Energy system

Abstract

Energy system, comprising: a first storage unit for storing a heat transfer medium; a second storage unit for storing heat transfer medium, the second storage unit having a smaller volume than the first storage unit; a heat source for supplying thermal energy to the heat transfer medium; a first heat exchanger; a fluid circuit with a pump for circulating the heat transfer medium at least between the first reservoir, the second reservoir, the heat source, and the first heat exchanger; and a first valve arranged in the fluid circuit such that a volume flow rate of the heat transfer medium through the first reservoir and a volume flow rate of the heat transfer medium through the second reservoir can be adjusted, in particular limited.

Description

The invention relates to an energy system, in particular a heat pump heating system.Prior ArtEnergy systems comprising storage devices for heat energy extracted from an environment are used in many countries for heating buildings and infrastructure. In many cases, such energy systems include a heat pump which removes heat energy from the store and emits it at the desired location in the building or infrastructure. In the heat pump, a refrigerant circulates, which is vaporized by the thermal energy taken from the storage and compressed by the use of mechanical energy in order to raise the pressure and thus the energy level (compression heat pump). Due to the relatively low ambient temperature in many installation situations, large heat accumulators with large quantities of a heat transfer medium (WTM), such as brine or water, are required in order to collect sufficient heat energy at an inlet of the heat pump. Known reservoirs include groundwater aquifers, geothermal heat probes, geothermal heat collectors, trench collectors, geothermal heat baskets, and ice reservoirs.Efficient operation of a heat pump is only possible with difficulty with such large reservoirs with a low temperature of the heat transfer medium, since a large amount of compression energy has to be used in order to achieve a sufficiently high temperature of the refrigerant at an outlet of the heat pump. The annual work number (COP), known as a measure of the efficiency of heat pumps, is in the prior art at values between 5 and 6, which means that between 5 and 6 kWh of heating heat are generated per kilowatts hour (kWh) of energy used.It is an object of the invention to provide alternative or improved solutions for an energy system.Disclosure of the InventionThe object of the invention is achieved by means of a method according to claim 1, by an energy system according to claim 4, by a control unit according to claim 15, and by a computer program according to claim 16.According to a first aspect, the present disclosure discloses a method for controlling a power system, comprising the steps of:S1. taking heat transfer medium from a reservoir, the reservoir comprising a first reservoir (20) and a second reservoir (30), wherein the second reservoir (30) has a smaller volume than the first reservoir (20);S2. transporting the heat transfer medium to a first heat exchanger (90) of a heat pump (100) for delivering heat to the first heat exchanger (90); andS3. returning the heat transfer medium into the reservoir;wherein in step S 1 a proportion of heat transfer medium removed from the first store and a proportion of heat transfer medium removed from the second store is determined at least partially on the basis of a difference between a setpoint temperature of the heat transfer medium at the first heat exchanger and an actual temperature of the heat transfer medium at the first heat exchanger.According to a further aspect, the present disclosure discloses a control unit of an energy system, configured to carry out the method described above.According to a further aspect, the present disclosure discloses a computer program for carrying out the method described above when the computer program is executed by a control unit of an energy system.In step S 1, in a step 1 a, the heat transfer medium can be conducted, if necessary, via a first heat source or a first heat sink.In step S 1, in a step 1 bsubstantial to step 1 a, the heat transfer medium can be returned to the storage device again. Steps S 1 aand S 1 bmay also be carried out repeatedly one after the other if necessary until a specific temperature of the heat transfer medium is reached. Subsequently, in step S 2, the heat transfer medium can then be transported to the first heat exchanger.According to a further aspect, the present disclosure discloses an energy system comprising: a first store for storing a heat transfer medium; a second store for storing heat transfer medium, wherein the second store has a smaller volume than the first store; a first heat source for supplying thermal energy to the heat transfer medium; a first heat exchanger; a fluid circuit having a first pump for circulating the heat transfer medium at least between the first store, the second store, the heat source and the first heat exchanger; and a first valve (V1) which is arranged in the fluid circuit in such a way that a level of a volume flow of the heat transfer medium via the first store and a level of a volume flow of the heat transfer medium via the second store can be set, in particular limited.A second valve can be arranged in the fluid circuit in such a way that a level of a volume flow of the heat transfer medium via the first heat exchanger can be set, in particular limited.The first heat source can comprise solar collectors, in particular photovoltaic-thermal solar collectors.The first heat source can comprise at least one second heat exchanger for transferring heat from the solar collectors to the heat transfer medium.The energy system may comprise a heat pump, wherein the first heat exchanger is an evaporator of the heat pump.The energy system may comprise a industrial warm water plant thermally coupled to the heat pump, wherein the coupling is preferably produced behind a compressor of the heat pump and in front of a condenser of the heat pump.The industrial warm water plant may be thermally coupled to the first heat source.The energy system may include a heating water reservoir thermally coupled to the heat pump. The thermal coupling can be effected, for example, via the condenser of the heat pump.The heating water reservoir may be thermally coupled to the first heat source.The energy system can also comprise a combination of industrial hot water installation and heating water storage.The first and / or the second storage can be designed as a geothermal heat absorber, in particular as a two-media geothermal heat absorber.The first and / or the second accumulator can comprise at least one water / brine heat accumulator, wherein the at least one water / brine heat accumulator comprises a housing which fluidically seals a cavity, and a fluid conductor which is arranged within the cavity and is connected fluidically to the fluid circuit via an inlet and an outlet.The cavity of the at least one water / brine heat store can be filled with water and with plastic-coated PCM bodies (phase change material) and / or the PCM bodies can enclose the cavity.Brief Description of the FiguresThe invention is explained in more detail below on the basis of exemplary embodiments with reference to the appended schematic drawing, which is not true to scale. The figures (FIG.) of the drawing show: FIG. 1 schematically shows an embodiment of a power system; FIG. 2 schematically shows an embodiment of a power system; FIG. 3 schematically shows an embodiment of a power system; FIG. 4 schematically shows an embodiment of a heat store; and FIG. 5 schematically shows various embodiments of heat accumulators.With reference to FIGS. 1 to 5, the structure and the mode of operation of an energy system will be described schematically in the following.FIG. 1 shows an energy system 10 comprising a first storage 20 and a second storage 30 for storing a heat transfer medium. The heat transfer medium, which can be a brine / water mixture, for example, removes thermal energy from an environment of the first accumulator 20 and the second accumulator 30. This operation will be described in more detail later. When no distinction needs to be made between the first memory 20 and the second memory 30, but both are meant in combination, the first memory 20 and the second memory 30 are collectively also referred to simply as "memories 20, 30".The first 20 and the second accumulator 30 are connected via a fluid circuit 50 to a first heat exchanger 90, which in the embodiment shown is an evaporator of a heat pump 100. The heat transfer medium contained in the first 20 and second accumulators 30 is circulated in the fluid circuit 50 by a first pump 80 so that heat energy is taken from the first accumulator 20 and the second accumulator 30 and transported to the first heat exchanger 90. In a manner known per se, the thermal energy arriving at the first heat exchanger 90 is used to evaporate a refrigerant circulating in a refrigerant circuit 120 of the heat pump 100, which refrigerant is conducted on the refrigeration circuit side via the first heat exchanger 90. The refrigerant circuit 120 and the fluid circuit 50 are in this case fluidically separated, but thermally coupled.The gaseous refrigerant is compressed downstream of the heat exchanger 90 by a suitable compressor 130 and is thus brought to