WO2017002127A1

WO2017002127A1 - Solar collector with absorber integrated heat storage

Info

Publication number: WO2017002127A1
Application number: PCT/IN2015/000269
Authority: WO
Inventors: Milind Vishwanath Rane; Medha Milind Rane; Pooran Mal Menna; Sudhinath Jinnappa Shankargouda
Original assignee: Indian Institute Of Technology Bombay
Priority date: 2015-06-27
Filing date: 2015-06-29
Publication date: 2017-01-05

Abstract

The present disclosure discloses a solar heat collector. The solar heat collector comprise a housing. The housing further house at least one evacuated glass tube within the housing. Further a heat storage medium may be filled within the evacuated glass tube. Thus forming a thermal storage integrated into the absorber of the solar heat collector. Further the solar heat collector comprises a top cover mounted over the housing. A plurality of heat extractor are positioned within the at least one evacuated glass tube. The plurality of heat extractors are configured to extract heat from the heat storage medium. A flexible fin is attached to the heat extractor tube positioned within the evacuated glass tube along with the thermal storage material to extract heat more effectively from the storage medium. Further at least one reflector (114) is mounted within the housing and below the at least one evacuated glass tube.

Description

TITLE

SOLAR COLLECTOR WITH ABSORBER INTEGRATED HEAT STORAGE

FIELD OF INVENTION

The disclosure in general relates to a solar heat collector and a storage device using evacuated glass tubes, and specifically to an integrated solar heat collector and storage device, which can collect, store and deliver stored heat as required.

BACKGROUND OF INVENTION

Gas and electricity which are used as primary sources of energy are now becoming scarce and thereby the cost of the same is increasing at steady intervals. There is also a low supply of electricity to schools and hospitals in rural areas. The existing solar devices are also incapable of providing heat and electricity in the absence of solar energy. Frequent power cuts also lead to inconvenience for the public. Most solar cooking system do not have a storage medium to store heat to be used in non-solar hours. Most solar cooking systems have a top door or a side door which leads to heat loss due to heat escaping when opening the doors. Installing PV cells and providing grid connection to houses in rural areas is also difficult. Most solar cookers do not have temperature control features also. OBJECTIVE OF INVENTION:

1. The main object of this invention is to provide an integrated solar collector cum storage device

2. Another object of the present invention is to enable easy control of heat delivery and temperature 3. Yet another object of the present invention is to reduce the cost of the installation

4. Yet another object of the present invention is to increase the durability while reducing the cost

SUMMARY:

The general purpose of the invention is to disclose a solar heat collector cum storage device using evacuated glass tubes which can collect, store and deliver stored heat as required. It increases collector efficiency by increasing the radiation intercepted by the absorber of the collector, by providing means of concentrating radiation on the absorber surface of the evacuated glass tube/s. Also it increases the collector efficiency by reducing the heat losses from the outer glass tube by providing means of enclosing the evacuated glass tube with transparent glass tube, transparent glass tube with reflector inside or transparent plastic cover with suitably configured reflector located inside the plastic cover on the bottom side, or a linear Fresnel concentrator as a top cover/in segmented flat or curved configuration, with insulation sheet located on the lower side, the sheet provided with reflecting surface on the side facing the evacuated glass tube. Increasing the temperature at which collected solar heat is stored and/or delivered while achieving higher collector efficiency by integrating a serviceable heat pipe with one or more evaporators and a common condensing section integrated with the storage subsystem, a flexible fin is attached to the evaporator of the heat pipe or the heat extractor tube located in the evacuated glass tube along with the thermal storage material.

