the grid-connected
information, so that the electric power quality of the
electric power system of the commercial power source is
stabilized. Furthermore, the solar cells 3 and the like can
output a greater amount of electric power generated to the
electric power system of the commercial power source.
(5) In case of an electric power generated by the
solar cells 3 whose generation pattern is gradually varied
by illuminance of the sunlight and is not consistent with a
power consumption pattern, such electric power can be stored
in a battery without waste if it is not consumed. By doing
so, the electric power generated by the solar cells 3 is
efficiently outputted to the electric power system of the
commercial power source based on the grid-connected
information regardless of the timing of the generation, and
therefore the electric power quality of the electric power
system of the commercial power source can be stabilized, and
further the solar cells 3 can output a greater amount of
power to the electric power system of the commercial power
source.
(6) In case where the electric power generated by the
solar cells 3 cannot be outputted to the electric power
system of the commercial power source in accordance with the

determination based on the grid-connected information, the
electric power, which is not consumed, is stored in the
battery 16, thereby minimizing the waste of the generated
power.
(7) In case where the electric power generated by the
solar cells 3 can be outputted to the electric power system
of the commercial power source in accordance with the
determination based on the grid-connected information, the
electric power of the power conditioner 50 can be outputted
to the electric power system of the commercial power source
based on the preferred conditions, and therefore an increase
in the amount of output power can be expected. Accordingly,
when power is output to the electric power system of the
commercial power source, the electric power can be
efficiently outputted to the electric power system of the
commercial power source and there is no concern about the
output power making the power quality of the electric power
system of the commercial power source unstable.
(8) The power conditioner 50 is controlled by the
grid-connected server 61 such that the electric power is
outputted to the electric power system of the commercial
power source by the power conditioner 50 based on the
conditions for power output included in the grid-connected
information which is produced based on a situation such as
the power generation of the solar cells 3 or the like.
Therefore, the power quality of the electric power system of

the commercial power source is further improved.
(9) Since the conditions for power output are
generated based on power generation information and
environmental information, more appropriate conditions for
power output can be provided to the power conditioner 50, so
that the stabilization of the electric power system of the
commercial power source and the efficient use of the power
generated by the solar cells 3 are further promoted.
(10) Since the conditions for power output included in
the grid-connected information are produced based on the
power generation amount of the solar cells 3 obtained from
the illuminance information and power generation
information, the electric power generated by the solar cells
3 can be efficiently outputted to the electric power system
of the commercial power source.

(11) Since the location of the power meter 29 is
individually designated in the grid-connected server 61, a
cnange in illuminance or atmospheric temperature can be
estimated by referring to the weather forecast and the like.
Such estimation can be used to generate grid-connected
information.
(12) The actually measured illuminance is collected
through each power meter 29, and a change in the illuminance
of the solar cells 3 corresponding to each power meter 2 9 is
estimated based on the collected illuminance information.
Accordingly, the accuracy of the estimation of the power

generation amount of the solar cells 3 is improved, and the
stabilization of the electric power system of the commercial
power source can be improved using the grid-connected
information generated based on the above estimation.
(13) Since the high-precision estimation of the power
consumption amount of the power conditioner 50 can be
performed, the grid-connected server 61 can perform the
stabilization of the electric power system of the commercial
power source in a planned manner.
(14) Since the communications between the power meter
29 and the power conditioner 50 are performed in the form of
wired communications, the stability of the transfer of the
information can be increased.
(15) Since the communications between the power meter
29 and the base unit 66 is performed in a wired manner,
communications equipment is simplified, and stable
communications is ensured. Further, by using power line
communications, the wired communications between the power
meter and the base unit can be performed without requiring
new wiring installation for communications, thereby saving
on wiring in the electric power management system.
(Second Embodiment)
Next, the electric power management system in
accordance with a second embodiment of the present invention
will be described with reference to Fig. 7. Fig. 7
schematically illustrates a case where communications

