EP4151924A1

EP4151924A1 - Hot water storage-type hot water supply device

Info

Publication number: EP4151924A1
Application number: EP21818875.3A
Authority: EP
Inventors: Kouji Chida
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2020-06-02
Filing date: 2021-06-01
Publication date: 2023-03-22
Also published as: EP4151924A4; JP7108220B2; WO2021246406A1; JP2021191991A

Abstract

A hot water storage-type hot water supply device performs a first heating-up operation in which water in a hot water storage tank (11) is heated at a first heating capacity using electric power supplied from a commercial power supply in a first time zone, and a second heating-up operation in which water in the hot water storage tank (11) is heated using surplus electric power obtained by subtracting electric power consumed by other appliances from electric power supplied from a natural energy power generation device in a second time zone, which is a time zone other than the first time zone. A first amount of hot water to be produced in the first heating-up operation is set equal to a hot water amount obtained by subtracting a second amount of hot water to be produced in the next second heating-up operation from a predetermined necessary hot water amount per day. In the second heating-up operation, when the surplus electric power is less than electric power that exhibits the first heating capacity, a control unit controls a heating unit (2) to heat water in the hot water storage tank (11) using the surplus electric power at the second heating capacity less than the first heating capacity.

Description

TECHNICAL FIELD

The present disclosure relates to a hot water storage-type hot water supply device.

BACKGROUND ART

A hot water storage-type hot water supply device is known which includes a heat pump heater, a hot water storage and supply unit that stores water heated by the heat pump heater, and a photovoltaic generation device as a household power generation device (see, for example, JP 2019-173977 A (Patent Literature 1)).
In such a hot water storage-type hot water supply device, in order to use surplus electric power generated by the household power generation device as much as possible to thereby reduce the use of commercial electric power, a heating capacity of the heat pump heater during a hot water accumulation operation using the surplus electric power is limited so as not to exceed surplus electric power predicted..

CITATION LIST

PATENT LITERATURE

Patent Literature 1: JP 2019-173977 A

SUMMARY OF INVENTION

TECHNICAL PROBLEMS

In the hot water storage-type hot water supply device, before the use of hot water, a necessary amount of heat is stored on the basis of a prediction on the use of hot water, but electric power in the nighttime zone in which an electric power cost is low is not used for heating-up. Instead, the commercial electric power is used in the daytime zone when the surplus electric power is not enough. That is, the surplus electric power has not been effectively used.
The present disclosure provides a hot water storage-type hot water supply device capable of effectively using surplus electric power of a natural energy power generation device.

SOLUTIONS TO PROBLEMS

A hot water storage-type hot water supply device of the present disclosure includes a hot water storage tank, a heating unit that heats water in the hot water storage tank, and a control unit that controls the heating unit,
wherein the device is configured to:

perform, in a first time zone, a first heating-up operation in which water in the hot water storage tank is heated at a first heating capacity, using electric power supplied from a commercial power supply, and
perform, in a second time zone which is a time zone other than the first time zone, a second heating-up operation in which water in the hot water storage tank is heated using surplus electric power obtained by subtracting electric power consumed by the other appliances from electric power supplied from a natural energy power generation device, and
wherein in the second heating-up operation, when the surplus electric power is less than electric power that exhibits the first heating capacity, the control unit controls the heating unit to heat water in the hot water storage tank using the surplus electric power at a second heating capacity less than the first heating capacity.