In one implementation of the present disclosure, a solar heat collector is disclosed. The solar heat collector may comprise a housing (1202}. The housing (1202] may further house at least one evacuated glass tube (105) within the housing (1202). The at least one evacuated glass tube (105) may be configured to capture incident solar rays. Further a heat storage medium (205) may be filled within the evacuated glass tube (105). Thus forming a thermal storage integrated into the absorber of the solar heat collector. Further the solar heat collector may comprise a top cover (330) mounted over the housing (1202). The top cover (330) may be configured to resist effect of adverse environmental conditions. Further a plurality of heat extractor (215) may be positioned within the at least one evacuated glass tube (105). The plurality of heat extractor (215) may be configured to extract heat from the heat storage medium (205). A flexible fin (225) may be attached to the heat extractor tube (215) positioned within the evacuated glass tube (105) along with the thermal storage material to extract heat more effectively from the storage medium (205) and enabling better thermal contact with the evacuated glass tube (105) by touching inner wall of the at least one evacuated glass tube (105) as it gets pressed outward by the heat storage media (205) filled within. Further at least one reflector (114) may be mounted within the housing and below the at least one evacuated glass tube.

BRIEF DESCRIPTION OF DRAWINGS:

Exemplary embodiments of the present invention are described hereinafter with reference to the following drawings, in which:

Figure 1 shows front and side sectional views of an evacuated glass tube with a heat capturing element filled with heat storage material in the powder form

Figure 2. shows front and side sectional views of an evacuated glass tube with a heat capturing element located around the heat storage material in the form of metal rods " Figure 3 shows an EGT assembly inclined at an angle

Figure 4a shows a sectional view of the solar collector with absorber integrated heat storage located on a horizontal surface

Figure 4b shows a sectional view of the solar collector with absorber integrated heat storage mounted on a vertical surface with evacuated glass tubes in horizontal orientation Figure 4c shows an isometric view of Figure 4a, the solar collector with absorber integrated heat storage mounted on a parapet

Figure 5a shows an isometric view of the solar collector with absorber integrated storage mounted on a vertical wall with primary and secondary solar reflectors

Figure 5b shows a front elevation and top plan view of the solar collector with absorber integrated storage mounted on the vertical wall with primary and secondary solar reflectors

Figure 6 shows a first arrangement comprising a series of parallel arranged EGTs of Figure 1 in which headers are shown

Figure 7 shows a first arrangement comprising a series of parallel arranged EGTs of Figure 2 in which headers are shown

Figure 8 shows a first arrangement comprising a series of parallel arranged EGTs with both side open ends in which headers are shown, hot fluid header is at one end and cold side header at other end of EGTs Figure 9a is the side view and sectional view of solar collector with absorber integrated heat storage and with evacuated glass tubes in which solar concentrators are used for each EGT Figure 9b shows the isometric view of Figure 9a

Figure 10a shows the front and sectional top view of solar collector with absorber integrated heat storage with reflectors deployed outside the top cover used to concentrate radiation on each EGT

Figure 10b shows isometric view of Figure 10a

Figure 11, illustrates the front and sectional top view of the exemplary embodiment of solar collector with absorber integrated heat storage with reflectors deployed inside the top cover used to concentrate radiation on each EGT for steam generation in accordance with present disclosure.

Figure 12, illustrates a sectional view of Figure 11. Figure 12a, illustrates an enlarged sectional view of one EGT of Figure 11.

Figure 13 illustrates an exemplary embodiment of a reflector in accordance with present disclosure.

Figure 14, illustrates the front and sectional top view of the exemplary embodiment of solar collector with absorber integrated heat storage with reflectors deployed inside the top cover used to concentrate radiation on each EGT which is deployed with evaporator of heat pipe having multiple evaporator sections and with common condenser. DETAILED DESCRIPTION OF INVENTION:

High temperature solar collector with absorber integrated thermal storage unit consists of vacuum tube collectors also known as evacuated glass tube collectors, outer surface of the inner glass tube absorbs the solar thermal energy and directly transfers it to the heat storage medium. A set of pipe/s or direct contact heat exchangers to enable extraction of stored heat using a heat transfer fluid. Wall integrated passages may be optionally provided to enable heat extraction from the heat storage material. Alternately heat exchange passages may be integrated into the bed of the heat storage material integrated with solar thermal absorber. Heat exchange passages may be integrated into the bed of the heat storage material within the heat storage enclosure may be optionally provided with longitudinal or radial fins to enable effective heat transfer without significant temperature difference between the bed and the heat transfer fluid. These fins may be deployed on the outside and if require on the inside of the heat exchange passages.

