WO2006045145A1

WO2006045145A1 - Energy management method and system

Info

Publication number: WO2006045145A1
Application number: PCT/AU2005/001655
Authority: WO
Inventors: Patrick Pussell
Original assignee: Dux Manufacturing Limited
Priority date: 2004-10-25
Filing date: 2005-10-25
Publication date: 2006-05-04
Also published as: NZ554607A; WO2006045145A8

Abstract

The present invention relates to methods and systems for operating energy- consuming devices or systems in accordance with consumer specific data, which may comprise historical energy consumption by that consumer. In one particular embodiment, a hot water system (100) comprises a water tank (110) for storing water, a heating element (116) for heating water stored in the water tank (110) and an electronic controller (120) configured to operate the heating element (116) in accordance with data specific to a consumer of hot water from the hot water system (100). The consumer specific data may be specified by an authority and/or the consumer and may be based on energy tariffs and/or electricity spot pricing.

Description

ENERGY MANAGEMENT METHOD AND SYSTEM

Field of the Invention

The present invention relates to management of energy consumption and more particularly to operating devices or systems that consume a significant amount of energy.

Background

Energy sources such as electricity and gas are limited resources and reduced consumption of such resources thus features strongly in environmental sustainability studies, initiatives and policies. Additionally, a reduction in energy consumption results in less pollution and environmental destruction. As a consequence, methods and systems for managing energy consumption are highly desirable.

Electricity represents the most significant source of energy for domestic consumers in developed countries. Consumers purchase electricity from retailers, who purchase electricity in bulk from generators. Bulk electricity may be traded by fixed price contracts or by spot pricing. Every half hour, the supply offers of generators and the demand bids of retailers are matched up to derive a common price called the spot price. The spot price can rise dramatically if the generation capacity is insufficient to meet the demand of consumers. Retailers typically sell electricity to consumers, especially domestic consumers, on the basis of a fixed-price tariff. Whilst this shields consumers from spot price fluctuations, the tariff normally includes a premium to cover the retailer's exposure to the electricity market.

It is desirable for consumers to reduce their consumption of electricity and also to change their consumption patterns to reduce the requirements during peak periods of demand. Strategies for lowering electricity costs by consumers include:

• Shedding load (reducing consumption during peak usage periods),

• Drawing load in off-peak periods, and • Varying load (changing usage based on current levels of demand).

The supply of hot water accounts for approximately 30% of domestic energy usage. Furthermore, usage of hot water by domestic consumers is characterised by spikes in demand at certain times during the day. This makes hot water systems a prime candidate for energy management. A need thus exists to provide methods and systems for managing energy consumption by controlling operation of devices that consume significant amounts of energy.

5

Summary

According to one aspect of the present invention, there is provided a hot water system comprising a water tank for storing water, a heating element for heating water stored in the water tank and an electronic controller configured to operate the heating io element in accordance with data specific to a consumer of hot water from the hot water system. The hot water system may comprise at least one device coupled to the electronic controller for determining consumption of hot water from the hot water system by the consumer and the electronic controller may be configured to record hot water consumption as a function of time and to operate the heating element in accordance with

I₅ recorded historical hot water consumption. The electronic controller may comprise a radio frequency receiver for receiving consumer specific data from an authority. Operation of the heating element may be subject to the availability of solar energy provided by a solar sub-system.

20 Another aspect of the present invention provides a method for operating a hot water system. The method comprises the steps of obtaining data relating to a specific hot water consumer and operating the hot water system in accordance with the data specific to said consumer. Hot water consumption from the hot water system may be determined and the hot water system operated in accordance with the historical hot water consumption.

2₅ Consumer specific data may be obtained via radio frequency communication such as via a cellular telephone communications network.

Another aspect of the present invention provides an apparatus for operating a device or system. The apparatus comprises a memory for storing data and instructions to be ₃o performed by a processor and a processor coupled to the memory. The processor is programmed to obtain data relating to a specific energy consumer and operate the device or system in accordance with the data specific to the consumer. The processor may be programmed to determine energy consumption by the device or system and operate the device or system in accordance with historical energy consumption. The apparatus may comprise a radio frequency receiver for receiving consumer specific data from an authority.

