WO2016005840A1

WO2016005840A1 - Photovoltaic-thermal passive system

Info

Publication number: WO2016005840A1
Application number: PCT/IB2015/054606
Authority: WO
Inventors: Behrooz MIRZAEI ZIAPOUR; Palideh VAHID
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-07-11
Filing date: 2015-06-18
Publication date: 2016-01-14
Anticipated expiration: 2017-01-11

Abstract

A photovoltaic–thermal device includes a housing unit, a photovoltaic panel, a fluid collector storage, and an absorber plate. The photovoltaic panel is placed within the housing unit and includes a plurality of photoelectric cells configured to generate an electrical output in response to incident electromagnetic radiations. The fluid collector storage is placed within the housing unit and configured to store fluid. The absorber plate is placed within the housing unit between the photovoltaic panel and the fluid collector storage and configured to collect heat by absorbing electromagnetic radiations and to pass the collected heat to the fluid collector. The absorber plate separates the photovoltaic panel from the fluid collector storage.

Description

PHOTOVOLTAIC-THERMAL PASSIVE SYSTEM

Cross Reference To A Related Application

[0001] This application claims priority to an Iran patent application having serial number

139350140003004075 filed on July 11, 2014, the entire content of which is incorporated herein by reference.

Background

[0002] There has been for many years substantial interest in turning the energy of the sun into useful power for various purposes, including the heating of water for residential use. To date, solar water heaters have heated the water directly by exposure to solar radiation, for example, by pumping the water to be heated through solar collector panels. Such systems involve relatively complicated plumbing in relatively inconvenient locations, increasing initial cost and maintenance expense. The foregoing may result in loss of heat to the surrounding and the reduction of water temperature as the water travels through various pipes to reach its final storage location. Furthermore, the extensive pluming can increase the cost of such solar water heating devices.

[0003] Hence, there is a need for a solar water heating device without a complicated plumbing to transfer water from the storage to be heated and returning the heated water back to the storage.

Summary

[0004] In one general aspect, the instant application describes a photovoltaic-thermal device that includes a housing unit, a photovoltaic panel, a fluid collector storage, and an absorber plate. The photovoltaic panel is placed within the housing unit and includes a plurality of photoelectric cells configured to generate an electrical output in response to incident electromagnetic radiations. The fluid collector storage is placed within the housing unit and configured to store fluid. The absorber plate is placed within the housing unit between the photovoltaic panel and the fluid collector storage and configured to collect heat by absorbing electromagnetic radiations and to pass the collected heat to the fluid collector. The absorber plate separates the photovoltaic panel from the fluid collector storage. [0005] The above general aspect may include one or more of the following features. The photovoltaic-thermal device may further include a fin panel placed within the housing unit between the absorber plate and the fluid collector storage and configured to increase an amount of the transfer of the absorbed heat from the absorber plate to the fluid collector storage. The fin panel may separate the absorber plate from the fluid collector storage. The photovoltaic-thermal device may further include a cover placed within the housing unit over the photovoltaic panel. The cover may include a glass cover.

[0006] The plurality of photoelectric cells may be spaced apart from each under the glass cover on the absorber plate. The absorber plate may be configured to absorb the heat generated from the electromagnetic radiations incident on the plurality of the photoelectric cells and incident directly on the absorber plate due to existing space between the plurality of photoelectric cells. The electromagnetic radiation may include radiations generated from sunlight.

[0007] The fluid collector storage may include a water collector storage. The water collector storage may include a thermometer shape having a neck portion and a body portion connected to the neck portion. The neck portion may include half circular shape and the body portion may include a rectangular elongated shape when viewed from a side portion of the passive collector device. The neck portion may be configured to store more water than the body portion.

