DESC:FIELD OF THE INVENTION:
This invention relates to the field of solar engineering.

Particularly, this invention relates to a hybrid energy system.

BACKGROUND OF THE INVENTION
Solar Photovoltaic (PV) with monocrystalline silicon has an efficiency of around 26% which is better than the polycrystalline silicon with efficiency 15-20% at the standard test conditions, but it is a costly affair. Solar photovoltaic, based on polycrystalline silicon, is economical and a promising renewable energy technology. However, in PV most of the solar energy gets dissipated in the form of heat. This waste heat causes increase in temperature of PV cell and simultaneously decreases PV efficiency and performance.

An increase in the efficiency of polycrystalline silicon to come closer to the efficiency of monocrystalline silicon was attempted earlier using various adjunct systems to the PV.

Various adjunct systems were used to either cool the PV to maintain its efficiency or to utilize the dissipated heat in the PV to generate power. Photovoltaic thermal system (PV/T) is one such system in which water or air based thermal collector was used as a passive cooling unit to reduce the PV temperature. Yang et. al. used cylindrical pin fin heat sink (CHS) as a thermal collector in the PV/T hybrid system. This CHS, when used with PV in the PV-CHS system, reduced the PV surface temperature and increased its efficiency. Thermoelectric (TE) is a device that converts temperature difference across it into electric voltage. Lamba et. al. did a comparative study between PV and PV-TE hybrid system using theoretical model. The efficiency of the hybrid PV-TE system showed increase by 5% as compared to the concentrated PV system. Salari et. al. used TE along with PV/T to engage the dissipated heat in energy generation. The electrical efficiency of the hybrid PV/T-TE system, when exposed to solar radiation of 600 and 1000 W/m2, was 6.23% and 10.41% higher than that of the PV/T system. Another important outcome was that in case of hybrid PVT/TE, because of TE, the electrical efficiency increased by 0.82% with increase in temperature from 26° C to 34° C. Kang et. al. studied the TE assembled with a water-film cooling pond (EC) in the TE-EC system and observed that the performance of TE got enhanced. They concluded that the output power and efficiency of water-film evaporative cooling were respectively 100.53 and 10.53 times higher than finned heat sink used for cooling the cold side of the TE. Kanimba et. al. focused their research on the TE performance and they observed that the TE power output got improved using multiple layers of TE. A two-layer cascaded TE was found to produce an efficiency of 8.3% while a three-layer cascaded TE produced an efficiency of 10.2%.

Various combinations of any two methods, for example, PV/T, PV/T-TE, PV-TE, PV-EC, and TE-EC were tried in earlier research works to expand their boundary of energy extraction from the solar spectrum.

Prior Art US 7763792 discloses Multistage Heat Pumps and Method of Manufacture. In this, design modification in multistage or cascaded low temperature thermoelectric (TE) has been suggested to maintain its efficiency and increase the heat pumping ability.

Prior Art US 7638705 discloses Thermoelectric Generator for Solar Conversion and Related Systems and Methods. In this, the solar energy was concentrated on three layered TE (First layer: Bismuth telluride, Second layer: Lead telluride, Third layer: Silicon) using metamaterial and finned heat sink was used to increase the efficiency of conversion of solar energy to electricity to around 24%. However, the consideration over here is that all the energy falling on the metamaterial layer is reaching the TE top surface.

Prior Art US 0048488 discloses Combined Thermoelectric / Photovoltaic Device and Method of Making the same. In this, a commercially available photovoltaic (PV) was proposed to be attached to a commercially available bismuth telluride based TE to add on the decreasing efficiency of PV because of rise in temperature. The patent also proposes use of heat sink to further increase the efficiency of hybrid system. However, the results pertaining to the same were not explored.

Prior Art US 9331258 discloses Solar Thermoelectric Generator. In this, Solar concentrators were placed over the heat source to conduct the thermal energy to TE and to perform energy conversion analysis of the TE at various concentration ratios. The energy conversion efficiency was found to be around 15% and 23 % for TE material with ZT 1 and 2 respectively.

