Field of the Invention
The present invention relates to an electricity supply
management device, including a solar cell, a commercial AC
power source and a storage battery, and charging the storage
battery with the power from the solar cell and supplying the
power from at least one of the solar cell, the commercial AC
power source and the storage battery to one or more load
devices.
Background of the Invention
An electricity supply management device has been known,
in which a solar cell and a storage battery are combined.
The electricity supply management device generates an
electric power by using the solar cell during the daytime,
supplies some of the generated power to one or more electric
devices, supplies a surplus power to the storage battery to
thereby charge the storage battery with the surplus power.
During the nighttime, an electric power is discharged from
the storage battery to be supplied to one or more electric
devices (for example, Japanese Patent Application
Publication No. 2004-023879).
Meanwhile, it is desired that solar energy is
effectively used such that a power consumption by a load

device is automatically and optimally adjusted to save the
energy. In the meantime, in a conventional electricity
supply management device, when the power consumption amount
by a load device in a home exceeds the amount of solar power
generated, a deficit in power is supplemented for by the
power from a commercial AC power source. Accordingly,
improvements are required to meet the above-described
desires.
Summary of the Invention
In view of the above, the present invention provides an
electricity supply management device that is capable of
automatically and optimally controlling the power
consumption by a load device based on the amount of an
electric power generated by a solar cell and the charge
level of a storage battery.
Units for accomplishing the above object and the
advantages thereof will be described below.
In accordance with an aspect of the present invention,
there is provided an electricity supply management device,
including a solar cell; a commercial Alternating Current
(AC) power source; and a storage battery, in which the
storage battery is charged by an electric power from the
solar cell, and a power from at least one of the solar cell,
the commercial AC power source and the battery is supplied

to one or more load devices. A power consumption level by
the load devices is controlled based on comparison result
between a power generation amount by the solar cell and a
power consumption amount by the load devices, and a charge
level of the storage battery indicative of a ratio of
charging to capacity of the battery.
With the configuration, the power consumption by the
load devices is controlled based on the amount of surplus
power, which is obtained by comparing the amount of power
generated by the solar cell with the amount of power
consumed by the load devices, and the charge level of the
battery, which is charged by the power generated by the
solar cell. That is, the power consumption by the load
devices is limited based on the state of the generation and
storage of solar energy, so that the power consumption
amount can be automatically and optimally controlled.
An electric power from the solar cell, in preference
to an electric power from the commercial AC power source,
may be supplied to the load devices and the storage battery.
When the power generation amount by the solar cell is larger
than the power consumption amount by the load devices and
the charge level of the storage battery is equal to or lower
than a reference charge level, power consumption by the load
devices may be limited not to exceed a preset power level.
With the configuration, when the power generation
amount by the solar cells is smaller than the amount of

power consumed by the load devices, the power from the solar
cells is supplied to the load devices. When the power
generation amount by the solar cells is larger than the
power consumption amount by the load devices, the power is
supplied from the solar cells to the load devices and the
storage battery. When the charge level of the storage
battery is lower than the reference charge level, the power
consumption by the load devices is limited to the preset
power level. Accordingly, the power consumption amount by
the load devices can be automatically and optimally reduced.
As a result, the use of the power from the commercial AC
power source can be suppressed.
When the power generation amount by the solar cell is
larger than the power consumption amount by the load devices
and the charge level of the storage battery is higher than
the reference charge level, no limitation may be imposed on
the power consumption by the load devices.
With this configuration, when the power generation
amount by the solar cells is larger than the power
consumption by the DC devices and the charge level of the
storage battery is higher than the reference charge level,
that is, when the power consumption by the DC devices can be
afforded by the power from the solar cells and the storage
battery, it is prohibited to impose a limitation on the
power consumption by the DC devices. Accordingly, even when
the power from the commercial power source is not used, the

performance of the load devices can be maintained.
When the power generation amount by the solar cells is
equal to or smaller than the amount of power consumption by
the load devices and the charge level of the storage battery
is higher than the reference charge level, the power
consumption by the load devices may be limited not to exceed
a reference power level lower than the preset power level.
With the configuration, when the power generation
amount by the solar cells is equal to or smaller than the
power consumption amount by the load devices and the charge
level of the storage battery is higher than the reference
charge level, that is, when it is expected that the power
consumption amount of the power from the storage battery
will be increased, the power consumption by the load devices
is limited to the reference power level lower than the
preset power level. Accordingly, an excessive reduction in
the charge level of the storage battery can be suppressed.
Furthermore, since the reference power level lower than the
preset power level is used as the limiting level, the
suppression of a reduction in the charge level can be
ensured.
When the power generation amount by the solar cells is
equal to or lower than the power consumption amount by the
load devices and the charge level of the storage battery is
equal to or lower than the reference charge level, the power
consumption by the load devices may be limited not to exceed

a backup power level lower than the reference power level.
With the configuration, when the power generation
amount by the solar cells is equal to or smaller than the
power consumption amount by the load devices and the charge
level of the storage battery is equal to or lower than the
reference charge level, that is, when it is expected that
the power consumption amount from the storage battery will
be increased, the power consumption by the load devices is
limited not to exceed the backup power level lower than the
reference power level. Accordingly, an excessive reduction
in the charge level of the storage battery can be
suppressed.
Furthermore, since the backup power level lower than
the reference power level is used as the limiting level, the
suppression of a reduction in the charge level can be
ensured.
The reference charge level may be set to a level
corresponding to an amount of power consumed by the load
devices.
With the configuration, when the charge level of the
storage battery is equal to or lower than the level
corresponding to the amount of power consumed by the load
devices during the nighttime, an excessive reduction in the
charge level to below the level corresponding to the amount
of power consumed during the nighttime can be suppressed in
order to limit the power consumption by the load devices to