[0008] The photovoltaic-thermal device may further include a fin panel placed within the housing unit between the absorber plate and the fluid collector storage and configured to increase an amount of transfer of the absorbed heat from the absorber plate to the water collector storage. The fin panel may separate the absorber plate from the water collector storage. The heat may be transferred from the absorber plate to the water located at a top surface of the water collector storage in direct contact with the fin panel to thereby warm the water inside the water collector storage. The water located inside the body portion may be heated faster than the water located a bottom surface of the water collector storage. The convective movement of the water inside the water collector storage may start when water in the body portion is heated, causing the water in the body portion to expand and become less dense, and thus more buoyant than cooler water in the bottom surface of the water collector portion thereby replacing the cooler water in the bottom surface of the water collector portion. [0009] The photovoltaic-thermal device may be located on a house roof at an inclination angle. The inclination angle may be selected so as to maximize an amount of solar radiation incident in a perpendicular direction on the photovoltaic panel. The photovoltaic-thermal device may be configured to transfer heat from the absorber plate to the fluid storage collector without using a pump and a fluid pipe. The fluid collector storage may be covered by an insulator layer to prevent heat scape from an interior of the fluid collector storage.

[0010] The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present application when taken in conjunction with the accompanying drawing.

Brief Description of the Drawings

[0011] The drawing figure depicts one or more implementations in accord with the present teachings, by way of example only, not by way of limitation.

[0012] FIG. 1 illustrates an exemplary PVT passive system that can be used to generate both heat and electricity.

Detailed Description

[0013] In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent to those skilled in the art that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings.

[0014] In one implementation, the instant application describes a photovoltaic-thermal

(PVT) module including a photovoltaic (PV) panel and a thermal collector for co-generation of heat and electricity. The PV panel may include solar cell array. The solar cell array may be subjected to a solar radiation for generating electrical power for a variety of purposes, including powering conventional appliances. The solar cell array may not convert all the solar radiation into the electrical power. Some of the radiation may, for example, be converted into heat, which may be absorbed by the thermal collector. [0015] The thermal collector may be an integrated collector-storage solar water heater

(ICSSWH). The ICSSWH is combined with the PV panel in a single housing unit and may include an absorber plate and a fluid collector storage. The fluid collector storage may a water collector storage. Due to its simple and compact structure, the ICSSWH may offer a promising approach for the solar water heating in the varied climates.

[0016] The absorber plate is configured to absorb the wasted heat from the solar cells arranged in the PV panel and transfer the heat to the water collector storage. This transfer of the heat from the solar cells to the water collector storage results in heating the water inside the collector storage. The heated water can be used for variety of purposes inside the house including providing hot water for the house. The transfer of the heat from the solar cells to the water collector storage may also result in increasing the productivity of the solar cells by keeping the solar cells cool. That is, the transfer of the heat can prevent the increase of the temperature of the solar cells, which result in reduction of their productivity.

[0017] In one implementation, the PVT system is a PVT passive system. To this end, the

PVT passive system may not use PV driven water pump to maintain a flow of water inside the collector. The effects of the solar cell packing factor, the tank water mass and the collector area on the performance of the present PVT passive system have been investigated. The simulation results showed that the high solar cell packing factor and the tank water mass are caused to the high total PVT passive system efficiency. Also, larger area of the collector is resulted to lower total PVT passive system efficiency. This is described in more details in Behrooz Mirzaei Ziapour et al., "Study of an Improved Integrated Collector-Storage Solar Water Heater Combined with the Photovoltaic Cells," Energy Conversion and Management, 86 (2014), 587- 594, the content of which is incorporated herein in its entirety.

[0018] The PVT passive system of the instant application may be advantageous compared to the prior art systems for several reasons. For example, in the prior art system, the water collector storage may be separated from the absorber plate (e.g., not be located in the same housing unit as the absorber plate) and may be connected to the absorber plate via various pipes. To this end, the water may travel from the water collector storage to the vicinity of the absorber plate via a first pipe. At the vicinity of the absorber plate the water may be heated by transfer of heat from the solar radiation to the water through the absorber plate. The heated water may then be transferred back to the water collector storage through a second pipe. This circulation of the water may be made possible via a pump. In contrast, in one implementation, the PVT passive system of the instant application does not require a pump or plumbing to heat the water inside the water collector storage. The water can be directly heated through the absorber plate since the water collector heater is located within the same housing unit as the absorber plate. To this end, the PVT passive system of the instant application may be more economical to use than that the prior art system since the PVT passive system of the instant application does not require a pump or a pluming. Furthermore, the PVT passive system of the instant application may be more efficient in heating the water inside the water collector storage since it can avoid the heat loss during the transfer of the heated water through return pipes to the water collector storage. Furthermore, the PVT passive system of the instant application has a simpler design and can be designed by less skilled individuals in the field. To this end, the maintenance and repair of the PVT passive system of the instant application may be easier than that of the prior art. Additionally, the PVT passive system of the instant application can occupy less space than that of the prior art.