between a power meter 29 and a power conditioner 50 is
performed through an external communications network N.
Further, the second embodiment differs from the first
embodiment in that the communications between the power
meter 29 and the power conditioner 50 is performed through
the external communications network N. Other points remain
"he same as those of the first embodiment. In the present
embodiment, description will be focused on the points
differing from the first embodiment. Like reference
numerals will be given to like parts, and redundant
description thereof will be omitted for the sake of
convenience.
As shown in Fig. 7, the extension unit 68 of the power
meter 29 is communicatively connected to a base unit 66.
The base unit 66 is communicatively connected to an electric
power company 60 through a communications line 64, and is
also communicatively connected to the external
communications network N. That is, the extension unit 68 of
the power meter 29 is communicatively connected to the
external communications network N through the base unit 66.
Furthermore, the extension unit 68 of the power meter 29 can
logically select one from the communications line 64 and the
external communications network N to perform communications
through the appropriate use of network addresses depending
on the recipient of the communications.
Meanwhile, the subordinate extension unit 70 of the

power conditioner 50 is communicatively connected to the
home server 31, and is communicatively connected to the
external communications network N through the home server
31. Since the extension unit 68 of the power meter 29 and
the subordinate extension unit 70 of the power conditioner
50 are communicatively connected to the external
communications network N as described above, the extension
unit 68 of the power meter 29 and the subordinate extension
unit 70 of the power conditioner 50 are communicatively
connected to each other through the external communications
network N.
Accordingly, the power information 29J of the power
meter 29 and the grid-connected information 29K from the
grid-connected server 61 are transferred to the power
conditioner 50 through the external communications network
M, and the power information 50J of the power conditioner 50
is also transferred to the power meter 29 and the grid-
connected server 61 through the external communications
network N.
As described above, the present embodiment can provide
effects identical with or similar to effects (1) to (15)
provided by the first embodiment. In addition, the present
embodiment can provide the following effects.
(16) The power meter 29 and the power conditioner 50
communicate with each other through the external
communications network N, and therefore dedicated

communications equipment for enabling the power meter 29 and
the power conditioner 50 to directly communicate with each
other is not necessary. For example, the power meter 29
allows a communications device of the grid-connected server
61 to be also used over the external communications network
N and the power conditioner makes connections with the
external communications network N by using communications
infrastructures in a house, so that there is no need to
provide devices in the power meter 29 and the power
conditioner 50 to make the direct communications
therebetween. Accordingly, it is possible to increase the
degree of freedom of the application of the electric power
management system.
(Third Embodiment)
Next, an electric power management system in
accordance with a third embodiment of the present invention
will be described with reference to Fig. 8. Fig. 8
schematically illustrates a case where the communications
between a power meter 29 and a power conditioner 50 is
performed through a relay server 77 provided on the external
communications network N.
Further, the third embodiment differs from the second
embodiment in that the communications between the power
meter 29 and the power conditioner 50 is performed through
the relay server 77 provided on the external communications
network N. Other points remain the same as those of the

second embodiment. In the present embodiment, description
will be focused on the points differing from the second
embodiment. Like reference numerals will be given to like
parts, and redundant description thereof will be omitted for
the sake of convenience.
As shown in Fig. 8, the relay server 77 that enables
the extension unit 68 of the power meter 29 and the
subordinate extension unit 70 of the power conditioner 50 to
communicate with each other is connected to the external
communications network N. Accordingly, the extension unit
6 3 of the power meter 29 communicates with the relay server
7 7 connected to " the external communications network N
through the base unit 66, and the power information 29J and
the grid-connected information 2 9K transmitted to the power
conditioner 50 are temporarily stored in the relay server
77. Further, the subordinate extension unit 70 of the power
conditioner 50 communicates with the relay server 77 of the
external communications network N through a home server 31,
and acquires the power information 29J and the grid-
connected information 29K transmitted to the corresponding
power conditioner 50.
Meanwhile, the power information 50J transmitted from
the power conditioner 50 to the power meter 29 is
temporarily stored in the relay server 77, and the power
meter 29 acquires the power information 50J transmitted to
the corresponding power meter 29 from the relay server 77.

By providing the relay server 77, the degree of freedom in
time of the communications between the power meter 29 and
the power conditioner 50 can be increased.
As described above, the present embodiment can provide
effects identical with or similar to effects (1) to (16)
provided by the first and the second embodiment. In
addition, the present embodiment can provide the following
effects.
(17) Even in case where the power meter 29 and the
power conditioner 50 communicate with the relay server 77 in
an asynchronous fashion, the grid-connected information can
be transferred to each other, and therefore the
configuration of communications unit or communications
conditions used to transfer the grid-connected information
are simplified, so that the degree of freedom of the
configuration of the power management system can be
increased.
(Fourth Embodiment)
Next, the power management system in accordance with a
fourth embodiment of the present invention will be described
with reference to Fig. 9. Fig. 9 schematically illustrates
a case where the communications between a power meter 29 and
a power conditioner 50 is performed through an information
server 71 provided in an electric power company 60.
Furthermore, the fourth embodiment differs from the
first embodiment in that the information server 71 is