the preset power level.
When a normal time span during which the electricity
rate is normal and a low-rate time span during which the
electricity rate is lower than the normal power rate are set
as time spans based on which electricity rate of the power
from the commercial AC power source is determined, a level
corresponding to an amount of power obtained by subtracting
an amount of power consumed during the low-rate time span
from an amount of power consumed by the load devices during
the nighttime may be set as the reference charge level.
With the configuration, the level corresponding to the
amount of power obtained by subtracting the amount of low-
rate power during the low-rate time span from the amount of
power consumed by the load devices is set as the reference
charge level, so that the reference charge level is lower
than that in the case where the level corresponding to the
amount of power consumed by the load devices during the
nighttime is set as the reference charge level.
Accordingly, in order to decrease the frequency at which the
charge level of the storage battery drops below the
reference charge level, the frequency at which the power
consumption by the load devices is limited not to exceed the
first power level can be reduced.
When a time at which the power consumption by the load
devices is controlled falls within the low-rate time span,
the limiting level of the power consumption by the load

devices may be made less stringent compared to the limiting
level of the power consumption by the load devices in a time
span other than the low-rate time span.
With the configuration, the limitation to power
consumption during the low-rate time span is mitigated,
which increases the power consumption by the load devices,
compared to the case where there is no mitigation of the
limitation for the same time span. In this case, the power
is supplied to the load devices from the commercial AC power
source and the storage battery, and the frequency of using
the power supply of the commercial AC power source can be
increased. Accordingly, limitation on the use of the load
devices during the nighttime at relatively low power rate
can be mitigated.
In accordance with the aspect of the present invention,
it is possible to provide an electricity supply management
device that is capable of suppressing the use of the
electric power from a commercial AC power source.
Brief Description of the Drawings
The objects and features of the present invention will
become apparent from the following description of
embodiments, given in conjunction with the accompanying
drawings, in which:
Fig. 1 is a block diagram illustrating a configuration

of an electricity supply system including an electricity
supply management in accordance with an embodiment of the
present invention;
Fig. 2 is a schematic diagram illustrating a
configuration of a power control device of the electricity
supply management device;
Fig. 3 is a flowchart illustrating a sequence of a
power control processing that is performed by the power
control device;
Fig. 4 is a flowchart illustrating a sequence of a
power consumption limitation processing that is performed
by the power control device;
Fig. 5 shows timing charts of examples of a control
state of the electricity supply management device of the
embodiment; and
Fig. 6 is a flowchart illustrating a modification of
the power consumption limitation processing that is
performed by the power control device.
Detailed Description of the Embodiments
An embodiment of the present invention will be
described in detail below with reference to the accompanying
drawings which form a part hereof. Same reference numerals
will be assigned to same or similar components throughout
the drawings, and redundant descriptions thereof will be

omitted.
Referring to Figs. 1 to 6, an embodiment of the
present invention will be described. Furthermore, the
present embodiment illustrates the case where the
electricity supply management device of the present
invention is practiced as a part of an electricity supply
system.
As shown in Fig. 1 a house is provided with an
electricity supply system 1 that supplies an electric power
to various types of household devices (a lighting device, an
air conditioner, household electronic appliances, audio and
visual devices, and the like). The electricity supply
system 1 supplies to a variety of types of devices an
electric power from a household commercial AC power source
(AC power source) 2 and an electric power from a solar cell
3, using solar light.
The electricity supply system 1 supplies an electric
power not only to DC devices 5 but also to an AC device 6.
Each of the DC devices 5 is operated by a DC electric power,
and the AC device 6 is operated by an AC electric power from
the commercial AC power source 2. Although, in the
following descriptions of the embodiment, the house is given
as an example of a place where the electricity supply system
1 is installed, the place is not limited thereto.
Alternatively, the electricity supply system 1 may be
installed and used in a multi-family house, an apartment, an

office, or a factory.
As a distribution board of the electricity supply
system 1, a controller 7 and a DC distribution board 8
(including a DC breaker) are provided in the electricity
supply system 1. Furthermore, in the electricity supply
system 1, a control unit 9 and a relay unit 10 are provided
as a device for controlling the operation of the DC devices
5 in the house.
An AC distribution board 11 for branching an 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 through a DC power line 13.
The controller 7 receives an AC power from the AC
distribution board 11, receives a DC power from the solar
cell 3, and converts the powers into a predetermined DC
power as a power for the devices Furthermore, the
controller 7 outputs the resulting DC power to the DC
distribution board 8 through a DC power line 14 and to a
storage battery 16 through a DC power line 15. The
controller 7 receives the AC power, converts the DC power
from the solar cell 3 or the storage battery 16 into an AC
power, and supplies the AC power to the AC distribution
ooard 11. The controller 7 exchanges data with the DC
distribution board 8 through a signal line 17.
The DC distribution board 8 is a kind of DC power

breaker. The DC distribution board 8 branches the DC power
inputted from the controller 7, and outputs the resulting DC
power to the control unit 9 through a DC power line 18, or
to the DC relay unit 10 through a power line 19.
Furthermore, 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.
The plural DC devices 5 are connected to the control
unit 9 through DC supply lines 22 each of which is capable
of carrying both DC power and data. A communications
signal, carrying data by using a high frequency carrier
wave, is superimposed on a DC voltage supplied as a power to
the DC device 5 through the DC supply line 22. That is,
both power and data are carried to the DC device by means of
the power line carrier communications through the DC supply
line 22 that has a pair of wires. The control unit 9
obtains the DC power for the DC devices 5 through the DC
power line 18, and determines an operation control state of
the DC devices 5 based on an operating instruction obtained
from the DC distribution board 8 through the signal line 20.
Furthermore, the control unit 9 outputs the DC power and the
operating instruction to the corresponding DC device 5
through the corresponding DC supply line 22, and controls
the operation of the DC device 5.
Switches (SW) 23 are connected to the control unit 9
through the DC supply line 22. The switches 23 are

