Stored hot water supply device

Abstract

To provide a storage water heater capable of efficiently using electric power generated by a photovoltaic generation system and suppressing a burden on electricity charge.SOLUTION: A storage water heater includes: a heat pump unit 19 that is operated by using private power generation electric power generated by a photovoltaic generation system 3 and commercial electric power supplied from a commercial power source and boils up hot water; a weather prediction information acquisition section 41 acquiring weather prediction information 61 in a predetermined time zone that is updated at predetermined time; and an execution determination section 42 calculating prediction power generation amount calculated on the basis of the weather prediction information 61 at a primary determination time, determining whether or not daytime boiling-up is executed in the predetermined time zone on the basis of the calculated prediction power generation amount and determining a start time of the daytime boiling-up. When the weather prediction information 61 is updated, the execution determination section 42 recalculates the prediction power generation amount on the basis of the weather prediction information 61, and determines again a daytime boiling-up time and a night boiling-up time in accordance with the recalculated prediction power generation amount.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hot water storage type water supply device that boils hot water with electric power generated by a solar power generation system.

Background Art

[0002] Conventionally, a technology for centrally managing the energy used in a house using a HEMS (Home Energy Management System) is known. For example, there is a technology in which a HEMS predicts a time zone that becomes a generated power value at which a boiling operation can be executed so that a hot water storage type water supply device linked with a solar power generation system can efficiently boil hot water with the electric power generated by the solar power generation system.

[0003] Although many merits can be enjoyed by introducing a HEMS, on the other hand, there are also demerits such as introduction costs and construction work for introduction, and there are cases where it is difficult to introduce a HEMS. Even in such a case, there is a demand for a method of efficiently using the electric power generated by a solar power generation system by linking existing devices while reflecting the wishes of each user for boiling hot water.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a solar power generation system without using a HEMS, the predicted power generation amount obtained during the daytime of the next day is predicted from the weather forecast information of the next day, and the amount of boiling for performing the daytime boiling operation using the predicted power generation amount is reduced from the amount of boiling during the nighttime night boiling operation. However, when the weather forecast information is off, it is necessary to boil the insufficient amount using the commercial power supply during the daytime when the electricity rate per unit is high, which poses a problem of burdening the user with the electricity bill for that portion.

Means for Solving the Problem

[0006] The hot water storage type water supply device according to the present invention includes a hot water storage tank for storing hot water, a heat pump unit that operates with self-generated power generated by a solar power generation system and commercial power supplied from a commercial power source to boil the hot water, a weather forecast information acquisition unit that acquires weather forecast information for a predetermined time zone updated at a predetermined time, calculates a predicted power generation amount of the self-generated power based on the weather forecast information at a primary determination time, and based on the calculated predicted power generation amount, determines whether to execute boiling with the self-generated power to boil the hot water by operating the heat pump unit with the self-generated power in the predetermined time zone, and an execution determination unit that determines the start time of daytime boiling. In the hot water storage type water supply device, a predetermined first determination section is set from after the primary determination time until the start of the night boiling operation using the commercial power source. When the weather forecast information acquired by the weather forecast information acquisition unit is updated within the predetermined first determination section, the execution determination unit recalculates the predicted power generation amount of the self-generated power based on the updated weather forecast information. If the recalculated predicted power generation amount is changed in an increasing direction, the execution determination unit changes the start time of the night boiling in a later direction and lengthens the daytime boiling time.

[0008] In addition, a hot water storage tank for storing hot and cold water, a heat pump unit that operates with self-generated power generated by a solar power generation system and commercial power supplied from a commercial power source to boil the hot and cold water, and a weather prediction information acquisition unit that acquires weather prediction information for a predetermined time zone updated at a predetermined time. Calculate the predicted power generation amount of the self-generated power based on the weather prediction information at the primary determination time, and based on the calculated predicted power generation amount, determine whether to execute boiling with the self-generated power that operates the heat pump unit with the self-generated power to boil the hot and cold water in the predetermined time zone. In a hot water supply device equipped with an execution determination unit that determines the start time of daytime boiling, After the first determination time and until a predetermined time before the end after the start of the night heating operation by the commercial power supply is set as a predetermined second determination section. When the weather prediction information acquired by the weather prediction information acquisition unit is updated within the predetermined second determination section, the execution determination unit recalculates the predicted power generation amount of the self-generated power based on the updated weather prediction information. If the recalculated predicted power generation amount is changed in an increasing direction, the execution determination unit changes the end time of the nighttime boiling earlier and lengthens the daytime boiling time.