According to the present disclosure, in the first time zone (for example, a nighttime zone), the first heating-up operation is performed in which water in the hot water storage tank is heated at the first heating capacity using the electric power supplied from the commercial power supply , and then in the second time zone (for example, a daytime zone), which is a time zone other than the first time zone, the second heating-up operation is performed in which water in the hot water storage tank is heated using the surplus electric power obtained by subtracting the electric power consumed by the other appliances from the electric power supplied from the natural energy power generation device (for example, a photovoltaic generation device) . Accordingly, in a case where low cost electric power from the commercial power supply is available in the first time zone, some of the predetermined necessary hot water amount per day is heated up using the electric power supplied from the commercial power supply, and the remaining of the predetermined necessary hot water amount per day is heated using the surplus electric power in the second time zone. In the second heating-up operation, when the surplus electric power is less than the electric power that exhibits the first heating capacity, water in the hot water storage tank is heated using the surplus electric power even at the second heating capacity less than the first heating capacity (for example, a standard heating capacity of the heating unit), so that the surplus electric power of the natural energy power generation device can be effectively used.
In the hot water storage-type hot water supply device according to one aspect of the present disclosure, in the second heating-up operation, when the surplus electric power is greater than the electric power that exhibits the first heating capacity, the control unit controls the heating unit to heat water in the hot water storage tank using the surplus electric power at a third heating capacity greater than the first heating capacity.
According to the present disclosure, it is possible to use the surplus electric power of the natural energy power generation device effectively.
In the hot water storage-type hot water supply device according to one aspect of the present disclosure, a first amount of hot water to be produced in the first heating-up operation is set equal to a hot water amount obtained by subtracting a second amount of hot water to be produced in the next second heating-up operation from a predetermined necessary hot water amount per day.
According to the present disclosure, it is possible to reliably secure the necessary hot water amount per day.
The hot water storage-type hot water supply device according to one aspect of the present disclosure further includes a prediction unit that predicts a generation status of the surplus electric power available for the second heating-up operation.
According to the present disclosure, it is possible to efficiently divide the predetermined necessary hot water amount per day between the first heating-up operation and the second heating-up operation, using the generation status of the surplus electric power predicted by the prediction unit. Thus, the predetermined necessary hot water amount is efficiently obtainable.
The hot water storage-type hot water supply device according to one aspect of the present disclosure further includes a prediction unit that predicts a generation status of the surplus electric power available for the second heating-up operation, and
the control unit determines, on the basis of the generation status of the surplus electric power predicted by the prediction unit, whether to heat in the hot water storage tank using the surplus electric power at the second heating capacity or heat water in the hot water storage tank using the surplus electric power at the third heating capacity in the second heating-up operation.
According to the present disclosure, it is possible to use the surplus electric power of the natural energy power generation device effectively by heating water in the hot water storage tank at a heating capacity based on the generation status of the surplus electric power.
In the hot water storage-type hot water supply device according to one aspect of the present disclosure, a first amount of hot water to be produced in the first heating-up operation is set equal to a hot water amount obtained by subtracting a second amount of hot water to be produced in the next second heating-up operation from a predetermined necessary hot water amount per day. The hot water storage-type hot water supply device further includes a prediction unit that predicts a generation status of the surplus electric power available for the second heating-up operation, a learning and storage unit that learns and stores past hot water usage by a user, a second hot water amount calculation unit that calculates, before start of the first heating-up operation, the second amount of hot water to be produced in the next second heating-up operation on the basis of the generation status of the surplus electric power predicted by the prediction unit and the hot water usage stored in the learning and storage unit, and a first hot water amount calculation unit that calculates, before start of the first heating-up operation, the first amount of hot water by subtracting the second amount of hot water calculated by the second hot water amount calculation unit from the predetermined necessary hot water amount per day. The control unit controls to produce, in the first heating-up operation, the first hot water amount calculated by the first hot water amount calculation unit at the first heating capacity using the electric power supplied from the commercial power supply and produce, in the second heating-up operation subsequent to the first heating-up operation, the second amount of hot water calculated by the second hot water amount calculation unit, at a heating capacity using the surplus electric power.
According to the present disclosure, it is possible to efficiently divide the predetermined necessary hot water amount per day between the first heating-up operation and the second heating-up operation, using the predicted generation status of surplus electric power and the learned past hot water usage by the user. Thus, the predetermined necessary hot water amount is efficiently obtainable.
In the hot water storage-type hot water supply device according to one aspect of the present disclosure, when hot water usage in a predetermined time zone of the second time zone, determined based on the past hot water usage stored in the learning and storage unit may cause the hot water amount produced by the second heating-up operation in the second time zone to run short, the first hot water amount calculation unit adds at least a hot water amount corresponding to the shortage to the first amount of hot water.
According to the present disclosure, it is possible to prevent a shortage of hot water in the second time zone.
In the hot water storage-type hot water supply device according to one aspect of the present disclosure, in the second heating-up operation, when the heating capacity using the surplus electric power is less than the first heating capacity, the control unit makes a heating-up time of the heating unit longer as compared with a case where heating-up is performed at the first heating capacity.
According to the present disclosure, it is possible to produce the required second amount of hot water.
In the hot water storage-type hot water supply device according to one aspect of the present disclosure, in the second heating-up operation, when the surplus electric power becomes greater than the electric power that exhibits the first heating capacity by at least a first predetermined value during heating-up at a heating capacity less than the first heating capacity, heating-up is performed using the surplus electric power at a heating capacity greater than the first heating capacity. Also, in the second heating-up operation, when the surplus electric power becomes less than or equal to a value obtained by adding a second predetermined value less than the first predetermined value to the electric power that exhibits the first heating capacity during heating-up using the surplus electric power at a heating capacity greater than the first heating capacity, heating-up is performed using the surplus electric power at the second heating capacity less than the first heating capacity.
According to the present disclosure, even when the supply of the electric power generated by the natural energy power generation device is unstable, it is possible to prevent hunting in which switching of the heating capacity frequently occurs.
The hot water storage-type hot water supply device according to one aspect of the present disclosure has no capability of storing the electric power generated by the natural energy power generation device
According to the present disclosure, it is possible to effectively use the surplus electric power of the natural energy power generation device as compared with a case where the surplus electric power that cannot be stored is sold to an electric power company, and electricity costs can be reduced accordingly.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a schematic configuration diagram of a hot water supply system including a hot water storage-type hot water supply device of a first embodiment of the present disclosure.
Fig. 2 is a block diagram of a control device of the hot water storage-type hot water supply device.
Fig. 3 is a flowchart for describing processing before start of a first heating-up operation of the control device of the hot water storage-type hot water supply device.
Fig. 4 is a flowchart for describing processing before start of a second heating-up operation of the control device of the hot water storage-type hot water supply device.
Fig. 5A is a diagram for describing how the first heating-up operation and the second heating-up operation of the hot water storage-type hot water supply device are performed.
Fig. 5B is a diagram for describing how the first heating-up operation and the second heating-up operation of the hot water storage-type hot water supply device are performed.
Fig. 5C is a diagram for describing how the first heating-up operation and the second heating-up operation of the hot water storage-type hot water supply device are performed.
Fig. 6A is a diagram for describing how a first heating-up operation and a second heating-up operation of a hot water storage-type hot water supply device of second and third embodiments of the present disclosure are performed.
Fig. 6B is a diagram for describing how the first heating-up operation and the second heating-up operation of the hot water storage-type hot water supply device of the second and third embodiments of the present disclosure are performed.
Fig. 6C is a diagram for describing how the first heating-up operation and the second heating-up operation of the hot water storage-type hot water supply device of the second and third embodiments of the present disclosure are performed.
Fig. 7 is a block diagram of a main part of a hot water storage-type hot water supply device of a fourth embodiment of the present disclosure.
Fig. 8 is a block diagram of a main part of a hot water storage-type hot water supply device of a fifth embodiment of the present disclosure.

DESCRIPTION OF EMBODIMENTS

Hereinafter, hot water storage-type hot water supply devices of the present disclosure will be described in detail with reference to illustrated embodiments. In the drawings, the same reference numerals represent the same or corresponding parts.