provided in the electric power company 60 and the electric
power company is connected to the external communications
network N. In the present embodiment, description will be
focused on the points differing from the first embodiment.
Like reference numerals will be given to like parts, and
redundant description thereof will be omitted.
As described in Fig. 9, the subordinate extension unit
70 of the power conditioner 50 is connected to a home server
31, and the home server 31 is connected to the electric
power company 60 through the external communications network
N. Further, an information server 71 that is not connected
to a grid-connected server 61 but is connected to the
external communications network N is provided in the
electric power company 60. That is, the electric power
company 60 is communicatively connected to the power
conditioner 50 through the base unit 66 and the extension
unit 68 of the power meter 29, and is also communicatively
connected to the power conditioner 50 through the external
communications network N.
In general, the dedicated communications line 64 of
the electric power company 60 disposed along the electric
power system of the commercial power source has a high level
of security by, for example, physically separating it from
the external communications network N and the like.
Accordingly, information requiring high security such as
grid-connected information 61K is transferred from the

electric power company 60 to the power conditioner 50
through a path including the communications line 64, the
base unit 66, the extension unit 68 and the subordinate
extension unit 70. Further, information not requiring high
security, such as the power information 50J of the power
conditioner 50 and the like, is transferred from the power
conditioner 50 to the information server 71 of the electric
power company 60 through a path including the home server 31
and the external communications network N.
As described above, the present embodiment can provide
effects identical with or similar to effects (1) to (15)
provided by the first embodiment. In addition, the present
embodiment can provide the following effect.
(18) In performing communications between the electric
power company 60 and the power supply system 1, an
appropriate communications method can be selected depending
on the type, quantity or required security level of the
information to be communicated.
Further, the respective embodiments described above
may be modified as follows.
In the respective embodiments described above, there
is illustrated a case where the power conditioner 50
includes the control unit 7 and the DC distribution board 8.
However, the present invention is not limited thereto.
Various devices, e.g., an AC distribution board, a control
box and a home server, may be included in the power

conditioner 50 as long as they enable the power supply
system to properly perform the management of electric power.
On the contrary, the DC distribution board 8 may be excluded
from the power conditioner 50. This makes it possible to
increase the degree of freedom in configuring the power
conditioner and to increase the applicability of the
electric power management system.
In the respective embodiments described above, there
is illustrated a case in which the power conditioner 50 is
provided with the memory device 50DB. However, the present
invention is not limited thereto. The memory device may not
be provided in the power conditioner as long as the power
conditioner can manage the power information. In this case,
the power information may be stored in the home server or
the like so that the power conditioner can gain access
thereto. This makes it possible to increase the degree of
freedom in configuring the power conditioner and to increase
the applicability of the electric power management system.
In the respective embodiments described above, there
is illustrated a case where the environmental information is
illuminance information. However, the present invention is
not limited thereto. The environmental information may be
information related to an environment where the power supply
system is disposed, and may include information, e.g.,
atmospheric temperature, humidity, wind direction, and wind
velocity as long as the information is related to the power

generation or changes in consumption. For example,
information on atmospheric temperature and humidity may be
used to estimate changes in the power consumption of an air
conditioner in a house, and information on the direction of
the wind and the velocity of the wind may be used to predict
the movement of the clouds.
In the respective embodiments described above, there
is illustrated a case where the first communications unit is
wired communications in which the communications between the
grid-connected server 61 and the power meter 29 is performed
by using the communications line 64 and the lead-in power
line 2A as communications mediums. However, the present
invention is not limited thereto. The communications
between the base unit on the electric pole and the power
meter may be performed through, e.g., wireless
communications as shown in Fig. 10A. Accordingly, wiring
installation for communications is not necessary between the
power meter and the base unit, and the time and space are
not required for the wiring installation of a communications
line to the power meter.
In the respective embodiments described above, there
is illustrated a case where the extension unit 68 of the
power meter 29 and the subordinate extension unit 70 of the
power conditioner 50 perform wired communications through
the dedicated communications line 69.
However, the present invention is not limited thereto.

