DESC:FIELD OF THE INVENTION:
Typically, this invention relates to the field of solar electric, thermal energy, and renewable energy.

Particularly, this invention relates to solar photovoltaic modules.

Specifically, this invention relates to a Solar Photovoltaic-Thermal Collector System.

BACKGROUND OF THE INVENTION:
Photovoltaic thermal collectors, typically abbreviated as PVT collectors and also known as hybrid solar collectors, photovoltaic thermal solar collectors, PV/T collectors or solar cogeneration systems, are power generation technologies that convert solar radiation into usable thermal and electrical energy.

According to a first prior art system, vide Rosa-Clot et al. as seen in Figure 2, there was observed a serpentine channel, PV/T water system, in a Polycarbonate box. Here, thermal efficiency was 5% and electrical efficiency was 13%.

According to a second prior art system, Allan et al. as seen in Figure 3, there was observed a serpentine channel, PV/T water system, having Copper pipes and Aluminum sheet. Here, thermal efficiency was 57.1% and electrical Efficiency was 7.46%.

According to a third prior art system, Hossain et al. as seen in Figure 4, there was observed a serpentine channel, PV/T water system, having Copper pipes with Aluminum plate. Here, thermal efficiency was 70.9%.

According to a fourth prior art system, Hossain et al. as seen in Figure 5, there was observed a serpentine channel, PV/T water system, having Copper pipes with Aluminum plate. Here, thermal efficiency was 87.7% and electrical efficiency was 11.08%.

According to a fifth prior art system, Joy et al. as seen in Figure 6, there was observed a serpentine channel, PV/T water system, having Copper pipes with aluminum plate. Here, thermal efficiency was 46.19 % and electrical efficiency was 10.93 %.

According to a sixth prior art system, Khelifa et al. as seen in Figure 7, there was observed a serpentine channel, PV/T water system, having Copper pipes with Copper plate with insulation. Here, thermal efficiency was 63%.

According to a seventh prior art system, Y. Tripanagnostopoulos et al. as seen in Figure 8, there was observed rib parallel channels, PV/T water system, having Copper pipes with Copper sheet. Here, thermal efficiency was 65.1% and electrical efficiency was 18.5%.

According to an eighth prior art system, Salem et al. as seen in Figure 9, there was observed straight channels and helical channels, with Aluminum plate. Here, for straight channels, thermal efficiency was 47.2 % and electrical efficiency was 12.9 %. Here, for helical channels, thermal efficiency was 57.2 % and electrical efficiency was 13.5%.

According to a ninth prior art system, Poredos et al. as seen in Figure 10, there was observed Serial Channel, Parallel Channel, and Bionic Channel PVT water system, with Copper sheet. Here, thermal efficiency was 33.5% and electrical efficiency was 14.5%.

According to a tenth prior art system, N. Aste et al. as seen in Figure 11, there was observed a PV/T water system with Roll bond aluminum absorber. Here, thermal efficiency was 40.6 % and electrical efficiency was 13.6%.

According to an eleventh prior art system, Sardouei et al. as seen in Figure 12, there was observed a cross fined box with Copper fins. Here, thermal efficiency was 54.7 % and electrical efficiency was 11.8%.

Therefore, there was a need to improve thermal as well as electrical efficiency.

OBJECTS OF THE INVENTION:
An object of the invention is to achieve a thermally improved flow pattern in a solar photovoltaic-thermal collector system.

Another object of the invention is to achieve reduction of metallic part in a solar photovoltaic-thermal collector system.

Yet another object of the invention is to achieve direct contact, off fluid, with panel, in a solar photovoltaic-thermal collector system.

Still another object of the invention is to provide inlet fluid, in a solar photovoltaic-thermal collector system, having uniform temperature.

SUMMARY OF THE INVENTION:
According to this invention, there is provided a Solar Photovoltaic-Thermal Collector System comprising:
- an operative topmost layer, being a first layer, which is a glass cover layer, solar radiation being incident on said operative topmost layer;
- a second layer, beneath said operative first layer, being an EVA solar cell and EVA layer;
- a third layer, beneath said second layer, being a Tedlar layer;
o an encapsulant configured to attach said first layer, said second layer, and said third layer;
- a fourth layer, beneath said third layer, being a cooling channel layer;
- an operative bottommost layer, being a fifth layer, being a thermal insulator layer;
o an acrylic sheet being placed on an operative back side of said second layer with a gap between said second layer and said acrylic sheet, said gap being a cooling channel, said gap providing a modified fluid path,
? said cooling channel being in communication with said operative bottommost layer being said fifth layer; and
? said cooling channel receiving fluid from one end and exiting fluid from another end.