The delivery temperature of the hot utility can be controlled using a fan or a pump to circulate heat transfer fluid through the heat storage media or through the heat exchange passages integrated within the heat storage material or using a heat pipe/s. One of the applications of the solar collector integrated with heat storage is for hot air or steam based indoor solar cooking. The co-generation of electricity and hot utility like hot water, hot air, desalinated water, drying of various products including clothes, agro produce, herbs, spices, etc., regenerating liquid desiccants for air- conditioning that is for heating humidification or cooling dehumidification. The solar collector with absorber integrated heat storage is for generation of steam or vaporizing various fluids in the chemical and pharmaceutical industries, generating hot air for drying of milk and concentrating effluents, etc.

Storage medium can be of sensible heat storage type, consisting of single or combination of mediums like; stone, AI2O3, steel; of single or multiple particle size/s; filling the interstices of one medium/particle size with different medium/particle size to increase the bulk density and heat capacity per unit volume; typical properties are listed here: for stone [cp 1 kJ/(kg.K), density 2,300 kg/m³, storage density 0.64 kWh/(m³.K)], AI2O3 [cp 1.024 to 1.132 k)/(kg. ), density 2,225 kg/m³, 0.633 to 0.699 kWh/(m³.K)], steel [(cp 0.48 to 0.51 kJ/(kg. ), 7,800 kg/m³, 1.04 to 1.105 kWh/(m³.K)], etc. for temperature range of 200 to 400°C. Storage medium can be of latent heat storage type, consisting of pure or eutectic mixtures of organic or inorganic materials like NaN0₃ 59 to 61%/ N0₃ 41 to 39% eutectic mixture, LiN0₃, encapsulated or filled in storage pipes, and the interstices of the encapsulations may be optionally filled with sensible heat storage medium; single or combination of mediums like stone, AI2O3, steel, etc.; of single or multiple particle size/s; filling the interstices of one medium/particle size with different medium/particle size to increase the bulk density and heat capacity per unit volume; typical properties are provided as follows: NaN0₃ (MP 306°C, L_f 175 kj/kg, density 1,910 kg/m³, 93 kWh/m³), NaN0₃ 59 to 61%/ NO3 41 to39% eutectic mixture (MP 222°C, L_f 100 kj/kg, density 1,960 kg/m³, 54 kWh/m³), L1NO3 (MP 253°C, L_f 363 kj/kg, density 2,380 kg/m³, 240 kWh/m³).

The generation of power using vapour power generation cycle, where working fluid such as water, pentane, propane, n-perfluropentane, R134a, R601, R744, n-hexane etc. here is vaporized and optionally superheated using the heat stored in the storage media expanded through the turbine of the vapor power generation cycle and then after rejecting heat to the heat sink using a sink heat exchanger, is pumped back to the vaporizer/boiler placed in the heat storage bed.

The heat sink in the vapor power generation system can be an ambient heat sink like an air cooled heat exchanger or a cooling tower water cooled heat exchanger, evaporatively cooled heat exchanger or cogeneration heat exchangers where the heat is recovered/transferred to heat water and/or air to serve various low temperature heating needs or for drying of various materials including agro produce, herbs, spices, cloths, etc or regeneration of liquid desiccants used to dehumidify air, or desalinate water, concentrate effluents, dry sludge, etc. It serves as a generator of sorption refrigeration systems or sorption heat pumps.

The thermoelectric power generation can provide electricity in rural areas where the power supply is very unreliable and low. This system also cogenerates hot water for different uses in both rural and urban areas.

Power generation in vapour power generation cycle using ORC fluids which are superheated by the heat from the heat storage media and expanded through the turbine to generate electricity in the vapour power generation cycle and then after rejecting heat to the heat sink using a sink heat exchanger, is pumped back to the vaporizer/boiler placed in the heat storage bed. This invention can provide electricity to the rural areas where institutions like schools and hospitals can use this electricity.

The PV cells with battery storage option is costly whereas the thermoelectric co-generation with heat storage can provide sufficient amount of electricity for the illumination of a rural household and schools with a comparatively lower installation and maintenance costs. The decrease in the time for drying of spices, crops and other agricultural products with the help of present invention leads to the increase in the productivity. Temperature control mechanism introduced is in the form of fan (for uniform heating of food.