Effects of the Invention

[0009] In the hot water supply device according to the present invention, it is possible to set a boiling time suitable for the latest weather prediction information according to changes in the weather prediction information, so that the burden of electricity charges can be suppressed.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0011] An embodiment of the storage-type water heater 1 according to the present invention will be described with reference to the accompanying drawings.

[0012] FIG. 1 is a system configuration diagram of a hot water supply system 100 including the storage-type hot water supply device 1 in the present embodiment.

[0013] The hot water supply system 100 includes a distribution board 2, a solar power generation system 3, a server 6, and a storage-type hot water supply device 1 (hereinafter simply referred to as "hot water supply device 1").

[0014] The distribution board 2 is installed in a building such as a house (hereinafter simply referred to as "house") together with the solar power generation system 3 and the hot water supply device 1. The distribution board 2 is connected to the commercial power supply 2a and the solar power generation system 3. The distribution board 2 supplies commercial power supplied from the commercial power supply 2a and self-generated power generated by the solar power generation system 3 to the hot water supply device 1 used in the house and electrical load devices in the house such as an air conditioner other than the hot water supply device 1 (simply referred to as "air conditioner etc. 7" in the following description and FIG. 1).

[0015] The solar power generation system 3 includes a solar power generation panel 4 and an inverter 5. The solar power generation panel 4 is installed on the roof of a house or the like. The inverter 5 converts the generated power of the solar power generation panel 4 into AC power.

[0016] The server 6 is connected to the water heater 1 and the user terminal 9 via the network 8. The server 6 transmits and receives information (details will be described later) necessary for various processes executed by the water heater 1 to and from the water heater 1 and the user terminal 9. The user terminal 9 is a device that can communicate with the server 6 via the network 8 and is owned by the user of the water heater 1, such as a smartphone, tablet, or personal computer.

[0017] The water heater 1 includes a hot water storage tank 10, a heat pump unit 19, a circulation circuit 27, a remote control 32, and a control unit 31.

[0018] The hot water storage tank 10 stores hot water to be supplied to hot water supply terminals such as a bathtub or a kitchen. The hot water storage tank 10 includes a water supply pipe 11, a hot water outlet pipe 12, a water supply bypass pipe 13, a hot water supply pipe 15, and a hot water storage temperature sensor 18.

[0019] The water supply pipe 11 is connected to the hot water storage tank 10 at the bottom of the hot water storage tank 10 and supplies water to the hot water storage tank 10. The hot water outlet pipe 12 is connected to the hot water storage tank 10 at the top of the hot water storage tank 10 and discharges hot water from the hot water storage tank 10. The water supply bypass pipe 13 is a pipe branched from the water supply pipe 11 and is connected to the hot water outlet pipe 12 via a mixing valve 14. The mixing valve 14 mixes the hot water from the hot water outlet pipe 12 and the water from the water supply bypass pipe 13 so that the temperature of the hot water supply reaches the hot water supply set temperature set by the remote control 32.

[0020] The hot water supply pipe 15 supplies the hot water supplied via the mixing valve 14 to the hot water supply terminal. The hot water supply pipe 15 includes a hot water supply flow rate sensor 16 and a hot water supply temperature sensor 17. The hot water supply flow rate sensor 16 detects the hot water supply flow rate and outputs a corresponding detection signal to the control unit 31. The hot water supply temperature sensor 17 detects the hot water supply temperature and outputs a corresponding detection signal.

[0021] The hot water storage temperature sensor 18 detects the temperature of the hot water in the hot water storage tank 10 and outputs a corresponding detection signal to the control unit 31. A plurality of hot water storage temperature sensors 18 are provided on the side surface of the hot water storage tank 10 at different height positions. Each of these multiple hot water storage temperature sensors 18 outputs a corresponding detection signal to the control unit 31 when it detects hot water temperature equal to or higher than a predetermined threshold value, which is preset corresponding to the temperature of hot water in a sufficiently heated state, for example. The control unit 31 detects the amount of hot water (i.e., the hot water storage amount) in the hot water storage tank 10 that is in a state where the hot water is sufficiently heated based on the number of hot water storage temperature sensors 18 that output detection signals.

[0022] The heat pump unit 19 operates with self-generated power and commercial power, performs heat exchange with the hot water, and boils up the hot water. The heat pump unit 19 includes a compressor 20, a water-cooled refrigerant heat exchanger 21, an expansion valve 22, an air heat exchanger 23, a refrigerant pipe 26, and a blower 24.

