WO2014000895A1

WO2014000895A1 - Device for receiving solar energy and method for producing electricity and heating a fluid simultaneously

Info

Publication number: WO2014000895A1
Application number: PCT/EP2013/053559
Authority: WO
Inventors: Louis Guerin
Original assignee: Gpc International S.A.
Priority date: 2012-06-29
Filing date: 2013-02-22
Publication date: 2014-01-03
Also published as: LU92036B1

Abstract

The present invention concerns a three-stage device for receiving solar energy comprising at least one convergent Fresnel lens (1.3) focusing solar energy on at least one heating element (2.1) coplanar to at least one photovoltaic cell (2.5). The present invention also concerns a method for producing electricity and for heating a fluid (5) simultaneously.

Description

Device for receiving solar energy and

method of generating electricity and heating a fluid simultaneously.

The use of renewable energy will become more and more important in the future. Possible solutions include wind power and solar energy. These two sources of energy are still limited, but they are expected to play an increasingly larger role in the future.

The present invention deals with solar energy (energy from sunlight or light).

There are currently two kinds of systems exploiting this source of energy.

The first consists of photovoltaic systems, which convert sunlight directly into electricity. The second consists of photo-thermal systems, where solar energy is used to heat a fluid.

The two systems of the prior art are employed independently, which means that one can produce either electricity or heat but not both simultaneously. Very few existing systems today combine photovoltaics and photo-thermics. An example of such a system is described in JP 200720800, where photovoltaic cells are mounted on a plate in which a fluid circulates to cool the cells. This makes it possible to increase the energy efficiency of the photovoltaic cells and to extract heat for heating applications.

Another system is described in US Patent 2011226308 where parabolic mirrors concentrate sunlight on a tube inside which circulates a fluid that will be heated and outside which are fixed photovoltaic cells producing electricity.

Other systems are described in patents KR 20110330248, KR 101009688, US 2010147347, EP 2188847, DE 102008013523, US 2009065046, KR 20070080179, DE 202005019, JP 2007081097, WO 2006019091, KR20050106164, JP 2004176982, JP 2004039942, JP 2002310516. and EP 0820105.

All the systems described in the patents mentioned above have in common that they are fixed and that they do not follow the course of the sun. Sun tracking can be useful to optimize the amount of light entering the system at any time.

In order to remedy this, different methods have been developed.

FIRE I LLE OF REM PLACEM ENT (RULE 26) There are two main categories. The first uses "tracking" systems or in other words "tracking the sun". The solar modules are mounted on a motorized structure in at least two axes of rotation. By turning the motors, we can direct the modules to the sun and have optimal illumination.

However, these systems are complex and require a lot of floor space.

The second broad category includes mirror systems. These mirrors are also very often mobile and can reflect the sunlight in a specific place. Finally, there is a third method, using lens systems, most often Fresnel lenses.

US398118 discloses a system using Fresnel lenses for focusing sunlight onto thermal conductors through which a fluid passes. Thus, it is possible to produce water vapor supplying a turbine coupled to an electric generator. Sun tracking is done by rotating the lenses according to the position of the sun.

The patent DE02004001248 describes a system composed of several Fresnel lenses mounted with different positions and angles around a focal point common to all the lenses. Depending on the position of the sun a different lens focuses the light. This system does not need active tracking of the sun.

The patents HK6897 and US4848319 are similar to the previous patent.

All these patents use flat Fresnel lenses. A system using non-planar lenses is disclosed in GB1598335. The lens is a linear Fresnel lens, curved to form a half-cylinder. The focal length is a line in the axis of the cylinder and it is located on a pipe in which a fluid circulates. This system is fixed and does not follow the sun. Due to the shape of the lens, the sunlight remains fairly focused in the same place as a function of time. Such a system is also described in R. Leutz et al, Nonimaging lens concentrators for photovoltaic applications, Proceedings of ISES Solar World (1999).

US 2005/0133082 discloses a system that allows the transformation of solar energy into electrical energy and thermal energy. US 2005/0133082 focuses

especially on the photovoltaic aspect, the exploitation of heat energy is a secondary aspect. The photovoltaic cell is disposed above a copper foil, ie the photovoltaic cell and the copper foil are not arranged in the same horizontal plane. Their module can operate and extract electrical energy even in the absence of the fluidic part. Solar cells are absolutely necessary for

FIRE I LLE OF REM PLACEM ENT (RULE 26) extract heat. US 2005/0133082 discloses a system that can use Fresnel lenses to focus sunlight on solar cells. In US 2005/0133082, the Fresnel lens is optional and a detailed analysis, taking into account the physics of the semiconductors, shows that, in fact, the Fresnel lens is detrimental to the performance of the US 2005/0133082 system.

In US 2005/0133082, Fresnel lenses do not focus light on the surface of solar cells, and therefore the focal point is below this surface. This is clear from paragraph [0050] of US 2005/0133082. As a result, on the surface of the solar cells, a circle of intense light appears. The situation of US 2005/0133082 is illustrated below.

o n oca

The purpose of US 2005/0133082 is to illuminate solar cells with more intense light. It is well known that this increases the electric current supplied by the solar cells and at the same time increases their energy efficiency. But this implementation also has two problems. The first is that the cells heat up more and have to be cooled heavily. The second problem is more important. In the system described in US 2005/0133082, only a portion of the cells are illuminated more strongly, while another part is less illuminated and these cells therefore have lower yields. It is very likely that a system like D1 works better without a Fresnel lens.

WO 2008/020462 discloses a system for transforming solar energy into thermal energy. In a first version, this system does not use a Fresnel lens. The system consists of a metallic opaque box the size of a tile for a roof. Pipes pass through the box and in these pipes circulates a fluid that will be heated. The solar energy heats the box and the heat will be transferred into the fluid inside the pipes. In a second version, an opening is made in the box and

FIRE I LLE OF REM PLACEM ENT (RULE 26) this hole is covered by a Fresnel lens. Its role is to concentrate the sunlight somewhere in the box. The light is then absorbed by the walls, causing additional heating and this heat is then transferred back into the fluid. In a third version, solar cells are placed under a window in the box and allow the transformation of solar energy into electrical energy. Solar cells are not placed under the Fresnel lens (see Figure 7 (26)) or in the same horizontal plane as the metal plate (2). In addition Fresnel lenses are not used to focus the light in a specific place, but only to bring as much light as possible inside the box.