The consumer specific data may be specified by an authority and/or the consumer and may be based on energy tariffs and/or electricity spot pricing. The data may comprise times of operation of the hot water system.

Another aspect of the present invention provides a hot water system that comprises a water tank for storing water, a heating element for heating water stored in the water tank, consumption measuring means for measuring consumption of hot water from the water tank, and an electronic controller coupled to the heating element and the consumption measuring means. The electronic controller is configured to operate the heating element in accordance with hot water consumption measured by the consumption measuring means. The hot water system may further comprise a solar sub-system for heating water stored in the water tank and the electronic controller may be further configured to operate the heating element in accordance with heating energy delivered by the solar sub-system. Operation of the heating element may be disabled when energy delivered by the solar sub-system is sufficient to heat the water in the hot water system to meet current demand.

Brief Description of the Drawings

Embodiments are described hereinafter, by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a system block diagram of a hot water system according to an embodiment of the present invention;

Fig. 2 is a block diagram of an energy management controller for the hot water systems of Fig. 1 and Fig. 6;

Fig. 3 is a flow diagram of a method for operating a hot water system (or other energy consuming device or system) in accordance with data relating to energy consumption of a specific consumer;

Fig. 4 is a flow diagram of a method for operating a hot water system (or other energy consuming device or system) in accordance with historical consumption of a specific consumer; Fig. 5 is a flow diagram of a method for operating a hot water system in accordance with data relating to hot water consumption for a specific consumer;

Fig. 6 is a system block diagram of a hot water system according to an embodiment of the present invention; Fig. 7 is a flow diagram of a method for operating a solar-boosted, gas-heated hot water system; and

Fig. 8 is a flow diagram of a method for operating a solar-boosted, electrically- heated hot water system.

Detailed Description

Methods, apparatuses and systems are described herein for managing energy consumption by controlling operation of devices or systems that consume significant amounts of energy. The methods, apparatuses and systems are described with specific reference to electrically heated hot water systems. However, the present invention is not intended to be limited in this manner as the principles of the present invention have general applicability to other types of hot water systems such as gas heated hot water systems and heat pump driven hot water systems. Furthermore, the methods and principles of the present invention may also be applied to other types of devices or systems that consume significant amounts of energy such as air-conditioning systems.

Embodiments of the present invention use information that relates to a specific energy consumer to control operation of that consumer's hot water system. Such information may comprise, but is not necessarily limited to comprising, one or more of the following: • historical consumption of hot water by the consumer,

• information specified by the consumer, and

• information specified by a relevant authority such as an electricity retailer or local government.

Use of the term "consumer" in the context of this specification includes, but is not limited to, households and commercial premises within the scope intended.

Fig. 1 is a system block diagram of a hot water system 100 that comprises a hot water tank 110, a controller 120, a flow measuring device 130, a solar collector 140 and a circulation pump 150. Cold water is introduced into the hot water tank 110 via the inlet path 112, typically from a water supply main. Hot water is drawn from the hot water tank

110 for consumption via the outlet path 114. The amount of water consumed from the hot water tank 110 may be measured by the flow measuring device 130. However, other means for determining hot water consumption may alternatively be practiced, as described hereinafter. Furthermore, certain embodiments do not require the determination of hot water consumption and a consumption determining device (e.g., the flow measuring device 130) is thus not essential for all embodiments.

Water in the hot water tank 110 is heated by a heating element 116 and/or an optional solar heating sub-system that comprises the solar collector 140 and the pump 150. Colder water is pumped from the bottom of the hot water tank 110 by the pump 150 to the solar collector 140 via paths 144 and 146. The water in the solar collector 140 is heated by solar panels and re-enters the hot water tank 110 via path 142.

The controller 120 is processor-based (i.e., microprocessor or microcontroller) for controlling operation of the hot water system 100. Specifically, the controller 120 may activate and de-activate the heating element 116 in accordance with information that relates to the specific consumer of hot water from the hot water system 100.

Alternatively, the controller 120 may control the amount of energy delivered to the heating element 116 in an analog manner.

The hot water system 100 described with reference to Fig. 1 may be operated in accordance with any of the methods described herein, either alone or in combination.