[0019] By start of day and radiation of solar energy on the PV panel, the panel can generate electricity which can be used for variety of purposes. For example, the electricity can be used to provide lighting for the house. For another example, the electricity can be used to provide power for electrical appliances within the house such as, dishwasher, washing machine, microwave, etc. For yet another example, the electricity can be used to charge a battery. During the process of converting the solar energy into electricity, the solar cells' temperature may increase. This increased temperature may be absorbed by the absorber plate and transferred to the water collector storage. In additional to absorbing the heat generated from the electromagnetic radiations incident on the plurality of the photoelectric cells, the absorber plate can absorb heat incident directly on the absorber plate due to existing space between the plurality of photoelectric cells. The absorber plate transfers the absorbed heat to the water collector storage. The transfer of heat results in raising the temperature of the water within the water collector storage.

[0020] The water near the surface of the absorber plate may be heated first. This heated water may have a lesser density than the water located farther away from the absorber plate. This difference in density may cause a pressure difference between the water located near the absorber plate and the water located farther away from the absorber plate, which may in turn result in circulation of the water within the water collector storage. As a result of this circulation, the water heated near the absorber plate may travel to the bottom and the water at the bottom of the water collector storage may travel to the top near the absorber plate. This circulation may be called a thermos phonic movement. This movement may be slow and may be suitable for an environment in which slow movement of the water is desired and in which the solar radiation is weak such as for example in areas with cloudy or rainy weather. Due to the natural circulation of water, the PVT passive system of the instant application may not require a pump and therefore may be cheaper to design. Furthermore, the generated electricity may not be wasted for powering the pump.

[0021] Reference now is made in detail to the examples illustrated in the accompanying drawings and discussed below. FIG. 1 illustrates an exemplary PVT passive system 100 that can be used to generate both heat and electricity. The PVT passive system 100 may include a housing unit 102, a cover 110, a PV panel 112, an absorber plate 114, a fin panel 116, and a fluid collector storage 118. The housing unit 102 as shown integrates the PV panel 112, the absorber plate 114, and the fluid collector storage 118 into a single housing.

[0022] The cover 110 may be placed within the housing unit 102 over the PV panel 112.

The cover 110 may include a glass cover. Alternatively, the cover 110 may include material other glass as long as the material is suitable for transferring the solar radiation to the PV panel 112 and the absorber plate 114.

[0023] The PV panel 112 may be placed within the housing unit 102 and may include a plurality of solar cells configured to generate an electrical output in response to incident electromagnetic radiations. Radiation from the sun 104 is incident on solar cells. The solar cells generate electrical power responsive to incident solar energy. In one implementation, the solar cells are spaced apart from each other under the glass cover 110 on the absorber plate 114.

[0024] The absorber plate 114 is placed within the housing unit between the PV panel

112 and the fluid collector storage 118 and is configured to collect heat by absorbing electromagnetic radiations and to pass the collected heat to the fluid collector storage 118. To this end, the absorber plate 114 is configured to absorb the heat generated from the electromagnetic radiations incident on the plurality of the photoelectric cells 112 and incident directly on the absorber plate 114 due to existing space between the plurality of photoelectric cells. The absorbed heat is then passed to the fluid collector storage 118. The absorber plate may be made of aluminum material with thermal conductivity of 250 (W/mk) and the plate thickness of 0.002 (m). In one implementation, the PV panel 112 is configured to convert only a small percentage of incident solar radiation to electricity and the rest is converted into heat, which can significantly increase the temperature of the PV panel 112 and reduce its productivity. The absorber plate 114 is configured to absorb this heat and thereby reduce the temperature of the PV panel 112 and increase its productivity, as described in Ziapour, B., "Study of an Improved Integrated Collector-Storage Solar Water Heater Combined with the Photovoltaic Cells," Energy Conversion and Management, 86 (2014), pp. 587-594, the content of which is incorporated herein in its entirety.

[0025] The fluid collector storage 118 may include a water collector storage. The water collector storage may include a thermometer shape having a body portion 120 and a neck portion 122. The body portion 120 may be connected to the neck portion 122. The neck portion 122 may include half circular shape and the body portion 120 may include a rectangular elongated shape when viewed from a side of the PVT passive system 100. The neck portion 122 may be configured to store more water (higher volume) than the body portion 120. In one specific example, the neck portion 122 may be configured to store 4 times more water than the body portion 120.