[0023] The compressor 20 compresses and conveys the refrigerant to high temperature and high pressure. The water-cooled refrigerant heat exchanger 21 performs heat exchange between the high-temperature and high-pressure refrigerant and the water from the hot water storage tank 10. The expansion valve 22 decompresses and expands the refrigerant heat-exchanged in the water-cooled refrigerant heat exchanger 21. The air heat exchanger 23 performs heat exchange between the outside air and the low-pressure refrigerant and evaporates the low-pressure refrigerant. The refrigerant pipe 26 circulates the refrigerant through the compressor 20, the water-cooled refrigerant heat exchanger 21, the expansion valve 22, and the air heat exchanger 23. The blower 24 blows the outside air to the air heat exchanger 23.

[0024] Also, the heat pump unit 19 includes a discharge temperature sensor 25 and an outside air temperature sensor 30. The discharge temperature sensor 25 detects the temperature of the refrigerant discharged from the compressor 20 and outputs a corresponding detection signal to the control unit 31. The outside air temperature sensor 30 detects the outside air temperature and outputs a corresponding detection signal to the control unit 31.

[0025] The circulation circuit 27 circulates the hot water in the hot water storage tank 10 between the hot water storage tank 10 and the water-cooled refrigerant heat exchanger 21. The circulation circuit 27 includes a heating forward pipe 27a, a heating return pipe 27b, a heating circulation pump 28, and a boiling-up temperature sensor 29.

[0026] The forward heating pipe 27a connects the lower part of the hot water storage tank 10 and the water-side inlet of the water-cooling medium heat exchanger 21. The return heating pipe 27b connects the water-side outlet of the water-cooling medium heat exchanger 21 and the upper part of the hot water storage tank 10. The heating circulation pump 28 is arranged on the forward heating pipe 27a to circulate the hot water. The boiling temperature sensor 29 is arranged on the return heating pipe 27b and outputs a detection signal to the control unit 31.

[0027] The remote controller 32 receives instructions from the user regarding the water heater 1, such as the set temperature of the hot water supplied to the hot water supply terminal.

[0028] The control unit 31 has a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and stores various programs and data necessary for the control of the control unit 31. The control unit 31 controls the operation of the entire water heater 1 according to various programs. The control unit 31 is connected to the remote controller 32 and communicates with the remote controller 32 in a two-way manner.

[0029] The control unit 31 particularly has a function for executing a daytime boiling determination process (described later). Here, FIG. 2 is a functional block diagram of the control unit 31 and the server 6. In FIG. 2, only the functions necessary for the daytime boiling determination process and the boiling time change process are shown, and the illustration of other functions is omitted. The control unit 31 has a storage unit 50, a weather prediction information acquisition unit 41, and an execution determination unit 42.

[0030] The storage unit 50 stores the information acquired from the user terminal 9 for the daytime boiling determination process, namely, the system capacity information 51, the in-house power consumption information 52, and the regional information 53, which will be described later.

[0031] The weather forecast information acquisition unit 41 acquires weather forecast information 61 for a predetermined time period from the server 6. The weather forecast information 61 is the weather defined for each cloud amount, and for example, there are three types: sunny (first weather), cloudy (second weather), and rainy. Sunny is the weather with the least cloud amount and the highest power generation efficiency of the photovoltaic power generation system 3. Cloudy is the weather with more cloud amount than sunny, and the power generation efficiency of the photovoltaic power generation system 3 is lower than that of sunny. Rainy is the weather in which the photovoltaic power generation system 3 does not generate power, or even if it generates power, the power generation efficiency is lower than that of sunny and may be lower than that of cloudy.

[0032] The predetermined time period is a time period included in the daytime when the photovoltaic power generation system 3 can generate power (hereinafter referred to as the "power generation time period"), for example, from 9:00 to 15:00. The weather forecast information acquisition unit 41 acquires the weather forecast information 61 for each predetermined time (for example, every hour) in the power generation time period from the server 6.

[0033] The execution determination unit 42 determines whether to execute boiling up by self-generated power at any time during the power generation time period based on the predicted power generation amount of the self-generated power. The predicted power generation amount is calculated based on the weather forecast information 61 acquired by the weather forecast information acquisition unit 41 (described later). Boiling up by self-generated power is an operation in which the heat pump unit 19 is operated with self-generated power at any time during the power generation time period to boil up the hot and cold water circulating in the circulation circuit 27.

[0034] Next, the details of the daytime boiling-up determination process executed by the control unit 31 of the water supply device 1 in the present embodiment will be described. First, as a premise of the daytime boiling-up determination process, the problems of the water supply device 1 will be described.