In at least an embodiment, said operative topmost layer being low iron content tempered glass.

In at least an embodiment, said encapsulant being Ethyl vinyl acetate (EVA).

In at least an embodiment, said tedlar layer being produces of Polyvinyl fluoride (PVF) film.

In at least an embodiment,
- cooling channel being divided into a set of first channels and a set of second channels such that each first channel, from the set of first channels, is spaced apart from an adjacent first channel by a second channel from the set of second channels;
- each first channel is adjacent to a second channel and each second channel is adjacent to a first channel;
- said first channels have, at their operative top, fluid inlet ports and fluid flows in a first direction, through these first channels;
- said second channels have, at their operative top, fluid outlet ports and fluid flows in a second direction, through these second channels, the first direction being opposite to the second channel;
- all the channels, seamlessly, interface at the other end (non-entry, non-exit) so that fluid flows from the fluid inlet ports, from first channels, to second channels, and to fluid outlet ports; and
- a first set of input inlets are provided at an operative top;
o at a time, the entire set of first channels are filled with fluid entering from corresponding fluid inlet ports and, then, at a time, the fluid flows out from the entire set of second channels through corresponding fluid outlet ports.

In at least an embodiment,
- said fluid inlet ports are gravity-fed fluid inlet ports;
- a flow control valve controls flow of fluid in said system in order to achieve optimum outlet temperature of said fluid such that addition of photovoltaic and thermal efficiencies is optimized to keep operating temperature of panel between 50 degrees Celsius and 55 degrees Celsius; and
- said fluid outlet ports outputting fluid at an optimized value for thermal applications.

In at least an embodiment,
- thermal part of said system is constructed of a non-metallic material being selected from a group of non-metallic materials consisting of acrylic, HDPE, LDPE, PVC, plastics, and other materials which are light weight insulating waterproof non-metallic materials; and
- thermal part being retrofitted on an existing photovoltaic module / panel.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 2 illustrates a first prior art system, vide Rosa-Clot et al.;
Figure 3 illustrates a second prior art system, vide Allan et al.;
Figure 4 illustrates a third prior art system, vide Hossain et al.;
Figure 5 illustrates a fourth prior art system, vide Hossain et al.;
Figure 6 illustrates a fifth prior art system, vide Joy et al.;
Figure 7 illustrates a sixth prior art system, vide Khelifa et al.;
Figure 8 illustrates a seventh prior art system, vide Y. Tripanagnostopoulos et al.
Figure 9 illustrates an eighth prior art system, vide Salem et al.;
Figure 10 illustrates a ninth prior art system, vide Poredos et al.;
Figure 11 illustrates a tenth prior art system, vide N. Aste et al.; and
Figure 12 illustrates a eleventh prior art system, vide Sardouei et al.

The invention will now be described in relation to the accompanying drawing, in which:
Figure 1 illustrates a layered Solar Photovoltaic-Thermal Collector System (100) of this invention;
Figure 13 illustrates various flow types in a Solar Photovoltaic-Thermal Collector System;
Figure 14 illustrates simulation results of thermal profile;
Figure 15 illustrates a schematic flow pattern achieved by the Solar Photovoltaic-Thermal Collector System (100) of this invention;
Figure 16 illustrates a temperatures throughout a panel, achieved by the Solar Photovoltaic-Thermal Collector System (100) of this invention; and
Figure 17 illustrates comparisons of power output of PV and PVT.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
According to this invention, there is provided a Solar Photovoltaic-Thermal Collector System.

Figure 1 illustrates a layered Solar Photovoltaic-Thermal Collector System (100) of this invention.
Figure 15 illustrates a schematic flow pattern achieved by the Solar Photovoltaic-Thermal Collector System (100) of this invention.