manipulated when the operations of the DC devices 5 are
switched. Furthermore, a sensor 24 for detecting, for
example, radio waves transmitted from an infrared remote
control is connected to the control unit 9 through the DC
supply line 22. Accordingly, the DC devices 5 are
controlled by communications signals transmitted thereto
through the DC supply line 22 in response not only to an
operating instruction from the DC distribution board 8 but
also to the manipulation of the switches 23 or the detection
of the sensor 24.
Some of the DC devices 5 are connected to the relay
unit 10 through respective DC power lines 25. The relay
unit 10 obtains the DC power for the DC devices 5 through
the DC power line 19, and determines which one of the DC
devices 5 is to be operated based on an operating
instruction obtained from the DC distribution board 8
through the signal line 21. Furthermore, the relay unit 10
controls the operation of the determined DC device 5 by
selectively turning on and off the supply of power through
the DC power line 25 by a relay provided therein.
Furthermore, a plurality of switches 26 for manually
manipulating the DC devices 5 are connected to the relay
unit 10, and the DC devices 5 are controlled by selectively
turning on and off the supply of power thereto through the
DC power line 25 by the relay in response to the
manipulations of the switches 26.

A DC outlet 27 that is uprightly attachable to the
house, for example, in the form of a wall outlet or a bottom
outlet, is connected to the DC distribution board 8 through
the DC power line 28. By inserting the plug (not shown)
from the DC device into the DC outlet 27, a DC power can be
directly supplied to the DC device.
Furthermore, a power meter 29 capable of remotely
measuring the amount of power from the commercial AC power
source 2 used is connected to the AC distribution board 11.
The power meter 2 9 has not only the function of remotely
measuring the amount of commercial power used but also , for
example, the function of power line carrier communications
and/or wireless communications. The power meter 29
transmits the results of the measurement to an electric
power company or the like through the power line carrier
communications or wireless communications.
The electricity supply system 1 includes a network
system 30 that enables various types of household devices to
be controlled through network communications. The network
system 30 includes a home server 31 that functions as a
control unit of the network system 30. The home server 31
is connected to an external management server 32 through a
network N, such as the Internet, and also to a customer
premises equipment 34 through a signal line 33.
Furthermore, the home server 31 is operated by a DC power,
obtained from the DC distribution board 8 through a DC power

line 35.
A control box 36 for managing the operational control
of various types of home devices by using 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 the
signal line 17, and also directly controls the DC devices 5
through a DC supply line 38. A gas/water meter 39 capable
of remotely measuring, for example, the amount of gas or
water used is connected to the control box 36, and a
manipulation panel 40 of the network system 30 is also
connected to the control box 36. A monitoring device 41
including, for example, a door phone receiver, a sensor
and/or a camera is connected to the manipulation panel 40.
When operating instructions from the various types of
home devices are inputted to the home server 31 through the
network N, the home server 31 notifies the control box 36 of
the operating instructions, and operates the control box 36
to control the various types of the home devices to perform
operations based on the operating instructions.
Furthermore, the home server 31 may provide various types of
information, obtained from the gas/water meter 39, to the
management server 32 through the network N. When receiving
from the manipulation panel 40 a notification that the
monitoring device 41 has detected an abnormality, the home
server 31 may also provide the notification to the

management server 32 through the network N.
The electricity supply management device 100 includes
the solar cell 3, the storage battery 16, the controller 7,
and a power control device 70. The electricity supply
management device 100 limits the power consumption by the DC
devices 5 depending on the amount of power generated by the
solar cell 3 and the charge level CL of the storage battery
16.
The solar cell 3 periodically measures the solar power
generation amount PWS, and outputs the measured solar power
generation amount PWS to the power control device 70 through
a signal line 51. Furthermore, the solar power generation
amount PWS varies depending on both the intensity of solar
light and the load connected to the solar cell 3. For
example, even when the solar cell 3 has a sufficiently large
capacity to generate a power, if the total amount of DC
powers used by the DC devices 5 connected to the solar cell
3 is smaller than the amount of power generated by the solar
cell 3, the solar cell 3 may generate the power in
proportion to the total power consumption amount of the DC
devices 5.
The storage battery 16 is charged or discharged in
response to a request from the power control device 70. The
storage battery 16 is managed based on two levels, that is,
a backup level CLB and a reserve charge level CLA (reference
charge level) . The backup level CLB is set in such a way

that an electric power can be supplied for a predetermined
period of time when the supply of power is interrupted in
case of emergency such as a power failure in the nighttime
or a fire. For example, the backup level CLB is set to a
charge level CL in proportion to the amount of power that is
used in case of emergency. The storage battery 16 is
generally controlled such that the charge amount of the
storage battery 16 does not become less than the backup
level CLB.
The reserve charge level CLA is set to be a charge
level higher than the backup level CLB in order to supply
the power to be consumed by the DC devices 5 during the
nighttime. For example, the reserve charge level CLA is set
to the charge level CL in proportion to the amount of power
per night that is consumed by the DC devices 5 during the
nighttime. The storage battery 16 periodically measures the
charge level CL, and outputs the measured charge level CL to
the power control device 70 through a signal line 52.
The controller 7 includes a DC/DC converter that
converts an electric power from the solar cell 3 into a low-
voltage DC power. By the DC/DC converter, the electric
power generated by the solar cell 3 is converted into a
power of a predetermined voltage. The controller 7 converts
an electric AC power from the commercial AC power source 2
into a DC power or converts the DC power from the solar cell
3 or the storage battery 16 into an electric AC power in