a defined pressure level. The gaseous refrigerant condenses at a condenser 110 of the heat pump 100, which is arranged behind the compressor 130, and emits the thermal energy arising in the process to a suitable medium, such as a liquid coolant or an air stream, for example, which is or is thermally coupled to the condenser 110. Arranged behind the condenser 110 in the refrigeration circuit is an expansion valve 140, at which the refrigerant is expanded before it is fed back to the first heat exchanger 90 and the compressor 130.In order that the heat pump 100 can be operated with the highest possible efficiency, it is desirable for the source temperature of the heat transfer medium at the first heat exchanger 90 to have a temperature which is as close as possible to a maximum permissible value which, depending on the type of heat pump and operating mode, can be, for example, 25° Celsius. One reason for this is, among other things, that as the difference between the source temperature and a temperature to be reached at the condenser 110 decreases, the energy required for the mechanical compression of the refrigerant and thus for the temperature increase likewise decreases.In many installation situations of the energy system 10, however, it is not possible to keep the heat transfer medium in the first storage 20 and the second storage 30 permanently at about 25° C., for example not when the energy system is operated in north geographical widths in winter, or when a groundwater aquifer is used as heat store. The energy system 10 disclosed here therefore comprises features which make it possible to bring the temperature of the heat transfer medium at the first heat exchanger 90 as quickly as possible to the maximum permissible source temperature and to maintain it there.The energy system 10 comprises a heat source 40, via which thermal energy can be supplied to the heat transfer medium before it is conducted to the first heat exchanger 90. In principle, any desired technologies can be used as the heat source 40, for example electrical resistance heating, fuel cells, or fossil fuels such as gas, oil, diesel, or gasoline. In the embodiment described in connection with FIGS. 1 to 3, the heat source 40 comprises a thermal solar installation with solar collectors 44, in particular photovoltaic-thermal solar collectors 44, which will be described in more detail later. The solar collectors 44 can either transfer the heat to the heat transfer medium of the fluid circuit 50 by means of a second heat exchanger 42 shown in FIG. 1 or else be integrated directly in the fluid circuit 50. In the embodiment shown in FIG. 1, the second heat exchanger 42 is connected to the solar collectors 44 via a feed line 47 and a return line 48, through which heat transfer medium is circulated by means of a second pump 46. In this case, the second pump 46 must be supplied with current for moving the heat transfer medium circulating through the solar collectors 44, while in the case that the solar collectors 44 are integrated directly into the fluid circuit 50, the pump 80 must be dimensioned somewhat more powerfully, since the solar collectors 44 must be operated with a more viscous heat transfer medium for protection against freezing. Since in both cases the pumps 46, 80 only require a power of the order of magnitude of a few 10 W for circulation, but the efficiency of the heat pump 100 increases by approximately 2.5% per 1° C. temperature increase of the source temperature, this leads to an average energy saving of 42.5 W / ° C. for a small heat pump 100 of 6 kW and an annual operating number of 4.In the fluid circuit 50, a first valve (V1) V1 is furthermore arranged, with which a level of a volume flow of the heat transfer medium can be controlled via the first accumulator 20 and / or the second accumulator 30. In the embodiment shown in FIG. 1, the first valve V 1 is disposed between the first reservoir 20 and the second reservoir 30 and the heat source 40. In the embodiment shown in FIG. 1, the first valve V 1 is a three-way valve having a first controllable valve opening V 1.1, by means of which the volume flow from the second accumulator 30 is adjusted, and a second controllable valve opening V 1.2, by means of which the volume flow from the first accumulator 20 is adjusted. The first valve V 1 or opening cross sections of the first valve opening V 1.1 and second valve opening V 1.2 are controlled electronically and separately by an electronic control unit, not shown, which also controls the adjustment of all further components shown in FIG. 1, such as valves, pumps, heat exchangers, compressors, etc., and is equipped for this purpose with suitable sensor systems and motor systems.As can be seen in FIG. 1, the second reservoir 30 has a smaller volume than the first reservoir 20, and in order to bring the source temperature of the heat pump 100 as quickly and efficiently as possible to the maximum permissible value during its startup, a volume flow of the heat transfer medium from the first reservoir 20 is therefore initially completely blocked by the first valve V 1, so that only heat transfer medium is circulated from the smaller second reservoir 30 via the heat source 40 to the first heat exchanger 90 and back again to the second reservoir 30. As a result of the relatively small mass of the circulated heat transfer medium, it is thus possible to achieve a more rapid heating of the heat transfer medium from the temperature originally present in the second store 30 to the maximum permissible source temperature at the first heat exchanger 90.In embodiments of the power system 10, a second valve V 2 is disposed in the fluid circuit 50 between the heat source 40 and the first heat exchanger 90 and is connected to a bypass 53 in the fluid circuit 50. The second valve V2 can be a three-way valve with a first controllable valve opening V2.1, the opening cross section of which is directed towards the first heat exchanger 90, and a second controllable valve opening V2.2, the opening cross section of which is directed towards the bypass 53. By adapting the opening cross sections of the first controllable valve opening V2.1 and of the second controllable valve opening V2.2, it is possible to regulate or set a level of the volume flow of the heat transfer medium via the first heat exchanger 90 or by the bypass 53. If necessary, the first heat exchanger 90 can thus be removed from the fluid circuit 50 to a desired degree or even completely until the heat transfer medium thus circulating only between the second accumulator 30 and the heat source 40 has a desired source temperature at the first heat exchanger 90.If more heat is available from the first heat source 40 than the heat pump 100 draws from the heat transfer medium, the temperature of the heat transfer medium in the second store 30 continues to rise. If the temperature of the heat transfer medium then reaches a temperature at an outlet 32 of the second store 30, which would suggest that the maximum permissible source temperature of the heat pump 100 is reached behind the heat source 40, the electronic control unit correspondingly limits the outlet temperature via the first valve V 1 by admixing heat transfer medium from the first store 20. By this regulation of the first valve V 1 as a function of a measured or expected source temperature at the heat exchanger 90, the heat pump 100 can be operated as far as possible constantly at its efficiency maximum.If the heat yield of the solar collectors 44 in combination with the temperature of the heat transfer medium in the first 20 and second storage 30 is overall too low to keep the source temperature of the heat pump 100 at the maximum permissible temperature, the electronic control unit can control the energy system 10 such that the heat transfer medium is heated in the cycle pauses of the heat pump 100 as described above, such that the maximum permissible source temperature is present at least at the beginning of the heating phases of the heat pump 100.To measure the temperature of the heat transfer medium and to control the first valve V 1 and / or the second valve V 2 and the pump 80 carried out on the part of the electronic control unit as a function of the temperature, temperature sensors can be arranged at a suitable location of the fluid circuit 50, for example between the heat source 40 and the first heat exchanger 90, or at the outlet 32 of the second store 30.As indicated in FIG. 1, the fluid circuit 50 can be divided in a simplified manner into a first or "warm" sub-circuit 52 between the first store 20 and the first heat exchanger 90, in which thermal energy is transported from the first store 20 and the second store 30 in the direction of the first heat exchanger 90, and a second or "cold" sub-circuit 54 behind the first heat exchanger 90, in which the heat transfer medium is fed back to the first store 20 and the second store 30 after transferring a part of its thermal energy to the first heat exchanger 90. In the embodiment shown, the first valve V 1 is arranged in the first sub-circuit 52 between the second accumulator 30 and the heat source 40, and the first accumulator 20 is arranged in the first sub-circuit 52 upstream of the first valve V 1.Another embodiment of the power system 10 will now be described with reference to FIG. 2. Corresponding features have the same reference numerals in FIGS. 1 to 5.In the embodiment shown in FIG. 