[First embodiment]

Fig. 1 is a schematic configuration diagram of a hot water supply system including a hot water storage-type hot water supply device of a first embodiment of the present disclosure.
As illustrated in Fig. 1, the hot water supply system of the first embodiment includes the hot water storage-type hot water supply device including a hot water storage unit 1 and a heat pump unit 2, a photovoltaic generation device 3 as an example of a natural energy power generation device, a power conditioner 4, a distribution board 5 installed in a house H, and a home energy management system (HEMS) controller 6 installed in the house H. The heat pump unit 2 is an example of a heating unit.
The hot water storage unit 1 includes a control device 10, a hot water storage tank 11, a flow rate sensor 12, and a circulation pump P1. The circulation pump P1 is disposed in a pipe L1 having one end connected to a lower side of the hot water storage tank 11. The pipe L1 has the other end connected to an inflow port 21a of a water heat exchanger 21 of the heat pump unit 2. A pipe L2 has one end connected to an outflow port 21b of the water heat exchanger 21 and has the other end connected to an upper side of the hot water storage tank 11. A hot water outflow pipe L3 has one end connected to the upper side of hot water storage tank 11. The flow rate sensor 12 is disposed in the hot water outflow pipe L3.
Hot water flowing out through the hot water outflow pipe L3 is mixed with tap water by a mixing valve (not illustrated) and then flows out from a faucet or is used to fill a bathtub or for a shower.
A DC voltage output from the photovoltaic generation device 3 is converted into a predetermined AC voltage by the power conditioner 4, and the resulting AC voltage is input to the distribution board 5.
An AC voltage VA from a commercial power supply (e.g. system power facilities or the like) and an AC voltage VB from the power conditioner 4 are applied to the distribution board 5. The distribution board switches as necessary between the commercial power supply and surplus electric power of the photovoltaic generation device 3 for the heat pump unit 2. The surplus electric power of the photovoltaic generation device 3 is electric power obtained by subtracting electric power consumed by the other home appliances from the electric power supplied from the photovoltaic generation device 3.
The HEMS controller 6 calculates the surplus electric power of the photovoltaic generation device 3 on the basis of the electric power input from the power conditioner 4 to the distribution board 5, the electric power supplied from the distribution board 5 to the other home appliances, and the electric power (purchased electric power) input from the commercial power supply to the distribution board 5 or electric power (sold electric power) output from the distribution board 5 to the commercial power supply, and provides information on the surplus electric power to the control device 10 of the hot water storage-type hot water supply device. The HEMS controller 6 provides information on electric power consumed by the other home appliances to the control device 10 of the hot water storage-type hot water supply device.
Fig. 2 is a block diagram of the control device 10 of the hot water storage-type hot water supply device, and the control device 10 includes a microcomputer, an input/output terminal, and the like.
The control device 10 includes a prediction unit 10a that predicts a generation status of surplus electric power available for the second heating-up operation, a learning and storage unit 10b that learns and stores past hot water usage by a user, a first hot water amount calculation unit 10c that calculates a first amount W1 of hot water to be produced in a first heating-up operation, a second hot water amount calculation unit 10d that calculates a second amount W2 of hot water to be produced in a second heating-up operation, and a heating-up control unit 10e that controls the heat pump unit 2 and the circulation pump P1. The heating-up control unit 10e is an example of a control unit.
The prediction unit 10a predicts a generation status of surplus electric power of the photovoltaic generation device 3 in a daytime zone on the basis of weather forecast information from an information source such as a weather forecast company and the information on electric power consumed by the other home appliances from the HEMS controller 6. Specifically, the prediction unit 10a predicts electric power to be generated by the photovoltaic generation device 3 in the daytime zone on the basis of the weather forecast information. The prediction unit 10a also predicts electric power to be consumed by the other home appliances in the daytime zone on the basis of past information on electric power consumed by the other home appliances. Then, the prediction unit 10a calculates surplus electric power of the photovoltaic generation device 3 on the basis of the predicted electric power to be generated by the photovoltaic generation device 3 and the predicted electric power to be consumed by the other home appliances. Then, the prediction unit 10a predicts the generation status of the surplus electric power in the daytime zone.
Upon receipt of a signal representing a flow rate detected by the flow rate sensor 12, the learning and storage unit 10b learns and stores a cumulative hot water amount per unit time for each day of the week on the basis of, for example, the history of the cumulative hot water amount per unit time for each day of the last one week as the past hot water usage by the user.
As the past hot water usage, for example, the cumulative hot water amount per unit time may be obtained through learning based on historical record information representing hot water usage in the last one month or one year.
The first hot water amount calculation unit 10c calculates the first amount W1 of hot water by subtracting the second amount W2 of hot water calculated by the second hot water amount calculation unit 10d from a predetermined necessary amount W3 of hot water per day before the start of the first heating-up operation (for example, at 22:55). In the first heating-up operation, water in the hot water storage tank 11 is heated up at a standard heating capacity (first heating capacity) using normal electric power based on electric power supplied from the commercial power supply in a nighttime zone (first time zone) from "23:00 to 7:00" during which a midnight power rate lower than a daytime power rate is applied. For example, when the capacity of the hot water storage tank 11 is 370 liters in the hot water storage-type hot water supply device using the heat pump unit 2, the normal electric power consumed when the heating-up operation is performed by the heat pump unit 2 using the electric power supplied from the commercial power supply is about 4.5 kW. The normal electric power is rated electric power (i.e., maximum electric power that can be used in a continuous operation state at a specified ambient temperature) at which the heat pump unit 2 exhibits the standard heating capacity.
In the first embodiment, the predetermined necessary amount W3 of hot water per day is an average hot water usage amount per day calculated by the control device 10 on the basis of the history of hot water amounts supplied from the hot water storage tank 11. For example, the hot water supply device may be provided with a machine learning unit having a learned neural network that uses the hot water amounts supplied from the hot water storage tank 11 as input information and outputs the average hot water usage amount per day as output information, or a user may set the predetermined necessary amount W3 of hot water per day using a remote controller (not illustrated).