Prior Art EP 2345087 discloses Combined Solar / Thermal (CHP) Heat and Power for Residential and Industrial Buildings. In this, A CHP was developed based on PV-TE combination with usable range of temperature 100-400°C. The cold side of TE was connected to the water based heat sink which used the stored thermal energy on the TE cold side to heat the water present in the heat sink and make it available for household usage.

In the prior arts, permutations of two systems, out of PV, TE, and EC were tried, but all three systems, together, were neither considered nor evaluated; this needs to be addressed.

Further, in most of published researches, efficiency of PV decreases with increase in solar concentration ratio or temperature; this needs to be addressed.

Additionally, prior art mathematical models or the tried experimental setups do not establish a condition for constant efficiency of PV based systems throughout the day; this needs to be addressed.

There is a need to establish synergy between PV, cascaded TE, and EC; all, in order to combine the best of each of these green systems to maximize usable electrical energy conversion efficiency.

OBJECTS OF THE INVENTION:
An object of the invention is to establish synergy between PV, cascaded TE, and EC; all, in order to combine the best of each of these green systems to maximize usable electrical energy conversion efficiency.

Another object of the invention is to extend usable electromagnetic spectrum for PV.

SUMMARY OF THE INVENTION:
According to this invention, there is provided a hybrid energy system comprising:
- an operative top layer being a photovoltaic (PV) layer, incident sunlight falling on an optical concentrator system placed atop said operative top layer;
- an operative bottom layer being a direct evaporative cooling (EC) layer; and
- one or more middle layers, sandwiched between said operative top layer and said operative bottom layer, each of said middle layers being a cascaded thermoelectric (TE) layer;
o wherein, a thermally conductive adhesive coating said operative bottom layer (EC) on its operative top surface;
o wherein, a first thermoelectric layer (TE1) (22) being placed over said operative bottom layer (EC) with said a thermally conductive adhesive therebetween;
o wherein, an operative bottom surface of said first thermoelectric layer (TE1) being thermally conductive but electrically insulating with said connected operative bottom layer (EC);
o wherein, an operative top surface of said first thermoelectric layer (TE1) becoming an operative bottom surface of said second thermoelectric layer (TE2) placed atop said first thermoelectric layer (TE1);
o wherein, an operative top surface of said second thermoelectric layer (TE2) becoming an operative bottom surface of said third thermoelectric layer (TE3) placed atop said second thermoelectric layer (TE2);
o wherein, said first thermoelectric layer (TE1) and said second thermoelectric layer (TE2) are thermally connected, to each other, by a shared oxide layer and are electrically connected to each other by a conducting element;
o wherein, said second thermoelectric layer (TE2) and said third thermoelectric layer (TE3) are thermally connected, to each other, by a shared oxide layer and are electrically connected to each other by a conducting element;
o wherein, p-type legs and n-type legs are provided with said first thermoelectric layer (TE1), said thermoelectric layer (TE2), and said third thermoelectric layer (TE3), these legs being electrically connected in series using a conducting element; and
o wherein, a thermally conductive adhesive coating said operative top layer of said third thermoelectric layer (TE3) on its operative top surface, said adhesive layer ensuring thermal contact between said third thermoelectric layer (TE3) and said Photovoltaic (PV) layer but electrical contact between said two layers being established using conducting elements.

In at least an embodiment, said one or more middle layers are three layers of middle layers, each layer is a cascaded thermoelectric layer.

In at least an embodiment, said bottom layer is a porous sintered copper layer which holds water for direct evaporative cooling (EC).

In at least an embodiment, said thermally conductive adhesive or gel have coating thickness of 0.5 mm and thermal conductivity of 1.15 Wm-1K-1.

In at least an embodiment, said operative bottom surface of said first thermoelectric layer (TE1) is made of thermally conducting but electrically insulating oxide layer.

In at least an embodiment, each of said middle layers is a thermally resisting layer imposing thermal resistance of 8.0675KW-1

In at least an embodiment, said operative top layer is a Pc-Si layer having temperature coefficient equal to 0.38%/°C with a working temperature up to 85°C.

In at least an embodiment, each of said operative middle layers are fabricated from p-type and n-type bismuth telluride.

In at least an embodiment, said operative bottom layer comprise a porous layer connected to a water reservoir, continuous supply of water to the porous layer is ensured through thermal siphoned effect.