The communications between the extension unit of the power
meter and the subordinate extension unit of the power
conditioner may be performed through wireless communications
as the second communications unit. That is, for example, as
shown in Fig. 10B, the extension unit 68 of the power meter
29 and the subordinate extension unit 70 of the power
conditioner 50 are provided with a wireless device that
enables reciprocal wireless communications, and therefore
the corresponding power meter 29 and the corresponding power
conditioner 50 can communicate with each other in a wireless
manner. Accordingly, wiring installation is not required
for the communications between the power meter 29 and the
power conditioner 50, and such electric power management
system can be easily introduced.
In the respective embodiments described above, there
is illustrated a case where the extension unit 68 of the
power meter 29 and the subordinate extension unit 70 of the
power conditioner 50 perform wired communications through
the dedicated communications line 69.
However, the present invention is not limited thereto.
The communications between the extension unit of the power
meter and the subordinate extension unit of the power
conditioner may be performed through power line
communications (PLC) as the second communications unit by
using the power line, carrying electric power between the
power meter and the power conditioner. The power line is

used as a communications medium. That is, for example, as
shown in Fig. 11, the extension unit 68 of the power meter
29 and the subordinate extension unit 70 of the power
conditioner 50 are provided with a power line communications
device capable of reciprocal communications therebetween,
and therefore the corresponding power meter 29 and the
corresponding power conditioner 50 can perform
communications by using power line communications (PLC).
Accordingly, wiring installation for communications is not
required for the communications between the power meter and
the power conditioner, and the stable information transfer
is achieved through the wired communications.
In the respective embodiments described above, there
is illustrated a case where a driving power of the power
meter 29 is supplied from the electric power system of the
commercial power source.
However, the present invention is not limited thereto.
The driving power of the power meter may be supplied from
the battery through the power conditioner when there is the
power failure in the electric power system of the commercial
power source. For example, as shown in Fig. 12, when the
switching determination unit 74 of the power meter 29
detects a power failure, the supply of electric power from
the battery 16 is requested to the power conditioner 50
through the communications between the extension unit 68 and
the subordinate extension unit 70. Therefore, the electric

power is supplied from the power conditioner 50 through the
power line 2B and, then, the electric power outputted from
the power conditioner 50 is supplied to a power source unit
72 by opening a switch 74A between the power meter 29 and
the lead-in power line 2A. Further, from the power source
unit 72, the electric power is supplied to the memory 73.
Accordingly, the operation of the power meter 29 is ensured
during a power failure, and backup can be performed more
rapidly and reliably than a case where a power failure is
detected by the power conditioner 50 during a power failure.
Meanwhile, when the switching determination unit 74 of
the power meter 29 detects the recovery of electric power,
an interruption in the supply of the electric power from the
battery 16 is reguested to the power conditioner 50, and the
switch 74A is closed in synchronization with the
interruption of the supply of the electric power from the
battery 16. Therefore, the connection between the power
meter 29 and the lead-in power line 2A is recovered. This
makes it possible to reduce the concern about the
information stored in the power meter 29 being lost because
of the power failure, and the communications with the power
conditioner 50 is ensured even during the power failure,
thereby improving the convenience of the operation of the
electric power management system.
In the respective embodiments described above, there
is illustrated a case where the location of the power meter

29 is individually designated using an address registered in
the electric power company 60. However, the present
invention is not limited thereto. The location of the power
meter may be individually designated by using data acquired
using a location measuring device such as Global Positioning
system (GPS) provided in the power meter, or may be set in
the power meter, the power conditioner or the electric power
company by a constructor by using a setting device provided
with a GPS (not shown) For example, as shown in Fig. 13,
the power meter 29 is provided with a GPS 75, and location
information that can be acquired by the corresponding GPS 75
is transferred from the power meter 29 to the grid-connected
server 61 by means of communications, so that the location
of the power meter 29 can be individually designated by the
grid-connected server 61. Accordingly, when the power meter
29 is installed, the setting of a location is not required
and there is no concern about the erroneous setting of a
location, so that the specification of the location of the
power meter 29 can be performed more reliably and easily.
In the respective embodiments described above, there
is illustrated a case where power information 29J, such as
voltage, current and the amount of power measured by the
power meter 29, is transferred to the meter reading center
of the electric power company 60 or the power conditioner
50. However, the present invention is not limited thereto.
Power information such as voltage, current and the amount of