2, the energy system 10 comprises a industrial warm water plant 300 which is thermally coupled to the heat pump 100 behind the compressor 130 of the heat pump 100 and in front of the condenser 110 of the heat pump 100. The thermal coupling takes place via a heat exchanger 310 arranged in the industrial warm water plant 300 and connected to the refrigerant circuit of the heat pump 100 on the high-pressure side thereof by means of an electronically switchable valve 101 arranged in the refrigerant circuit of the heat pump 100 and by an inlet 302 and an outlet 304.The industrial warm water plant 300 is also thermally coupled to the first heat source 40, namely in the case shown in FIG. 2 via a heat exchanger 320, which can be integrated via an electronically controllable fifth valve V 5 and a sixth valve V 6 and via corresponding lines 322 and 324 into the feed line 47 or the return line 48 of the heat source 40.The fifth valve V5 is a three-way valve and comprises a first controllable valve opening V5.1, which is fluidically connected to the third valve V3, and a second controllable valve opening V5.2, which controls the flow through a bypass between the return line 48 and the feed line 47.The sixth valve V 6 is likewise a three-way valve and comprises a first controllable valve opening V 6.1, which is fluidically connected to the fifth valve V 5, and a second controllable valve opening V 6.2, which controls a volume flow from the heat exchanger 320 of the industrial warm water plant 300.In the embodiment of FIGS. 2 and 3, the first heat source 40 comprises solar collectors 44. In order to increase the efficiency of the energy system 10, it is advantageous that photovoltaic-thermal solar collectors (PVTK) known per se are used for the solar collectors 44, which collect both current and heat energy. For this purpose, a pipe register is mounted behind a photovoltaic module, through which the heat transfer medium flows. The heat transfer medium absorbs the waste heat of the photovoltaic modules and the ambient heat and transports them to the downstream heat exchangers. In the case of these collectors, the efficiency of the photovoltaic modules can be increased by 0.4-0.5% per 1° C. by means of cooling by the coupled thermal collectors. This gain in current yield is then available to the operation of the electrical components of the energy system 10 and no longer has to be obtained from the outside.Although the terms "first heat source 40" and "solar collectors 44" or "photovoltaic solar collectors 44" are used interchangeably for the following explanations, it is pointed out that the first heat source 40 can also comprise further or alternative technologies for heat generation, for example those based on electrical resistance heating, fossil energy carriers such as gas, oil, diesel, or gasoline, and also fuel cell technology. Depending on the embodiment of the first heat source 40, instead of the second heat exchanger 42, another technology known per se to the person skilled in the art may have to be chosen in order to thermally couple the first heat source 42 to the fluid circuit 50, for example heating rods, combustion chamber or the like.The second heat exchanger 42 is connected to the fluid circuit 50, as in the embodiment shown in FIG. 1, but via an eighth valve V 8 arranged behind the first valve V 1 in the first sub-circuit 52. On the side of the first heat source 40, which generates heat and electrical energy by photovoltaic solar collectors 44 in the embodiment shown, the second heat exchanger 42 is connected via a fourth valve V 4 to the feed line 47 to the solar collectors 44 and via a third valve V 3 to the return line 48. The third valve V 3 is a three-way valve having a first controllable valve opening V 3.1, which is fluidically connected to the second heat exchanger 42, and a second controllable valve opening V 3.2, which is fluidically connected to a third heat exchanger 43.The second valve V 2 is arranged behind the second heat exchanger 42 in the first sub-circuit 52 as well as in the embodiment of FIG. 1, and the pump 80 is integrated into the second sub-circuit 54 behind the first heat exchanger 90. The third heat exchanger 43 is arranged behind the pump 80. The third heat exchanger 43 is fluidly coupled to a seventh valve V 7 that regulates a return path to the second accumulator 30 and the first accumulator 20, and to the first heat source 40. The coupling to the first heat source 40 takes place, as shown in FIG. 2, via a fluidic connection to the feed line 47 and via a further line to the third valve V 3, which is also connected to the second heat exchanger 42 as mentioned above. Both the second heat exchanger 42 and the third heat exchanger 43 are fluidically connected via the feed line 47 to the second pump 46, behind which a fourth valve V 4 is arranged, which can regulate a bypass between the return line 48 and the feed line 47. The fourth valve V4 is a three-way valve and comprises a first controllable valve opening V4.1 which is fluidically connected to the solar collector 44 and a second controllable valve opening V4.2 which controls the flow from the feed line 47 through the bypass to the return line 48.A method for operating the energy system 10 illustrated in FIG. 2 is described below, in which the energy system 10 is operated in different operating modes. The individual method steps are controlled by an electronic control unit, as also mentioned in connection with the embodiment explained in FIG. 1, which also controls the adjustment of all further components shown in FIG. 2, such as valves, heat exchangers, compressors, etc., and is equipped with suitable sensor systems and motor systems for this purpose. The electronic control unit comprises an electronic memory on which a corresponding software with the individual method steps is stored.To explain the principle, it is assumed here that the energy system 10 is operated in a granular moderate climate zone in a transition year period, for example in the branch that the heat pump 100 operates in the heating mode, and that a maximum permissible source temperature max for this mode. QT is 25° C. This temperature is dependent on the type of heat pump used and could well be higher in the case of operation of heating the industrial warm water (BWW).To bring the heat transfer medium to max. QT=25° C. is preheated, the second heat exchanger 42 is installed in the fluid circuit 50 between the outlet of the accumulator 20, 30 and the inlet of the heat pump 100, which heat exchanger thermally couples the fluid circuit 50 to the circuit of the heat transfer medium of the first heat source 40. Both circuits can optionally be additionally coupled via the third heat exchanger 43 between the return of the heat pump 100 and the inlet of the heat accumulator 20, 30. If the heat yield of the solar collectors 44 is sufficient and / or the temperature of the heat transfer medium is sufficiently high, the third heat exchanger 43 can be used, for example, to heat the heat transfer medium of the storage 20, 30 even higher, even faster, or after cooling by the heat pump 100 again. Which of the two heat exchangers 42, 43 transfers much heat is adjusted via the third valve V 3. In embodiments of the energy system 10, the second heat exchanger 42 and the third heat exchanger 43 are replaced with a three-media heat exchanger.At the beginning of the heat transfer from the first heat source 40 to the heat transfer medium of the fluid circuit 50, initially only the heat transfer medium from the second storage 30 is used and heated, as already explained in connection with FIG. 1. Depending on the level of the heat yield of the first heat source 40 which is solar in the embodiment of FIG. 2 and further parameters such as weather forecast, the control unit makes the decision to switch on the heat pump 100 immediately or only later, or also only with a lower flow than that set by the first pump 80 of the fluid circuit 50. The latter is regulated with the aid of the second valve V 2. If the heat transfer medium of the second store 30 has reached a specific temperature, max in the example. QT=25° C., the inlet temperature of the second heat exchanger 42 is kept constant via the first valve V 1 by mixing from now on a certain amount of the heat transfer medium from the first storage 20. If the inlet temperature is less than 25° C., the second heat exchanger 42 continues to supply thermal energy to the heat transfer medium.In summer, the storage 20, 30 can be thermally regenerated again or even thermally charged via the second heat exchanger 42 and the third heat exchanger 43. Alternatively, the industrial warm water plant 300 can also be heated directly via the first heat source, which is made possible by the fifth valve V 5 and the sixth valve V 6.By appropriately controlling the flow through the fifth valve V 5 and the sixth valve V 6, a mixed operation with heating of the industrial warm water plant 300 and partial regeneration of the reservoirs 20, 30 is also possible. A direct heating operation, for example of a floor heating system or the heating of a heating water reservoir, would also be possible, but is not shown in FIG. 2.Table 1 is used to show the various operating modes of the method for controlling the energy system 10 shown in FIG. 2.V1.1g.x x x x x x xx x x x x x xg.g.x x x x x x xg.g.g.V1.2g.x x x x x x xx x x x x x xg.g.x x x x x x xg.g.g.V2.1toox x x x x