Figure 1 shows front and side sectional views of an evacuated glass tube with a heat capturing element 108 filled with heat storage material 205 in the powder form for solar heat storage. The EGTs comprise of heat capturing element 108 filled with heat storage material 205 such as aluminium oxide (A1₂0₃), slag like copper slag, zinc slag, stone, sand, garnet sand or a combination thereof for solar heat storage. Multiple parallel tubes 215 integrated into end plates, one end plate at the open end of the EGT 217 and the second end plate at the closed end of the EGT 218. These tubes made of high temperature resistant materials such as copper, brass, stainless steel, aluminum and galvanized iron, glass/ceramic, plastic [such as Kynar, Teflon) can be used for air to pass through with lesser pressure drop while air gets heated as the tube is in contact with the heat storage media. In this example, there are six heat utilizing elements 215 arranged circularly. The number of heat extractor tubes 215, depend on the diameter of the heat capturing element. The inner wall of the tube can be grooved internally or externally ribbed/finned or fluted to enhance heat transfer between the storage media and the air passing through the tubes. This arrangement is for decreasing the pressure drop on the air side as it picks up heat from the heat storage material as compared to the air directly passing through the medium. Fluid or air can be allowed to flow through the heat extractor element 215 and come out through the central tube 216. The central tube 216 is insulated by insulating paint 131 from inside and or outside and a high temperature insulating sleeve 133 from outside to reduce reverse heat transfer from heated air passing through the central tube and the relatively cooler storage media on the outside at the air inlet end of the heat capturing element 108. Air while entering gets heated. The insulating paint prevents the cooling of air by losing heat. A porous high temperature filter media 132 like stainless steel mesh or ceramic wool; mesh is provided primarily to filter the air and also ensure that there is some expansion space available for the storage media to expand and contract as the temperatures change during operation. Air can also be replaced with other suitable fluid which needs to be heated. 5 Figure 2 shows front and side sectional views of an evacuated glass tube with a heat capturing element filled with heat storage material in the form of

together are used for thermal storage and inserted in the BG . Alternately, an end cap 219 can be deployed at tite secoiKiend iate at the dosed end of the EGT 217 to enable

MltS retunringoff rJte fluid beii^ the central tube without exposing the inner tti ie^ of the EGT to of fluid being circulated through. Evacuated glass tube/s similar to 108 but open at both ends may also be used. Central tube 216 if not needed can be replaced by heat storage materials a in 105 and 106. Heat transfer fluid enters from end and leaves

15 from the otherend. Gold fluid header is at one end and the hot fluid header is at opposite end of both side open end evacuated glass tube with solar heat capturing element.: ¾ be headered into a square header 221 running perpendicular to the EGT using a large diameter circular tube extension 220 of diameter same as that of the end cap at the far end. A 0 second circular tube header 222 can be used to header the multiple central larger tubes 216 at the hot air outlet end, at the open end of the EGTs. A gap of about 50 mm should be provided to ensure placement of adequate amount of insulation between the cold and hot air headers. 5 Figure 3 shows an EGT assembly. The EGT comprises side reflectors 110 on the sides with insulation 130 at the back sides. The side reflectors 110 can be adjusted to concentrate solar energy on the EGT 108. During non-solar hours, these reflectors can be used to enclose the EGT from the top to provide insulation. The EGTs are insulated with insulator 130 from the bottom. After 0?

the reflector covers can be closed from the top to provide insulation from the top side. Air or fluid can be passed through the heat storage material for its utilization. Reflectors 111 aluminum corrugated sheet arranged at 45° or parabolic reflector sheet 112 can be used to concentrate solar energy on the heat capturing element 108 of EGT 105.

Figure 4a shows a side sectional view of the solar collector with absorber integrated heat storage mounted on a horizontal surface like window parapet. Figure 4b shows a sectional view of the solar collector with absorber integrated heat storage mounted vertically with horizontal evacuated glass tubes. Figure 4c shows an isometric view of the solar collector shown in Figure 4a with absorber integrated heat storage mounted on a window parapet. The reflector of aluminum parabolic sheet 112 or corrugated reflector 111 is used to concentrate solar energy on the heat capturing element 108. To capture and store solar heat energy, 105 or 106 can be used in Figures 4a, 4b and 4c.