power measured by the power meter may be easily referred.
For example, as shown in Fig. 13, a web server 76 may be
provided in the power meter 29, and the power meter 29 may
return power information 29J, such as voltage, current and
the amount of power measured by the power meter 29, in
response to a request from the browser of a computer 78
accessed via a home server 31 and the power conditioner 50.
Accordingly, access to the power meter 29 is facilitated,
and therefore the maintenance thereof is improved. As a
result, the information of the power meter, for example, the
amount of power input from the electric power system of the
commercial power source or the amount of power outputted to
the electric power system, and the like, can be easily
checked by using the web browser of a personal computer.
In the respective embodiments described above, there
is illustrated a case where the grip-connected server
generates grid-connected information based on information
acquired from the power conditioner of each power supply
system via the power meter and transmits the grid-connected
information to the power conditioner of each power supply
system. However, the present invention is not limited
thereto, and instead the power conditioner of each power
supply system may generate grid-connected information, or
may receive grid-connected information from the power
conditioner of another power supply system via the power
meter. For example, the power conditioner of the power

supply system 1AA may receive information from the power
conditioner of another power supply system 1AD via the base
unit 66A and the communications line 64.
In the respective embodiments described above, there
is illustrated a case where the power meter 29 is commonly
installed on the outside a house, for example, an outer wall
of a house. Accordingly, the power meter may be provided
with a surveillance camera capable of photographing an area
surrounding the corresponding power meter. For example, as
shown in Fig. 14, a camera 86 having a seat 85 whose
direction can be changed is provided under the measurement
unit 83 of the power meter 29 which can be installed on an
outer wall via a seat 80 and to which power lines 81 and 82
are connected, and inside a protective cover 84 which
protects the measurement unit 83 from the rain and wind.
Accordingly, the exterior of a house can be monitored using
the power meter 29 installed outside the house. This power
meter 29 may be used for prevention of crimes, and makes the
wiring for the camera 86 unnecessary using the supply of
power from the power meter 29 and the communications of the
power meter 29.
In the respective embodiments described above, there
is illustrated a case where the grid-connected server 61 and
the power conditioner 50 communicate with each other through
the base unit 66. However, the present invention is not
limited thereto. The power conditioner may communicate with

some other power conditioner through the base unit. For
example, seven to ten houses are connected to step-down
transformers. Base units are provided in a corresponding
relationship with every step-down transformer or some of the
step-down transformers. In this case, the power conditioner
can make communications through the base unit with another
power conditioner connected to the step-down transformer
corresponding to the base unit. This makes it possible to
make interactive communications through the power
conditioner in a limited area. For example, the information
on the availability of electric power can be exchanged
between the adjoining power conditioners. This
configuration can also be used in transferring various kinds
of information, which is not directly related to the
electric power, such as the notice information and the crime
prevention information. The information, such as a notice
information in a limited area may be provided in the form of
an image or a voice through a device having a user
interface, such as an operation panel 40, a door phone
extension unit or a television set, each of which is
communicatively connected to the power conditioner 50.
In the respective embodiments described above, there
is illustrated a case in which the solar cell 3 is used as a
power generating device. However, the present invention is
not limited thereto. The power generating device may be
other devices having a power generating function, such as a

battery, a fuel cell and a wind power generation device.
While the invention has been shown and described with
respect to the embodiments, it will be understood by those
skilled in the art that various changes and modification may
be made without departing from the scope of the invention as
defined in the following claims.

What is claimed is:
1. An electric power management system comprising:
a power generation apparatus for generating electric
power;
a power meter for receiving grid-connected
information, which is information related to stabilization
of electric power of an electric power system from a
management center for managing the electric power of the
electric power system; and
a power conditioner for outputting the electric power
generated by the power generation apparatus to the electric
power system based on the grid-connected information.
2. An electric power management system connected to an
electric power system of a commercial power source, the
electric power management system comprising:
a power generation apparatus configured to generate
electric power;
an electric appliance configured to consume electric
power;
a power meter connected to the electric power system,
and configured to detect an amount of electric power
inputted from the electric power system and an amount of
electric power outputted to the electric power system; and
a power conditioner connected to the power generation

apparatus and the electric applicance through respective
power lines;
wherein the electric power management system
coordinates and manages the amount of the electric power
inputted from the electric power system and the amount of
the electric power outputted to the electric power system
based on an amount of the electric power generated by the
power generation apparatus and an amount of the electric
power consumed by the electric appliance,
wherein the power conditioner outputs the electric
power, generated by the power generation apparatus, to the
electric power system based on grid-connected information,
and
wherein the grid-connected information is acquired
from a management center managing the power of the electric
power system and from a power conditioner of another
electric power management system.
3. The electric power management system of claim 2,
wherein the power meter receives the grid-connected
information from the management center managing the electric
power of the electric power system through a first
communications unit, and the power conditioner acquires the
grid-connected information from the power meter through a
second communications unit.