x x, bBgg.toog.g.auftooV2.2aufx x x x x x xzu,bBgg.aufg.g.tooaufV3.1g.x x x x x x xg.g.g.g.g.x x x x x x xx x x x x x xV3.2g.x x x x x x xg.g.g.g.g.x x x x x x xx x x x x x xV4.1aufauf, bBgaufauf, bBgaufx x x x x x xx x x x x x xV4.2tootoozu,bBgtootoozu,bBgtoox x x x x x xx x x x x x xV5.1auftoog.g.g.aufauftootooV5.2tooaufg.g.g.tootoox x x x x x xx x x x x x xV6.1auftoog.g.g.aufaufx x x x x x xx x x x x x xV6.2tooaufg.g.g.tootoox x x x x x xx x x x x x xV7.1aufx x x x x x xtooaufauftooaufaufaufV7.2toox x x x x x xauftootooauftootootooV8.1aufx x x x x x xtooaufauftooaufaufaufV8.2toox x x x x x xauftootooauftootootoog. = controlled; bBg = controlled as needed; x = not relevant to the modeThe valve settings shown in Table 1 correspond to the default setting for the respective operating mode. They can be changed during operation by the electronic control unit for control technology reasons, in particular for changing flows and temperatures, for adaptation to external circumstances or for optimizing purposes of specific components, or manually by a user. In addition, still other modes may be enabled. This is in particular the case when the energy system 10 comprises a heating water reservoir.The operating states shown in columns a) to i) are explained schematically below by switching valves V 1 to V 8. As already mentioned in connection with the embodiment explained in FIG. 1, the individual method steps are controlled by an electronic control unit which also controls the adjustment of all further components shown in FIG. 2, such as valves, heat exchangers, compressors, etc., and is equipped for this purpose with suitable sensor systems and motor systems. The electronic control unit comprises an electronic memory on which a corresponding software with the individual method steps is stored.Regeneration / Charging / Cooling and Snow Clearing / Freeze Protection a)In this operating mode, the heat transfer medium is only taken from the storage 20, 30, conducted via the second heat exchanger 42 and the third heat exchanger 43 and returned directly to the storage 20, 30. In summer, the heat transfer medium of the storage 20, 30 is heated, as a result of which the storage 20, 30 is regenerated or even loaded when the regeneration has already been concluded. In this case, the valves V 1 and V 3 are regulated in such a way that the photovoltaic modules of the photovoltaic-thermal solar collectors 44 are cooled to the maximum. In winter, the heat flow in the heat exchangers 42, 43 is reversed, so that the heat transfer medium of the fluid circuit 50 heats the heat transfer medium of the solar circuit. The solar collectors 44 are heated to such an extent that the snow slips off and they are again fully irradiated by the sun. The first valve V 1 and the third valve V 3 are preferably adjusted in such a way that the solar collectors 44 are freed from the snow most efficiently. The solar collectors 44 are thus prevented from freezing even in comparatively cold winters. Should it occur that the reservoir 20, 30 is too full, the system may also release excess heat to the environment in this mode, preferably at night. During the transition times when the industrial warm water plant does not have to be heated, this operating mode can be used to bring the temperature of the heat transfer medium in the second storage 30 as quickly as possible to or above the maximum permissible source temperature max in the cycle pauses of the heat pump 100. QT and hold it there.b) heating the industrial hot water only via first heat source 40In summer, it is generally most efficient to heat the industrial hot water plant 300 directly via the solar collectors 44. This operating mode of the energy system 10 is therefore preferred if the power gain of the photovoltaic modules of the photovoltaic-thermal solar collectors 44 by using the cooling is smaller than the electrical power of the heat pump 100 required for hot water heating.c) Brauchwarmwassererrwärmung via solar collectors 44 and heat via heat pump 10 without admixture from the storageThis operating mode is preferably used at the beginning of a loading of the industrial hot water plant 300. This is particularly useful as long as the temperature at the outlet 324 of the industrial warm water plant 300 can be kept low enough that the maximum permissible source temperature max is obtained by heating the heat transfer medium of the fluid circuit 50 via the heat exchangers 42, 43. QTof the heat pump 100 is not exceeded. If possible, the temperature of the heat transfer medium downstream of the outlet 324 of the industrial hot water plant 300 can be heated via the sixth valve V 6 by a specific part of the heat transfer medium being guided past the industrial hot water plant 300. Furthermore, the heat transfer medium can also be cooled via the fourth valve V 4 downstream of the outlet 324. The flow of the heat transfer medium via the second heat exchanger 42 and the third heat exchanger 43 is optimized via the fifth valve V 5 by a portion of the heat transfer medium being fed back directly to the solar collectors 44. The third valve V 3 is adjusted by the control unit such that the heat transfer at the heat exchangers 42, 43 is optimum. The delivery capacity of the first pump 80 also sets the optimum flow for the heat pump 100. If a higher flow is preferred for the second heat exchanger 42 and / or the third heat exchanger 43, this can also be adjusted at the first pump 80. In this case, the optimum flow for the heat pump 100 is adjusted via the second valve V 2.d) heating industrial hot water via solar collectors 44 and heating heat via heat pump 100 or loading of the store 20, 30If the control unit in operating mode c) can no longer set the source temperature at the first heat exchanger 90 at or below the maximum permitted value max. Holding QT, it may enter the mode described herein. If the temperature of the heat transfer medium in the second storage 30 is initially below the maximum permissible source temperature max. QT (related to industrial hot water or heating operation), the control unit adjusts the first valve V 1 such that only the second storage 30 is used in order to thus bring the temperature of the heat transfer medium contained in the second storage 30 as quickly as possible to the maximum permissible source temperature max. QT. As long as the maximum permissible source temperature max. If QT has not yet been reached, the flow through the second heat exchanger 42 can be regulated via the third valve V 3 such that the heat transfer medium of the fluid circuit 50 is either at the maximum permissible source temperature max. QT, or the maximum possible temperature increase is achieved. If the heat input through the solar collectors 44 is large enough, the third heat exchanger 43 can also be incorporated in order to increase the inlet temperature of the storage 20, 30. If the heat transfer medium of the second store 30 has the maximum permissible source temperature max. When the flow rate through the second heat exchanger 42 is reached QT, the flow rate is prevented via the third valve V 3 and the source temperature is brought to the maximum value max via the first valve V 1. Q is limited by the fact that heat transfer medium from the first reservoir 20 is mixed in. The heat input from the first heat source 40 is then used completely via the third heat exchanger 43 for regeneration, charging and / or minimizing discharge of the store 20, 30. Here too, the flow of the heat transfer medium via the heat exchangers 42, 43 and the heat pump 100 can be optimally adjusted via the pumping capacity of the first pump 80 and via the second valve V 2, as already described in connection with the operating mode c). In the solar circuit 47, 48 as well, the control unit can optimize the inlet temperature of the heat exchangers 42, 43 and the flows through the heat exchangers 42, 43 and the industrial warm water plant 300 via the output of the second pump 46 and the opening cross sections of the fifth valve V 5 and of the sixth valve V 6.