In at least an embodiment, an operative topmost layer, being a first layer (12), is a glass cover layer. Solar radiation is incident (22) on the topmost glass cover. In order to extract maximum possible solar irradiance, the top layer of PVT panel is made up of low iron content tempered glass. To protect the PV cells from extreme weather conditions and impact from hail or airborne debris, a front glass sheet is used. As per IEC standard impact test, the solar panel has to withstand an impact of 25 mm diameter aluminum ball, traveling up to 27 m/s. Preferably, the glass cover has a thickness of 0.005m.

In at least an embodiment, a second layer (14), beneath a first layer, is an EVA solar cell and EVA sandwich layer. The glass cover (12), solar cell (14), and tedlar (16), of the PVT system (100) are attached with an encapsulant. Most commonly, Ethyl vinyl acetate (EVA) is used as encapsulant for adherence of the layers. It protects the PV panel from penetrating moisture and dirt. Also, it protects solar cells from shocks and vibrations by softening their impact. Preferably, thickness of solar cell is 0.0003m and EVA is 0.0005m.

In at least an embodiment, a third layer (16), beneath a second layer, is a Tedlar layer. A Polyvinyl fluoride (PVF) film is used to produce the tedlar layer of the PVT panel (100). Tedlar protects against moisture and harsh environment as it is inert and non-stick which gives a better finish. Preferably, Tedlar has a thickness of 0.005m.

In at least an embodiment, a fourth layer (18), beneath a third layer, is a cooling channel layer. An acrylic sheet is placed on the back side of tedlar (16) with some spacing. This gap between tedlar and acrylic sheet is considered as a cooling channel. A modified fluid path is designed, in this layer, in accordance with this invention. The cooling channel layer is in communication with the thermal insulator (20) and receives fluid from one end (24a) and exits (24b) fluid from another end. Preferably. the cooling channel has maximum thickness of 0.018m.

In at least an embodiment, an operative bottommost layer, being a fifth layer (20), is a thermal insulator layer. It is acrylic sheet which is highly resistant to weather conditions, is waterproof and lighter in weight. It also acts as a thermal insulator. Holes of diameter, preferably 0.008 m are provided in the acrylic for fluid (maybe, water) inlet and outlet. An epoxy sealant is used to paste the acrylic sheet and the frame. Preferably, thickness of acrylic sheet is 0.005m.

Figure 13 illustrates various flow types in a Solar Photovoltaic-Thermal Collector System.
Figure 14 illustrates simulation results of thermal conductivity.

Layer Thickness
(mm) Thermal Conductivity
(W/mK) Density
(Kg/m3) Specific Heat Capacity
(J/KgK)
Glass Cover 0.003 1.8 3000 500
Solar Cell 0.0002 148 2330 677
EVA 0.0003 0.35 960 2090
Tedlar 0.005 0.2 1200 1250
Thermal Insulator 0.005 0.2 1200 1470
Table 1: Thickness and Material properties of different layers of solar PVT panel

Figure 15 illustrates a Fluid flow pattern diagram

In at least an embodiment, the cooling channel is divided into a set of first channels (32) and a set of second channels (34) such that each first channel from the set of first channels is spaced apart from an adjacent first channel by a second channel from the set of second channels. Thus, each first channel is adjacent to a second channel and each second channel is adjacent to a first channel. The first channels have, at their operative top, fluid inlet ports (24a) and fluid flows in a first direction, through these first channels. The second channels have, at their operative top, fluid outlet ports (24b) and fluid flows in a second direction, through these second channels, the first direction being opposite to the second channel. All the channels, seamlessly, interface (35) at the other end (non-entry, non-exit) so that fluid flows from the fluid inlet ports, from first channels, to second channels, and to fluid outlet ports. A first set of input conduits / inlets are provided at an operative top. At a time, the entire set of first channels (32) are filled with fluid entering from corresponding fluid inlet ports (24a) and, then, at a time, the fluid flows out from the entire set of second channels (34) through corresponding fluid outlet ports (24b).

The fluid flow pattern, shown in figure 15, is replicated at the back side of the PV panel. The fluid inlets are arranged so that the fluid enters in cold fluid chamber only. As the fluid inside the panel start getting hot; the hot fluid will automatically travel upwards, through the second channels (34) since density of cold fluid is higher than that of hot fluid. The hot fluid then is taken out from the outlet pipe. For the purpose of taking all fluid from the panel, a tap is provided.