response to a request from the power control device 70. For
example, when the amount of DC power used by the DC devices
5 (that is, the power consumption amount) is larger than the
solar power generation amount PWS by the solar cell 3 and
the DC power is insufficient, the AC power is converted into
a DC power by the controller 7, thereby compensating for a
deficit in the DC power.
Meanwhile, when a DC power usage amount PWD by the DC
devices 5 is smaller than the solar power generation amount
PWS by the solar cell 3 and an excess of power is generated
by the solar cell 3, the remaining DC power is converted
into an AC power. The controller 7 measures an AC-DC power
amount obtained by converting the AC power into a DC power
and a DC-AC power amount obtained by converting the DC power
into an AC power, and outputs these measured power amounts
to the power control device 70 through the signal line 53.
As shown in Fig. 2, the power control device 70
includes an operation device 71; a communications unit 72
for performing information communications with an external
device including the solar cell 3, the controller 7 and the
storage battery 16; a solar power generation amount storage
unit 73; a AC-DC power amount storage unit 74; a battery
charge level storage unit 75; a DC power usage amount
storage unit 76; and a battery reference value storage unit
77.
The communications unit 72 receives information such

as the solar power generation amount PWS, the charge level
CL, the AC-DC power amount, and the DC-AC power amount
outputted from the solar cell 3, the storage battery 16 and
the controller 7 through the signal lines 51-53. In
addition, the communications unit 72 outputs the information
to the operation device 71. Furthermore, the communications
unit 72 transmits operating instructions, transmitted from
the operation device 71, to the solar cell 3, the storage
battery 16 and the controller 7.
The operation device 71 creates a power generation
change data DTA having the solar power generation amount PWS
therein. The power generation change data DTA has the time
when a measured solar power generation amount PWS is
transmitted and the measured solar power generation amount
PWS. Furthermore, the operation device 71 performs a power
control process and a power consumption limitation process.
In the power control process, a power supply source is
selected for the DC devices 5 depending on the solar power
generation amount PWS by the solar cell and the charge level
CL of the storage battery. In the power consumption
limitation process, the power consumption by the DC devices
5 is limited depending on the power generation amount by
the solar cell and the charge level CL of the storage
battery.
The solar power generation amount storage unit 73
stores the power generation change data DTA and the total

power generation amount DTB per day as a solar power
generation data DT. The solar power generation data DT is
kept for several years. The AC-DC power amount storage unit
74 stores an AC-DC power amount and an DC-AC power amount.
The battery charge level storage unit 75 stores the charge
level CL of the storage battery 16. The DC power usage
amount storage unit 76 stores the DC power usage amount.
The battery reference value storage unit 77 stores the
backup level CLB and the reserve charge level CLA.
Referring to Fig. 3, a sequence of the power control
process performed by the power control device 70 will now be
described. This process is repeatedly performed by the
power control device 70 every predetermined operational
period.
At step S110, an electric power of the solar cell 3
may be assigned to the supply of power to the DC devices 5
preferentially. That is, although an electric power is
supplied to the DC devices 5 from the commercial AC power
source 2 and the solar cell 3, the devices 5 preferentially
consume the electric power supplied from the solar cell 3.
At step S120, the solar power generation amount PWS is
compared with the DC power usage amount PWD by the DC
devices 5. At step S120, if it is determined that the solar
power generation amount PWS is larger than the DC power
usage amount PWD, that is, if the solar power generation
amount PWS is excessive, it is determined whether or not the

charge level CL of the storage battery 16 reaches a full
charge level CLC at step S130.
If the charge level CL of the storage battery 16 has
not reached the full charge level CLC, the power from the
solar cell 3 is assigned to the supply of power to the DC
devices 5 and the surplus power thereof may be assigned to
the charging of the storage battery 16 at step S140. In
this case, the solar power generation amount PWS is
equivalent to the sum of the DC power usage amount PWD by
the DC devices 5 and the charged power amount PWE of the
storage battery 16.
Meanwhile, if the charge level CL of the storage
battery 16 has reached the full charge level CLC, the power
from the solar cell 3 may be assigned to the supply of power
to the DC devices 5 and the surplus power thereof is
discarded at step S150. In this case, the amount of solar
power generation PWS can be made equivalent to the DC power
usage amount PWD by the DC devices 5.
If it is determined that the solar power generation
amount PWS is smaller than the DC power usage amount PWD at
step S120, it is determined whether or not the charge level
CL of the storage battery 16 is higher than the backup level
CLB at step S160.
If it is determined that the charge level CL of the
storage battery 16 is higher than the backup level CLB at
step S160, a power is supplied from the storage battery 16

in proportion to a deficit in the DC power usage amount PWD
at step S170. In this case, the sum of the solar power
generation amount PWS and the supplied power amount PWF from
the storage battery 16 becomes equivalent to the DC power
usage amount PWD by the DC devices 5.
Meanwhile, if it is determined that the charge level
CL of the storage battery 16 is equal to or lower than the
backup level CLB, the AC power in proportion to a deficit in
the DC power usage amount PWD is converted into a DC power
and the DC power is supplied to the DC devices 5 at step
S180. In this case, the sum of the solar power generation
amount PWS and the AC-DC power amount obtained by converting
the AC power into a DC power becomes equivalent to the DC
power usage amount PWD by the DC devices 5.
Referring to Fig. 4, a sequence of the power
consumption limitation process performed by the power
control device 70 will now be described. Furthermore, this
process is repeatedly performed by the power control device
70 every predetermined operational period of time.
At step S210, the solar power generation amount PWS by
the solar cell 3 is compared with the DC power usage amount
PWD by the DC devices 5. If it is determined that the solar
power generation amount PWS is larger than the DC power
usage amount PWD at step S210, it is checked to determine
whether or not the charge level CL of the storage battery 16
is higher than the reserve charge level CLA at step S220.