Figure 5a shows an isometric view of the solar collector with absorber integrated storage mounted on a vertical wall. Figure 5b shows a front elevation and top plan view of the solar collector with absorber integrated storage mounted on the vertical wall. The reflectors work in the same way as described earlier in Figure 3 and 4. In the figures described above (Figures 3, 4a, 4b and 5b), 105 is the solar heat capturing and heat storing element shown in Figure 1. In place of 105, 106 can be used.

Figure 6 shows a first arrangement comprising a series of parallel arrangement of EGTs for Figure 1 in which cold fluid square header is 221 and hot fluid circular header is 222. Figure 7 shows a first arrangement comprising a series of parallel arrangement of EGTs for Figure 2 in which cold fluid square header is 221 and hot fluid circular header is 222. Figure 8 shows the evacuated glass tubes with both side open ends (109), filled with heat storage material like in Figure 1 and Figure 2 but the central tube (216) is replaced by heat storage material (205 or 206) itself. Cold fluid header (221) is one side and hot side header (222) is at another side. Evacuated glass tube with both side open end (109) filled with heat storage material like in Figure 1 or Figure 2 is 106.

Figure 9a (9b is its isometric view) shows the solar collector with absorber integrated heat storage in which evacuated glass tubes 108 (with Figure 1 and 6 or with Figure 2 and 7) or 109 (with Figure 8) are used. Parabolic / circular / compound reflector 1 12 is used to concentrate solar energy which tracks the sun. Evacuated glass tubes with reflectors are placed in north south direction with local declination angle to get sun rays perpendicular to the plane of solar collector.

Figure 10a is the wall mounted solar collector with absorber integrated heat storage and Figure 10b is its isometric view. Evacuated glass tubes 106 shown in figure may be with Figure 6 or Figure 7 or Figure 8 arrangements. Two reflectors 1 10, like in Figure 5 with same function are used as secondary reflectors. In addition to it, a Fresnel mirror 113 as shown in Figure 10b is used to reflect solar energy on EGTs 106 as well as on secondary reflectors 1 10. This arrangement is to get temperatures of heat storage above 550°C using evacuated glass tubes which have selective absorber coatings which can tolerate a temperature of over 600°C.

Figure 1 1a is the front and sectional top view of solar collector with absorber integrated heat storage with reflector 1 14 as shown in figures. Insulation 130 is optional but preferred for high temperature applications. In this configuration the heat extraction tube coil (227) is configured to transfer heat from the storage medium (205) to the water or fluid being heated which pass through it. The serpentine heat extraction tube coil (227) is such that there is a U shaped tube inside each evacuated glass tube (105). A flexible fin (225) is attached to the heat extractor tube (227) positioned within the evacuated glass tube (105) along with the thermal storage material to extract heat more effectively from the storage medium (205). It also enables better thermal contact with the evacuated glass tube (105) by touching its inner wall as it gets pressed outward by the heat storage media (205) filled within. This configuration can be used for generating steam. Alternately the heat extraction tube coil (227) can be a helical tube coil inside each evacuated glass tube (105) with or without the flexible fin. Evacuated glass tube of arrangement shown in Figure 6, Figure 7 of Figure 8 may be used in this type of cover, reflector and insulation arrangement of the solar collector with thermal storage.

In Figures 3, 4a, 4b and 5b and 8, the reflectors backed with insulation are used to cover the evacuated glass tubes during non-sunny hours. The reflective covers 110 backed with insulation 130 also act as a hinge and cover the top to be reasonably air tight to minimize the top heat loss.