Fig. 2 is a block diagram of an embodiment of the controller 120 in Fig. 1. Control of the hot water system 100 is performed by a software control program resident in the memory of the microcontroller 210. In one particular embodiment, the microcontroller 210 comprises a Microchip PIC 16F676 CMOS 8-bit microcontroller. The PIC 16F676 has 1,792 bytes of flash-based program memory, 64 bytes of RAM and 128 bytes of EEPROM and also includes an on-board 10-bit analog-to-digital (A/D) converter. However, as would readily be appreciated by those skilled in the art, other microcontrollers or microprocessors may alternatively be practiced in the controller 210. Various memory and peripheral configurations may also be practiced, such as a combination of on-board and off-board memory.

The microcontroller 210 controls devices in the hot water system 100 via output ports that are interfaced to the devices by means of input/output interface circuitry 220. In one embodiment, the heating element 116 and the pump 150 are controlled via relays, which form part of the input/output interface circuitry 220. However, alternative control elements may also be practiced, including solid state switches such as thyristors and triacs.

The microcontroller 210 obtains data from devices in the hot water system 100 via

5 input ports that are interfaced to the devices by means of input/output interface circuitry 220. This enables the volume of hot water consumed (i.e., drawn from the hot water system 100), which is measured by the flow measuring device 130, to be communicated to the microcontroller 210. Thus, the microcontroller 210 is able to control operation of the heating element 116 in accordance with historical usage of hot water from the hot o water system 100. The microcontroller 210 may also obtain data relating to the temperature of the water in the hot water tank 110 and the solar collector 140 from temperature sensors (not shown in Fig. 1) coupled via the input/output interface circuitry to input ports of the microcontroller 210. Thus, the microcontroller 210 is able to control the pump 150 to circulate the water in the solar heating sub-system in accordance with the s differential in temperature between the water in the hot water tank 110 and the solar .. collector 140.

The microcontroller 210 is also coupled to an RF transceiver 250 via an RF communications interface 240 for receiving information from and/or transmitting information to a remote entity. The RF transceiver 250 may comprise a communications 0 module for cellular telephone type communication (e.g., GSM or CDMA). Other types of communications transceivers may alternatively be practiced, which may use communications channels such as the ultra-high frequency (UHF), very-high frequency . (VHF) or microwave bands. Still further, a receiver only may be practiced in place of the RF transceiver 250. 5 The microcontroller 210 is coupled to an RS-232 communications interface 230 to provide a communication link to a computer apparatus (not shown). Various other types of communications interfaces may be practiced in place of the RS-232 interface, such as a RS-485 interface, a parallel interface, a Universal Serial Bus (USB) interface, or any other commonly available or proprietary communications interfaces. The computer o apparatus may comprise a Personal Computer (PC), a Personal Digital Assistant (PDA), a mobile telephone, or any other off-the-shelf or proprietary computer apparatus. Parameters for operation of the controller 210 may be adjusted by, and/or downloaded to, the controller 210 from such a computer apparatus via the RS-232 communications interface 230. In other embodiments, bootstrap loader software installed in the program memory of the microcontroller 210 enables downloading of new and/or revised control software to the controller 210 via the RS-232 communications interface 230.

The microcontroller 210, RF communications interface 240, the RF transceiver 250 and the RS-232 communications interface are powered by a power supply 260, which 5 receives input power from the mains supply.

The controller of Fig. 2 may also be practiced as the controller 620 of Fig. 6. In this instance, the volume of hot water consumed (i.e., drawn from the hot water system 600) is determined by the temperature sensors 632 and 634, which are coupled to the controller 620 and enable measurement of a change in temperature over time of the water in the hot I₀ water tank 610. Thus, the controller 620 is able to control operation of the heating element 616 in accordance with historical usage of hot water from the hot water system 600, as described hereinafter with reference to Fig. 6.

Fig. 3 is a flow diagram of a method for operating an energy consuming device or is system in accordance with data relating to a specific consumer.

Referring to Fig. 3, data relating to a specific consumer is obtained at step 310. Such data may relate to historical energy consumption by the specific user. At step 320, the consumer's hot water system (or other energy consuming device or system) is operated in accordance with the data.

20 The method of Fig. 3 may be practiced as a computer program executed by the controller 120 or the controller 620 shown in Figs. 1 and 6, respectively.

Fig. 4 is a flow diagram of a method for operating a hot water system in accordance with historical consumption of hot water of a specific consumer.