[0026] The PVT passive system 100 may additionally include a fin panel 116. The fin panel 116 may be placed within the housing unit 102 between the absorber plate 114 and the fluid collector storage 118. The fin panel 116 is a surface that extends from the absorber plate 114 and is configured to increase the heat transfer from the absorber plate 114 to the water collector storage 118 by convection. In one specific example, the fin panel 116 include parallel aluminum fins installed longitudinally back of the absorber plate 114 in the direction of the natural flow of the water to enhance the heat transfer rate and efficiency. The effects of both of the heights and number of fins on the collector performance has been student, the result of which is mentioned in Behrooz Mirzaei Ziapour, "Performance comparison of four passive types photovoltaic-thermal systems," Energy Conversion and Management 88 (2014) 732-738, the content of which is incorporated herein by reference in its entirety. In one specific example, the number of fins are 20 and the height of the fins are 0.04 m. Other values of the system are shown in Table 1 below.

Labs 0.002 τ_ε 0.96

Parameter Name Parameter Name

Kabs Thermal conductivity Nfin Number of fins

of absorber surface

(W/(mK))

Kins Thermal conductivity Mf Water mass inside of insulation storage tank (Kg) (W/(mK))

Kfin Thermal conductivity W Width of PV panel of fin material (m)

(W/(mK))

Kg Thermal conductivity Wfin Fin thickness (m) of cover glass

(W/(mK))

K_sc Thermal conductivity _sc Solar cell absorbance of solar cell

(W/(mK))

Lins Insulation thickness _abs Absorber front

(m) surface absorbance, black oil color absorbance

Lfin Height of fin (m) ηο Efficiency at standard test condition (I(t) = 1000W/m² and T_sc = 25° C

Lg Cover glass thickness Bo Temperature

(m) coefficient of solar cell efficiency (1/K)

Lsc Solar cell thickness Θ Tilt angle of

(m) ICSSWH system

Labs Absorber surface ¾ Transmittance of the thickness cover glass

Tal ble 1 [0027] The fin panel 116 may separate the absorber plate 114 from the water collector storage 118. In this manner, the heat may be transferred from the absorber plate 114 to the water located at a top surface of the water collector storage 118 in direct contact with the fin panel 116 to thereby warm the water inside the water collector storage 118. In one implementation, the fin panel 116 is a fin array which is an elongated one piece element that includes a plurality of fins. The size and the number of the fins may vary.

[0028] The water located inside the body portion 120 may be heated faster than the water located a bottom surface of the neck portion 122. The convective movement of the water inside the water collector storage 118 may start when water in the body portion 120 is heated, causing the water in the body portion 120 to expand and become less dense, and thus more buoyant than cooler water in the bottom surface of the water collector portion (e.g., the water at the bottom of the neck portion 122) thereby replacing the cooler water in the bottom surface of the water collector portion. That is, the water inside the body portion 120 may be heated first and this heat may be transferred to the water at the bottom neck portion 122 via a thermos phonic movement. In this manner, the water inside the water collector storage 118 circulates and becomes warm.

[0029] The PVT passive system 100 may be located on a house roof at an inclination angle facing the sun. The inclination angle may be selected so as to maximize the amount of solar radiation incident in a perpendicular direction on the PV panel 112. Thus, inclination angle means, with respect to any flat collector surface, the angle formed between the horizontal (sometimes referred to herein as the "earth") and a line perpendicular to the PV panel 112 in the direction of the sun.

[0030] Other implementations are contemplated. For example, the PVT passive system of the instant application can be used to power and provide heated water for a single family home. To this end, a single or multiple small PVT passive systems may be mounted in the signal family home (e.g., on the roof) to simultaneously provide electricity and heated water for the single family home. The small PVT passive system may mean a module with an absorber plate having a size of one or two square meter. For another example, the fluid collector storage may be covered by an insulator layer to prevent the heat from the fluid collector storage to escape to the surround environment.

[0031] While the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present teachings.

[0032] Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain.