(e) heating industrial hot water via first heat source 40 and charging of the storage 20, 30In this mode, the store of the industrial warm water system 300 is first heated. The second priority is to bring the heat transfer medium of the second accumulator 30 to the maximum permissible source temperature max. QT. As long as this is not achieved, the second controllable valve opening V1.2 of the first valve V1 remains closed and the first controllable valve opening V1.1 of the first valve V1 remains open. The first valve V 1 is then controlled in such a way that the heat transfer medium of the second accumulator 30 is not below the maximum permissible source temperature max. QT falls. It may also be advantageous for system efficiency if appropriate to heat the heat transfer medium to a higher level. By regulating the pump output of the first pump 80, an optimized flow rate in the heat exchangers 42, 43 can be achieved again, as described above. In order to prevent a drop in the temperature of the heat carrier medium in the fluid sub-circuit 54, a part of the heat carrier medium in the fluid sub-circuit 48 can be conducted past the heat exchanger 320 if required via the sixth valve V 6, such that the temperature at the inlet of the heat exchangers 42, 43 does not drop below a temperature required for this purpose. In order to further enable optimum heating of the industrial warm water, the flow of the heat transfer medium can be correspondingly regulated by means of the pumping capacity of the second pump 46 in the circuit 47, 48 of the first heat source 40. The flow control for the heat exchangers 42, 43 can take place in this case via the third V 3 and fifth valve V 5.f) Support of the heat pump 100 only by the first heat source 40In the case that the heat yield of the first heat source 40 is equal to or slightly higher than the heat requirement for reaching the maximum permissible source temperature max. In QT at the heat pump 100, the controller may couple the heat pump 100 only to the first heat source 40. As described above, the optimum flow can be adjusted via the heat exchangers 42, 43 and the heat pump 100 via the pumping capacity of the first pump 80 and via the second valve V 2. The return temperature of the first heat source 40 should ideally be so high that the maximum permissible source temperature max. QT for hot water preparation or for heating by the heat pump 100. A certain adjustment possibility is provided by the regulation of the second controllable valve opening V4.2 of the fourth valve V4, by the opening of which a brief exceeding of the return temperature of the first heat source 40 can be counteracted.The cycle pauses of the heat pump 100 can be used to load the storage 20, 30 or to heat up the heat transfer medium in the first heat source 40.g) Support of the heat pump 100 by the first heat source 40 and the storage device 20, 30If, in operating mode f), the heat input by the first heat source 40 is so high that its return temperature exceeds the maximum permissible source temperature max. If QT of the current operating mode of the heat pump 100, i.e. would cause treatment of industrial warm water or heating, the heat exchangers 42, 43 must be supplied again with the heat transfer medium from the storage 20, 30. In this mode as well, the first pump 80 can generate a higher flow of the heat transfer medium optimized for the heat exchangers 42, 43, since the optimum flow for the heat pump 100 can be adjusted via the second valve V 2 as already described above. If it is expected that the optimum flow with regard to the heat exchangers 42, 43 is regularly smaller than the flow optimized with regard to the heat pump 100, the bypass, which is realized by the second controllable valve opening V2.2 of the second valve V2 between the forward and return of the first heat exchanger 90, can also be arranged downstream of the first pump 80 in the flow direction. It must then be taken into account that the outlet temperature of the heat exchanger 42 must be increased accordingly in order to compensate for the cooling by the heat transfer medium of the heat pump outlet. When the installation conditions are such that both situations may occur, a valve may also be installed on both sides of the first pump 80. The regulation of the first valve V 1 in this operating mode aims to increase the temperature of the second storage 30 as quickly as possible, provided that the first heat source 40 has a sufficiently high heat yield. However, if the heat transfer medium of the second accumulator 30 reaches the maximum permissible source temperature max. QT, by closing the third valve V3, the first heat exchanger 42 is removed from the circuit and via the first valve V1 the source temperature is brought to the maximum permissible source temperature max. QTis limited by the heat transfer medium from the first reservoir 20 being mixed in. The heat yield from the first heat source 40 is then used completely via the third heat exchanger 43 for regeneration, charging or minimizing discharge of the store 20, 30.h) Operation of the heat pump 100 without raising the temperature of the heat carrier mediumIn this operating mode, the heat pump 100 draws its full heat requirement from the store 20, 30, which has been brought to the highest possible temperature level in summer. In this case, the first valve V 1 is regulated in such a way that the heat pump 100 is supplied with heat transfer medium which is as warm as possible for as long as possible.i) Mixing of Heat Transfer Medium from First Reservoir 20 and Second Reservoir 30Depending on the weather situation, it may be advantageous to transfer the heat of the second store 30 to the first store 20. This is possible with the combination of valve settings defined in column i). The first valve V 1 is regulated in such a way that the heat transfer medium of the second store 30 assumes the temperature of the heat transfer medium in the first store 20 as quickly as possible.The embodiment of the energy system 10 described in connection with FIG. 2 has the advantage that the circuits of the heat transfer media for the storage 20, 30, the first heat source 40 and the industrial warm water plant 300 are thermally coupled to one another via the heat exchangers 42, 43. As a result, the regulations of the two circuits can easily be optimized, and the two heat transfer media used can likewise be selected in an optimized manner for the respective circuit, for example can also be fundamentally different. Thus, in this embodiment, the energy system 10 can also combine, for example, the typical brine circuit of photovoltaic-thermal solar collectors 44 with a groundwater heat pump 100. When using geothermal probes as the storage means 20, 30, for example, it is not necessary to work with a heat transfer medium of higher viscosity, which would have to be used for freeze protection of the solar collectors in a common circuit because of the increased frost protection fraction. In embodiments where the latter is necessary, the more viscous fluid results in a greater pressure drop in the geothermal probes, which must be compensated for by a higher pump output and thus reduces system efficiency.Another embodiment of the power system 10 will now be described with reference to FIG. 3.In this embodiment, the hydraulic interconnection of industrial hot water plant 300, photovoltaic-thermal solar collectors 44, heat pump 100, and storage 20, 30, which is normally operated with a heat transfer medium similar to that of the photovoltaic-thermal solar collectors 44, has an advantage with regard to comparatively low investment costs, since the heat exchangers 42, 43 and the first pump 80 are not required compared to the solution described in connection with FIG. 2. The temperature gain due to the omission of the heat exchangers 42, 43 can also be used to generate more current (about 0.4% / ° C.) or to raise the storage 20, 30 to a higher temperature level and thus to operate the heat pump 100 more efficiently (by about 2.5% / ° C.).The hydraulic interconnection (in the sense of brine circuit regulation) of the storage 20, 30, photovoltaic-thermal solar collectors 44, industrial warm water installation 300 and heat pump 100 illustrated in FIG. 3 enables at least ten different operating modes with which the efficiency of the energy system 10 can be improved, which will be described below. Depending on the heat requirement of heat pump 100 and industrial warm water plant 300 and the current boundary conditions of the four components interconnected with one another, the most efficient of the ten operating modes is set. If heat is required and there is no possibility of increasing the efficiency of the heat pump 100, the energy system 10 or the electronic control unit switches into the eleventh mode, the normal function of a heat pump 100. The electronic control unit of the energy system 10 is programmed such that all thermal energy obtained by the photovoltaic-thermal solar collectors 44 is either passed directly to the industrial warm water installation 300 or to the heat pump 100, or else the storage 20, 30 is regenerated, loaded or its discharge is minimized. At the same time, the current yield is to be maximized as much as possible by cooling the photovoltaic-thermal solar collectors 44. In order to meet these possibly also opposite requirements in the best possible manner, a computer-controlled control method is implemented in the software of the electronic control unit, which control method precomputes the most varied scenarios, for example also supported by so-called artificial intelligence, from all necessary measurement data, the current weather situation, and the weather forecast. From the calculated data, it is then determined which operating mode, or which sequence of operating modes, permits the most likely efficient operating mode of the energy system 10 over the course of a day. By monitoring the current and already acquired data, the control method can also make corrections to the previously selected operating mode.As can be seen from FIG. 3, the industrial warm water plant 300 is, similar to the embodiment shown in FIG. 2, thermally coupled to the heat pump 110 behind the compressor 130 of the heat pump 100 and in front of the condenser 110 of the heat pump 100. The thermal coupling also takes place here via the heat exchanger 310 arranged in the industrial warm water plant 300 which is connected to the refrigerant circuit of the heat pump 100 on the high-pressure side thereof by means of the electronically switchable valve 101 arranged in the refrigerant circuit of the heat pump 100 and by the inlet 302 and the outlet 304.The industrial warm water plant 300 is also thermally coupled to the first heat source 40, namely in the embodiment shown in FIG. 3 via the heat exchanger 