₂₅ Consumption of hot water from a specific consumer's hot water system is determined at step 410. At step 420, the hot water system is operated in accordance with the historical hot water consumption.

Historical consumption of hot water supplied by the hot water system may be determined by means of a flow measurement device located in the outflow line of the hot

₃o water system. The flow measurement device is typically coupled to a controller to provide the controller with an indication of the volume of hot water consumed. Alternatively, historical consumption of hot water supplied by the hot water system may be determined by means of one or more temperature sensors coupled to a controller. The temperature sensor/s detect/s a drop in temperature when hot water is consumed and is replenished with cold water. Thus, no communication with an authority such as the electricity retailer is necessary to practice the method of Fig. 4.

The method of Fig. 4 may be practiced as a computer program executed by the controller 120 or the controller 620 shown in Figs. 1 and 6, respectively.

Fig. 5 is a flow diagram of a method for operating a hot water system in accordance with data relating to hot water consumption for a specific consumer.

Data relating to hot water consumption for a specific consumer is determined at step

510. The data may be determined by an authority such as an electricity retailer or local government, by the relevant consumer, or jointly by both parties. At step 520, the data is transmitted to the hot water system controller by radio frequency communication. The hot water system is operated in accordance with the data relating to the specific consumer.

The data may be transmitted to an electronic controller of the hot water system via a radio frequency communication network such as a GSM or CDMA cellular telephone network, or any other public or private radio network.

Electricity tariffs may vary with time according to fixed tiered pricing and/or spot pricing. Tariffs may be increased and/or decreased during particular time periods by retailers to manage demand loading. Using the method of Fig. 5, a hot water system (or another energy consuming device or system), may be automatically operated in accordance with data relating to a specific consumer.

In one particular embodiment, the consumer may elect to cap the maximum tariff the consumer is prepared to pay for electricity. The capped tariff may be an overall cap or a series of caps that apply to different time periods during a day. Then, if the current tariff or the current spot price exceeds the cap, the consumer's hot water system (or other energy consuming device or system) may be operated in a reduced duty cycle or prevented from operating at all until expiry of the cap. The cap may equate to a base rate or a maximum spot price.

In another embodiment, a hot water system (or another energy consuming device or system) of a specific consumer may be automatically operated in accordance with an operating profile for the consumer. The profile may be based on historical consumption of hot water by the consumer and/or specified electricity tariffs. The specified tariffs may be determined by an authority such as an electricity retailer or local government. Alternatively, the tariffs may be specified by the consumer or be jointly specified by the consumer and the authority. The tariffs may be based on fixed tiered pricing and/or spot pricing.

The method of Fig. 5 may be practiced as a computer program executed by the controller 120 or the controller 620 shown in Figs. 1 and 6, respectively.

Fig. 6 is a system block diagram of a hot water system 600 that is similar to the hot water system 100 of Fig. 1.

The hot water system 600 comprises a hot water tank 610, a controller 620, a solar collector 640 and a circulation pump 650, each of which are equivalent or similar to the corresponding components shown in Fig. 1. Cold water is introduced into the hot water tank 610 via the inlet path 612, typically from a water supply main. Hot water is drawn from the hot water tank 610 for consumption via the outlet path 614. Water in the hot water tank 610 is heated by a heating element 616 and/or an optional solar heating sub¬ system that comprises the solar collector 640 and the pump 650. Colder water is pumped from the bottom of the hot water tank 610 by the pump 650 to the solar collector 640 via paths 644 and 646. The water in the solar collector 640 is heated by solar panels and re- enters the hot water tank 610 via path 642.

The controller 620 is processor-based (i.e., microprocessor or microcontroller) for controlling operation of the hot water system 600. Specifically, the controller 620 may activate and de-activate the heating element 616 in accordance with information that relates to the specific consumer of hot water from the hot water system 600. Alternatively, the controller 620 may control the amount of energy delivered to the heating element 616 in an analog manner.

The hot water system 600 further comprises temperature sensors 632 and 634, which are coupled to the controller 620, and which enable measurement of a change in temperature over time of the water in the hot water tank 620. In particular, a drop in temperature resulting from drawing off of hot water from the hot water tank 610 (and consequential cold water replenishment) can be measured to provide an indication of hot water consumption. This arrangement may thus be practiced in place of the flow measuring device 130 of Fig. 1 for determining hot water consumption.