DE 202007000300 discloses solar cells which are cooled by a fluid system passing under these solar cells. Fresnel lenses are used to focus the light on solar cells to increase their efficiency. The photovoltaic cells (20) are disposed above the copper or aluminum plate (32) (see FIG. 1 of DE 202007000300) and are therefore not coplanar.

All of the above describes the state of the art. The present invention aims to go beyond the state of the art.

FIRE I LLE OF REM PLACEM ENT (RULE 26) The closest state of the art is US 2005/0133082 because it has the most technical features in common with the present invention and allows the transformation of solar energy into electrical energy and thermal energy.

The difference between the device of the present invention and that of document US 2005/0133082 is that at least one photovoltaic cell (2.5) is coplanar with at least one heating element (2.1) and that said at least one photovoltaic cell (2.5) is cooled by a cold fluid (5) circulating respectively in the conduits (2.6), (2.7), (2.12), said fluid (5) having been preheated by said at least one photovoltaic cell (2.5) before passing into the duct (2.2) and into channels (4.3) located directly under said at least one heating element (2.1) to be heated.

This represents a combination of characteristics revealing a functional interaction between the photovoltaic cell and the heating element and therefore a synergy between the photovoltaic cell and the heating element.

The technical effect of this difference is that the temperature of the fluid (5) goes from 18 ° C (when it enters the duct (2.6) of Figure 2) to 22 ° C (when it arrives at the entrance of the duct (2.2) of FIG. 2) before passing into the channels (4.3) located under the heating element (2.1) and this fluid (5) comes out at a temperature of between 30 ° C. and 45 ° C. (in winters ) and at a temperature between 45 ° C and 65 ° C (in summer) through the conduit (2.3) after passing under the heating element (2.1). The problem to be solved by the present invention is therefore to provide a device for preheating the fluid (5) before passing under the heating element (2.1) in order to increase the temperature of the fluid (5) at the outlet of the conduit ( 2.3).

The solution is not obvious in view of US 2005/0133082 alone because US 2005/0133082 discloses a device where a photovoltaic cell (41) is disposed above a copper foil (47) and the focal point is not not found on the horizontal plane where the photovoltaic cell (41) (according to paragraph 50, last sentence) is located but much lower to avoid the formation of hot spots. No indication is given that the focal point could be on the copper foil (47).

In US 2005/0133082 the photovoltaic cell (41) is maintained at a temperature between 70 ° F and 100 ° F, ie between 21 ° C and 37 ° C (according to claim 1 of US 2005/0133082). This does not encourage the person skilled in the art to place the heating element

FIRE I LLE OF REM PLACEM ENT (RULE 26) on the same plane as the photovoltaic cell (41), nor to focus the sun's rays on the heating element located in the same horizontal plane as the photovoltaic cell as in the present invention in order to be able to heat a fluid (5) and obtain a temperature between 35 ° C and 45 ° C after preheating the fluid (5) and also after passing under a heating element (2.1). The problem to be solved in US 2005/0133082 is diametrically opposed to the problem of the present invention because in US 2005/0133082 the objective is not to heat the photovoltaic cell (41) and the solution is thus to focus the light on a level lower than the one where the photovoltaic cell (41) is located, whereas in the present invention the objective is to heat the heating element (2.1) by focusing the light on this heating element (2.1) which is located in the same plane horizontal than the photovoltaic cell (s). The cooling of the photovoltaic cell (s) (2.5) of the present invention is effected by passing a fluid (5) (the temperature of the fluid is the ambient temperature, which varies with the seasons) under the Photovoltaic cell (s) (2.1) (see Figure 2).

The solution is not obvious in view of US 2005/0133082 combined with WO 2008/020462 because WO 2008/020462 does not indicate that at least one photovoltaic cell (2.5) is coplanar with at least one heating element ( 2.1) and that at least one photovoltaic cell (2.5) is cooled by a fluid (5) which will be preheated after passing under at least one photovoltaic cell, which will then pass into channels (4.3) directly below said a heating element (2.1) to be heated. In addition, there is no indication that the light is focused on the hot plate.

Indeed, FIG. 7 (26) of document WO 2008/020462 clearly shows that the photovoltaic cell (26) is located above the heating plate (2) of concave shape (cf claim 7 and page 7, lines 23-26 of WO 2008/020462). In addition, Figure 1 of WO 2008/020462 shows that the light entering through the top of the tile is diffracted (proof is that the author has represented the sun's rays by 4 arrows (3) divergent, see Figure 1 and Figure 7), while in the present invention the object is to focus the light on the heating element (2.1) (see Figures 7A-7B and 10A-11D of the present invention).

The solution is not obvious either in view of the document US 2005/0133082 combined with DE 202007000300 because the characterizing part of the independent claims is not disclosed and the person skilled in the art would have no incentive to reproduce the characterizing part of the independent claims of the present invention. Indeed, the photovoltaic cells (20) are disposed above the copper or aluminum plate (32) (see Figure 1 of DE 202007000300) and are not coplanar.

FIRE I LLE OF REM PLACEM ENT (RULE 26) The present invention relates to a solar energy receiving device according to claim 1 comprising an upper stage (1) for receiving solar energy comprising at least one Fresnel convergent optical lens (1.3), said upper stage (1). ) being located above an intermediate stage (2), said intermediate stage (2) comprising at least one heating element (2.1) under which channels wind in which a fluid (5) heated by solar energy flows , and at least one photovoltaic cell (2.5), said intermediate stage (2) being connected to a lower stage (3) by at least one fluid transport pipe (2.10) connected to said at least one heating element (2.1), and at least one electric cable (2.8) connected to said at least one photovoltaic cell (2.5), said intermediate stage (2) being disposed above the lower stage (3), said stage lower (3) comprising said at least one tu a fluid transport means (2.10) connected to said at least one heating element (2.1), said at least one electrical cable (2.8) connected to said at least one photovoltaic cell (2.5), at least one insulator thermal device (2.4) surrounding said at least one heating element (2.1) and at least one cooling pipe (2.6) connected to said at least one photovoltaic cell (2.5) said device being characterized in that the solar energy is focused on said at least one heating element (2.1) and said at least one photovoltaic cell (2.5) is coplanar with said at least one heating element (2.1) and said at least one photovoltaic cell (2.5) is cooled by a fluid (5) circulating ns under said at least one photovoltaic cell (2.5), said fluid (5) having been preheated by said at least one photovoltaic cell (2.5) before passing into a pipe (2.2) and in channels (4.3) located directly beneath said at least one heating element (2.1) to be heated.