320, which can be integrated into the feed line 47 or the return line 48 of the heat source 40 via the electronically switchable fifth valve V 5 and the sixth valve V 6 and via corresponding lines 322 and 324.The first valve V 1 is arranged in the first sub-circuit 52 between the first accumulator 20 and the second accumulator 30 and the first heat source 40, as in the embodiments described above. A third valve V 3 ais arranged behind the first valve V 1, wherein a first controllable valve opening V 3 a.1 is arranged in the direction of the inlet 47 to the photovoltaic-thermal solar collectors 44 and a second controllable valve opening V 3 a.2 is arranged in the direction of the flow of the first heat exchanger 90.Behind the third valve V 3 a, a bypass 325 is arranged to a second controllable valve opening V 3 b.2 of a third valve V 3 b, which is arranged in a return of the first heat exchanger 90. A first controllable valve opening V 3 b.1 of the third valve V 3 bis arranged in the direction of the return to the reservoir 20, 30.The arrangement of the pump 46, the fourth valve V4, the fifth valve V5 and the sixth valve V6 is similar to the corresponding arrangement of the embodiment explained in connection with FIG. 2. The pump 46 is arranged behind the bypass 325, and the fourth valve V 4 is installed behind the pump 46, which valve regulates a flow through a bypass between the return line 48 and the feed line 47. The fourth valve V4 is a three-way valve and comprises a first controllable valve opening V4.1, which is fluidically connected to the solar collector 44, and a second controllable valve opening V4.2, which controls the flow through the bypass between the return line 48 and the feed line 47.The sixth valve V 6 is arranged in the return line 48 behind the photovoltaic thermal solar collectors 44. It is a three-way valve and comprises a first controllable valve opening V6.1, which is fluidically connected to the fifth valve V5, and a second controllable valve opening V6.2, which controls a volume flow from the heat exchanger 320 of the industrial warm water system 300.The fifth valve V 5 is arranged in the return line 48 behind the sixth valve V 6 and the heat exchanger 320 of the industrial warm water plant 300. The fifth valve V5 is also a three-way valve, which comprises a first controllable valve opening V5.1, which is fluidically connected to the second valve V2, and a second controllable valve opening V5.2, which controls the flow through a bypass between the return line 48 and the feed line 47.Similar to the embodiment shown in FIG. 2, the second valve V 2 is arranged in the first sub-circuit 52 and upstream of the first heat exchanger 90. The second valve V2 is also in this embodiment a three-way valve with a first controllable valve opening V2.1, the opening cross section of which is directed towards the first heat exchanger 90, and a second controllable valve opening V2.2, the opening cross section of which is directed towards the return to the reservoir 20, 30 in this embodiment.In the following, a method for operating the energy system 10 shown in FIG. 3 is described with reference to Table 2, in which the energy system 10 is operated in different operating modes. The individual method steps are controlled, as already mentioned, by the electronic control unit which also controls the adjustment of all further components shown in FIG. 3, such as valves, heat exchangers, compressors, etc., and is equipped for this purpose with suitable sensor systems and motor systems. The electronic control unit comprises an electronic memory on which a corresponding software with the individual method steps is stored. The valve settings shown in Table 2 correspond to the default setting for the respective operating mode. They can be changed during operation for control technology reasons, in particular for changing flows and temperatures, for adaptation to external circumstances or for optimizing purposes of specific components. In addition, still other modes may be enabled. This is in particular the case when the energy system 10 comprises a heating water reservoir.Regeneration / Charging / Cooling and Snow Clearing / Freeze Protection a)In this operating mode, the heat transfer medium is removed from the storage 20, 30, conducted via the photovoltaic-thermal solar collectors 44 and returned directly to the storage 20, 30. In summer, the heat transfer medium heats up in the photovoltaic-thermal solar collectors 44, as a result of which the storage 20, 30 is regenerated or also loaded when the regeneration has already been concluded. In this case, the first valve V 1 is regulated in such a way that the solar collectors 44 are cooled to the maximum. In winter, the solar collectors 44 are heated until the snow slips off and the solar collectors 44 are thus again fully irradiated by the sun. The first valve V 1 is advantageously set in such a way that the solar collectors 44 are freed from the snow most efficiently. In extremely cold winters, the solar collectors 44 are thus also prevented from freezing. Should the storage 20, 30 be too full, the energy system 10 can also release excess heat to the environment in this mode, preferably at night. During the transition times when the industrial warm water does not have to be heated, this operating mode can be used to bring the temperature of the heat transfer medium in the upstream second storage 30 as quickly as possible to or above the maximum permissible source temperature max in the cycle pauses of the heat pump 100. QT and hold it there.b) Hot water heating only via solar collectors 44In summer, it is most often most efficient to heat the industrial warm water directly via the solar collectors 44. In this mode, the energy system 10 operates if the power gain of the solar collectors 44 by cooling is smaller than the electrical power of the heat pump 100 required for heating the industrial warm water.c) hot water heating via solar collectors 44 and heating heat via heat pump 100 without admixture from the storage 20, 30This operating mode can be used at the beginning of a loading of a store of the industrial hot water plant 300. This is expedient as long as the outlet temperature at the reservoir of the industrial warm water plant 300 is less than the maximum permissible source temperature max. QT of the heat pump 100. If this condition is fulfilled, the temperature of the heat transfer medium downstream of the storage outlet of the industrial warm water plant 300 can be adjusted to the maximum permissible source temperature max via the sixth valve V 6. QT for heat generation by the heat pump 100. This ensures that the heat pump 100 runs with maximum efficiency, provided that the optimum flow rate can be set via the pump 46. If the flow has to be increased and the outlet temperature at the reservoir of the industrial warm water plant 300 thereby rises, the temperature can be lowered again by regulating the second controllable valve opening V4.2 of the fourth valve V4. In a cycle pause of the heat pump 100, another suitable mode can be activated.d) heating industrial hot water via solar collectors 44 and heating heat via heat pump 100 / solar collectors 44 before the inflow of heat pump 100 / charging of the store 20, 30In operating mode c), the source temperature can no longer be below the maximum permissible value max. If QT is maintained, the electronic control unit may switch to the mode described herein. By way of the second controllable valve opening V4.2 of the fourth valve V4, colder medium from the reservoir 20, 30 can be added to the return of the industrial warm water system 300, so that the maximum permissible source temperature max. QT is not exceeded. A higher medium flow can now be generated via the pump 46, since the optimum flow of the heat transfer medium with regard to the operation of the heat pump 100 can also be adjusted via the second valve V 2. The first valve V1 is adjusted in such a way that it optimally supports the second controllable valve opening V4.2 of the fourth valve V4. Since the temperature drop of the heat transfer medium above the heat pump 100 is only a few degrees Celsius, heat is also supplied to the store 20, 30 at high source temperatures. In the cycle pauses of the heat pump 100, another suitable mode can be activated.Heat heating by means of solar collectors 44 and heat by means of heat pump 100 / solar collectors 44 behind the return of heat pump 100 / loading of storage device 20, e), 30If the upstream second storage device 30 is heated up to such an extent that its outlet temperature reaches the maximum permissible source temperature max. When the temperature reaches QT, the outlet can be coupled directly to the inlet of the heat pump 100, and the solar collectors 44 heat the heat transfer medium before it is supplied to the service water plant 300. The source temperature is limited to the maximum permissible value by adding it from the first storage unit 20 via the first valve V 1. The flow optimized with regard to the operation of the heat pump 100 is adjusted via the pump 46. The control should be designed as far as possible such that the outlet temperature from the storage of the industrial warm water plant 300 is so high that the second storage 30 is not discharged. For this purpose, for example, the first controllable valve opening V6.1 of the sixth valve can be easily opened. In the cycle pauses of the heat