If it is determined that the charge level CL of the
storage battery 16 is higher than the reserve charge level
CLA at step S220, the power consumption by the DC devices 5
is not limited at step S230. That is, since the solar power
Generation amount PWS is sufficient and the power sufficient
for night power consumption has been accumulated in the
storage battery 16, the power limitation is not carried out.
On the other hand, if the charge level CL of the
storage battery 16 is equal to or lower than the reserve
charge level CLA, the power consumption by the DC devices 5
is limited not to exceed a first power level at step S240.
For example, the limitation of the power corresponding to
the first power level, e.g., 10%, of the total power
consumption by all the DC devices 5 is imposed at the time
at which the determination is performed at step S220.
Specifically, some devices whose use can be limited are
selected from all the DC devices 5. Then, one or more
devices are specified among the selected devices to enable
the total power consumption to be reduced by 10% by cutting
off the power supply to the specified DC devices when the
power limitation is carried out. Thereafter, when the power
consumption limitation processing is performed, the supply
of power to the specified DC devices 5 is blocked in
response to an operating instruction from the power control
device 70 to the relay unit 10 or the control unit 9.
If it is determined that the solar power generation

amount PWS is equal to or smaller than the DC power usage
amount PWD at step S210, it is checked to determine whether
or not the charge level CL is higher than the reserve charge
level CLA of the storage battery 16 at step S250.
If the charge level CL of the storage battery 16 is
higher than the reserve charge level CLA, the power
consumption by the DC devices 5 is limited not to exceed a
second power level at step S260. The second power level is
set such that the reduction in the power consumption at the
second power level is greater than that at the first power
level.
Since the DC power usage amount PWD cannot be met by
the power from the solar cell 3, it is expected that the
charge level CL will become equal to or lower than the
reserve charge level CLA after a while. For this reason, a
reduction in the charge level CL is mitigated by limiting
the power consumption by the DC devices 5 to the second
power level at which the extent of limitation is stricter
than at the first power level. For example, the limitation
of the power corresponding to the second power level, e.g.,
20%, of the total power consumption of the DC devices 5 is
imposed at the time at which the determination is performed
at step S250.
On the other hand, if the charge level CL of the
storage battery 16 is equal to or lower than the reserve
charge level CLA, the power consumption by the DC devices 5

is limited not to exceed a third power level at which the
extent of limitation is stronger than that at the second
power level at step S270. That is, since the DC power usage
amount PWD cannot be met by the power from the solar cell 3
and the charge level CL is equal to or lower than the
reserve charge level CLA, it is expected that the charge
level CL will become equal to or lower than the backup level
CLB after a while. For this reason, the power consumption
by the DC devices 5 is further limited to the third power
level which imposes a stricter limitation than the second
power level. For example, the power consumption is limited
to the third power level, e.g., 30%, of the total power
consumption of the DC devices 5 at the time when the
determination is performed at step S250.
Referring to Fig. 5, an example of the control state
of the electricity supply management device will be
described.
At time tl, that is, at midnight, if the solar power
generation amount PWS is equal to or lower than the DC power
usage amount PWD and the charge level CL of the storage
battery 16 is equal to or lower than the reserve charge
level CLA, the power consumption by the DC devices 5 is
limited to the third power level.
Here, since a power is not generated by the solar cell
3 and the standby power of the DC devices 5 is consumed, the
DC power usage amount PWD becomes larger than the solar

power generation amount PWS. Furthermore, the charge level
CL of the storage battery 16 becomes equal to the backup
level CLB. The commercial AC power is used to maintain the
charge level CL to be the backup level CLB of the storage
battery 16. In this case, the power consumption by the DC
devices 5 is limited to the third power level. At midnight,
the number of DC devices 5 being used is small, and
therefore, in practice, the operation of the DC devices 5 is
rarely substantially limited.
Thereafter, as the sun rises up, the solar power
generation amount PWS is increased. Further, the power
consumption by the DC devices 5 is increased. Accordingly,
the solar power generation amount PWS starts to be increased
from the state in which it is smaller than the DC power
usage amount PWD by the DC devices 5 for a while after the
generation of the solar cell 3 is started.
At time t2, that is, when the solar power generation
amount PWS becomes larger than the DC power usage amount PWD
by the DC devices 5 and the charge level CL of the storage
battery 16 becomes equal to or lower than the reserve charge
level CLA, some of the solar power generation amount PWS
becomes excessive, and therefore the storage battery 16
starts to be charged. At this time, the power consumption
by the DC devices 5 is limited to the first power level.
At time t3, that is, when the solar power generation
amount PWS becomes larger than the DC power usage amount PWD

by the DC devices 5 and the charge level CL of the storage
battery 16 becomes higher than the reserve charge level CLA,
the limitation on the power consumption by the DC devices 5
is released. In this case, all the DC devices 5 can be
operated.
At time t4, that is, when the charge level CL of the
storage battery 16 reaches the full charge level CLC, the
solar power generation amount PWS becomes identical to the
total power consumption amount by the DC devices 5. That
is, it is estimated that the solar cell 3 generates an
electric power whose curve is drawn along the two-dot chain
line as shown in Fig. 5(A). Meanwhile, since the total
power consumption amount by the DC devices 5 connected to
the solar cell 3 is smaller than the solar power generation
amount PWS, the actual solar power generation amount PWS
becomes a value appropriate for the load of the DC devices
5. In this case, it is concluded that the power obtained by
subtracting the actual solar power generation amount PWS
from the potential solar power generation amount PWS is
discharged.
Thereafter, as the sun goes down, the solar power
generation amount PWS is gradually decreased. While the
solar power generation amount PWS is larger than the DC
power usage amount PWD, the DC devices 5 are powered from
the solar cell 3. Accordingly, a power is not supplied from
the storage battery 16. For this reason, the charge level