[0035] The water supply device 1 boils up hot and cold water by commercial power or self-generated power. The commercial power has a lower electricity price per unit at night (second time period) than during the daytime (first time period). For this reason, when the water supply device 1 uses commercial power, from the perspective of reducing the user's electricity cost burden, it is preferable to boil up hot and cold water at night (night boiling-up operation) rather than boiling up hot and cold water during the daytime (daytime boiling-up operation).

[0036] However, when a solar power generation system 3 is installed together with the water heater 1 in a house, it is preferable to boil hot water with self-generated power instead of commercial power. The power generation efficiency of the solar power generation system 3 varies according to the sunshine duration and solar radiation amount. Therefore, in order for the water heater 1 to boil hot water with self-generated power, the solar power generation system 3 needs to know whether the amount of electric power required to boil the amount of hot water needed by the user can be obtained during the daytime.

[0037] For example, when the HEMS centrally manages the energy used in the house, since the water heater 1 can obtain the actual power generation amount of the solar power generation system 3 and the predicted value of the power consumption amount in the house, it is possible to judge whether boiling with self-generated power is possible according to the power generation amount. However, in houses where the HEMS is not installed, there is a current situation that it is difficult.

[0038] That is, when it is determined by the water heater 1 that the self-generated power required for boiling during the daytime of the next day can be obtained based on the weather prediction information 61, by reducing the amount of hot water to be boiled at night, the usage amount of commercial power can be reduced and the usage amount of self-generated power can be increased.

[0039] When the HEMS can grasp the actual power generation amount and the actual power consumption amount consumed by electrical load devices other than the water heater 1, this actual power generation amount and actual power consumption amount can be used for predicting the surplus power amount available for boiling with self-generated power during the daytime. However, in houses where the HEMS is not installed, since the actual power generation amount cannot be used, the prediction accuracy of the surplus power amount becomes relatively low. Therefore, even when it is decided to boil during the daytime of the next day, there is a possibility that the power amount cannot be actually obtained and boiling will be done with commercial power during the daytime with a high electricity rate.

[0040] In order to surely obtain the surplus power generation amount of the solar power generation system 3 used for boiling water in the hot water supply apparatus 1, it is preferable to determine to execute daytime boiling only when the weather forecast information 61 indicating sunny weather with high power generation efficiency is obtained, and to execute boiling of all the required amount of hot water by night boiling during cloudy or rainy weather and not to perform daytime boiling.

[0041] Therefore, the hot water supply apparatus 1 in the present embodiment acquires the weather forecast information 61 every predetermined time in the power generation time zone from the server 6, and executes a daytime boiling determination process for actively performing daytime boiling using self-generated power when the weather is sunny.

[0042] FIG. 3 is a flowchart for explaining the daytime boiling determination process executed by the control unit 31.

[0043] This daytime boiling determination process is repeatedly executed, for example, while the hot water supply apparatus 1 is activated.

[0044] In step S1, the weather forecast information acquisition unit 41 determines whether or not the primary determination time has arrived. The primary determination time is a preset time for acquiring the weather forecast information 61 in the power generation time zone of the next day from the server 6. The primary determination time is, for example, the timing at which all the required amount of hot water that needs to be boiled can be boiled by night boiling when it is determined in step S4 described later that all the required amount of hot water can be boiled by night boiling. Also, from the viewpoint of the accuracy of the weather forecast, the primary determination time is preferably a time (for example, 23:00) as close as possible to the power generation time zone.

[0045] When the weather forecast information acquisition unit 41 determines that the primary determination time has not yet arrived (NO in step S1), it waits until the primary determination time arrives. On the other hand, when the weather forecast information acquisition unit 41 determines that the primary determination time has arrived (YES in step S1), in step S2, it acquires the weather forecast information 61 from the server 6.

[0046] The weather forecast information acquisition unit 41 acquires the corresponding regional weather forecast information 61 from the server 6 based on the regional information 53 regarding the region where the water heater 1 is installed. Here, FIG. 8 is a diagram showing an example of a display screen when receiving information necessary for performing the daytime boiling-up determination process from the user on the user terminal 9.

[0047] The user terminal 9, for example, downloads and installs an application program (app) dedicatedly created and provided by the water heater 1 from a predetermined server 6, and then transmits instructions for operating the water heater 1 or browses the current usage status and past usage history of the water heater 1. The control unit 31 provides the necessary information required for these processes to the user terminal 9 or executes the instructions acquired from the user terminal 9 on the water heater 1. In the present embodiment, as an initial setting for executing the daytime boiling-up determination process, the control unit 31 receives the necessary information from the user terminal 9 on the display screen 9a of FIG. 8.