Although the embodiment of Fig. 6 comprises two temperature sensors, it will be obvious to those skilled in the art that other numbers of temperature sensors may be practiced. For example, a single temperature sensor may be employed to monitor temperature within a range defined by upper and lower limits (e.g., 60° and 48°, respectively), relative to a reference. Alternatively, more than two temperature sensors may be practiced. The temperature sensors may be attached to an external surface of the hot water tank 620 or be located within the hot water tank 620 and are preferably located near the top of the hot water tank 620. The hot water system 600 described with reference to Fig. 6 may be operated in accordance with any of the methods described herein, either alone or in combination.

Fig. 7 is a flow diagram of a method for operating a solar-boosted, gas-heated hot water system. The method of Fig. 7 may be practiced as a computer program executed by the controller 120 or the controller 620 shown in Figs. 1 and 6, respectively.

The method begins at step 710. At step 715, a determination is made whether the temperature of the water in the solar panels T_c is more than 4° higher than the temperature of the water in the hot water tank T_t. If not (N), a determination is made at step 720 whether the temperature of the water in the hot water tank T_t is less than or equal to 70 °. If so (Y), at step 720, the hot water tank is cooling and no solar heating is available. Accordingly, the gas heating is turned on and the solar pump is turned off, at step 740. If not (N), at step 720, the hot water tank is at thermal capacity and no further heating is required. Accordingly, both the gas heating and the solar pump are turned off, at step 735. Returning to step 715, if so (Y), a determination is made, at step 725, whether the temperature of the water in the solar panels T_c is more than 6° higher than the temperature of the water in the hot water tank T_t (this constitutes a second check on solar availability). If not (N), at step 725, processing reverts to step 715. If so (Y), at step 725, a determination is made whether the temperature of the water in the hot water tank T_t is less than or equal to 46 ° at step 730. If so (Y), at step 730, the hot water tank is cooling and no solar heating is available. Accordingly, the gas heating is turned on and the solar pump is turned off, at step 740. If not (N), at step 730, only solar heating is required. Accordingly, the gas heater is turned off and the solar pump is turned on, at step 745. Processing continues at step 750 after each of steps 735, 740 and 745.

At step 750, a determination is made whether the temperature of the water in the solar panels T_c is less than or equal to 5° and the solar heating is turned off. If so (Y), the solar pump is turned on at step 760. If not (N), a determination is made whether the temperature of the water in the solar panels T₀ is greater than or equal to 120° and the solar pump is turned off. If not (N), at step 755, processing continues at step 715. If so (Y), at step 755, the solar pump is turned on at step 760. After step 760, a determination is made, at step 765, whether the temperature of the water in the solar panels T_c is greater than 9 ° and less than or equal to 115°. Processing remains in a loop at step 765 until the temperature of the water in the solar panels T_c is greater than 9° and less than or equal to 115°. When the temperature of the water in the solar panels T_c is within the noted range (Y), at step 765, the solar pump is turned off at step 770 and processing returns to step 715.

Fig. 8 is a flow diagram of a method for operating a solar-boosted, electrically- heated hot water system. The method of Fig. 8 may be practiced as a computer program executed by the controller 120 or the controller 620 shown in Figs. 1 and 6, respectively.

The method begins at step 810. At step 815, a determination is made whether the temperature of the water in the solar panels T_c is more than 4° higher than the temperature of the water in the hot water tank T_t. If not (N), a determination is made at step 820 , whether the temperature of the water in the hot water tank T_t is less than or equal to 60 °. If so (Y), at step 820, the hot water tank is cooling and no solar heating is available. , Accordingly, the electric heating element is turned on and the solar pump is turned off, at step 840. If not (N), at step 820, the hot water tank is at thermal capacity and no further heating is required. Accordingly, both the electric heating and the solar pump are turned off, at step 835. Returning to step 815, if so (Y), a determination is made, at step 825, whether the temperature of the water in the solar panels T_c is more than 6° higher than the ; temperature of the water in the hot water tank T_t (this constitutes a second check on solar availability). If not (N), at step 825, processing reverts to step 815. If so (Y), at step 825, a, determination is made whether the temperature of the water in the hot water tank T_t is less than or equal to 46 ° at step 830. If so (Y), at step 830, the hot water tank is cooling and . no solar heating is available. Accordingly, the electric heating is turned on and the solar pump is turned off, at step 840. If not (N), at step 830, only solar heating is required. Accordingly, the electric heater is turned off and the solar pump is turned on, at step 845. Processing continues at step 850 after each of steps 835, 840 and 845.