CL of the storage battery 16 remains at the full charge
Level CLC while the solar power generation amount PWS is
larger than the DC power usage amount PWD.
At time t5, that is, when the solar power generation
amount PWS becomes smaller than the DC power usage amount
PWD by the DC devices 5, the power from the solar cell 3 to
be supplied to the DC devices 5 is insufficient, and
therefore the power starts to be supplied from the storage
battery 16. Meanwhile, the power consumption by the DC
devices 5 is limited to the second power level. Since the
supply of power from the storage battery 16 is suppressed
compared to the case where there is no limitation, a
reduction in the charge level CL of the storage battery 16
is suppressed.
Thereafter, the solar power generation amount PWS
becomes decreased, and the charge level CL of the storage
battery 16 also becomes reduced.
Furthermore, since the solar cell 3 generates no power
during the nighttime, the power is further supplied from the
storage battery 16.
At time t6, that is, when the solar power generation
amount PWS becomes smaller than the DC power usage amount
PWD by the DC devices 5 and the charge level CL of the
storage battery 16 becomes equal to or lower than the
reserve charge level CLA, the power consumption by the DC
devices 5 is limited to the third power level.

That is, at this time, the amount of power generated
by the solar cell 3 becomes smaller than the DC power usage
amount PWD by the DC devices 5 and the charge level CL of
the storage battery 16 becomes egual to or lower than the
reserve charge level CLA, and therefore the limitation
degree on the power consumption by the DC devices 5 may be
increased from the second power level to the third power
level.
At time t7, that is, when the charge level CL of the
storage battery 16 reaches the backup level CLB, the power
is prohibited from being supplied from the storage battery
16. Meanwhile, in order to maintain the charge level CL of
the storage battery 16, a deficit in power is compensated
for by the power from the commercial AC power source 2.
With the power supply management device 100 of the
present embodiment, the following advantages can be
achieved.
(1) In the present embodiment, the power consumption
level by the DC devices 5 is controlled based on the surplus
power amount, which is obtained by comparing the power
generation amount by the solar cell 3 with the power
consumption amount by the DC devices 5, and the charge level
CL of the storage battery 16, which is charged by the power
generation by the solar cell 3.
With this configuration, the power consumption amount
by the DC devices 5 is limited based on the statuses of the

generation and storage of solar energy, so that the power
consumption amount thereof can be automatically and
optimally controlled.
(2) In the present embodiment, when the power
generation amount by the solar cell 3 is larger than the DC
power usage amount PWD by the DC devices 5, the power from
the solar cell 3 is supplied to the DC devices 5 and the
storage battery 16. When the power generation amount by the
solar cell 3 is equal to or smaller than the DC power usage
amount PWD by the DC device 5, the power from the solar cell
3 is supplied to the DC devices 5. When the power
generation amount by the solar cell 3 is larger than the DC
power usage amount PWD by the DC devices 5 and the charge
level CL of the storage battery 16 is equal to or lower than
the reserve charge level CLA, the power consumption by the
DC devices 5 is limited not to exceed the first power level.
With this configuration, when the power generation
amount by the solar cell 3 is equal to or smaller than the
DC power usage amount PWD by the DC devices 5, the power
from the solar cell 3 is supplied to the DC devices 5. When
the power generation amount by the solar cell 3 is larger
than the DC power usage amount PWD by the DC devices 5, the
power from the solar cell 3 is supplied to the DC devices 5
and the storage battery 16. When the power generation
amount by the solar cell 3 is larger than the DC power usage
amount PWD by the DC devices 5 and the charge level CL of

the storage battery 16 is equal to or lower than the reserve
charge level CLA, the power consumption by the DC devices 5
is limited not to exceed the first power level.
Accordingly, the power consumption amount by the DC devices
5 can be automatically and optimally reduced. As a result,
the use of power from the commercial AC power source 2 can
be suppressed.
(3) In the present embodiment, when the power
generation amount by the solar cell 3 is larger than the DC
power usage amount PWD by the devices 5 and the charge level
CL of the storage battery 16 is higher than the reserve
charge level CLA, the power consumption by the DC devices 5
is not limited.
With this configuration, when the power generation
amount by the solar cell 3 is larger than the power
consumption amount by the DC devices 5 and the charge level
CL of the storage battery 16 is higher than the reserve
charge level CLA, that is, when the power consumption by the
DC devices 5 can be afforded by the powers from the solar
cell 3 and the storage battery 16, it is prohibited to
impose a limitation to the power consumption by the DC
devices 5. Accordingly, even when the power from the
commercial AC power source 2 is not used, the performance of
the DC devices 5 can be maintained.
(4) In the present embodiment, when the power
generation amount by the solar cell 3 is equal to or smaller