Before the start of the first heating-up operation, the second hot water amount calculation unit 10d calculates the second amount W2 of hot water to be produced in the next second heating-up operation on the basis of the generation status of the surplus electric power predicted by the prediction unit 10a and the hot water usage stored in the learning and storage unit 10b. In the second heating-up operation, water in the hot water storage tank 11 is heated using the surplus electric power obtained by subtracting the electric power consumed by the other appliances from the electric power supplied from the photovoltaic generation device 3 in the daytime zone (second time zone), which is a time zone other than the nighttime zone (first time zone).
The heating-up control unit 10e receives a signal representing the second amount W2 of hot water from the second hot water amount calculation unit 10d, a signal representing the flow rate detected by the flow rate sensor 12, information on the current surplus electric power from the HEMS controller 6, and temperature information such as a hot water outflow temperature of the heat pump unit 2 or a hot water temperature of each layer in the hot water storage tank 11. The heating-up control unit 10e then controls the heat pump unit 2 and the circulation pump P1 to perform the first heating-up operation in the nighttime zone (first time zone) to produce and store the first amount W1 of hot water in the hot water storage tank 11, and performs the second heating-up operation in the next daytime zone (second time zone) to produce the second amount W2 of hot water.
Assuming that a target temperature of hot water to be produced and stored in hot water storage tank 11 is constant, the sum of the first amount W1 of hot water and the second amount W2 of hot water is equal to the predetermined necessary amount W3 of hot water per day. When the target temperature of hot water to be produced and stored in hot water storage tank 11 is increased from 60°C to 70°C, however, the first amount W1 of hot water and the second amount W2 of hot water each become 0.86 (≈ 60/70) times as large such that the sum of the amount of heat of the first amount W1 of hot water and the amount of heat of the second amount W2 of hot water becomes equal to the total amount of heat of the predetermined necessary amount W3 of hot water per day. Likewise, when the target temperature of hot water to be produced and stored in hot water storage tank 11 is lowered from 60°C to 50°C, the first amount W1 of hot water and the second amount W2 of hot water each become 1.2 (= 60/50) times as large.
In the hot water storage-type hot water supply device configured as described above, in the heating-up operation in which hot water in the hot water storage tank 11 is heated up by the heat pump unit 2, the heating-up control unit 10e of the control device 10 brings the heat pump unit 2 and the circulation pump P1 into operation to circulate the hot water in the hot water storage tank 11 through the pipe L1, the water heat exchanger 21, and the pipe L2.
The heating-up control unit 10e controls the heat pump unit 2 so as to make the hot water outflow temperature of the heat pump unit 2 equal to a target hot water outflow temperature TS during the heating-up operation. The target hot water outflow temperature TS is calculated by the heating-up control unit 10e on the basis of the past hot water usage and the like. For example, when the amount of hot water usage is large, the target hot water outflow temperature TS is as high as 85°C, for example, and when the amount of hot water usage is small, the target hot water outflow temperature TS is as low as 65°C, for example. The target hot water outflow temperature TS may be set with a remote controller (not illustrated).
In the heating-up operation, since high temperature hot water having a relatively small flow rate is supplied to the upper side of the hot water storage tank 11, convection caused by a temperature difference does not occur in the hot water storage tank 11, and mixing of water hardly occurs in the hot water storage tank 11. Accordingly, a region of the high temperature hot water expands from the upper side toward a bottom side in the hot water storage tank 11 during the heating-up operation.
In the hot water storage tank 11, the hot water temperature of each layer in the hot water storage tank 11 is detected by a plurality of temperature sensors (not illustrated) provided at intervals from the lower side toward the upper side. The heating-up control unit 10e of the control device 10 calculates, on the basis of the hot water temperature of each layer in the hot water storage tank 11 detected by the plurality of temperature sensors, an amount of high temperature hot water remaining in the hot water storage tank 11. The amount of the remaining high temperature hot water is an amount of hot water having a temperature higher than or equal to the target temperature (for example, 60°C) stored in the hot water storage tank 11.
Fig. 3 is a flowchart for describing processing before the start of the first heating-up operation of the control device 10 of the hot water storage-type hot water supply device.
First, at the start of the nighttime zone ("22:55" in this embodiment), load prediction information for the next day is acquired in step S1. Specifically, the second hot water amount calculation unit 10d reads a cumulative hot water amount per unit time of the day of the week corresponding to the next day stored in the learning and storage unit 10b.
Next, the processing proceeds to step S2 in which the generation status of surplus electric power of the next day is predicted. Specifically, the prediction unit 10a predicts the generation status of surplus electric power of the photovoltaic generation device 3 in the daytime zone on the basis of the weather forecast information from an information source such as a weather forecast company and the past generation status of surplus electric power.
Next, the processing proceeds to step S3 in which the hot water amount (second amount W2 of hot water) to be produced in the daytime zone is determined. Specifically, the second hot water amount calculation unit 10d calculates the second amount W2 of hot water to be produced in the second heating-up operation in the next daytime zone on the basis of the prediction information on the generation status of surplus electric power predicted by the prediction unit 10a and the information on the cumulative hot water amount per unit time on a corresponding day of the week stored in the learning and storage unit 10b.
Next, the processing proceeds to step S4 in which the hot water amount (first amount W1 of hot water) to be produced in the nighttime zone is determined. Specifically, the first hot water amount calculation unit 10c calculates the by subtracting the second amount W2 of hot water calculated by the second hot water amount calculation unit 10d from the predetermined necessary amount W3 of hot water per day, and then brings this processing to an end.
Note that if some hot water having a temperature higher than or equal to the target temperature remains in the hot water storage tank 11 at the time when the first hot water amount calculation unit 10c calculates the first amount W1 of hot water, the first amount W1 of hot water minus the remaining hot water amount is heated up in the first heating-up operation.