In the Figures described in this patent application, 108 is the evacuated glass tube with one side open end and other side closed end, 109 is the evacuated glass tube with both side open ends, 110 is the flat aluminum solar reflector sheet, 111 is the aluminum solar reflector sheet with 45° corrugation, 112 is the aluminum parabolic solar reflector sheet, 113 is the Fresnel mirror, 130 is the insulation, 131 is the insulation paint, 132 is the insulation and air filter, 133 is the high temperature insulating sleeve, 205 is the heat storage material (aluminum oxide/sand), 206 is the heat storage material (metal rods), 207 is the spring for creating turbulent flow to enhance heat transfer, 215 is the heat utilization element, 216 is the central tube insulated outside and or inside, 217 is the end plate at open end of EGT, 218 is the end plate at closed end of EGT, 219 is the hemispherical end cap, 220 is the circular extension for cold air/fluid from square header, 221 is the square header for cold or inlet fluid, 222 is the circular header for hot or outlet air/fluid, 223 and 224 are the evaporator and condenser sides of the heat pipe respectively, 225 and 228 are the flexible fins attached to the heat pipe evaporator 223 and heat extraction coil 227 respectively, 605 is the vertical wall and 606 is the parapet.

Various applications of the integrated heat capture and storage apparatus are thermo electric cogeneration, air heating for industrial, commercial and residential markets like preheating of air to a temperature range of 150 to 300°C, heat source for steam or organic Rankin cycle based power generation or cogeneration, heat source with integrated heat storage for absorption, adsorption and desiccant cooling and refrigeration systems.

Referring to Figure 12, illustrates an exemplary embodiment of a solar collector in accordance with present disclosure. The exemplary embodiments illustrates a housing 1202. The housing 1202 may further comprise at least one evacuated glass tube 105. The evacuated glass tube/s 105, may be enabled to receive the incident sun rays and capture the heat generated due to incident radiation. Further, distance between two adjacent evacuated glass tubes 105 can be varied based on the highest temperature required and the relationship between distance and maximum temperature is directly proportional.

The captured radiation may further be transferred through thermal conduction to a heat storage medium 205. The heat storage medium 205 may comprise of aluminum oxide (AI2O3), copper slag, stone, sand, or a i :, :., · :^'■ combination of mem. In; an exemplary em medium 205 may

> be in .powder form tha¾by completely filing the evacuated glass tube 105. The ; storage medians 205_» may store the radiation or heat, thereby serving as heat storage integrated within the solar collector.

5

Further the housing 1202 may comprise a top cover 330 mounted over the fidnra;^:& & aii&3t-a& .bottom insulation* 13(Lt¾he top cover 330 may resist effec of adverse environmental conditions;; such as protect the evacuated glasstuhe 105 from dust or small object that can break or damage the glass.

10S-^; The top cover 330 may also enable easy maintenance of the solar collector and also reducse the top convective and radiative heat losses. Further the solar collector may comprise plurality of heat extractor 215 positioned within the evacuated glass tube 105. The heat extractor can extract heat from the heat storage medium 205 and transfer the heat to another medium like

15 fluid, wherein the fluid can carry away the heat for various purposes. Heat exchange between the fluid may happen, using, direct contact, or through fins. The fluid may be configured to flow through a central tube 216. The central tube 216 can be positioned within the at least one evacuated glass tube 105. Further the central tube 216 maybe painted either on inside or outside or

20 both with an insulating paint 131. In another exemplary embodiment an insulating sleeve 133 on outside may also be provided. The solar heat collector may also be provided with an insulated base 130 mounted within the housing 1202 and below at least one reflector 1 14.

25 Now referring to Figure 13 illustrates an exemplary embodiment of a reflector in accordance with present disclosure. The reflector 114 may be mounted within the housing and below the at least one evacuated glass tube 105. Further the reflector 114 may have a parabolic shape. In an embodiment the reflector 114 may be positioned such that center of the ^■:■ 30 parabolic shape is at an offset with respect to a first center of the at least one evacuated glass tube 105. Further, in another embodiment the reflector may have different shape for example the reflector may be fabricated such that there are three distinct planes visible like a horizontal plane, another at 30 degree and yet another at 45 degree or compound parabolic shape or semi- circular shape or flat.