The present invention also relates to a method for producing electricity and heating a fluid (5) according to claim 2 from the device of claim 1, said method comprising the following steps:

-sorption of solar energy at an upper stage (1) by means of a convergent Fresnel optical lens (1.3),

-transformation of the solar energy diffracted into electrical energy by at least one photovoltaic cell (2.5) and transformation into heat of the solar energy focused by at least one heating element (2.1) at said intermediate stage (2), said intermediate stage (2) being connected to a lower stage (3) by at least one fluid transport pipe (2.10) connected to said at least one heating element (2.1) and by at least one electric cable ( 2.8) connected to at least one photovoltaic cell (2.5),

the electrical energy and thermal energy being transferred to said lower stage comprising said at least one electrical cable (2.8), said at least one fluid transport pipe (2.10), at least one thermal insulation (2.4) and, at least one pipe of

FIRE I LLE OF REM PLACEM ENT (RULE 26) cooling (2.6) of said at least one photovoltaic cell, said method being characterized by a step of preheating the fluid (5) by passing said fluid (5) under said at least one photovoltaic cell (2.5) before passing through channels (4.3) located directly under said at least one heating element (2.1) for preheating said fluid (5) and a step of heating a fluid (5) at an intermediate stage (2) by focusing the solar energy on at least one heating element (2.1) and activation of at least one photovoltaic cell (2.5) by diffraction of solar energy at said intermediate stage (2), said at least one photovoltaic cell ( 2.5) being coplanar with said at least one heating element (2.1).

In a preferred embodiment the device of the present invention comprises at least one heating element (2.1) where directly below the surface of which serpentines channels in which circulates a fluid (5) which is heated by solar energy focused on said at least one heating element (2.1).

FIRE I LLE OF REM PLACEM ENT (RULE 26) The present invention relates to a solar energy receiving device comprising three stages. The upper stage (1) is used to collect solar energy by means of an optical system comprising at least one Fresnel convergent optical lens (1.3) which concentrates the sunlight on the intermediate stage (2). An upper side wall (1.2) separates the upper stage (1) from the intermediate stage (2) by a distance equal to the focal length of the optical system (between 1 cm and 20 cm, preferably between 5 cm and 10 cm). cm, more preferably between 6 cm and 8 cm). The intermediate stage (2) transforms solar energy into useful and exploitable energy. It comprises at least a heating element (2.1) under which channels wind in which circulates a fluid (5) heated by solar energy focused by the upper stage (1). The heating element converts solar energy into heat energy (unit: Joules). The intermediate stage also comprises at least one photovoltaic cell (2.5) which will transform the solar energy into electrical energy (unit: Joules). The third floor (3), said lower floor, is used to harvest the energy from the intermediate stage (2) and make it accessible to the user. The intermediate stage (2) is connected to the lower stage (3) by at least one fluid transport pipe (5) connected to said at least one heating element (2.1), and by at least one electric cable (2.8) connected to at least one photovoltaic cell (2.5). The intermediate stage (2) is arranged on the lower stage (3), a wall (1.1) separating these two stages. Said lower stage comprises at least one fluidic connector (2.2; 2.3) inserted in said lower sidewall (1.1), at least one fluid transporting pipe (2.10; 2.11) connected to said at least one heating element ( 2.1), at least one electrical cable (2.8, 2.9) connected to said at least one photovoltaic cell (2.5), at least one thermal insulator (2.4) surrounding said at least one heating element (2.1) and at least one cooling pipe (2.6; 2.7) connected to said at least one photovoltaic cell (2.5).

The present invention further relates to a use of the solar energy receiving device described above for producing electricity and heating a fluid (5) simultaneously.

The device of the present invention comprises an upper side wall (1.2) and a lower side wall (1.1) having a height of between 1 cm and 20 cm, preferably between 5 cm and 10 cm, more preferably between 6 cm and 8 cm. .

The device of the present invention comprises at least one heating element which is a metal plate, preferably copper, aluminum, brass or iron, rectangular, square, oval, round, triangular or parallelogram-shaped.

The device of the present invention comprises at least one heating element (2.1) placed at the center of the intermediate stage (2).

FIRE I LLE OF REM PLACEM ENT (RULE 26) The device of the present invention comprises a surface around said at least one heating element covered with a plurality of photovoltaic cells.

The device of the present invention is fully waterproof and airtight.

In the device of the present invention the vacuum can be realized.

The device of the present invention comprises at least one convergent Fresnel optical lens (1.3) having a spherical dome shape (concave shape) or a planar shape.

The device of the present invention comprises at least one heating element surmounted by a transparent micro-greenhouse for storing heat.

The device of the present invention comprises a partial vacuum under the micro-greenhouse.

The device of the present invention comprises at least one cold-cooled photovoltaic cell, which will then pass into channels located directly beneath said at least one heating element to be heated. The essential points and advantages of the present invention are:

- A water heating system by a superimposed Fresnel lens assembly (s) that does not require active tracking of the sun.

- a hybrid system allowing the generation of electricity and hot water simultaneously.

- a system with different methods to increase energy efficiency (unit =%).

The problem solved by the present invention is to provide a passive and static sun tracking device, thanks to at least one Fresnel convergent optical lens, not requiring heavy mechanics in order to have optimal exploitation of sunlight.

The problem solved by the present invention is also to simultaneously supply electricity and hot water.

The term "solar cells" is a synonym for the term "photovoltaic cells" in the present invention described hereinafter.

The term "system" is a synonym for the term "device" in the present invention described hereinafter.

FIRE I LLE OF REM PLACEM ENT (RULE 26) Description of the Figures of the Present Invention

Figure 1 shows an exploded isometric section of a solar module subject of the present invention.