In at least an embodiment, said first thermoelectric layer (TE1), said second thermoelectric layer (TE2), and said third thermoelectric layer (TE3) are connected to each other in series.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be described in relation to the accompanying drawings, in which:
Figure 1 illustrates: (a) schematic representation of the structural diagram, (b) thermal circuit, and (c) electrical circuit for the proposed hybrid PV-3TE-EC system according to this invention;
Figure 2 illustrates hot side PV temperature profile (Th-PV), cold side PV temperature profile (Tc-PV), temperature difference across the PV (Th-Tc), and power output from PV, PV-TE, PV-EC, PV-TE-EC, PV-2TE-EC and PV-3TE-EC modules with respect to solar concentration ratio of 7;
Figure 3 illustrates the power output from hybrid PV-TE-EC, PV-2TE-EC and PV-3TE-EC modules with respect to solar concentration ratios (1 to 7;
Figure 4 illustrates an efficiency profile for various hybrid systems, all in accordance with this invention: PV-EC, PV-TE-EC, PV-2TE-EC, and PV-3TE-EC systems) with respect to time in a sunny day and various concentration ratios (1, 3, 5, 7); and
Figure 5 illustrates a flowchart showing the simulating process in ANSYS 19.2 software used to extract the mathematical results of PV, PV-TE, PV-EC, PV-TE-EC, PV-2TE-EC and PV-3TE-EC hybrid modules.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
It has been observed that high temperature of PV (Photovoltaic), though adverse for PV efficiency, is advantageous for TE (Thermoelectric) power output. Further, it has been observed that maximum power output for TE depends on square of temperature difference across it. TE with EC (Evaporative Cooling) shows more temperature difference across TE and hence gives more power output then TE; supported only with natural convective cooling. Further increase in TE power output was found in its cascaded assembly. Unfortunately, these three popular systems i.e. PV, cascaded TE, and EC, are not analyzed together in one hybrid system to capitalize on their electrical efficiencies.

According to this invention, there is provided a hybrid energy system.

In the current invention, it was observed that it, significantly, establishes synergy between PV (Photovoltaic), cascaded TE (Cascaded Thermoelectric), and EC (Direct Evaporative Cooling) and to combine the best of each one of these systems to maximize the efficiency.

Figure 1 illustrates: (a) schematic representation of the structural diagram, (b) thermal circuit, and (c) electrical circuit for the proposed hybrid PV-3TE-EC system according to this invention.

In at least an embodiment, an operative top layer is a PV (Photovoltaic)system.
In at least an embodiment, an operative bottom layer is an EC (Direct Evaporative Cooling) system.
In at least an embodiment, the middle layers, between the operative top layer and the operative bottom layer, are three layers, each layer being a TE (Cascaded Thermoelectric) system.

Incident sunlight falls on an optical concentrator system (30) placed atop the operative top layer. In the system, the radiation flux is uniform throughout the plane perpendicular to the sunlight.