According to a preferred embodiment, details of the dimensions are provided in the table 2, below.
Sr. no. Parameter Dimension (mm)
1 Solar panel length 954
2 Solar panel width 616
3 Frame length 1004
4 Frame width 666
5 Frame thickness 27
6 Cooling Channel length 934
7 Cooling Channel width 596
8 Cooling Channel thickness 18
9 Inverted U-section length 704
10 Inverted U-section width 90
11 Inverted U-section thickness 8
12 Gap Between Inverted U-sections 79
13 Inlet-Outlet pipe diameter 8
Table 2: PVT panel dimensions

More the fluid, higher the cooling of PV panel. This improves the electrical performance but subsequently reduces temperature of outlet fluid. As this invention aims to maximize energy harvesting for electric and thermal applications, lowering the outlet fluid temperature won’t be beneficial; hence optimization of the gap, of channel, is vital.

The fluid flow rate would be constricted by lowering the gap of the cooling channel. But this leads to an increase in the operating temperature of the panel and subsequently reduces the electrical power output, which is undesirable.

In the PVT system, of this invention, an additional pump is not used as it is based on the natural circulation of fluid. Also, acrylic sheets can be damaged by the pressure applied by the pumping system. The pump can be used to control fluid flow, but it will cost and add maintenance. Here, the flow rate is regulated using a valve connected to the fluid tank. It is attached to the central fluid system to ensure a constant fluid level in a cold fluid tank.

Table 3 shows experimental output of a PVT system from morning 8 AM to 4 PM. The experimental output shows around 24% (absolute) rise in the average output power in comparison with normal PV panel output (as shown in table 4). The panel surface temperature is also reduced in PVT panel by 12.3 % compared to PV panel. The average thermal efficiency obtained from PVT panel in a day is around 60%.
Time Voltage (V) Current (A) Inlet Temp
(oC) Outlet Temp.
(oC) SurfaceTemp.
(oC) Solar irradiance
(W/m2) Ambient Temp.
( oC) Power (W) ?elec (%) ?th (%)
8:00 14.16 3.00 20.2 25.1 27.4 685.145 29.3 42.53 15.28 63.9
9:00 17.33 3.12 23.7 30.5 34.8 700.365 32.7 54.06 14.95 63.64
10:00 18.73 3.45 27.5 35.4 36.3 722.3875 33.8 64.6185 14.49 61.2
11:00 18.9 3.6 29.6 38 37.7 794.825 35.6 69.12 13.17 60.51
12:00 19 3.43 32.2 43.6 43.1 929.1875 37.2 65.17 11.27 59.23
13:00 19.1 3.5 35.9 45.9 48 957.425 38 66.85 10.93 57.35
14:00 18.85 3.47 33.4 42.2 44.8 904.3125 36.4 65.409 11.58 58.01
15:00 18.16 3.33 31 37.5 39.3 835.525 35 60.47 12.53 58.88
16:00 15 2.74 30 34.7 36.7 812.87 33.5 41.1 12.88 58.6

Table 3: Experimental output of a PVT panel system
Time Voltage(V) Current (A) Surface temperature (oC) Power (W)
8:00 12.31 2.57 32 31.64
9:00 15.64 2.88 44 45.04
10:00 16.87 3.1 48.8 52.297
11:00 17.18 3.15 55 54.12
12:00 17.1 3.1 63 54.87
13:00 17.07 3.1 52.5 52.917
14:00 16.82 3.03 55.8 50.9646
15:00 16.3 2.98 54.8 48.574
16:00 13.6 2.52 53 34.272
Table 4: Experimental output of normal PV panel

The TECHNICAL ADVANCEMENT of this invention lies in providing a channelized system for fluid inlet and outlet such that is achieves a thermally improved flow pattern in a solar photovoltaic-thermal collector system. This also results in reduction of temperature gradient in the PV panel. The channel paths are wide enough to support pump-less natural fluid flow. The structure is made up of Acrylic sheet, hence no need of extra insulations on the back side of the panel. The fluid is in direct contact with the PV panel back for efficient heat extraction.