Then, the heating-up control unit 10e performs heating-up at the standard heating capacity (first heating capacity) using the electric power supplied from the commercial power supply in the nighttime zone (first time zone) until the first amount W1 of hot water is stored in the hot water storage tank 11. At this time, a heating-up start time T1 is set by the heating-up control unit 10e such that the heating-up is completed by "7:00" at which the application of the midnight power rate is terminated.
Fig. 4 is a flowchart for describing processing before the start of the second heating-up operation of the control device 10 of the hot water storage-type hot water supply device.
In step S11, the heating-up control unit 10e calculates a scheduled start time T2 of the second heating-up operation. Specifically, the heating-up control unit 10e determines the scheduled start time T2 of the second heating-up operation in the next daytime zone on the basis of the generation status of the surplus electric power predicted by the prediction unit 10a and the hot water usage stored in the learning and storage unit 10b such that the heating-up at the heating capacity using the surplus electric power is completed without causing a shortage of hot water.
Next, the processing proceeds to step S12, and when the heating capacity using the predicted surplus electric power in a scheduled start time zone (section from the scheduled start time T2 until a predetermined time elapses) is greater than the standard heating capacity (first heating capacity), the processing proceeds to step S13 in which the standard heating capacity is set as a heating-up capacity, and is then brought to an end.
On the other hand, when the predicted surplus electric power in the scheduled start time zone is less than or equal to standard electric power in step S12, the processing proceeds to step S14, and the heating capacity using the surplus electric power is set as the heating-up capacity.
The processing then proceeds to step S15 in which the scheduled start time T2 of the second heating-up operation is adjusted, and is then brought to an end. When the heating capacity using the surplus electric power is less than the standard heating capacity, heating-up time is longer in duration than heating-up at the standard heating capacity, so that the scheduled start time T2 is moved forward.
Note that the processing in Fig. 4 is repeatedly performed during a period from the end of the first heating-up operation to the start of the second heating-up operation, and the scheduled start time T2 of the second heating-up operation is revised in accordance with a change in the generation status of the predicted surplus electric power.

Then, the heating-up control unit 10e starts the second heating-up operation using the surplus electric power of the photovoltaic generation device 3 at the scheduled start time T2 in the daytime zone (second time zone) to produce the second amount W2 of hot water.
Fig. 5A illustrates a case where a predetermined necessary amount W3 of hot water per day is produced only in the first heating-up operation in the nighttime zone ("23:00 to 7:00"), in which heating at the standard heating capacity (first heating capacity) produces the predetermined necessary amount W3 of hot water per day. In Fig. 5A, electric power that exhibits the standard heating capacity is referred to as "normal electric power", and the same applies to Figs. 5B and 5C.
Fig. 5B illustrates a case where the first amount W1 of hot water is produced in the first heating-up operation in the nighttime zone ("2:00 to 7:00"), and the second amount W2 of hot water is produced in the second heating-up operation in the daytime zone ("11:30 to 15:30"). As shown in Fig. 5B, heating at the standard heating capacity (first heating capacity) is performed in the first heating-up operation using the commercial power supply to produce the first amount W1 of hot water. Then, when the heating capacity using the surplus electric power for the second heating-up operation is less than the standard heating capacity by a1 , heating at a second heating capacity (= standard heating capacity - a1), which is less than the standard heating capacity, is performed in the second heating-up operation using the surplus electric power to produce the second amount W2 of hot water.
Fig. 5C illustrates a case where the first amount W1 of hot water is produced in the first heating-up operation in the nighttime zone ("2:00 to 7:00"), and the second amount W2 of hot water is produced in the second heating-up operation in the daytime zone ("11:30 to 15:00"). As shown in Fig. 5C, in the first heating-up operation using the commercial power supply, heating is performed at the standard heating capacity (first heating capacity) to produce the first amount W1 of hot water. In the second heating-up operation using the surplus electric power, when the heating capacity using the surplus electric power is less than the standard heating capacity by a1 ("11:30 to 12:30" and "14:00 to 15:00"), heating is performed at the second heating capacity using the surplus electric power (< standard heating capacity), and when the heating capacity using the surplus electric power is greater than or equal to the standard heating capacity ("12:30 to 14:00"), heating is performed at the standard heating capacity using the surplus electric power, to produce the second amount W2 of hot water.
In the hot water storage-type hot water supply device configured as described above, the first heating-up operation in which water in the hot water storage tank 11 is heated up at the standard heating capacity (first heating capacity) using the electric power supplied from the commercial power supply is performed in the nighttime zone (first time zone), and then the second heating-up operation in which water in the hot water storage tank 11 is heated up using the surplus electric power of the photovoltaic generation device 3 (natural energy power generation device) is performed in the daytime zone (second time zone), which is a time zone other than the nighttime zone (first time zone). Some of the predetermined necessary amount W3 of hot water per day is thus produced using the low-cost electric power supplied from the commercial power supply in the nighttime zone (first time zone), and the remainder of the predetermined necessary amount W3 of hot water per day is produced using the surplus electric power in the daytime zone (second time zone). In the second heating-up operation, even when the surplus electric power is less than the normal electric power that exhibits the standard heating capacity, water in the hot water storage tank 11 is heated up using the surplus electric power at the second heating capacity less than the standard heating capacity, so that the surplus electric power of the photovoltaic generation device 3 can be effectively used.
Heating to produce the predetermined necessary amount W3 of hot water per day can be efficiently performed using the generation status of the surplus electric power predicted by the prediction unit 10a in both the first heating-up operation and the second heating-up operation.
The heating-up control unit 10e controls the first heating-up operation to produce the first amount W1 of hot water calculated by the first hot water amount calculation unit 10c at the standard heating capacity (first heating capacity) using the electric power supplied from the commercial power supply, and controls the second heating-up operation subsequent to the first heating-up operation to produce the second amount W2 of hot water calculated by the second hot water amount calculation unit 10d at the heating capacity using the surplus electric power. As a result, the predetermined necessary amount W3 of hot water per day can be efficiently produced using the generation status of the predicted surplus electric power and the learned past hot water usage by the user in both the first heating-up operation and the second heating-up operation.
When hot water usage in a predetermined time zone (for example, "7:00 to 8:59") of the daytime zone (second time zone), determined based on the past hot water usage stored in the learning and storage unit 10b. may cause the hot water amount produced by the second heating-up operation in the daytime zone to run short, the first hot water amount calculation unit 10c adds at least a hot water amount corresponding to the shortage to the first amount W1 of hot water. Thus, it is possible to prevent a shortage of hot water in the daytime zone (second time zone).
In the second heating-up operation, when the heating capacity using the surplus electric power is less than the standard heating capacity (first heating capacity), the heating-up control unit 10e sets the heating-up time longer, as compared with a case where heating-up is performed at the standard heating capacity, so that the required second amount W2 of hot water is produced.
Since the hot water storage-type hot water supply device of the first embodiment has no capability of storing the electric power generated by the photovoltaic generation device 3, the surplus electric power of the photovoltaic generation device 3 can be effectively used as compared with a case where the surplus electric power that cannot be stored is sold to an electric power company, and an electric power cost can be reduced accordingly.
In the first embodiment, the flow rate of hot water flowing out from the hot water storage tank 11 through the hot water outflow pipe L3 is detected by the flow rate sensor 12. Alternatively, the flow rate of mixed hot water whose temperature has been adjusted, the mixed hot water being a mixture of hot water flowing out from the hot water storage tank 11 and cold tap water made by the mixing valve, may be detected by the flow rate sensor, and the flow rate of the hot water flowing out from the hot water storage tank 11 may be calculated using a mixing ratio set for the mixing valve.
In the first embodiment, a heating-up circuit in which the circulation pump P1 circulates hot water in the hot water storage tank 11 through the pipe L1, the water heat exchanger 21, and the pipe L2, is used, but the configuration of the heating-up circuit is not limited to the above.