At step 850, a determination is made whether the temperature of the water in the solar panels T_c is less than or equal to 5° and the solar heating is turned off. If so (Y), the solar pump is turned on at step 860. If not (N), a determination is made whether the temperature of the water in the solar panels T_c is greater than or equal to 120° and the solar pump is turned off. If not (N), at step 855, processing continues at step 815. If so (Y), at step 855, the solar pump is turned on at step 860. After step 860, a determination is made, at step 865, whether the temperature of the water in the solar panels T_c is greater than 9 ° and less than or equal to 115°. Processing remains in a loop at step 865 until the temperature of the water in the solar panels T_c is greater than 9° and less than or equal to 115°. When the temperature of the water in the solar panels T₀ is within the noted range (Y), at step 865, the solar pump is turned off at step 870 and processing returns to step 815.

With reference to the methods of Figs. 7 and 8, solar heating operates when the temperature of the water in the hot water tank in the range of 46 ° to 70 ° (measured at the top of the tank). If solar is available but hot water consumption drives down the water temperature in the tank to 46 ° or less, gas or electric heating is automatically activated. Thus, short cycle gas or electrically assisted heating is only provided when solar is unavailable or during periods of high consumption. Furthermore, the skilled reader will appreciate that the temperature values and ranges referred to in Figs. 7 and 8 are for purposes of example only and other values and ranges may alternatively be practiced.

The methods of each of Figs. 7 and 8 may be integrated with the methods of Figs. 3 and/or 4. For example, during periods of increased hot water consumption, the electric or gas powered energy-consuming heating element may be operated in accordance with data relating to a specific consumer only when heating provided by solar energy (i.e., a solar sub-system) is insufficient to heat the water in the hot water system. In certain situations, the energy-consuming heating element may be disabled when energy delivered by the solar sub-system is sufficient to heat the water in the hot water system (e.g., to meet current consumption demand).

Methods, apparatuses and systems have been described hereinbefore for managing energy consumption by controlling operation of devices or systems that consume significant amounts of energy.

The foregoing detailed description provides exemplary embodiments only, and is not intended to limit the scope, applicability or configurations of the invention. Rather, the description of the exemplary embodiments provides those skilled in the art with enabling descriptions for implementing an embodiment of the invention. Various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the invention as set forth in the claims hereinafter. (Australia Only) Li the context of this specification, the word "comprising" means "including principally but not necessarily solely" or "having" or "including", and not "consisting only of. Variations of the word "comprising", such as "comprise" and "comprises" have correspondingly varied meanings.

Claims

Claims:

1. A hot water system, comprising: a water tank for storing water; a heating element for heating water stored in said water tank; and an electronic controller configured to operate said heating element in accordance with data specific to a consumer of hot water from said hot water system.

2. A hot water system according to claim 1, wherein said data relates to times of operation of said heating element.

3. A hot water system according to claim 1, further comprising a measuring device coupled to said electronic controller for measuring consumption of hot water from said hot water system by said consumer; and wherein said electronic controller is further configured to record hot water consumption as a function of time and to operate said heating element in accordance with recorded historical hot water consumption.

4. A hot water system according to claim 1, further comprising at least one temperature sensor coupled to said electronic controller for determining consumption of hot water from said hot water system by said consumer; and wherein said electronic controller is further configured to record hot water consumption as a function of time and to operate said heating element in accordance with recorded historical hot water consumption.

5. A hot water system according to claim 4, wherein a drop in temperature of hot water in said hot water system is indicative of consumption of hot water from said hot water system.

6. A hot water system according to claim 4, wherein said at least one temperature sensor is disposed on an external surface of said water tank.

7. A hot water system according to claim 1, wherein said electronic controller further comprises a radio frequency receiver for receiving said consumer specific data from an authority.