[0048] The regional information 53 is acquired by the control unit 31 by receiving information regarding prefectures and municipalities from the user terminal 9 via the app. The storage unit 50 stores the acquired regional information 53.

[0049] The server 6 preliminarily holds a plurality of pieces of weather forecast information 61 across the country provided, for example, by a weather information provider. Alternatively, when the weather forecast information 61 is requested from the water heater 1, the server 6 acquires the weather forecast information 61 from a predetermined data server. The weather forecast information acquisition unit 41 requests and acquires the corresponding weather forecast information 61 from the server 6 based on the regional information 53. The weather forecast information acquisition unit 41 acquires the weather forecast information 61 every hour during the power generation time zone from 9:00 to 15:00, for example, as shown in FIG. 4.

[0050] Since the provider of weather information updates the weather information at a predetermined time, the water heater 1 can obtain the latest weather prediction information 61 by requesting the weather prediction information 61 each time the predetermined time arrives, and can calculate the predicted power generation amount from more accurate weather information.

[0051] In step S3, the execution determination unit 42 determines whether to execute daytime boiling with self-generated power that operates the heat pump unit 19 with self-generated power to boil hot water during the power generation time zone. That is, the execution determination unit 42 determines whether it is possible to operate the heat pump unit 19 with self-generated power instead of commercial power to perform daytime boiling based on the predicted power generation amount of the self-generated power.

[0052] Specifically, the execution determination unit 42 calculates the predicted power generation amount based on the content of the obtained weather prediction information 61, that is, the power generation rates assigned to sunny, cloudy, and rainy respectively. Further, the execution determination unit 42 compares the surplus power generation amount obtained by subtracting the power consumption amount consumed by the air conditioner etc. 7 (hereinafter simply referred to as "indoor power consumption amount") from the predicted power generation amount with the power consumption amount consumed when the heat pump unit 19 boils hot water. The execution determination unit 42 compares with the amount consumed by the heat pump unit 19 (hereinafter simply referred to as heat pump power consumption amount), and if the surplus power generation amount is larger than the heat pump power consumption amount, determines to execute boiling with self-generated power.

[0053] When the weather prediction information 61 is sunny, the execution determination unit 42 sets the power generation rate to 0.6. Also, when it is cloudy or rainy, the power generation rate is set to 0 (in the case of cloudy, the power generation rate may be set to 0.3 and the power generation rate may be made different between cloudy and rainy).

[0054] The predicted power generation amount uses the value obtained by multiplying the system capacity of the solar power generation system 3 by the power generation rate assigned to the obtained weather prediction information 61. The system capacity is the power generation amount per unit time (per hour) of the solar power generation system 3, which represents the power generation ability and is a value unique to the solar power generation system 3. As shown in FIG. 8, the control unit 31 receives the system capacity from the user terminal 9 on the display screen 9a of the application and stores it in the storage unit 50 as the system capacity information 51.

[0055] When the execution determination unit 42 obtains weather prediction information 61 as shown in, for example, FIG. 4a, it calculates the predicted power generation amount per hour by multiplying the system capacity and the power generation rate respectively.

[0056] The in-house power consumption amount is, for example, the average value of the in-house power consumption amount per unit time (per hour) and is a value set by the user. The control unit 31 stores the in-house power consumption amount received from the user terminal 9 via the display screen 9a in the storage unit 50 as the in-house power consumption information 52.

[0057] The execution determination unit 42 calculates the surplus power amount by subtracting this in-house power consumption amount from the predicted power generation amount. That is, the surplus power amount is defined as system capacity × power generation rate - in-house power consumption amount.

[0058] The heat pump power consumption amount is a value obtained by multiplying the power consumption amount consumed by the heat pump unit 19 when boiling up, which is set in advance and held by the control unit 31, by a coefficient with a slight additional amount. The heat pump power consumption amount is a value that can vary depending on seasons, days of the week, etc. For example, the heat pump power consumption amount is set to a value obtained by multiplying 1 kW by a coefficient of 1.2 under normal conditions. Also, in winter when the usage frequency of the heat pump unit 19 is high, it is set to a value obtained by multiplying 1.5 kW by a coefficient of 1.2.

[0059] In step S4, the execution determination unit 42 determines whether it is possible to perform daytime heating of hot water using the surplus power generation power by determining whether the calculated surplus power amount is greater than the heat pump power consumption amount. The execution determination unit 42 determines that daytime heating is possible when the surplus power amount is continuously greater than the heat pump power consumption amount for the time required for heating (for example, 2 hours). For example, in the example of FIG. 4a, since the surplus power amount is continuously greater than the heat pump power consumption amount for 2 hours and the operation determination is ○, the execution determination unit 42 determines that daytime heating is possible.