than the DC power usage PWD amount by the DC devices 5 and
the charge level CL of the storage battery 16 is higher than
the reserve charge level CLA, the power consumption by the
DC devices 5 is limited not to exceed the second power level
stricter than the first power level.
With this configuration, when the power generation
amount by the solar cell 3 is lower than the DC power usage
amount PWD of the DC devices 5 and the charge level CL of
the storage battery 16 is higher than the reserve charge
level CLA, that is, when it is expected that the power
consumption amount of the power from the storage battery 16
will be increased, the power consumption by the DC devices 5
is limited not to exceed the second power level.
Accordingly, an excessive reduction in the charge level CL
of the storage battery 16 can be suppressed. Furthermore,
since the second power level stricter than the first power
level is used as the limiting level, the suppression of a
reduction in the charge level CL can be ensured.
(5) In the present embodiment, when the power
generation amount by the solar cell 3 is equal to or lower
than the DC power usage amount PWD by the DC devices 5 and
the charge level CL of the storage battery 16 is equal to or
lower than the reserve charge level CLA, the power
consumption by the DC devices 5 is limited not to exceed the
third power level stricter than the second power level.
With this configuration, when the power generation

amount by the solar cell 3 is equal to or smaller than the
DC power usage amount PWD by the DC devices 5 and the charge
level CL of the storage battery 16 is equal to or lower than
the reserve charge level CLA, that is, when it is expected
that the consumption of the power from the storage battery
16 will be increased, the power consumption by the DC
devices 5 is limited not to exceed the third power level.
Accordingly, an excessive reduction in the charge level CL
of the storage battery 16 can be suppressed. Furthermore,
since the third power level stricter than the second power
level is used as the limiting level, the suppression of a
reduction in the charge level CL can be ensured.
furthermore, although the limitation regarding power
corresponding to 30% of the total power consumption by the
DC devices 5 is imposed as the third power level in the
present embodiment, the stopping of the use of the DC
devices 5, instead of the limitation, may be performed.
(6) In the present embodiment, the level
corresponding to the amount of power consumed by the DC
devices 5 during the nighttime is set as the reserve charge
level CLA. With this configuration, when the power
generation amount by the solar cell 3 is larger than the DC
power usage amount PWD by the DC devices 5 and the charge
level CL of the storage battery 16 is equal to or lower than
the level corresponding to the amount of power consumed by
the DC devices 5 during the nighttime, the power consumption

by the DC devices 5 is limited not exceed to the first power
level, so that an excessive reduction in the charge level CL
to below the level corresponding to the power consumption
amount during the nighttime can be suppressed.
(Other embodiments)
Embodiments of the electricity supply management
device of the present invention are not limited to the
above-illustrated embodiment, but they may be modified, for
example, as described below and then practiced.
Furthermore, the following modifications are not applied
only to the embodiment, but they may be constructed by
combining other modifications.
In the above embodiment, when the power consumption is
limited in the power consumption limitation process, the
limitation is imposed based on the percentages of the total
power consumption amount by the DC devices 5. However, a
quantity limitation to the total power consumption amount by
the DC devices 5, instead of such limitation, may be
imposed. For example, with regard to the total DC power
usage amount by the DC devices 5, the power usage may be
limited based on a subtraction of 200 W from the maximum
amount of DC power usage as the first power level, a
subtraction of 400 W as the second power level, and a
subtraction of 600 W as the third power level.
Although the reserve charge level CLA is set to the
charge level CL corresponding to the amount of power

consumed during the nighttime in the above embodiment, such
setting may vary depending on the season instead. For
example, the reserve charge level CLA in the spring or the
fall is set to a lower value than that in the summer or the
winter. This set value can be changed by using an interface
such as a touch panel.
Furthermore, the reserve charge level CLA is not
necessarily set based on only the amount of power consumed
during the nighttime, and may be set in light of the maximum
capacity of the storage battery 16. For example, when the
capacity of the storage battery 16 is sufficiently larger
than the power usage amount by the DC devices 5 during the
nighttime, the reserve charge level CLA is set to a level
higher than the amount of power consumed during the
nighttime. By such setting, the frequency at which the
power is supplied from the commercial AC power source 2 when
the power is insufficient during the nighttime can be
suppressed.
Furthermore, when the capacity of the storage battery
16 is smaller than the amount of power consumed during the
nighttime, the reserve charge level CLA may be set to a
level lower than the amount of power consumed during the
nighttime. By such setting, the power consumption by the DC
devices 5 can be limited even when the capacity of the
storage battery 16 is small.
The reserve charge level CLA is not necessarily set

only based on the amount of power consumed during the
nighttime, and may be set for a low-rate time span of
electricity, as will be described below. That is, the
reserve charge level CLA may be set to a level corresponding
to the amount of power that is obtained by subtracting the
amount of power consumed during a low-rate time span from
the amount of power consumed by the DC devices 5.
With this configuration, the power consumption by the
DC devices 5 is limited by setting the charge level CL of
the storage battery 16 to the level corresponding to the
amount of power that is obtained by subtracting the amount
of power consumed during a low-rate time span from the
amount of power consumed by the DC devices 5. Accordingly,
by effectively using the power during the low-rate time
span, it is possible to reduce the amount of power that is
assignable to the charging of the storage battery 16 among
the amount of power generated by the solar cell 3, thereby
increasing a power to be supplied to the DC devices 5.
It is sometimes the case that a normal time span
during which the electricity rate is normal and a low-rate
time span during which the electricity rate is lower than
the normal electricity rate are set as time spans based on
which electricity rate of the commercial AC power source are
determined.
In this case, as shown in Fig. 6, in steps of the
power consumption limitation process after step S250, the