There is no contact thermal resistance between two adjacent layers.
In at least an embodiment, the layers are as follows:
- the operative bottom layer, which is the EC (Direct Evaporative Cooling) layer is a porous sintered copper layer which holds water for direct evaporative cooling (EC);
- over this operative bottom layer, a thermally conductive adhesive or gel (21) is coated (preferable coating thickness: 0.5 mm, preferable thermal conductivity: 1.15 Wm-1K-1);
- over the aforementioned layer, a first thermoelectric layer (TE1) (22) is placed;
- an operative bottom surface of the first thermoelectric layer (TE1) is made of Al2O3 (thermally conducting but electrically insulating oxide) which is in direct contact with water to establish thermal contact with the first thermoelectric layer (TE1) and to provide direct evaporative cooling effect to the bottom surface of first thermoelectric layer (TE1);
- an operative top oxide surface of the first thermoelectric layer (TE1) becomes a substrate or an operative bottom surface of the second thermoelectric layer (TE2) (23) placed atop the first thermoelectric layer (TE1);
- an operative top oxide surface of the third thermoelectric layer (TE3) (24) becomes a substrate or an operative bottom surface of the third thermoelectric layer (TE) (23) placed atop the second thermoelectric layer (TE2);
- the evaporative cooling (EC) layer has no role to play in electrical power output;
- the first thermoelectric layer (TE1) and the second thermoelectric layer (TE2) are thermally connected, to each other, by a shared oxide layer and are electrically connected to each other by a copper foil;
- the second thermoelectric layer (TE2) and the third thermoelectric layer (TE3) are thermally connected, to each other, by a shared oxide layer and are electrically connected to each other by a copper foil;
- p-type legs (12) and n-type legs (14) are provided with the first thermoelectric layer (TE1), these legs being electrically connected in series using copper foil;
- p-type legs (12) and n-type legs (14) are provided with the second thermoelectric layer (TE2), these legs being electrically connected in series using copper foil;
- p-type legs (12) and n-type legs (14) are provided with the third thermoelectric layer (TE3), these legs being electrically connected in series using copper foil;
- above the operative top surface of the third thermoelectric layer (TE3), thermally conductive adhesive or gel (25) is coated (preferable coating thickness: 0.5 mm, preferable thermal conductivity: 1.15 Wm-1K-1), the gel layer ensures thermal contact between third thermoelectric layer (TE3) and Photovoltaic (PV) layer but electrical contact between these two layers is established using copper wires;
- an operative top layer being a Photovoltaic (PV) layer is placed.

Figure 2 illustrates hot side PV temperature profile (Th-PV), cold side PV temperature profile (Tc-PV), temperature difference across the PV (Th-Tc), and power output from PV, PV-TE, PV-EC, PV-TE-EC, PV-2TE-EC and PV-3TE-EC modules with respect to solar concentration ratio of 7.

Moving along the hybrid systems from left to right (PV?PV-3TE-EC) at the solar concentration ratio 7, it was observed that the PV top and bottom surface temperature for PV and PV-TE systems are almost same. The PV top and bottom surface temperature for other hybrid systems is <85°C because of the thermal resistance of about 8.0675KW-1 imposed by each TE layer which is added to the hybrid systems. The effect of Th-PV and Tc-PV on the power output is also shown for the hybrid systems from left to right (PV?PV-3TE-EC). The addition of EC layer shows drastic improvement in power output of PV from 397Wm-2 to 950Wm-2 as shown by PV-EC. With addition of TE layer, thermal resistance is added and decrease in PV power output takes place because of increase in temperature. E.g. PV (397 Wm-2)?PV-TE (392 Wm-2). This reduces the power output from PVs but increases the power output from TEs. The TE layer contributes to the power output. E.g. PV-TE = PV(392) + TE(8) = 400 Wm-2. This leads to an increase in the overall efficiency of PV-TE-EC, PV-2TE-EC and PV-3TE-EC in the ascending order. At concentration ratio 7, PV-TE-EC, PV-2TE-EC and PV-3TE-EC produce the power output of around 970, 993 and 1015 Wm-2 respectively. Beyond triple layer TE cascading i.e. PV-3TE-EC module, the thermal resistance contribution from the TE layers (more than three) becomes so much that the PV surface temperature exceeds 85°C and reduces its lifetime. The efficiencies of PV-TE-EC, PV-2TE-EC and PV-3TE-EC are higher than PV-EC (15.71 %) by 2.15, 4.87 and 6.54% respectively.

Figure 3 illustrates the power output from hybrid PV-TE-EC, PV-2TE-EC and PV-3TE-EC modules with respect to solar concentration ratios (1 to 7).

When compared with the PV, PV-EC and PV-TE, the PV-3TE-EC system (three cascaded layers of TE sandwiched between PV and EC as shown in Figure 1) exhibits improvement in the efficiency as shown in Fig. 3. This efficiency can be further increased by using low temperature coefficient PV material (0.34-0.38%/°C), solar concentration ratio of 3 to 7 and keeping the complete PV-3TE-EC system setup at the lower wind speed location (= 1m/s). This combination of parameters will allow the PV-3TE-EC hybrid system to demonstrate nearly constant efficiency throughout the day as shown in Figure 4.