Figure 2 shows a bottom view of the open module (lower stage and intermediate stage). The temperature of the fluid (5) goes from 18 ° C (when it enters the conduit (2.6)) to 22 ° C (when it arrives at the entrance of the conduit (2.2) of Figure 2) before passing in the channels (4.3) located under the heating element (2.1) and this fluid (5) exits at a temperature between 30 ° C and 45 ° C (in winters) and at a temperature between 45 ° C and 65 ° C (in summer) through the duct (2.3) after passing under the heating element (2.1).

Figure 3 shows the assembly of several modules (three in this case) for the production of electricity and water heating. Figure 3 also shows the flow of cold water before entering the first module and then the circulation of hot water leaving the first module to enter the second module and pass into the third module. Figure 4 shows an exploded isometric view of the heating element of the solar module. Figure 5 shows the effect of temperature on the characteristics of a solar cell. There is interest in using cold solar cells.

Figure 6 shows an exploded isometric view of the solar cell cooling system.

Figure 7A shows the behavior of the focal point of an optical system as a function of the angle of incidence of the light focused on the device.

Figure 7B shows the focal point behavior of optical systems composed of one or more Fresnel lenses as a function of the angle of incidence of the light focused on the device.

Figure 8 shows the transmitted light power as a function of the number of Fresnel lenses.

Figure 9A defines the angles used for the measurements of Figures 10 and 11.

Figure 9B defines the altitude and azimuthal position of the sun.

FIGS. 10A, 10B and 10C show the displacement of the focal point of the optical system, composed of small Fresnel lenses, as a function of the number of lenses and the angles of incidence.

FIG. 11A shows the displacement of the focal point of the optical system composed of a Fresnel lens as a function of the angles of incidence.

FIG. 11B shows the displacement of the focal point of the optical system composed of two large Fresnel lenses as a function of the angles of incidence.

FIG. 11C shows the displacement of the focal point of the optical system, composed of three large Fresnel lenses as a function of the angles of incidence.

FIRE I LLE OF REM PLACEM ENT (RULE 26) FIG. 11D shows the displacement of the focal point of the optical system, composed of four large Fresnel lenses as a function of the angles of incidence.

Figure 12A shows the characteristics of a solar cell without Fresnel lens optics.

Figure 12B shows the characteristics of a solar cell with an optical system of Fresnel lenses.

Figure 13A illustrates a heating experiment performed with several modules.

Figure 13B shows the results obtained for the temperature of the water leaving the system, the outside air temperature and the temperature of a water tank serving as a reference. Figure 14 shows an isometric view of a solar module having a curved (concave) Fresnel optical lens ie domed lens.

Figure 15 gives the results of numerical simulations for different configurations of the heating system.

Figure 16 shows the displacement of the focal point in the case of a curved lens (concave) as a function of the angles of incidence.

Figure 17 shows the percentages of energy loss in a standard thermal module.

Figure 18 shows the yields of a standard module as a function of the fluid velocity.

Figure 19 shows the geometry of the hybrid module of the present invention for numerical simulations.

Figure 20 shows the simulation result "Simul_03" at time t = 0s and for a fluid velocity of 10 mm / s.

Figure 21 shows the simulation result "Simul_03" at time t = 600s and for a fluid velocity of 10 mm / s.

Figure 22 shows the simulation result "Simul_03" at time t = 1200s and for a fluid velocity of 10 mm / s.

Figure 23 shows the result of simulation "Simul_03" at time t = 2400s and for a fluid velocity of 10 mm / s.

Figure 24 shows the simulation result "Simul_03" at time t = 3600s and for a fluid velocity of 10 mm / s.

Figure 25 shows the yield (%) as a function of the fluid velocity.

The present invention describes a hybrid solar module for producing electricity and a hot fluid (5) (or a hot liquid such as water or glycerol or glycol for example) simultaneously.

FIRE I LLE OF REM PLACEM ENT (RULE 26) This increases the energy efficiency of the solar module (energy efficiency is calculated in percentage). Energy efficiency = efficiency (%) of solar cells + efficiency (%) of the heating plate. The sunlight is concentrated on a small surface (between 100 cm ² and 1000 cm ² , preferably between 150 cm ² and 600 cm ² , more preferably between 160 cm ² and 200 cm ² ) via an optical system composed of convergent Fresnel lenses.

Such a system has the advantage of allowing to follow the course of the sun, while leaving the fixed module.

The number of solar cells disposed on the intermediate stage of the device can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more.

The number of heating plate (s) (or heating element (s)) arranged on the intermediate stage of the device can be 1, 2, 3, 4, 5, 6, 7, 8 , 9, 10 or more.

The present invention describes a new hybrid solar module for generating electricity and hot water whose general structure is shown in Figure 1.

The two functions, thermal and photovoltaic work in synergy or independently. For example, the photovoltaic system can supplement the thermal system in case the surfaces to be heated are large or in countries with low sunshine or during low sunlight seasons, by sending some of the electrical energy to one or more of the heaters. electric water (s) to supplement the production of hot water or heating the water of a swimming pool.

Examples:

The module (device) of the present invention is composed of an opaque base or side wall (pos.1.1) (pos = position) and a superstructure with transparent sidewalls (item 1.2) and a system optical, made of an assembly of one or more Fresnel lenses (item 1.3). The optical system will focus the sunlight on a heating element (item 2.1) under which a fluid (5) (at room temperature) will be heated. If the optical system will focus much of the light, some will be diffracted and will not be used for heating. For this reason solar cells (item 2.5) are mounted around the heating element. The transparent walls of the superstructure (item 1.2) also allow the light that will be used by the solar cells (item 2.5) to be used to produce electricity. The module has six fluidic connections. In Figure 1, three of these connections are shown, the other three are on the opposite side, hidden in the figure. The middle connectors (pos.

FIRE I LLE OF REM PLACEM ENT (RULE 26) 1.7) are used to connect the fluidic system of the heating element. Under the solar cells are also fluidic elements, through which cold water circulates. These elements are connected to the external environment by the fluidic connectors (pos 1.6). The electricity produced by the solar cells is harvested by at least one electrical wire (pos.2.8) collected in a cable (item 2.9).