limiting level may be changed based on whether or not the
time at which the corresponding processing is performed
falls within the low-rate time span. That is, since the
power rate of the commercial AC power source 2 varies
depending on the time span, the power from the commercial AC
power source 2 can be effectively utilized by changing the
extent of the limitation on the amount of power consumed
during the low-rate time span. Furthermore, Fig. 6
illustrates a modification of the part surrounded by two-dot
chain lines in Fig. 4, with the same reference numerals
being assigned to the same steps.
Specifically, the following processing is performed.
That is, if the charge level CL of the storage battery 16 is
equal to or lower than the reserve charge level CLA at step
S250, it is determined whether or not the time (the
processing time) at which the processing is performed falls
within the low-rate time span at step S251. If the
processing time does not fall within the low-rate time span,
that is, if the processing time is within the normal-rate
time span, the power consumption by the DC devices 5 is
limited to the third power level at step S261. That is,
since the power rate is normal, the power consumption by the
DC devices 5 is limited to a relatively high level.
On the other hand, if the processing time is within
the low-rate time span, the power consumption by the DC
devices 5 is limited to a level higher than the second power

level and lower than the third power level at step S2 62.
That is, since the electricity rate is low, limitation to
the power consumption by the DC devices 5 is mitigated from
a relatively high level, and therefore the use of the power
from the commercial AC power source is promoted.
Accordingly, at the relatively low electricity rate,
limitation to the use by the DC devices 5 during the
nighttime can be mitigated.
In the above embodiment, in the power control process,
when the solar power generation amount PWS by the solar cell
3 becomes larger than the DC power usage amount PWD by the
DC devices 5 and the storage battery 16 becomes at a full
charge level CLC, the surplus power from the solar cell 3 is
discarded. In this case, the surplus power may be converted
from the DC power into an AC power by the controller 7 and
the AC power may be supplied to the AC device 6. When the
DC-AC supply control is performed, the controller 7 is
considered to be a kind of DC device 5. Here, the amount of
power converted from the DC power to the AC power by the
controller 7 is treated as the DC power usage amount PWD.
Although, in power control process, the power
consumption by one or more specific DC devices 5 is limited
in the above embodiment, the power consumption by all the DC
devices 5 may be uniformly limited instead. Furthermore,
when limitation to a predetermined power level is imposed,
one or more specific DC devices 5 are not selected, but

priorities may be given to respective DC devices 5 and
limitation may be imposed to power consumption in ascending
order of priority.
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 modifications
may be made without departing from the scope of the
invention as defined in the following claims.

What is claimed is:
1 . An electricity supply management device comprising a
solar cell; a commercial Alternating Current (AC) power
source; and a storage battery, in which the storage battery
is charged by an electric power from the solar cell, and a
power from at least one of the solar cell, the commercial AC
power source and the storage battery is supplied to one or
more load devices, wherein:
a power consumption level by the load devices is
controlled based on comparison result between a power
generation amount by the solar cell and a power consumption
amount by the load devices, and a charge level of the
storage battery indicative of a ratio of charging to
capacity of the storage battery.
2. The electricity supply management device of claim 1,
wherein an electric power from the solar cell, in preference
to an electric power from the commercial AC power source, is
supplied to the load devices and the storage battery, and
when the power generation amount by the solar cell is
larger than the power consumption amount by the load devices
and the charge level of the storage battery is equal to or
lower than a reference charge level, power consumption by
the load devices is limited not to exceed a preset power
level.

3. The electricity supply management device of claim 2,
wherein, when the power generation amount by the solar cell
is larger than the power consumption amount by the load
devices and the charge level of the storage battery is
higher than the reference charge level, no limitation is
imposed on the power consumption by the load devices.
4. The electricity supply management device of claim 2 or
3, wherein, when the power generation amount by the solar
cell is equal to or smaller than the amount of power
consumption by the load devices and the charge level of the
storage battery is higher than the reference charge level,
the power consumption by the load devices is limited not to
exceed a reference power level lower than the preset power
level.
5. The electricity supply management device of claim 4,
wherein, when the power generation amount by the solar cell
is equal to or lower than the power consumption amount by
the load devices and the charge level of the storage battery
is equal to or lower than the reference charge level, the
power consumption by the load devices is limited not to
exceed a backup power level lower than the reference power
level.


6. The electricity supply management device of any one of
claims 2 to 5, wherein the reference charge level is set to
a level corresponding to an amount of power consumed by the
load devices during the night time.
7. The electricity supply management device of any one of
claims 2 to 6, wherein, when a normal time span during which
the electricity rate is normal and a low-rate time span
during which the electricity rate is lower than the normal
power rate are set as time spans based on which electricity
rate of the power from the commercial AC power source is
determined, a level corresponding to an amount of power
obtained by subtracting an amount of power Consumed during
the low-rate time span from an amount of power consumed by
the load devices in the nighttime is set as' the reference
charge level.
8. The electricity supply management device of claim 7,
wherein, when a time at which the power consumption by the
load devices is controlled falls within the low-rate time
span, the limiting level of the power consumption by the
load devices is made less stringent compared.to the limiting
level of the power consumption by the load devices in a time
span other than the low-rate time span.
Dated this 04th day of April, 2012.

ABSTRACT

An electricity supply management device includes a
solar cell; a commercial Alternating Current (AC) power
source; and a storage battery, in which the storage battery
is charged by an electric power from the solar cell, and a
power from at least one of the solar cell, the commercial AC
power source and the storage battery is supplied to one or
more load devices. A power consumption level by the load
devices is controlled based on comparison result between a
power generation amount by the solar cell and a power
consumption amount by the load devices, and a charge level
of the storage battery indicative of a ratio of charging to
capacity of the storage battery.