[Second embodiment]

A hot water storage-type hot water supply device of a second embodiment of the present disclosure is the same in configuration as the hot water storage-type hot water supply device of the first embodiment except for the operation of the heating-up control unit 10e, and will be therefore described with reference to Figs. 1 and 2.
Fig. 6A illustrates a case where the first amount W1 of hot water is produced in the first heating-up operation in the nighttime zone ("2:00 to 7:00"), and the second amount W2 of hot water is produced in the second heating-up operation in the daytime zone.
In the hot water storage-type hot water supply device, the heating-up control unit 10e controls the heat pump unit 2 (heating unit) to produce the first amount W1 of hot water at the standard heating capacity (first heating capacity) in the first heating-up operation using the commercial power supply as illustrated in Fig. 6A. In Fig. 6A, electric power that exhibits the standard heating capacity is referred to as "normal electric power", and the same applies to Fig. 6B.
In the second heating-up operation using the surplus electric power, when the heating capacity using the surplus electric power is less than the standard heating capacity (first heating capacity) by a1 (i.e., "from 11:30 to 12:30" and "from 14:00 to 14:30"), heating-up is performed using the surplus electric power at the second heating capacity less than the standard heating capacity, wherein the second heating capacity is equal to the standard heating capacity minus a1 (second heating capacity = standard heating capacity - a1). On the other hand, in the second heating-up operation, when the heating capacity using the surplus electric power is greater than the standard heating capacity by b1 (i.e., "from 13:00 to 14:00"), heating-up is performed using the surplus electric power at a third heating capacity greater than the standard heating capacity, wherein the third heating capacity = standard heating capacity + b1. As a result, the surplus electric power of the photovoltaic generation device 3 can be used effectively, and the heating-up time can be shorter as compared with a case where heating-up is performed at the second heating capacity less than the standard heating capacity in the second heating-up operation.
When heating-up is performed using the surplus electric power at the third heating capacity (= standard heating capacity + b1) greater than the standard heating capacity (first heating capacity), the upper limit of the third heating capacity of heat pump unit 2 is set equal to about 1.3 times the standard heating capacity.
Fig. 6B illustrates a case where the first amount W1 of hot water is produced in the first heating-up operation in the nighttime zone ("2:00 to 7:00"), and the second amount W2 of hot water is heated up in the second heating-up operation in the daytime zone ("11:00 to 14:30"). Fig. 6B illustrates an example where the second heating capacity less than the standard heating capacity (first heating capacity) for the second heating-up operation using the surplus electric power include the standard heating capacity minus a1 (standard heating capacity - a1) and the standard heating capacity minus a2 (standard heating capacity - a2), where a1 > a2 .
In the hot water storage-type hot water supply device configured as described above, whether to heat up water in the hot water storage tank 11 using the surplus electric power at the second heating capacity less than the standard heating capacity (first heating capacity) or heat up water in the hot water storage tank 11 using the surplus electric power at the third heating capacity greater than the standard heating capacity in the second heating-up operation is determined on the basis of the generation status of the surplus electric power predicted by the prediction unit 10a, and water in the hot water storage tank is heated up at the heating capacity based on the generation status of the surplus electric power, so that the surplus electric power of the natural energy power generation device can be used more effectively.
In the second heating-up operation, when the surplus electric power becomes greater than the electric power that exhibits the standard heating capacity by at least a first predetermined value during heating-up at a heating capacity less than the standard heating capacity (first heating capacity), heating-up is performed using the surplus electric power at the third heating capacity greater than the standard heating capacity. On the other hand, in the second heating-up operation, when the surplus electric power becomes less than or equal to a value obtained by adding a second predetermined value less than the first predetermined value to the electric power that exhibits the standard heating capacity during heating-up using the surplus electric power at the third heating capacity greater than the standard heating capacity, heating-up is performed using the surplus electric power at the second heating capacity less than the standard heating capacity. As a result, even when the supply of the electric power generated by the photovoltaic generation device 3 is unstable, it is possible to prevent hunting in which switching of the heating capacity frequently occurs.
The hot water storage-type hot water supply device of the second embodiment has similar effects to those of the hot water storage-type hot water supply device of the first embodiment.