Figure 2 shows the inside of the base (item 1.1 in Figure 1) of a module (open module, view from below). In the middle is the heating element of the module. Cold water enters the pipe (item 2.2) and exits the heating element through the pipe (item 2.3). These are connected to fluidic connectors (pos 1.7 in Figure 1). In order to limit thermal losses, the hot part of the module, ie (pos 2.1, item 2.2 and item 2.3), is surrounded by a thermal insulation (item 2.4). The solar cells are mounted in the four corners of the base. They are assembled with cooling elements (6.1 in Figure 6). These elements are cooled by cold water flowing through them (see Figure 6). This water enters the module through the connector (item 2.6) and exits through the connector (item 2.12). The cooling elements (6.1) are interconnected in pairs by a pipe (item 2.7). The solar cells are connected to the external environment by means of electrical wires (item 2.8) joined in an electric cable (item 2.9). The heating element is described in detail in FIG. 4 and the cooling elements of the solar cells are shown in FIG.

Different modules of the present invention can be connected together to increase the power of the system. This connection is schematically illustrated in Figure 3, which shows the assembly of three solar modules (item 3.1). Cold water enters the system (item 3.2). It passes under the solar cells of the different modules by following the fluidic circuit going from pos. 3.2 to pos. 3.3. At this moment the water enters the hot part of the system (part of the fluidic system going from pos 3.3 to position 3.4). In order to limit thermal losses, the hot part is thermally insulated (item 3.5). The electrical cables (item 2.9) connecting the solar cells of the different modules enter a housing (item 3.7), in which the electrical signals are shaped to allow a user (item 3.8) to use the electricity for his needs.

Figure 4 illustrates the heating structure. It consists of a support (4.1) with an inlet and an outlet (4.2) for the fluid (5) and the fluid circulation channels (4.3). In order to limit the thermal losses the support is made of a polymer which is a bad thermal conductor.

FIRE I LLE OF REM PLACEM ENT (RULE 26) To increase the thermal capacity of the structure, part of these channels is made of metal (item 4.4). The channels are covered with a copper plate (item 2.1). This plate is a heat absorber that is heated by the sunlight focused by the Fresnel optical system (item 1.3). In order to limit thermal losses, the copper plate can be surmounted by a micro greenhouse, consisting of walls (item 4.6) and a cover (4.7). The walls and lid are transparent and made of polycarbonate, which is a low thermal conductor. The air in the space (item 4.8) delimited by the copper plate, the walls and the lid, will heat up, this heat will not be diffused outwards, but will be used to heat the liquid in the channels.

It is well known to those skilled in the art that solar cells work better and have better energy efficiency at low temperatures.

This is illustrated in Figure 5, which shows the electrical characteristics of cells at different temperatures (25 ° C, 50 ° C and 75 ° C) and illuminated with 1000 W / m ^{2 light} . The cell in question is a small module composed of different silicon solar cells. This kind of module is used in the prototype of the solar module of the present invention. The horizontal axis of the graph of FIG. 5 represents the electric potential or the voltage applied across the cell. The left vertical axis represents the current passing through the cell. The right vertical axis shows the electrical power provided by the cell.

The power is calculated by multiplying the applied voltage with the corresponding electric current. For low voltages, the current and power are the same for all temperatures. But for high voltages, the current supplied by the cell decreases at high temperatures. It follows that the power also decreases. By increasing the temperature by 50 ° C (from 25 ° C to 75 ° C), the power available from the cell drops by almost 30%. This clearly shows that it is necessary to cool a solar cell. In the context of this invention, the cooling of the solar cells is done through the structure shown in FIG.

In a support (item 6.1), the inputs and outputs are machined (item 6.2) for the fluid (5), as well as the circulation channels (item 6.3) of the liquid. The channel system is closed by a copper plate (item 6.4). On this assembly is fixed the solar cell (pos.2.5). The different cooling structures of a solar module can be connected together. The cold water entering the solar module or in an assembly of several modules passes first into the cooling structures of the cells and is then heated by the heating structures (2.1) as explained in Figure 3.

FIRE I LLE OF REM PLACEM ENT (RULE 26) One of the great innovations of the present invention is to use an optical system of one or more plane or dome-shaped (concave) Fresnel lenses for focusing the sunlight on the heating structure, preferably made of copper, solar module. Figure 7A shows the displacements of the focal point of a lens as a function of the angle of incidence of the light on the lens. If the light hits the lens perpendicularly, the focal point (point fp) is exactly below the middle of the lens on the optical axis of the system. But if the light hits the lens at an angle to the normal of the surface of the lens, the focal point moves (point fpa) and moves away from the optical axis of the system. Depending on the number of lenses used, the distance between fp and fpa can be very large and it can happen that fpa is no longer under the lens. The evolution of the distance between fp and fpa as a function of the number of lenses is schematically illustrated in FIG. 7B. These are three optical systems respectively comprising one, two and three Fresnel lenses. There are two important points to note. First, the distance between the points fp and fpa decreases as a function of the number of lenses. Secondly, the focal distance (distance between the lens and the focal point of the system) also decreases. By using several lenses, we can better focus the light and regardless of the angle of incidence the focal point is always close to the optical axis of the system.

However, it is important to note that increasing the number of lenses used decreases the transmitted power. This is shown in Figure 8 for lenses made of Plexiglas. The transmission rate of such a lens is 92%. For a system composed of four lenses, the transmitted power is only 72%. It is therefore a question of finding an optimum between the position and the evolution of the focal point as a function of the angle of incidence of the light and the power transmitted by the optical system.

Figures 10A, 10B, 10C and 11A, 11B, 11C, 11D show actual measurements with two kinds of optical systems. In both cases, the lenses are lenses made of PMMA (Poly-Methyl-Methyl-Acrilate), better known as Plexiglas.

In the case of Figures 10A, 10B and 10C the dimensions of a lens are 160mmx100mmx2mm and the focal length of such a lens is 120 mm. For 2 lenses, the focal length is 80 mm and for three lenses it is 24 mm.

For the optical system of FIGS. 11A, 11B, 11C and 11D the dimensions of a lens are 395mmx395mmx2mm. The focal length of a lens is 200 mm, for two lenses it is 150 mm, for three lenses it is 60 mm and for 4 lenses it is 30 mm.