4. The electric power management system of claim 3,
wherein the power meter receives the grid-connected
information from the management center managing the electric
power of the electric power system and a power meter of said
another electric power management system through the first
communications unit.
b. The electric power management system of claim 4,
wherein the power generation apparatus is provided in plural
numbers, and electric power generated by one of the power
generation apparatuses is stored in a battery device storing
electric power, the battery device being another one of the
power generation apparatuses.
6. The electric power management system of claim 5,
wherein if it is determined based on the grid-connected
information that the electric power generated by said one of
the power generation apparatuses cannot be outputted to the
electric power system of the commercial power source, the
power conditioner stores the electric power, which is not
consumed by the electric appliance, in the battery device.
7. The electric power management system of claim 5,
wherein if it is determined based on the grid-connected
information that the electric power generated by said one of
the power generation apparatuses can be outputted to the

electric power system of the commercial power source, the
power conditioner outputs the electric power, which is
generated by said one of the power generation apparatuses
and stores in the battery device, from the corresponding
battery device to the electric power system of the
commercial power source.
8. The electric power management system of any of claims 4
to 7, wherein the management center acquires, as the grid-
connected information, status information of the power
generation apparatus from the power meter through the first
communications unit, the status information being acquired
by the power meter from the power conditioner corresponding
to the power meter connected to the electric power system of
the commercial power source through the second
communications unit, and the management center generates,
based on the acquired information, grid-connected
information including conditions for output power under
which electric power is outputted to the electric power
system of the commercial power source by the power
conditioner.
9. The electric power management system of claim 8,
wherein the power generation apparatus further includes a
photovoltaic power generation apparatus,
wherein the status information of the power generation

apparatus includes generation information indicative of an
amount of electric power generated by the photovoltaic power
generation apparatus, and illuminance information indicative
of illuminance of light irradiating the photovoltaic power
generation apparatus, which serves as environmental
information indicative of surrounding environmental status
of the photovoltaic power generation apparatus, and
wherein the management center generates the conditions
for output power included in the grid-connected information
based on the amount of electric power generated by the
photovoltaic power generation apparatus, the amount of the
electric power being obtained based on the illuminance
information and the generation information of the
photovoltaic power generation apparatus.
10. The electric power management system of claim 9,
wherein the power meter is provided in plural numbers and
the power meters are connected to the electric power system
of the commercial power source, and
wherein the management center estimates a change in
illuminance of the photovoltaic power generation apparatus
corresponding to each of the power meters, based on the
illuminance information inputted through each of the power
meters and location information indicative of a location of
each of the power meters that outputs the illuminance
information, and the management center generates the grid-

connected information based on the estimated change in
illuminance.
11. The electric power management system of any of claims 4
to 10, wherein the power conditioner functions as a
estimation control unit for measuring and storing past power
management data and producing estimated power consumption
information indicative of an amount of electric power
currently consumed, based on the stored power management
data, and
wherein the management center generates the grid-
connected information by referring to the estimated power
consumption information acquired from the power conditioner.
12. The electric power management system of any of claims 4
to 11, wherein the management center and the power meter
perform relay communications through a base unit provided on
a pole, and, among the communications between the management
center and the base unit and the communications between the
base unit and the power meter, the first communications unit
is configured such that the communications between the base
unit and the power meter is wireless or wired
communications .
13. The electric power management system of claim 2,

wherein, if the grid-connected information has not been
received, the electric power generated by the power
generation apparatus is outputted to the electric power
system based on an arbitrarily appropriately generated
value.

ABSTRACT

An electric power management system includes a power
generation apparatus for generating electric power, a power
meter for receiving grid-connected information and a power
conditioner for outputting the electric power generated by
the power generation apparatus to the electric power system
based on the grid-connected information. The grid-connected
information is information related to stabilization of
electric power of an electric power system from a management
center for managing the electric power of the electric power
system.