[0033] The scope of protection is limited solely by the claims that now follow. That scope is intended and may be interpreted to be as broad as is consistent with the ordinary meaning of the language that is used in the claims when interpreted in light of this specification and the prosecution history that follows and to encompass all structural and functional equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirement of Sections 101, 102, or 103 of the Patent Act, should may they be interpreted in such a way. Any unintended embracement of such subject matter is hereby disclaimed.

[0034] Except as stated immediately above, nothing that has been stated or illustrated is intended or should be interpreted to cause a dedication of any component, step, feature, object, benefit, advantage, or equivalent to the public, regardless of whether it is or is not recited in the claims.

[0035] It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. Relational terms such as first and second and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "a" or "an" does not, without further constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0036] The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.

Claims

1. a photovoltaic-thermal device comprising:

a housing unit;

a photovoltaic panel placed within the housing unit and including a plurality of photoelectric cells configured to generate an electrical output in response to incident electromagnetic radiations;

a fluid collector storage placed within the housing unit and configured to store fluid; and an absorber plate placed within the housing unit between the photovoltaic panel and the fluid collector storage and configured to collect heat by absorbing electromagnetic radiations and to pass the collected heat to the fluid collector,

wherein the absorber plate separates the photovoltaic panel from the fluid collector storage.

2. The photovoltaic-thermal device of claim 1 , further comprising a fin panel placed within the housing unit between the absorber plate and the fluid collector storage and configured to increase an amount of the transfer of the absorbed heat from the absorber plate to the fluid collector storage, wherein the fin panel separates the absorber plate from the fluid collector storage.

3. The photovoltaic-thermal device of claim 1, further comprising a cover placed within the housing unit over the photovoltaic panel.

4. The photovoltaic-thermal device of claim 3, wherein the cover includes a glass cover.

5. The photovoltaic-thermal device of claim 4, wherein the plurality of photoelectric cells are spaced apart from each under the glass cover on the absorber plate.

6. The photovoltaic-thermal device of claim 1, wherein the absorber plate is configured to absorb the heat generated from the electromagnetic radiations incident on the plurality of the photoelectric cells and incident directly on the absorber plate due to existing space between the plurality of photoelectric cells.

7. The photovoltaic-thermal device of claim 1, wherein the electromagnetic radiations include radiations generated from sunlight.

8. The photovoltaic-thermal device of claim 1, wherein the fluid collector storage includes a water collector storage.

9. The photovoltaic-thermal device of claim 8, wherein the water collector storage includes a thermometer shape having a neck portion and a body portion connected to the neck portion.

10. The photovoltaic-thermal device of claim 9, wherein the neck portion includes half circular shape and the body portion includes a rectangular elongated shape when viewed from a side portion of the passive collector device.

11. The photovoltaic-thermal device of claim 10, wherein the neck portion is configured to store more water than the body portion.

12. The photovoltaic-thermal device of claim 10, further comprising a fin panel placed within the housing unit between the absorber plate and the fluid collector storage and configured to increase an amount of transfer of the absorbed heat from the absorber plate to the water collector storage, wherein:

the fin panel separates the absorber plate from the water collector storage,

the heat is transferred from the absorber plate to the water located at a top surface of the water collector storage in direct contact with the fin panel to thereby warm the water inside the water collector storage.

13. The photovoltaic-thermal device of claim 12, wherein the water located inside the body portion is heated faster than the water located a bottom surface of the water collector storage.

14. The photovoltaic-thermal device of claim 13, wherein convective movement of the water inside the water collector storage starts when water in the body portion is heated, causing the water in the body portion to expand and become less dense, and thus more buoyant than cooler water in the bottom surface of the water collector portion thereby replacing the cooler water in the bottom surface of the water collector portion.

15. The photovoltaic-thermal device of claim 1, wherein the passive collector device is located on a house roof at an inclination angle.

16. The photovoltaic-thermal device of claim 1, wherein the inclination angle is selected so as to maximize an amount of solar radiation incident in a perpendicular direction on the photovoltaic panel.

17. The photovoltaic-thermal device claim 1, wherein the photovoltaic-thermal device is configured to transfer heat from the absorber plate to the fluid storage collector without using a pump and a fluid pipe.

18. The photovoltaic-thermal device of claim 1, wherein the fluid collector storage is covered by an insulator layer to prevent heat scape from an interior of the fluid collector storage.