FIRE I LLE OF REM PLACEM ENT (RULE 26) In FIGS. 10A, 10B, 10C and 11A, 11B, 11C, 11D the position of the focal point is given as a function of the angle of inclination of the optical system with respect to the horizontal and as a function of time. Each time corresponds to a position or an altitude angle of the sun. The different angles used for the measurements of FIGS. 10A to 10C and 11A to 11D are defined in FIGS. 9A and 9B for the sake of clarity.

FIG. 10A shows the displacement of the focal point for an optical system composed of a lens of dimension of 160 mm × 100 mm.

The gray area represents the lens. For a large number of angles of incidence, the focal point is not located under the lens. For an optical system of two such lenses of the same size, all the focal points are located under the optical system (Figure 10B). The same is true for a three-lens system (Figure 10C). In the latter case, the focal points are all on an area of 60mmx40mm, centered around the optical axis of the system.

Figures 11A, 11B, 11C, and 11D show similar measurements for optical systems made of lenses with an area of 395mmx395mm. Again, for a lens (Figure 11A) the focal points are widely scattered under the lens. By increasing the number of lenses (Figure 11 B: 2 lenses, Figure 11C: three lenses and Figure 11 D: four lenses), this dispersion decreases and for a system of four lenses, all the focal points are on a surface of 70mmx60mm . This represents an area of 2.7% of the total area of the lens.

All of these measures demonstrate the merits of the present invention. It is therefore possible, by using Fresnel lenses to focus the sunlight on a small area and this independently of the sun position and orientation of the module. So we have a passive and static sun tracking system, not requiring heavy mechanics in order to have optimal exploitation of sunlight.

As the incident light is always focused on a small area around the optical axis, there is still a lot of space available under the lens. Thus for a three-lens system of 395mmx395mm, and which is the preferred configuration of the present invention, only 7% under the optical system is required for the heating portion of the solar module. A large part of the remaining 93% is used in the context of this invention for mounting solar cells. This is also justified by the fact that the optical system does not perfectly focus the incident light. Due to the geometric structure of a Fresnel lens, some of the light rays are diffracted. In the case of the present invention, the diffracted sunbeams illuminate the solar cells (photovoltaic cells) and allow the generation of electricity.

This is shown in FIGS. 12A and 12B, where practical measurements are shown on cells mounted in the solar module. Figure 12A shows the characteristics

FIRE I LLE OF REM PLACEM ENT (RULE 26) of a cell when the Fresnel lenses are removed, while Figure 12B shows these same characteristics in the presence of an optical system consisting of three Fresnel lenses. The incident power of light for both cases is 1000 W / m ² . Solar cells are small modules composed of individual silicon cells. The total size of the solar cells per module is 105mmx80mm.

In the case of measurements without lenses, the power supplied by the solar cells is 0.8 W. With a three-lens optical system, this efficiency drops by 19% to 0.65W. This remains acceptable, especially considering that the solar cells are effectively cooled in the solar modules of the present invention. It must be remembered that the cooling of existing photovoltaic modules on the market is very bad, which has a strong influence on the power achieved by these modules.

Figs. 13A and 13B provide practical results for water heating using the module of the present invention. The modules are made with lenses of small dimensions (160mmx100mm). The modules do not include solar cells, because the purpose of the experiment is to test the merits of the use of Fresnel lenses for water heating. Three modules are connected in series. Through a pump, the water is drawn from an isolated tank of a volume of 5 liters and containing 4 liters of water, and is pumped through the three solar modules. The pumping speed is 0.2 liters per minute. At the exit of the modules, the water is returned to the insulated tank.

The temperature will therefore increase in said isolated tank and at regular time intervals will be recorded. A second tank, placed under the same conditions, contains water that will not be heated. This second tank serves as a reference and its temperature is measured at the same times as that of the first tank. A third measured temperature is the ambient temperature.

Figure 13B shows the results of measurements made between 10 am and 5 pm. While the ambient temperature and that of the reference tank vary only between 17 and 25 ° C, the temperature of the water heated by the solar module system increases strongly against to reach more than 50 ° C. This experiment demonstrates the merits of the heating system of the present invention.

There are ways to increase the temperature of the water. We will present two methods that form part of the present invention.

The results of the first are based on numerical simulations by finite element calculations. These results are shown in Figure 15.

FIRE I LLE OF REM PLACEM ENT (RULE 26) In a first simulation, the heating element is heated by non-focused light rays. The incident power is 1000 W / m ² . The temperature of the system and more particularly the temperature of the liquid is 35 ° C.

In a second simulation, the light with the same power of 1000 W / m ² , is concentrated by lenses. The focal point has a diameter of 0.5 cm. The temperature of the water rises to 58 ° C. In this simulation, there is no micro-greenhouse (pos 4.8), consisting of pos pieces. 4.7 and pos 4.6. There is heat loss in the total system.

In a third simulation, the micro-greenhouse is included. She is filled with air. The other conditions are identical to that of simulation 2. In this case, the water temperature is 69 ° C.

In a fourth simulation, the air in the micro-greenhouse is replaced by a low partial vacuum of 700 mmHg or 93.3 hPa. In this case, the water temperature rises to 78 ° C.

There is therefore an interest in having on the heating element a micro greenhouse in which there is a partial vacuum in order to have maximum heat extraction.

The second improvement to be considered in the present invention relates to the optical system. In the modules presented so far, the lenses used are flat Fresnel lenses. In order to have a concentrated focus on a small area for all solar positions relating to the solar module, it is necessary to use multiple lenses superimposed. However, as previously explained, the absorption losses of light in such an optical system can be quite large. It is then a question of finding a system, which focuses the light well and which uses the least possible lenses. This can be done by employing an optical system consisting of a single domed (concave) Fresnel lens ie dome-shaped (item 14.1).

A module with such a lens is shown in FIG.

This module is similar to that of Figure 1, with the exception of the optical system. In Figure 1, this system consists of flat lenses (item 1.3), while in Figure 14 the system is made of a domed Fresnel lens, ie domed.

FIG. 16 shows the effect of the bending of the Fresnel lens on the displacement of the focal point as a function of the relative position of the sun with respect to the module. The results of Figure 16 compare with those of Figure 10A. In both cases, a 160mmx100mm size lens is used. The radius of curvature of the curved lens is 10 cm. It is not in the form of a dome, but only in the form of a cylinder. Nevertheless, it is very apparent that with such a lens, the displacement of the focal point is much smaller than with a flat lens.