[0060] When the execution determination unit 42 determines that daytime heating is not possible (NO in step S4), in step S5, it performs nighttime heating to heat the entire amount of hot water that needs to be heated. That is, since the required sunshine time and solar radiation amount cannot be obtained during the daytime of the next day and daytime heating cannot be performed, the entire amount of hot water is heated with commercial power at night when the electricity rate unit price is low. After that, the control unit 31 returns to step S1 and repeats the subsequent processing.

[0061] On the other hand, when the execution determination unit 42 determines that daytime heating is possible (YES in step S4), in step S6, it determines the start time of nighttime heating and the start time of daytime heating. The execution determination unit 42 sets the earliest time zone among the times obtained continuously for the time required for heating as the start time of daytime heating. This is because it can be said that the weather prediction information 61 at a time close to the timing of obtaining the weather prediction information 61 has a high accuracy. For example, in the example of FIG. 4a, the earliest 9 o'clock among the times when daytime heating can be continuously performed for 3 hours is determined as the start time, and daytime heating is performed for 3 hours.

[0062] Further, the execution determination unit 42 may accept from the user the setting of the time zone for performing daytime heating. The power generation peak of the solar power generation system 3 varies from user to user depending on the installation angle of the solar power generation panel 4 and the like. For this reason, the water heater 1 allows the user to select the time zone for performing daytime heating using self-generated power, so as to perform heating according to each user. On the display screen 9a of the user terminal 9 in FIG. 8, the setting of the time zone may be accepted by selecting the "earlier", "standard", or "later" button, and the time of daytime heating may be shifted.

[0063] When the start time of nighttime heating determined in step S7 is reached, in S8, the control unit 31 performs nighttime heating using commercial power for a partial amount of the hot water that needs to be heated (see FIG. 5a). That is, since it is predicted that the required sunshine duration and solar radiation amount will be obtained during the daytime of the next day, a part of the hot water that needs to be heated (for example, 20 to 60% of the total amount) is heated with commercial power at night when the electricity price per unit is low. This part of the hot water that needs to be heated is the amount of hot water that needs to be heated at night after subtracting the amount of hot water heated during daytime heating from the total amount of hot water that needs to be heated. Therefore, the start time of nighttime heating is changed according to the amount of hot water heated during daytime heating.

[0064] In step S9, the control unit 31 determines whether the start time of daytime heating determined in step S6 has arrived. If the control unit 31 determines that the start time has not yet arrived (NO in step S9), it waits until the start time arrives. On the other hand, if the control unit 31 determines that the start time has arrived (YES in step S9), in step S10, the remaining amount of the hot water that needs to be heated is heated using self-generated power (see FIG. 5a). Then, the control unit 31 returns to step S1 and repeats the subsequent processing.

[0065] The above is the daytime boiling-up determination process according to the flowchart of FIG. 3. However, if the weather forecast information 61 obtained at the primary determination time is changed after the primary determination time, there is a possibility that it is different from the calculated predicted power generation amount. Therefore, it is necessary to perform a boiling-up time change process executed by the control unit 31 separately from the daytime boiling-up determination process. FIG. 6 is a flowchart for explaining the boiling-up time change process.

[0066] In step S11, the weather forecast information acquisition unit 41 acquires the weather forecast information 61 from the server 6 every time a predetermined time is reached (here, 23:00, 24:00, 1:00 ··· 7:00, and every time one hour elapses from 23:00 to 7:00 is set as the predetermined time). If the weather forecast information acquisition unit 41 determines that the predetermined time has not been reached (NO in step S12), it waits until the predetermined time is reached. On the other hand, if the weather forecast information acquisition unit 41 determines that the predetermined time has been reached (YES in step S11), in step S12, it requests the weather forecast information 61 from the server 6, acquires the weather forecast information 61 every hour for the power generation time zone from the latest 9:00 to 15:00, and if the weather forecast information 61 from 9:00 to 15:00 is updated, the control unit 31 stores the latest weather forecast information 61.

[0067] In step S13, the execution determination unit 42 determines whether there is a change in the weather forecast information 61 acquired at the primary determination time (if the weather forecast information 61 at the primary determination time has already been updated, it is for the immediately preceding weather forecast information 61) compared to the weather forecast information 61 acquired in step S12. If the execution determination unit 42 determines that there is a change (YES in step S13), in step S14, the execution determination unit 42 checks whether full-scale boiling-up is to be performed or daytime boiling-up is to be performed. If full-scale boiling-up is to be performed (NO in step S14), it returns to step S11. On the other hand, if the execution determination unit 42 plans to execute daytime boiling-up (YES in step S14), it determines that the night boiling-up start time and the daytime boiling-up start time have already been determined.