Figure 4 illustrates an efficiency profile for various hybrid systems, all in accordance with this invention: PV-EC, PV-TE-EC, PV-2TE-EC, and PV-3TE-EC systems) with respect to time in a sunny day and various concentration ratios (1, 3, 5, 7).

The hybrid system of this invention is a green technology and there is no use of carbon.

The hybrid system of this invention establishes a, previously unknown, synergy between PV, cascaded TE, and EC and combines the best of each one of these green systems in order to maximize usable electrical energy conversion efficiency.

The hybrid system of this invention extends the usable electromagnetic spectrum for PV.

Furthermore, with increase in solar concentration ratio or temperature, the efficiency of the PV-3TE-EC system, according to this invention, increases in contrast to the PV system. This efficiency can be further increased by using low temperature coefficient PV material (0.34-0.38%/°C), high concentration ratio (3-7) radiation focusing unit, and keeping the complete PV-3TE-EC system setup at the lower wind speed location (= 1m/s). This combination of parameters allows the PV-3TE-EC hybrid system, of this invention, to demonstrate nearly constant efficiency throughout the day.

According to prior arts, permutations of two systems out of PV (Photovoltaic), TE (Thermoelectric), and EC (Evaporative Cooling) were tried, but all the three systems together were neither synthesized, synergistically, nor evaluated for synergistic performance. In most of the prior art work, efficiency of the PV decreased with increase in solar concentration ratio or temperature.

Figure 5 illustrates a flowchart showing the simulating process in ANSYS 19.2 software used to extract the mathematical results of PV, PV-TE, PV-EC, PV-TE-EC, PV-2TE-EC and PV-3TE-EC hybrid modules.

According to a non-limiting exemplary embodiment, the hybrid energy system is scientifically analyzed by means of simulation using ANSYS 19.2 software.

In at least a non-limiting exemplary embodiment, monofacial PV is used as a renewable energy source and TE and EC are used as its adjunct modules. On a sunny day, amount of solar energy concentrating on the PV surface is taken to be 940 W/m2 and later on using various focusing units, increment in the concentration ratio of 1 to 7 is achieved. The PV used is the Pc-Si (temperature coefficient = 0.38%/°C) with a working temperature up to 85°C. Out of the PV, TE, and EC, the commercially available TE module has a minimum area of 40x40 mm2 and the TE modules are connected in series to cover the PV back area with these TE modules. Each TE module is fabricated from p-type and n-type bismuth telluride (figure of merit (ZT) ~1). The three dimensional models, as shown in Fig. 1, are generated for these modules using SOLID WORKS. Fig. 1(a) and 1(b) represent the schematic representation of the structural diagrams of the PV-EC and PV-3TE-EC module respectively. The TEs labeled as TE1, TE2 and TE3 as shown in Fig. 1(b) are all bismuth telluride based with the same characteristics and are placed one below the other. The top side of the TE is always kept at the backside of the PV in PV-TE combinations. The EC layer is used with PV or TE at the cold side and covers their entire lower surfaces, respectively, and is considered to be consisted of a porous layer connected to the water reservoir. Continuous supply of water to the porous layer is ensured through thermal siphoned effect. The water consumption (m ?) by the EC for area 40x40 mm2 in the proposed model follows parabolic relationship (m ? = 0.004C2) with concentration ratio. It ranges from approximately 0.0042 to 0.19 l/h for the considered concentration ratios 1 to 7. The characteristics of each component used in the proposed models are given below on the basis of which electrical characteristics were evaluated. The PV, TE1, TE2 and TE3 are electrically connected in series and the power output from each of the module of the circuit is added to get the total power.

The Table 1, below, shows thickness and thermal conductivity of various materials used in this invention.