A lens in the form of a dome will allow to focus the light while decreasing the absorption losses in the optical system.

SUBSTITUTE SHEET (RULE 26) Certain features of the invention which are described as separate embodiments may also be provided in combination in a single embodiment. In contrast, certain features of the invention which are described as an embodiment in combination in a single embodiment may also be provided separately in the form of several separate embodiments.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations may be detected by a person skilled in the art. Thus, we intend to encompass such alternatives, modifications and variations that fall within the scope of the claims.

FIRE I LLE OF REM PLACEM ENT (RULE 26) Comparative tests: yield calculations of hybrid solar modules

The purpose of these tests is to present calculations and simulation results concerning the performance of the hybrid modules of the present invention. These calculations were performed by the finite element method (internationally recognized standard and which is well known to those skilled in the art). The program used for these tests is called the ComsoW.Oa program.

Only simulations in two dimensions (2D) have been considered.

Different cases were simulated. They are summarized in Table 1 below:

Table 1:

FIRE I LLE OF REM PLACEM ENT (RULE 26) The Simul_01 simulation is a comparison and calibration simulation of the ComsoW.Oa program.

Figure 17 shows the losses in a standard thermal module. Typically only 45% of incident solar energy is converted into usable heat. The yield is therefore 45%. The purpose of simulation Simul_01 is to calibrate the program and the calculation method before obtaining yields of the same order of magnitude for a standard module. The size of the module chosen is a square of 0.4 m (40 cm) side. These dimensions have been chosen because they are identical to the dimensions of the prototype of the hybrid module of the present invention.

Energy efficiency is defined as the ratio between the energy (or power) coming out of a system and the energy (or power) entering the same system. The yield is expressed as a percentage (%).

The yield of a photo-thermal module is given by the following formula:

where ^C P is the thermal capacity of the fluid passing through the module (in J / (kg K)), m is the mass of the heated fluid (in kg), ΔΤ is the temperature difference between the initial moment and the final moment ( in Kelvin), A is the surface of the module (in m ²⁾ and J ^p dt _e st solar energy received by the thermal module (in Joule) between the initial and final time point, where P is the incident solar power ( W / m ² ).

For the calculations presented here, the power varies linearly from 50 W / m ² to 500 W / m ² in 60 minutes (3600 seconds):

P = & i25 f + 5Q

with f being the time.

The formula for calculating the solar energy entering the upper stage of the module is then:

FIRE I LLE OF REM PLACEM ENT (RULE 26)

The mass is related to the speed of the fluid passing through the module. Let r be the inside radius of the tube through which the fluid flows. The mass of the fluid passing through this tube is given by: where ^v in is the velocity of the fluid through the tube (in m / s). The radius r considered here is 1.5 mm.

The formula for calculating energy efficiency is then:

with being the final time: 3600 s.

According to the last equation, the efficiency depends only on the speed of the fluid through the module.

The speeds considered in this work, as well as the corresponding masses, are summarized in Table 2 below:

FIRE I LLE OF REM PLACEM ENT (RULE 26) Table 2:

Figure 18 shows the performance of a standard module (Simul_01) as a function of the speed of a fluid. It is observed that the yield is not constant, but varies according to the speed. Maximum efficiency is achieved for speeds of the order of 20 mm / s. The efficiency achieved is 47%, which is comparable to what is achieved in standard thermal modules. The calibration of two-dimensional (2D) simulations is satisfactory and the methodology used is applied for two-dimensional (2D) simulations of hybrid modules. Note that the ComsoW.Oa program is only used for simulations Simul_02 to Simul_04. Simulations (Simul_05 to Simul_07) involve only solar cells and do not require finite element simulations, but yields can be calculated by considering the physics of solar photovoltaic cells.

The results of Simul_08 Simul_010 simulations are simply obtained by adding the corresponding results obtained previous (Simul_08 = Simul_02 + Simul_05; Simul_09 = Simul_03 + Simul_06; SimuMO = Simul_04 + Simul_07). Figure 19 shows the structure of the two-dimensional (2D) geometric model of the hybrid module for numerical simulations. The length of the tube and the absorbing surface (part 2) is 150mm. The light is concentrated on a surface (10) of 20 mm in length. Water (1) enters the system through a connector (8) and exits through a connector (9). The fluidic part consists of the inlet (7), the tube (2) and the outlet (7 '). The material

FIRE I LLE OF REM PLACEM ENT (RULE 26) constituting the tube (2) is copper, while the inlet and the outlet (7 and 7 ') are made of polyethylene. The lower part of the tube (2) is thermally insulated with Styropore (6). For simulation Simul_02, parts (3), (3 '), (4) and (5) are air. For simulations Simul_03 and Simul_04, parts (3), (3 ') and (5) are in plexiglass. Part (4) is air. For simulation Simul_03, the air is at a pressure of 1 atmosphere, while for simulation Simul_04, the pressure is 0.01 atmosphere, corresponding to a partial vacuum.

Figures 20 to 24 show simulation results "Simul_03" at different times and for a fluid velocity of 10 mm / s. The variation of the temperature distribution and the increase of the temperature as a function of time are well observed.

Figure 20: Simul_03; v _in : 10mm / s; t: 0s

Figure 21: Simul_03; v _in : 10mm / s; t: 600s

Figure 22: Simul_03; v _in : 10mm / s; t: 1200s

Figure 23: Simul_03; ¼ ": 10mm / s; t: 2400s

Figure 24: Simul_03; v _in : 10mm / s; t: 3600s

Figure 25 shows the results of simulations Simul_02, Simul_03 and Simul_04.

Simul_02 is the simplest structure. She has no greenhouse and no vacuum. Simul_03 has a greenhouse and Simul_04 has a greenhouse with partial vacuum. The lowest yield is reached for Simul_02. But it is interesting and important to note that the performance is much higher than a standard thermal photo module (see Figure 18). This shows the goodness of the idea of concentrating sunlight by Fresnel lenses on a small surface.

The greenhouse increases the yield once again. But the effect of the vacuum is weak. This is because the vacuum is only on one side of the hotplate. For a larger effect it would be necessary that the vacuum is all around the heating plate. This is possible, but would greatly complicate the construction of the module.