[0068] In step S15, it is determined whether the time when the updated latest weather prediction information 61 is acquired is within the first determination interval after the primary determination time and before the start of the night boiling-up operation. When the execution determination unit 42 determines that the time when the updated latest weather prediction information 61 is acquired is within the first determination interval (YES in step S15), in step S16, the execution determination unit 42 recalculates the predicted power generation amount.

[0069] In step S17, the execution determination unit 42 compares the predicted power generation amount calculated for the weather prediction information 61 acquired at the primary determination time with the updated predicted power generation amount calculated for the updated latest weather prediction information 61. When the weather prediction information 61 has changed in the direction of increasing the predicted power generation amount (see Fig. 4b), in step S18, the execution determination unit 42 delays the start time of the night boiling-up operation compared to the start time of the night boiling-up operation determined in step S6 and increases the time for daytime boiling-up (see Fig. 5b).

[0070] In this way, by comparing the predicted power generation amount calculated for the weather prediction information 61 acquired at the primary determination time with the updated predicted power generation amount calculated for the updated latest weather prediction information 61, when the weather prediction information 61 has changed in the direction of increasing the predicted power generation amount, the start time of the night boiling-up operation using commercial power is delayed to reduce the boiling-up amount at night, and the boiling-up amount corresponding to the reduced amount is ensured by increasing the time for the daytime boiling-up operation using self-generated power, and at the same time, the burden on the user's electricity bill can be reduced.

[0071] Also, in step S17, the execution determination unit 42 compares the predicted power generation amount calculated for the weather prediction information 61 acquired at the primary determination time with the updated predicted power generation amount calculated for the updated latest weather prediction information 61. When the weather prediction information 61 has changed in the direction of decreasing the predicted power generation amount (see Fig. 4c), in step S19, the execution determination unit 42 advances the start time of the night boiling-up operation compared to the start time of the night boiling-up operation determined in step S6 and shortens the time for daytime boiling-up (when the calculated predicted power generation amount is 0, the time for daytime boiling-up is eliminated) (see Fig. 5c).

[0072] In this way, the predicted power generation amount calculated for the weather prediction information 61 obtained at the primary determination time is compared with the updated predicted power generation amount calculated for the updated latest weather prediction information 61. When the weather prediction information 61 changes in the direction of decreasing predicted power generation amount, the start time of the night boost operation using commercial power is advanced, the boost amount at night is increased, and the time of the day boost operation using self-generated power is shortened. Thus, with the power generation amount determined at the primary determination time, the risk of hot water runout can be prevented because the required boost amount cannot be reached, and since the boost using commercial power during the day with a high electricity rate per unit is not performed, the burden on the user's electricity bill can be reduced.

[0073] Also, in step S15, it is assumed that the time when the updated latest weather prediction information 61 is obtained is not in the first determination section (NO in step S15). In step S20, it is determined whether the time when the updated latest weather prediction information 61 is obtained is within the second determination section after the primary determination time and during the period from the start to the end of the night boiling-up operation using commercial power (see FIG. 7a). When the execution determination unit 42 determines that the time when the updated latest weather prediction information 61 is obtained is in the second determination section (YES in step S20), in step S21, the execution determination unit 42 recalculates the predicted power generation amount.

[0074] In step S22, the execution determination unit 42 compares the predicted power generation amount calculated for the weather prediction information 61 obtained at the primary determination time with the updated predicted power generation amount calculated for the updated latest weather prediction information 61. When the weather prediction information 61 changes in the direction of increasing predicted power generation amount, in step S23, the execution determination unit 42 advances the end time of the night boost operation earlier than the end time of the night boost operation determined in step S6, shortens the time of the night boost, and lengthens the time of the day boost (see FIG. 7b).

[0075] In this way, the predicted power generation amount calculated for the weather prediction information 61 obtained at the primary determination time is compared with the updated predicted power generation amount calculated for the updated latest weather prediction information 61. When the weather prediction information 61 changes in the direction in which the predicted power generation amount is increasing, the end time of the night heating operation using the commercial power supply is advanced to reduce the heating amount at night, and the heating amount corresponding to the reduced amount is secured by extending the time of the daytime heating operation using the self-generated power, and at the same time, the burden on the user's electricity bill can be reduced.