8. A hot water system according to claim 7, wherein said radio frequency receiver comprises a cellular telephone communications network device.

9. A hot water system according to claim 8, wherein said data is specified by one or more entities selected from the group of entities consisting of: said consumer; and an authority.

10. A hot water system according to claim 9, wherein said data is determined based on energy tariffs.

11. A hot water system according to claim 9, wherein said data is determined based on electricity spot pricing.

12. A hot water system according to claim 9, wherein said data relates to times of operation of said heating element.

13. A hot water system according to any one of claims 1 to 12, wherein said heating element is selected from the group of heating elements consisting of: an electric element; a gas burner; and a heat pump.

14. A hot water system according to claim 13, further comprising a solar heating sub¬ system coupled to said water tank and said electronic controller for heating water in said hot water system, wherein said electronic controller is further configured to operate said heating element only when energy delivered by said solar sub^'-system is insufficient to heat the water in said hot water system, subject to said consumer specific data.

15. A hot water system according to claim 14, wherein said electronic controller is configured to disable operation of said heating element when energy delivered by said solar sub-system is sufficient to heat the water in said hot water system.

16. A method for operating a hot water system, said method comprising the steps of: obtaining data relating to a specific hot water consumer; and operating said hot water system in accordance with said data specific to said consumer.

17. A method according to claim 16, wherein said data relates to times of operation of said hot water system.

18. A method according to claim 16, comprising the steps of: determining historical consumption of hot water from said hot water system; and operating said hot water system in accordance with said historical hot water consumption.

19. A method according to claim 16, wherein said data is obtained from an authority via radio frequency transmission.

20. A method according to claim 19, wherein said data is transmitted via a cellular telephone communications network.

21. A method according to claim 19, wherein said data is specified by one or more entities selected from the group of entities consisting of: a consumer; and an authority.

22. A method according to claim 21, wherein said data is determined based on energy tariffs.

23. A method according to claim 21, wherein said data is determined based on electricity spot pricing.

24. A method according to claim 21, wherein said data comprises times of operation of said hot water system.

25. A method according to any one of claims 16 to 24, wherein said step of operating said hot water system in accordance with data specific to said consumer comprises the step of operating an energy-consuming heating element only when heating provided by solar energy is insufficient to heat the water in said hot water system, subject to said consumer specific data.

26. A method according to claim 25, wherein operation of said energy-consuming heating element is disabled when energy delivered by said solar sub-system is sufficient to heat the water in said hot water system.

27. An apparatus for operating an energy-consuming device or system, said apparatus comprising: a memory for storing data and instructions to be performed by a processing unit; and a processor coupled to said memory, said processor programmed to: obtain data relating to a specific energy consumer; and operate said device or system in accordance with said data specific to said consumer.

28. An apparatus according to claim 27, wherein said data relates to times of operation of said device or system.

29. An apparatus according to claim 27, wherein said processor is programmed to: determine historical energy consumption of a consumer; and operate said device or system in accordance with said historical energy consumption.

30. An apparatus according to claim 27, further comprising a radio frequency receiver for receiving said consumer specific data from an authority.

31. An apparatus according to claim 30, wherein said radio frequency receiver comprises a cellular telephone communications network device.

32. An apparatus according to claim 30, wherein said data is specified by one or more entities selected from the group of entities consisting of: said consumer; and an authority.

33. An apparatus according to claim 32, wherein said data is determined based on energy tariffs.

34. An apparatus according to claim 32, wherein said data is determined based on electricity spot pricing.

35. An apparatus according to claim 32, wherein said data relates to times of operation of said device or system.

36. A hot water system, comprising: a water tank for storing water; a heating element for heating water stored in said water tank; consumption measuring means for measuring consumption of hot water from said water tank; and an electronic controller coupled to said heating element and said consumption measuring means, said electronic controller configured to operate said heating element in accordance with hot water consumption measured by said consumption measuring means.

37. A hot water system according to claim 36, further comprising a solar sub-system for heating water stored in said water tank; and wherein said electronic controller is further configured to operate said heating element in accordance with heating energy delivered by said solar sub-system.

38. A hot water system according to claim 37, wherein operation of said heating element is disabled when energy delivered by said solar sub-system is sufficient to heat the water in said hot water system.