As mentioned above, simulations Simul_05, Simul_06 and Simul_07 do not require the finite element method (internationally recognized standard). In addition the performance will be the same for the three simulations because solar cells, which are considered here do not use greenhouse or vacuum.

The efficiency of the solar cells is of the order of 10 to 15%. For this report, an average value of 12.5% is considered. However this yield is valid for cells directly illuminated by the sun. In the modules, part of the solar power for the solar cells is lost by the Fresnel lenses (about 20%), the

FIRE I LLE OF REM PLACEM ENT (RULE 26) Cell yield in a hybrid module is 10%. This is the yield for the cases Simul_05 to Simul_07.

As noted above, the case performance Simul_08 to Simlu_10 are the sums of the previous corresponding cases.

It now becomes possible to summarize the results in the following table 3.

The device used is the one mentioned in FIG. 1, in which the heating plate has been removed as the case may be and / or the 4 solar cells (photovoltaic cells) have been removed as the case may be (with or without a greenhouse and with or without without a vacuum depending on the case) in order to be able to perform comparative tests where the unit of measure is a percentage yield (%).

For cases involving the hot plate, a fluid velocity of 20 mm / s is considered.

Energy efficiency (%) = efficiency (%) of solar cells + efficiency (%) of the heating plate.

FIRE I LLE OF REM PLACEM ENT (RULE 26) Table 3:

SUBSTITUTE SHEET (RULE 26)

Claims

claims:

A solar energy receiving device comprising:

an upper stage (1) for receiving solar energy, comprising:

at least one Fresnel convergent optical lens (1.3),

said upper stage (1) being located above an intermediate stage (2), said intermediate stage (2) comprising:

at least one heating element (2.1) under which channels wind in which a fluid (5) heated by solar energy flows,

and at least one photovoltaic cell (2.5),

said intermediate stage (2) being connected to a lower stage (3) by at least one fluid transport pipe (2.10) connected to said at least one heating element (2.1),

and at least one electrical cable (2.8) connected to said at least one photovoltaic cell (2.5),

said intermediate stage (2) being disposed above the lower stage (3), said lower stage (3) comprising:

said at least one fluid transport pipe (2.10) connected to said at least one heating element (2.1),

said at least one electrical cable (2.8) connected to said at least one photovoltaic cell (2.5),

at least one thermal insulator (2.4) surrounding said at least one heating element (2.1) and

at least one cooling pipe (2.6) connected to said at least one photovoltaic cell (2.5),

said device being characterized in that the solar energy is focused on said at least one heating element (2.1) and said at least one photovoltaic cell (2.5) is coplanar with said at least one heating element (2.1) and in that said at least one photovoltaic cell (2.5) is cooled by a fluid (5) circulating under said at least one photovoltaic cell (2.5), said fluid (5) having been preheated by said at least one photovoltaic cell (2.5) ) before passing into a pipe (2.2) and into channels (4.3) located directly under said at least one heating element (2.1) to be heated.

FIRE I LLE OF REM PLACEM ENT (RULE 26)

A method of generating electricity and heating a fluid (5) from the device of claim 1, said method comprising the steps of:

absorption of solar energy at an upper stage (1) by means of a convergent Fresnel optical lens (1.3),

transforming the diffracted solar energy into electrical energy by at least one photovoltaic cell (2.5) and transforming into heat of the solar energy focused by at least one heating element (2.1) at said intermediate stage (2), said intermediate stage (2) being connected to a lower stage (3) by at least one fluid transport pipe (2.10) connected to said at least one heating element (2.1) and by at least one electric cable ( 2.8) connected to at least one photovoltaic cell (2.5),

the electrical energy and thermal energy being transferred to said lower stage comprising:

said at least one electrical cable (2.8),

said at least one hose carrying a fluid (2.10),

at least one thermal insulation (2.4) and,

at least one cooling pipe (2.6) of said at least one photovoltaic cell,

said method being characterized by a step of preheating the fluid (5) by passing said fluid (5) under said at least one photovoltaic cell (2.5) before passing into a pipe (2.2) and into channels (4.3) situated directly under said at least one heating element (2.1) and,

a step of heating a fluid (5) at an intermediate stage (2) by focussing the solar energy on at least one heating element (2.1) and activating at least one photovoltaic cell (2.5) ) by diffraction of the solar energy at said intermediate stage (2), said at least one photovoltaic cell (2.5) being coplanar with said at least one heating element (2.1).

3. Use of the solar energy receiving device according to claim 1 for simultaneously producing electricity and for heating a fluid (5).

FIRE I LLE OF REM PLACEM ENT (RULE 26)

4. Device according to claim 1, wherein the upper side wall (1.2) and the lower side wall (1.1) have a height of between 1 cm and 20 cm, preferably between 5 cm and 10 cm.

5. Device according to claim 1 and method according to claim 2, wherein said at least one heating element (2.1) is a metal plate of rectangular, square, oval, round, triangular or parallelogram-shaped shape.

6. Device according to claim 1 and method according to claim 2, wherein said at least one heating element (2.1) is placed in the center of the intermediate stage.

7. Device according to claim 6, wherein the surface around said at least one heating element is covered with a plurality of photovoltaic cells (2.5).

8. Device according to claim 1, which is completely waterproof and airtight.

9. Device according to claim 1, wherein the vacuum has been realized.

The device of claim 1 and the method of claim 2, wherein the convergent Fresnel optical lens (1.3) has a spherical dome shape or a planar shape.

11. Device according to claim 1, wherein said at least one heating element is surmounted by a transparent micro-greenhouse for storing heat.

12. Device according to claim 11, wherein a partial vacuum exists under the microserre.

13. Device according to claim 1, wherein an upper side wall (1.2) separates the upper stage (1) from the intermediate stage (2) and a lower side wall (1.1) separates the intermediate stage (2) from the lower floor (3).

The device of claim 1 and the method of claim 2, wherein said lower stage (3) comprises at least one fluid connector (2.2) inserted in said lower side wall (1.1).

15. Device according to claim 1 and method according to claim 2, wherein the heating element (2.1) is located in the center of the intermediate stage (2) and a plurality of photovoltaic cells (2.5) are located around said heating element

(2.1).

FIRE I LLE OF REM PLACEM ENT (RULE 26)