Figure 14 is the sectional top view of solar collector with absorber integrated heat storage and heat pipes (with evaporator 223 and condenser 224) with reflector 1 14, insulation 130 is optional but preferred for high temperature applications. In this configuration the heat extraction is enabled using the heat pipe (evaporator 223) configured to transfer heat from the storage medium 205 to the water or fluid being heated which passes in contact with the condensing section of the heat pipe 224. A flexible fin 225 is attached to the heat pipe evaporator tube 223 positioned within the evacuated glass tube 105 along with the thermal storage material to extract heat more effectively from the storage medium 205. It also enables better thermal contact with the evacuated glass tube 105 by touching its inner wall as it gets pressed outward by the heat storage media 205 filled within. This configuration can be used for heating water, oil or other fluids, generating steam, boiling organic fluid for operating organic power generation system, operating a thermoelectric chip based power or co-generation system.

Claims

1. A solar heat collector, comprising:

a housing (1202);

at least one evacuated glass tube (105), wherein the at least one evacuated glass tube (105) is housed in the housing (1202) and is configured to capture incident solar rays;

a heat storage medium (205), wherein the heat storage medium is filled within the evacuated glass tube (105), thus forming a thermal storage, integrated into the absorber of the solar heat collector;

a top cover (330) mounted over the housing (1202), wherein the top cover (330) is configured to resist effect of adverse environmental conditions;

a plurality of heat extractor (215) positioned within the at least one evacuated glass tube (105) configured to extract heat from the heat storage medium (205);

a flexible fin (225) is attached to the heat extractor tube (215) positioned within the evacuated glass tube (105) along with the thermal storage material to extract heat more effectively from the storage medium (205) and enabling better thermal contact with the evacuated glass tube (105) by touching inner wall of the at least one evacuated glass tube (105) as it gets pressed outward by the heat storage media (205) filled within; and

at least one reflector (114) mounted within the housing and below the at least one evacuated glass tube.

2. The solar heat collector as claimed in claim 1, further comprises an insulated base (130) mounted within the housing and below the at least one reflector, wherein the insulated base is configured to insulate heat dissipation from below the housing.

3. The solar heat collector as claimed in claim 1, wherein the at least one reflector has a parabolic or a compound parabolic or a semi-circular or a flat or a flat segmented shape. 4. The solar heat collector as claimed in claim 3, wherein the at least one reflector is positioned such that focus of the parabolic or the compound parabolic shape or the center of the semi-circular shape is at an offset with respect to a first center of the at least one evacuated glass tube.

The solar heat collector as claimed in claim 1, wherein the heat storage medium (205) further comprises at least one of an Aluminium Oxide (AI2O3), slag like copper slag, zinc slag, stone, sand, garnet sand or a combination thereof.

The solar heat collector as claimed in claim 1, wherein the heat storage medium (206) further comprises at least one of a rod like structure made of metal, glass, ceramic.

The solar heat collector as claimed in claim 1, wherein the heat storage medium (206) further comprises a sealed tubular elements encapsulating a phase change materials such as NaN0₃, K O3, L1NO3 and their mixtures or wax or a combination thereof.

The solar heat collector as claimed in claim 1, further comprises a central tube (216), wherein the central tube (216) is configured to enable a fluid to flow through.

The solar heat collector as claimed in claim 7, wherein the central tube (216) further comprises an insulating paint (131) painted either inside the central tube, or outside the central tube, or on inside and outside of the central tube.

10. The solar heat collector as claimed in claim 7, wherein the central tube (216) further comprises an insulating sleeve (133) on outside of the central tube.

11. The solar heat collector as claimed in claim 1, further comprise of a central heat pipe (223), wherein the central heat pipe (223) is configured to enable extraction of heat from the storage medium (205) from at least one of the evacuated glass tubes.

12. The solar heat collector as claimed in claim 10, further comprises a central heat pipe (223), wherein the central heat pipe (223) is configured to deliver heat to the fluid being heated individually or through a common condenser (224) making it easy to service.

13. The solar heat collector as claimed in claim 1, further comprise of a heat extraction tube coil (227), wherein the heat extraction tube coil (227) is configured to transfer heat from the storage medium (205) to the fluid being heated and pass through.

14. The solar heat collector as claimed in claim 13, wherein the heat extraction tube coil (227) is a U shaped tube inside each evacuated glass tube (105). 15. The solar heat collector as claimed in claim 13, wherein the heat extraction tube coil (227) is a helical tube coil inside each evacuated glass tube (105).