[Third embodiment]

A hot water storage-type hot water supply device of a third embodiment of the present disclosure is the same in configuration as the hot water storage-type hot water supply device of the first embodiment except for the operation of the heating-up control unit 10e, and will be therefore described with reference to Figs. 1 and 2.
As illustrated in Fig. 6C, in the second heating-up operation, when the surplus electric power is less than the electric power that exhibits the standard heating capacity (first heating capacity), the electric power from the commercial power supply (purchased power) is used together with the surplus electric power for heating-up at the standard heating capacity. This allows, even when the surplus electric power of the photovoltaic generation device 3 whose electric power output depends on weather is not enough, the required second amount W2 of hot water in the second heating-up operation to be produced. In Fig. 6C, the electric power that exhibits the standard heating capacity is referred to as "normal electric power".
The distribution board of the third embodiment switches, as necessary, among the commercial power supply, the surplus electric power of the photovoltaic generation device 3, and both the commercial power supply and the surplus electric power of the photovoltaic generation device 3, as power source to be used for the heat pump unit 2.
The hot water storage-type hot water supply device of the third embodiment can prevent a shortage of hot water in the daytime zone in which the second heating-up operation is performed, which improves convenience.
The hot water storage-type hot water supply device of the third embodiment has similar effects to those of the hot water storage-type hot water supply device of the first embodiment.
In the first to third embodiments, the control device 10 of the hot water storage-type hot water supply device includes the prediction unit 10a that predicts the generation status of the surplus electric power available for the second heating-up operation and the learning and storage unit 10b that learns and stores the past hot water usage by the user. Alternatively, the prediction unit and the learning and storage unit may be installed in a server device or the like that communicates with the control device over a communication network.

[Fourth embodiment]

Fig. 7 is a block diagram of a main part including a control device 110 of a hot water storage-type hot water supply device of a fourth embodiment of the present disclosure. The hot water storage-type hot water supply device of the fourth embodiment of the present disclosure is the same in configuration as the hot water storage-type hot water supply device of the first embodiment except for the control device 110 and a HEMS controller 106, and will be therefore described also with reference to Fig. 1.
As illustrated in Fig. 7, the control device 110 of the hot water storage-type hot water supply device of the fourth embodiment is different from the control device of the first embodiment in that the control device 110 includes no prediction unit.
In the fourth embodiment, the HEMS controller 106 installed in the house H includes a prediction unit 106a. The control device 110 includes a communication unit (not illustrated) that communicates with the HEMS controller 106 over a local area network (LAN) or the like.
The prediction unit 106a predicts the generation status of the surplus electric power of the photovoltaic generation device 3 in the daytime zone on the basis of weather forecast information from an information source such as a weather forecast company and information on electric power consumed by the other home appliances. The second hot water amount calculation unit 10d calculates the second amount W2 of hot water to be produced in the second heating-up operation in the next daytime zone on the basis of prediction information on the generation status of the surplus electric power predicted by the prediction unit 106a and information on the cumulative hot water amount per unit time on a corresponding day of the week stored in the learning and storage unit 10b.
The hot water storage-type hot water supply device of the fourth embodiment has similar effects to those of the hot water storage-type hot water supply device of the first embodiment.

[Fifth embodiment]

Fig. 8 is a block diagram of a main part including a control device 110 of a hot water storage-type hot water supply device of a fifth embodiment of the present disclosure. The hot water storage-type hot water supply device of the fifth embodiment of the present disclosure is the same in configuration as the hot water storage-type hot water supply device of the first embodiment except that the control device 110 includes no prediction unit and that a cloud server 200 predicts the generation status of the surplus electric power, and will be therefore described also with reference to Fig. 1.
In the fifth embodiment, the cloud server 200 is connected to the control device 110 over a network NW. The control device 110 includes a communication unit (not illustrated) that communicates with the cloud server 200 over the network NW.
The cloud server 200 predicts, on the basis of weather forecast information from an information source such as a weather forecast company and information on electric power consumed by the other home appliances, the generation status of the surplus electric power of the photovoltaic generation device 3 in the daytime zone. The second hot water amount calculation unit 10d calculates the second amount W2 of hot water to be produced in the second heating-up operation in the next daytime zone on the basis of the prediction information on the generation status of the surplus electric power predicted by the cloud server 200 and the information on the cumulative hot water amount per unit time on a corresponding day of the week stored in the learning and storage unit 10b.
The hot water storage-type hot water supply device of the fifth embodiment has similar effects to those of the hot water storage-type hot water supply device of the first embodiment.
In the first to fifth embodiments, the hot water storage-type hot water supply device using the surplus electric power of the photovoltaic generation device 3 as a natural energy power generation device has been described, but the natural energy power generation device is not limited to the photovoltaic generation device 3, and the present disclosure may be applied to a hot water storage-type hot water supply device using surplus electric power of a different natural energy power generation device such as a wind power generation device, a hydraulic power generation device, and a geothermal power generation device.
Although specific embodiments of the present disclosure have been described, the present disclosure is not limited to the first to fifth embodiments, and various modifications can be made within the scope of the present disclosure. For example, an appropriate combination of the contents described in the first to fifth embodiments may be used as an embodiment of the present disclosure.