pump 100, another suitable operating mode can be selected.f) heating industrial hot water via solar collectors 44 and charging the storage tank 20, 30In this mode, the store of the service water installation 300 is first heated. The second priority is to bring the heat transfer medium of the second accumulator 30 to the maximum permissible source temperature max. QT. As long as this is not achieved, the second controllable valve opening V1.2 of the first valve V1 remains closed and the first controllable valve opening V1.1 of the first valve V1 remains open. The first valve V 1 is then controlled in such a way that the heat transfer medium of the second accumulator 30 does not, on the one hand, fall below the maximum permissible source temperature max. QT falls and, on the other hand, its temperature does not become unduly high, unpreferably. In terms of the system efficiency of the energy system 10, it may be advantageous to heat the heat transfer medium to a higher level. In order to prevent a drop in the temperature of the heat carrier medium, the first controllable valve opening V6.1 of the sixth valve V6 can be controlled, if required, in such a way that the temperature of the heat carrier medium at the outlet of the heat exchanger 320 does not drop below a desired temperature. In order to further enable optimum heating of the industrial warm water, the flow of the heat transfer medium can be correspondingly regulated via the pump 46.g) Support of the heat pump 100 only by solar collectors 44In the case that the heat yield of the solar collectors 44 is equal to or slightly higher than the heat requirement for achieving the maximum permissible source temperature max. QT at the heat pump 100 can only be coupled to the solar collectors 44. The optimum flow for the heat pump 100 is then set via the pump 46. The return temperature of the solar collectors 44 preferably corresponds to the maximum permissible source temperature max. QT for the preparation of hot water or for the heating by means of the heat pump 100. A briefly increased return temperature of the solar collectors 44 can be obtained by adapting the second controllable valve opening V4.2 of the fourth valve V4 to the maximum permissible source temperature max. QT. The cycle pauses of the heat pump 100 can be used to load the storage 20, 30 or to heat up the heat transfer medium in the solar collectors 44.h) Support of the heat pump 100 by solar collectors 44 and accumulators 20, 30 / solar collectors 44 before the inlet of the heat pump 100If, in mode g), the heat yield of the solar collectors 44 is high and therefore their return temperature could exceed the maximum permissible source temperature max. If the current operating mode of the heat pump 100 (industrial warm water or heating) rises, the control unit mixes the heat transfer medium directly with the colder heat transfer medium from the storage 20, 30 via the second controllable valve opening V4.2 of the fourth valve V4 in order to exceed the maximum permissible source temperature max. QT. In this mode as well, the pump 46 can generate an acceptable flow of the heat carrier medium, since the flow optimized with respect to the heat pump 100 can be adjusted again via the second valve V 2. The first valve V1 is adjusted in the first respect in such a way that the adjustment of the second controllable valve opening V4.2 of the fourth valve V4 is optimally assisted. In the second respect, the control unit attempts to increase the temperature of the second store 30, provided that the heat yield of the solar collectors 44 is sufficiently high. This operating mode is also advantageous if the heat yield of the solar collectors 44 is only sufficient to increase the temperature of the heat transfer medium from the store 20, 30 by a few degrees Celsius.i) Support of the heat pump 100 by solar collectors 44 and storage means 20, 30 / solar collectors 44 behind the return of the heat pump 100As long as the outlet temperature of the second storage 30 is greater than or equal to the maximum permissible source temperature max. If QT, the downspout of the accumulator 20, 30 may be directly coupled to the heat pump 100. In this case, the first valve V 1 is set such that the source temperature is always at the maximum permissible value of the source temperature max. QT. If the heat yield of the photovoltaic-thermal solar collectors 44 is greater than or equal to the heat requirement of the heat pump 100, the storage 20, 30 is not discharged and the energy system 10 remains in this mode.j) Normal operation of the heat pump 100In this operating mode, the heat pump 100 draws its full heat requirement from the store 20, 30, which has been brought to the highest possible temperature level in summer. Here, the first valve V 1 is regulated in such a way that the heat pump 100 is supplied with heat transfer medium that is as warm as possible for as long as possible.k) Mixing of heat transfer medium from first reservoir 20 and second reservoir 30Depending on the weather situation, it may be more advantageous to transfer the heat of the second store 30 to the first store 20. This is possible with the combination of valve settings defined in column j). The first valve V 1 is regulated in such a way that the heat transfer medium of the second store 30 assumes the temperature of the heat transfer medium in the first store 20 as quickly as possible.In the embodiments of the energy system 10 described in connection with FIGS. 1 to 3, different types of memories can be used as the first memory 20 and the second memory 30, respectively, which will be explained below with reference to FIGS. 4 and 5.In the first storage 20, basically any type of storage technology can be used which is suitable for storing supplied thermal energy. It may be a single large memory, or one composed of several small memories, also comprising different technologies. In the case that the first accumulator 20 is composed of a plurality of smaller accumulators, each one of the smaller accumulators may be hydraulically controlled separately, or appropriate control groups may be formed.In embodiments of the invention, the second reservoir 30 is a small geothermal heat reservoir such as a short geothermal probe, a small groundwater reservoir, a brine reservoir, or a heated water reservoir.In embodiments of the energy system 10, the first 20 and / or the second storage 30 each comprise one or more geothermal heat absorbers. In particular, the first 20 and / or the second storage 30 each comprise one or more water / brine heat storage units 400 with water / brine mixture as heat transfer medium, as described below with reference to FIGS. 4 and 5.The water / brine heat store 400 which is inserted in the first 20 and / or second store 30 comprises a housing 420 which fluidically seals off a cavity 410 and which is of cylindrical configuration in the embodiments shown in FIG. 4. At least partially within the cavity 410 a fluid conductor 430 is arranged, which is fluidically connectable to the fluid circuit 50 via an outlet 432 and an inlet 434.As shown in FIGS. 5 ato 5 d, a first section 431 of the fluid conductor 430 is formed in the shape of a helix along an inner circumference of the housing 420 and contacts an inner surface 422 of the housing 420 along its extension, such that there is a thermal coupling between the fluid conductor 430 and the housing 420. A first end of the first portion of the fluid conduit 430 is fluidly connected to the outlet 432 of the water / brine heat reservoir 400.A second portion 433 of the fluid conduit 430 extends centrally along a longitudinal axis X of the housing 420 and is connected to the inlet 434 of the water / brine heat store 400. As can be seen with reference to FIG. 4, for example, which is only schematic with regard to the configuration of the first section 431 and the second section 433, warm heat transfer medium reaches the first sub-circuit 52 of the fluid circuit 50 via the outlet 432 from the water / brine heat accumulator 400, while cooled heat transfer medium is supplied to the water / brine heat accumulator 400 via the inlet 434 from the second sub-circuit 54 of the fluid circuit 50.The cavity 410 of the water / brine heat store 400 is at least partially filled with water. The water serves first as a temporary temperature store. Thus, in summer, it can absorb the heat obtained by cooling rooms or by the solar collectors 44 during the day and emit it to the ground overnight and, conversely, in winter, absorb the heat from the ground during the cycle pauses of the heat pump 100 and then make it available to the heat pump 100. This process is supported by the so-called heat pipe effect, which ensures that the heat is distributed relatively uniformly over the entire cylinder.Features of the water / brine heat store 400 illustrated in FIG. 5 cause an increase in capacity thereof over other storage solutions over different temperature ranges, which will be described below.In the case of a comparatively high heat requirement of the environment to be heated, it may happen that the temperature of the heat transfer medium in the fluid conductor 430 falls to or below zero degrees Celsius. Under these conditions, the water in the cavity 410 begins to freeze. During the phase transition from liquid to solid, i.e. in the form of ice, the water emits thermal energy to the heat transfer medium circulating in the fluid conductor