Module Layer Material Thickness (mm) Thermal conductivity (W/mK)

PV Glass - 3 1.8
EVA - 0.5 0.35
PV Si 0.4 148
EVA - 0.5 0.35
Tedlar - 0.33 0.15
Gel - 0.5 1.15

TE Ceramic Al2O3 0.8 31
Interconnector Copper 0.3 398
TEG Bi2Te3 1 1.5
Interconnector Copper 0.3 398
Ceramic Al2O3 0.8 31
EC Water - 1.5 0.6
TABLE 1

Specifications of PV:
- Si (Polycrystalline)
- 100W/m2 at 25oC
- Efficiency – 17.5%
- Area – 1.002 cm2
- V – 0.664V
- J – 38 mA/cm2
- FF – 80.9%
- ß – 0.0038/oC
- 85oC PV limiting temperature

Specifications of TE:
- Bi2Te3 material
- a – 1.83 x 10-4 V/K
- ? – 7.23 x 10-6 Om
- K – 1.82 W/(m K)
- Ap/n – 1.96 mm2
- Lp/n – 1.6 mm
- Np/n – 127
- ATE – 40 x 40 mm2

Abbreviations Description

PV Photovoltaic
EC direct evaporative cooling module
TE Thermoelectric
2TE two stage cascaded TE layer
3TE three stage cascaded TE layer
PV-TE photovoltaic-thermoelectric
PV-EC photovoltaic- direct evaporative cooling module
PV-TE-EC a layer of TE sandwiched between PV and EC
PV-2TE-EC two cascaded layers of TE sandwiched between PV and EC
PV-3TE-EC three cascaded layers of TE sandwiched between PV and EC
FEM finite element analysis
Mc-Si monocrystalline Si
Pc-Si polycrystalline Si
STC standard test conditions


Symbols Description

A cross sectional area
C sun concentration ratio
G solar radiation intensity (W/m2)
L length (m)
Q heat flow rate (W)
P power (W)
h coefficient of heat transfer (W/m2K)
hm coefficient of mass transfer (m/s)
hfg latent heat of vaporization (kJ/kg)
T temperature (K)
R electrical resistance (O)
k thermal conductance (W/mK)
Z figure of merit of thermoelectric element (T-1)
Nu Nusselt number
Pr Prandtl number
Sh Sherwood number
Sc Schmidt number
Le Lewis number
N number of pairs of p-type and n-type TE legs
Cp specific heat of water (J/kg K)
D mass diffusivity (m2/s)
water consumption (l/h)


Greek Symbols Description

S Seebeck coefficient (V/K)
ag absorptivity of glass
ß PV temperature coefficient (%/°C)
eg emissivity of glass
tg transmissivity of glass
s Stefan-Boltzmann’s constant,5.67 x 10-8 (W/m2K4 )
d thickness of layer (m)
? difference
? efficiency (%)
? electrical resistivity (O m)
a thermal diffusivity (m2/s)
?v,w water vapour density in the water layer (kg m-3)
?v,a water vapour density in the ambient air (kg m-3)


Subscripts Description

a ambient
sky sky
ref reference
PV photovoltaic
TE thermoelectric
max maximum
n n-type semiconductor of TE module
p p-type semiconductor of TE module
h hot side TE module
c cold side TE module
e equivalent
s at the water film surface
evap evaporative
conv convective
in radiance incident on PV

TECHNICAL ADVANTAGES:
1. It is a green technology and there is no use or generation of any green house gases and is free from carbon.
2. The proposed innovative model, establishes a synergy between PV, cascaded TE and EC and combine the best of each one of these green systems to maximize the usable electrical energy conversion efficiency.
3. It extends the usable electromagnetic spectrum for PV.
4. With increase in solar concentration ratio or temperature, the efficiency of the PV-3TE-EC system increased in contrast to the PV system.
5. This efficiency can be further increased by using low temperature coefficient PV material (0.34-0.38%/°C), high concentration ratio (3-7) radiation focusing unit and keeping the complete PV-3TE-EC system setup at the lower wind speed location (= 1m/s). This combination of parameters will allow the PV-3TE-EC hybrid system to demonstrate nearly constant efficiency throughout the day.

The TECHNICAL ADVANCEMENT of this invention lies in providing a hybrid system which has been able to establish synergy between PV (Photovoltaic), cascaded TE (Thermoelectric), and EC (Evaporative Cooling); all, in order to combine the best of each of these green systems to maximize usable electrical energy conversion efficiency. This can be used to extend usable electromagnetic spectrum for PV. This efficiency can be further increased by using low temperature coefficient PV material (0.34-0.38%/°C), high concentration ratio (3-7) radiation focusing unit and keeping the complete PV-3TE-EC system setup at the lower wind speed location (= 1m/s). This combination of parameters will allow the PV-3TE-EC hybrid system to demonstrate nearly constant efficiency throughout the day.