REFERENCE SIGNS LIST

1: hot water storage unit
2: heat pump unit
3: photovoltaic generation device
4: power conditioner
5: distribution board
6, 106: HEMS controller
10, 110: control device
10a, 106a: prediction unit
10b: learning and storage unit
10c: first hot water amount calculation unit
10d: second hot water amount calculation unit
10e: heating-up control unit
11: hot water storage tank
12: flow rate sensor
21: water heat exchanger
21a: inflow port
21b: outflow port
200: cloud server
L1, L2: pipe
L3: hot water outflow pipe
NW: network
P1: circulation pump

Claims

A hot water storage-type hot water supply device comprising:
a hot water storage tank (11);

a heating unit (2) that heats water in the hot water storage tank (11); and

a control unit (10e) that controls the heating unit (2),

wherein the device is configured to:
perform, in a first time zone, a first heating-up operation in which water in the hot water storage tank (11) is heated at a first heating capacity, using electric power supplied from a commercial power supply, and

perform, in a second time zone which is a time zone other than the first time zone, a second heating-up operation in which water in the hot water storage tank (11) is heated using surplus electric power obtained by subtracting electric power consumed by other appliances from electric power supplied from a natural energy power generation device, and

wherein in the second heating-up operation, when the surplus electric power is less than electric power that exhibits the first heating capacity, the control unit (10e) controls the heating unit (2) to heat water in the hot water storage tank (11) using the surplus electric power at a second heating capacity less than the first heating capacity.
The hot water storage-type hot water supply device according to claim 1, wherein
in the second heating-up operation, when the surplus electric power is greater than the electric power that exhibits the first heating capacity, the control unit controls the heating unit (2) to heat water in the hot water storage tank (11) using the surplus electric power at a third heating capacity greater than the first heating capacity.
The hot water storage-type hot water supply device according to claim 1 or 2, wherein
a first amount of hot water to be produced in the first heating-up operation is set equal to a hot water amount obtained by subtracting a second amount of hot water to be produced in the next second heating-up operation from a predetermined necessary hot water amount per day.
The hot water storage-type hot water supply device according to any one of claims 1 to 3, further comprising a prediction unit (10a) that predicts a generation status of the surplus electric power available for the second heating-up operation.
The hot water storage-type hot water supply device according to claim 2, further comprising a prediction unit (10a) that predicts a generation status of the surplus electric power available for the second heating-up operation, wherein
the control unit (10e) determines, on the basis of the generation status of the surplus electric power predicted by the prediction unit (10a), whether to heat water in the hot water storage tank (11) using the surplus electric power at the second heating capacity or heat water in the hot water storage tank (11) using the surplus electric power at the third heating capacity in the second heating-up operation.
The hot water storage-type hot water supply device according to claim 3, further comprising:
a prediction unit (10a) that predicts a generation status of the surplus electric power available for the second heating-up operation;

a learning and storage unit (10b) that learns and stores past hot water usage by a user;

a second hot water amount calculation unit (10d) that calculates, before start of the first heating-up operation, the second amount of hot water to be produced in the next second heating-up operation on the basis of the generation status of the surplus electric power predicted by the prediction unit (10a) and the hot water usage stored in the learning and storage unit (10b); and

a first hot water amount calculation unit (10c) that calculates, before start of the first heating-up operation, the first amount of hot water by subtracting the second amount of hot water calculated by the second hot water amount calculation unit (10d) from the predetermined necessary hot water amount per day, wherein

the control unit (10e) controls to produce, in the first heating-up operation, the first amount of hot water calculated by the first hot water amount calculation unit (10c) at the first heating capacity using the electric power supplied from the commercial power supply and produce, in the second heating-up operation subsequent to the first heating-up operation, the second amount of hot water calculated by the second hot water amount calculation unit (10d), at a heating capacity using the surplus electric power.
The hot water storage-type hot water supply device according to claim 6, wherein
when hot water usage in a predetermined time zone of the second time zone, determined based on the past hot water usage stored in the learning and storage unit (10b) may cause the hot water amount produced by the second heating-up operation in the second time zone to run short, the first hot water amount calculation unit (10c) adds at least a hot water amount corresponding to the shortage to the first amount of hot water.
The hot water storage-type hot water supply device according to claim 6, wherein
in the second heating-up operation, when the heating capacity using the surplus electric power is less than the first heating capacity, the control unit (10e) makes a heating-up time longer as compared with a case where heating-up is performed at the first heating capacity.
The hot water storage-type hot water supply device according to any one of claims 1 to 8, wherein
in the second heating-up operation, when the surplus electric power becomes greater than the electric power that exhibits the first heating capacity by at least a first predetermined value during heating-up at a heating capacity less than the first heating capacity, heating-up is performed using the surplus electric power at a heating capacity greater than the first heating capacity, and

in the second heating-up operation, when the surplus electric power becomes less than or equal to a value obtained by adding a second predetermined value less than the first predetermined value to the electric power that exhibits the first heating capacity during heating-up using the surplus electric power at a heating capacity greater than the first heating capacity, heating-up is performed using the surplus electric power at the second heating capacity, which is less than the first heating capacity.
The hot water storage-type hot water supply device according to any one of claims 1 to 9, the hot water storage-type hot water supply device having no capability of storing the electric power generated by the natural energy power generation device.