without the temperature continuing to drop in the process. This effect is known in physics as "latent heat storage capacity" of the water.Since this heat storage based on conversion enthalpy takes place only in a small temperature range around the phase change, i.e. around 0° C., the heat storage made possible by the phase change of the water in moderate climate zones is limited to winter or extreme weather events.In order to likewise optimize the heat capacity of the geothermal heat absorber 400 at higher temperatures, it is at least partially filled with PCM bodies (bodies comprising phase change materials) 440, which are encapsulated in a thin plastic layer or are sheathed with a plastic layer. Since the melting temperature of a PCM is between about - 50° C. and 110° C., depending on the type used, suitably selected PCM bodies increase the storage capacity of the geothermal heat absorber 400 in a temperature band which is between 20° and 30° C., which is optimal for the operation of the heat pump 100.Figures 5a-5d show various arrangements of the PCM bodies 440 inside and outside the cavity 410. Due to the simple construction, a simple packing of the PCM bodies is conceivable. However, this is disadvantageous with regard to the heat pipe effect. In order to make optimum use of this effect or at least not to obstruct it, the PCM bodies 440 are preferably arranged in a defined manner. As can be seen in FIG. 5, in embodiments, the PCM bodies 440 are therefore arranged such that they are spaced apart from one another both in the direction of the longitudinal axis X of the housing 420 and perpendicular thereto. In this way, an obstruction to the heat transport by the PCM bodies 440 is minimized both along the longitudinal axis X and perpendicular thereto.This arrangement of the PCM bodies 440 advantageously allows the user to determine the installation position of the geothermal heat absorber 400 himself, i.e. vertically or horizontally in the ground, within wide limits.In the embodiment of the two-media geothermal heat absorber 400 shown in FIG. 5 a, spherical PCM bodies 440 are arranged in successive sections along and perpendicular to the longitudinal axis X in concentric circles around the longitudinal axis X. A radius R of the individual circles corresponds in embodiments of the two-media geothermal heat absorber 400 to approximately half a radius of the cylindrical housing 420.In the embodiment shown in FIG. 5 b, the PCM bodies 440 are formed as prisms which are continuous along the longitudinal axis X and are approximately triangular in cross section and are arranged along the circumference of a virtual cylinder lying in the cavity 410. A virtual cylinder radius Rz in embodiments of the dual media geothermal heat absorber 400 corresponds to approximately half a radius of the cylindrical housing 420.In the embodiment of the two-media geothermal heat absorber 400 shown in FIG. 5 c, similar to the embodiment shown in FIG. 5 a, spherical PCM bodies 440 are arranged in successive sections along and perpendicular to the longitudinal axis X in a circular manner around the longitudinal axis X, but in this variant in two concentric circles. An inner circle has the radius R1, and an outer circle has the radius R2.In the embodiment shown in FIG. 5 d, what are known as heat transfer PCM bodies 440 are used, which together with a second housing 421, which forms a second water-filled cavity 411, forms a cylindrical casing of the water / brine heat store 400. The heat transferexis oriented in the direction of the cylinder axis X. As can be seen in FIG. d, the second housing 421 is arranged along an inner radius Ri, while the housing 420 is arranged concentrically with respect to the second housing 421 along an outer radius Ra. In embodiments, the cavities 410 and 411 may be fluidly connected, for example, by holes or slots.The invention is not limited to the exemplary embodiments described and illustrated. Rather, it also includes all technical developments within the scope of the invention defined by the patent claims. In addition to the described and depicted embodiments, further embodiments are conceivable which can comprise further modifications and combinations of features.

Claims

Method for controlling a power system (10), comprising the steps: S1. taking heat transfer medium from a reservoir, the reservoir comprising a first reservoir (20) and a second reservoir (30), wherein the second reservoir (30) has a smaller volume than the first reservoir (20); S2. transporting the heat transfer medium to a first heat exchanger (90) of a heat pump (100) for delivering heat to the first heat exchanger (90); and S3. returning the heat transfer medium to the reservoir; wherein in step S 1, a proportion of heat transfer medium taken from the first reservoir (20) and a proportion of heat transfer medium taken from the second reservoir (30) are determined based at least in part on a difference between a target temperature of the heat transfer medium at the first heat exchanger (90) and an actual temperature of the heat transfer medium at the first heat exchanger (90).Method according to Claim 1, wherein in step S1, in a step 1a, the heat transfer medium is conducted, if required, via a first heat source (40) or a first heat sink.Method according to Claim 2, wherein in step S1, in a step 1b following the step 1a, the heat transfer medium is returned to the store again.Energy system (10) comprising: a first storage unit (20) for storing a heat transfer medium; a second storage unit (30) for storing heat transfer medium, wherein the second storage unit (30) has a smaller volume than the first storage unit (20); a first heat source (40) for supplying thermal energy to the heat transfer medium; a first heat exchanger (90); a fluid circuit (50) having a first pump (80) for circulating the heat transfer medium at least between the first storage unit (20), the second storage unit (30), the first heat source (40), and the first heat exchanger (90); and a first valve (V1), which is arranged in the fluid circuit (50) in such a way that a level of a volume flow of the heat transfer medium via the first reservoir (20) and a level of a volume flow of the heat transfer medium via the second reservoir (30) can be set, in particular limited.Energy system (10) according to Claim 4, characterized in that a second valve (V2) is arranged in the fluid circuit (50) in such a way that a level of a volume flow of the heat transfer medium can be set, in particular limited, via the first heat exchanger (90).Energy system (10) according to one of Claims 4 and 5, characterized in that the first heat source (40) comprises solar collectors (44), in particular photovoltaic-thermal solar collectors.Energy system (10) according to Claim 6, characterized in that the first heat source (40) comprises at least one second heat exchanger (42) for transferring heat from solar collectors (44) to the heat transfer medium.The power system (10) according to any of claims 4 to 7, comprising a heat pump (100), wherein the first heat exchanger (90) is an evaporator of the heat pump (100).The energy system (10) according to claim 8, comprising a industrial warm water plant (300) thermally coupled to the heat pump (100), wherein the coupling is preferably established behind a compressor (130) of the heat pump (100) and in front of a condenser (110) of the heat pump (100).The energy system (10) according to claim 9, characterized in that the industrial warm water plant (300) is thermally coupled to the first heat source (40).The energy system (10) according to any of claims 9 and 10, comprising a heating water reservoir thermally coupled to the heat pump (100).Energy system (10) according to claim 11, characterized in that the heating water reservoir is thermally coupled to the first heat source (40).Energy system (10) according to one of claims 11 and 12, characterised in that the energy system (10) comprises a combination of industrial hot water installation (300) and heating water storage.Energy system (10) according to one of Claims 4 to 13, characterized in that the first store (20) and / or the second store (30) is designed as an geothermal heat absorber, in particular as a two-media geothermal heat absorber.Energy system (10) according to one of Claims 4 to 14, characterized in that the first store (20) and / or the second store (30) comprises at least one water / brine heat store (400), the at least one water / brine heat store (400) having a housing (420) which fluidically seals off a cavity (410), and a fluid conductor (430) which is arranged within the cavity (410) and is connected fluidically to the fluid circuit (50) via an inlet (434) and an outlet (432).Energy system (10) according to Claim 15, characterized in that the cavity (410) of the at least one water / brine heat store (400) is filled with water and with plastic-coated PCM bodies (440), and / or the PCM bodies (440) enclose the cavity (410).The energy system (10) according to any one of claims 4 to 16, comprising a control unit configured to perform the method according to any one of claims 1 to 3.Control unit of an energy system (10), configured to carry out a method according to one of Claims 1 to 3.Computer program for carrying out a method according to one of Claims 1 to 3, when the computer program is executed by a control unit of an energy system (10).

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