[0076] Also, in step S20, when it is determined that the time when the updated latest weather prediction information 61 is obtained is neither in the first determination section nor in the second determination section (NO in step S20), in step S24, the execution determination unit 42 uses the start time and end time of heating determined in step S6 as not applicable.

[0077] After steps S18, S19, S23, and S24, the execution determination unit 42 returns to step S11 and repeats the subsequent processing each time a predetermined time is reached.

[0078] In this way, the start time of night heating and the start time of daytime heating are determined from the predicted power generation amount based on the weather prediction information 61 obtained at the primary determination time. However, if the weather prediction information 61 changes after the determination, the start time of night heating and the start time of daytime heating can be set in a distribution suitable for the latest weather prediction information 61 according to the change in the weather prediction information 61. Therefore, it is possible to suppress the burden of the electricity bill and prevent the risk of running out of hot water.

[0079] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention and are included in the invention described in the claims and its equivalent scope.

[0080] For example, the value of the power generation rate used in the daytime boiling-up determination process is just an example and may be set to any value.

[0081] Also, although the server 6 acquires and stores the information necessary for the daytime boiling-up determination process from the user, the control unit 31 may directly acquire it from the user.

[0082] Also, the second determination section in FIG. 7a is set to be after the primary determination time and from the start to the end of the night boiling-up operation using the commercial power supply. However, near the end time of the night boiling-up, since there is no carry-over to the daytime boiling-up, it may be set to be until a predetermined time (one hour before) before the end time of the night boiling-up. That is, the second determination section may be set to be after the primary determination time and from the start to a predetermined time before the end of the night boiling-up operation using the commercial power supply.

[0083] Also, in the present embodiment, when increasing or decreasing the time of the daytime boiling-up, the start time of the daytime boiling-up is changed, but the end time of the daytime boiling-up may also be changed. Particularly when the predicted power generation amount increases, the boiling-up time is increased, but it may also be increased for the time band with a high power generation rate based on the weather prediction information 61.

Explanation of Reference Numerals

[0084] 1 Storage water heating device (water heating device) 3 Photovoltaic power generation system 6 Server 7 Air conditioner etc. 8 Network 9 User terminal 10 Storage tank 19 Heat pump unit 27 Circulation circuit 31 Control unit 32 Remote control 41 Weather prediction information acquisition unit 42 Execution determination unit

Claims

1. A hot water storage tank for storing hot water, A heat pump unit that operates with self-generated power generated by a solar power generation system and commercial power supplied from a commercial power source, and boils the hot water, A weather prediction information acquisition unit that acquires weather prediction information for a predetermined time zone updated at a predetermined time, In a hot water supply device equipped with an execution determination unit that calculates a predicted power generation amount of the self-generated power calculated based on the weather prediction information at a primary determination time, and based on the calculated predicted power generation amount, determines whether to execute boiling with the self-generated power that operates the heat pump unit with the self-generated power to boil the hot water in the predetermined time zone, and determines the start time of daytime boiling, A predetermined first determination section is defined as the period after the primary determination time and until the start of night boiling operation by the commercial power source, When the weather prediction information acquired by the weather prediction information acquisition unit is updated within the predetermined first determination section, the execution determination unit recalculates the predicted power generation amount of the self-generated power based on the updated weather prediction information, The hot water supply device is characterized in that when the recalculated predicted power generation amount is changed in an increasing direction, the execution determination unit changes the start time of the night boiling operation in a direction to delay it and lengthens the daytime boiling time.

2. A hot water storage tank for storing hot water, A heat pump unit that operates with self-generated power generated by a solar power generation system and commercial power supplied from a commercial power source, and boils the hot water, A weather prediction information acquisition unit that acquires weather prediction information for a predetermined time zone updated at a predetermined time, In a hot water supply device equipped with an execution determination unit that calculates a predicted power generation amount of the self-generated power calculated based on the weather prediction information at a primary determination time, and based on the calculated predicted power generation amount, determines whether to execute boiling with the self-generated power that operates the heat pump unit with the self-generated power to boil the hot water in the predetermined time zone, and determines the start time of daytime boiling, A predetermined second determination section is defined as the period after the primary determination time and until a predetermined time before the end after the start of night boiling operation by the commercial power source, When the weather prediction information acquired by the weather prediction information acquisition unit is updated within the predetermined second determination section, the execution determination unit recalculates the predicted power generation amount of the self-generated power based on the updated weather prediction information, When the recalculated predicted power generation amount is changed in the increasing direction, the execution determination unit changes the end time of the night boiling up in the direction of making it earlier and increases the time of the daytime boiling up. A storage type water heater characterized by this.

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