Figure 16 illustrates a temperature gradient, throughout a panel, achieved by the Solar Photovoltaic-Thermal Collector System (100) of this invention.
This Figure 16 shows the temperature profile of a panel simulated in ANSYS. T1 is the water temperature outside the square U-tubes while T2 is the water temperature inside the square U-tube. It is observed that the temperatures in the regions outside the square U-tubes are lower than those observed inside the square U-tubes. Thus, the water at the outlet holes has a higher temperature as compared to that at the inlet holes indicating that the heat has been extracted from the panel. The temperature difference observed between T1 and T2 is around 5-6°C. Thus, indicating a reduction in the temperature gradient.

Figure 17 illustrates comparisons of power output of PV and PVT.
This Figure 17 shows the plot between power outputs for PV and PVT systems. As observed, the power outputs for PVT systems are greater than those of PV. Thus, the efficiencies obtained in case of PVT are also higher.

While this detailed description has disclosed certain specific embodiments for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

,CLAIMS:WE CLAIM,

1. A Solar Photovoltaic-Thermal Collector System comprising:
- an operative topmost layer, being a first layer (12), which is a glass cover layer, solar radiation being incident (22) on said operative topmost layer;
- a second layer (14), beneath said operative first layer, being an EVA solar cell and EVA layer;
- a third layer (16), beneath said second layer, being a Tedlar layer;
o an encapsulant configured to attach said first layer (12), said second layer (14), and said third layer (16);
- a fourth layer (18), beneath said third layer, being a cooling channel layer;
- an operative bottommost layer, being a fifth layer (20), being a thermal insulator layer;
o an acrylic sheet being placed on an operative back side of said second layer (16) with a gap between said second layer and said acrylic sheet, said gap being a cooling channel, said gap providing a modified fluid path,
? said cooling channel being in communication with said operative bottommost layer being said fifth layer; and
? said cooling channel receiving fluid from one end (24a) and exiting (24b) fluid from another end.

2. The system as claimed in claim 1 wherein, said operative topmost layer being low iron content tempered glass.

3. The system as claimed in claim 1 wherein, said encapsulant being Ethyl vinyl acetate (EVA).

4. The system as claimed in claim 1 wherein, said tedlar layer being produces of Polyvinyl fluoride (PVF) film.

5. The system as claimed in claim 1 wherein,
- cooling channel being divided into a set of first channels (32) and a set of second channels (34) such that each first channel, from the set of first channels, is spaced apart from an adjacent first channel by a second channel from the set of second channels;
- each first channel is adjacent to a second channel and each second channel is adjacent to a first channel;
- said first channels have, at their operative top, fluid inlet ports (24a) and fluid flows in a first direction, through these first channels;
- said second channels have, at their operative top, fluid outlet ports (24b) and fluid flows in a second direction, through these second channels, the first direction being opposite to the second channel;
- all the channels, seamlessly, interface (35) at the other end (non-entry, non-exit) so that fluid flows from the fluid inlet ports, from first channels, to second channels, and to fluid outlet ports; and
- a first set of input inlets are provided at an operative top;
o at a time, the entire set of first channels (32) are filled with fluid entering from corresponding fluid inlet ports (24a) and, then, at a time, the fluid flows out from the entire set of second channels (34) through corresponding fluid outlet ports (24b).

6. The system as claimed in claim 1 wherein,
- said fluid inlet ports (24a) are gravity-fed fluid inlet ports;
- a flow control valve controls flow of fluid in said system in order to achieve optimum outlet temperature of said fluid such that addition of photovoltaic and thermal efficiencies is optimized to keep operating temperature of panel between 50 degrees Celsius and 55 degrees Celsius; and
- said fluid outlet ports (24b) outputting fluid at an optimized value for thermal applications.

7. The system as claimed in claim 1 wherein,
- thermal part of said system is constructed of a non-metallic material being selected from a group of non-metallic materials consisting of acrylic, HDPE, LDPE, PVC, plastics, and other materials which are light weight insulating waterproof non-metallic materials; and
- thermal part being retrofitted on an existing photovoltaic module / panel.

Dated this 26th day of September, 2022

CHIRAG TANNA
of INK IDÉE
APPLICANT’S PATENT AGENT
REGN. NO. IN/PA - 1785