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.

Dated this 01st day of April, 2022

CHIRAG TANNA
of INK IDÉE
APPLICANT’S PATENT AGENT
REGN. NO. IN/PA – 1785
,CLAIMS:WE CLAIM,

1. A hybrid energy system comprising:
- an operative top layer being a photovoltaic (PV) layer, incident sunlight falling on an optical concentrator system placed atop said operative top layer;
- an operative bottom layer being a direct evaporative cooling (EC) layer; and
- one or more middle layers, sandwiched between said operative top layer and said operative bottom layer, each of said middle layers being a cascaded thermoelectric (TE) layer;
o wherein, a thermally conductive adhesive (21) coating said operative bottom layer (EC) on its operative top surface;
o wherein, a first thermoelectric layer (TE1) (22) being placed over said operative bottom layer (EC) with said a thermally conductive adhesive (21) therebetween;
o wherein, an operative bottom surface of said first thermoelectric layer (TE1) (22) being thermally conductive but electrically insulating with said connected operative bottom layer (EC);
o wherein, an operative top surface of said first thermoelectric layer (TE1) (22) becoming an operative bottom surface of said second thermoelectric layer (TE2) (23) placed atop said first thermoelectric layer (TE1);
o wherein, an operative top surface of said second thermoelectric layer (TE2) (23) becoming an operative bottom surface of said third thermoelectric layer (TE3) (24) placed atop said second thermoelectric layer (TE2) (23);
o wherein, said first thermoelectric layer (TE1) and said second thermoelectric layer (TE2) are thermally connected, to each other, by a shared oxide layer and are electrically connected to each other by a conducting element;
o wherein, said second thermoelectric layer (TE2) and said third thermoelectric layer (TE3) are thermally connected, to each other, by a shared oxide layer and are electrically connected to each other by a conducting element;
o wherein, p-type legs (12) and n-type legs (14) are provided with said first thermoelectric layer (TE1), said thermoelectric layer (TE2), and said third thermoelectric layer (TE3), these legs being electrically connected in series using a conducting element; and
o wherein, a thermally conductive adhesive (25) coating said operative top layer of said third thermoelectric layer (TE3) on its operative top surface, said adhesive layer ensuring thermal contact between said third thermoelectric layer (TE3) and said Photovoltaic (PV) layer but electrical contact between said two layers being established using conducting elements.

2. The hybrid energy system as claimed in claim 1 wherein, said one or more middle layers being three layers of middle layers, each layer being a cascaded thermoelectric layer.

3. The hybrid energy system as claimed in claim 1 wherein, said bottom layer being a porous sintered copper layer which holds water for direct evaporative cooling (EC).

4. The hybrid energy system as claimed in claim 1 wherein, said thermally conductive adhesive or gel (21) having coating thickness of 0.5 mm and thermal conductivity of 1.15 Wm-1K-1.

5. The hybrid energy system as claimed in claim 1 wherein, said operative bottom surface of said first thermoelectric layer (TE1) being made of thermally conducting but electrically insulating oxide layer.

6. The hybrid energy system as claimed in claim 1 wherein, each of said middle layers being a thermally resisting layer imposing thermal resistance of 8.0675KW-1

7. The hybrid energy system as claimed in claim 1 wherein, said operative top layer is a Pc-Si layer having temperature coefficient equal to 0.38%/°C with a working temperature up to 85°C.

8. The hybrid energy system as claimed in claim 1 wherein, each of said operative middle layers being fabricated from p-type and n-type bismuth telluride.

9. The hybrid energy system as claimed in claim 1 wherein, said operative bottom layer comprising a porous layer connected to a water reservoir, continuous supply of water to the porous layer is ensured through thermal siphoned effect.

10. The hybrid energy system as claimed in claim 1 wherein, said first thermoelectric layer (TE1), said second thermoelectric layer (TE2), and said third thermoelectric layer (TE3) being connected to each other in series.

Dated this 01st day of April, 2022

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