Claims:We claim
1. A hybrid energy harvesting system with improved solar efficiency comprises:
a) a photovoltaic (PV) cell (120);
b) a first solar irradiation concentrator (110) placed on the photovoltaic (PV) cell (120);
c) an array of Thermoelectric generators (140);
d) a second solar irradiation concentrator (130) placed on the array of Thermoelectric generators;
e) a heat sink (150); and
f) an array of water circulating copper tubes (160) which are placed in the heat sink.
2. The photovoltaic cell (120) according to claim 1 consists of different materials, ranging from monocrystalline, polycrystalline silicon.
3. The Thermoelectric generators (140) according to claim 1 are electrically connected in series.
4. The array of Thermoelectric generators (140) according to claim 1 is placed beneath the base of the photovoltaic (120) cell to trap the maximum available energy of the sun.
5. The Thermoelectric generators (140) according to claim 1 are selected semiconductor materials such as Bismuth Telluride, Bi2Te3 and lead telluride, PbTe.
6. The first irradiating concentrator (10) and the second irradiating concentrator (130) according to claim 1 is selected from an anti-reflecting glass.
7. The Thermocouple generators (140) according to claim 1 is disposed of between the Photovoltaic cell and the heat sink.
8. The method for energy harvesting with improved solar efficiency, the method comprising: the first solar irradiation concentrator (110) collects the sunlight and helps the light to concentrate on the photovoltaic cell (120); the photovoltaic cell (120) converts a part of incident light into electricity; the generated waste or excess heat is further concentrated on the second solar irradiation concentrator (130) and passes the heat on to the array of Thermoelectric generators (140) which are connected electrically in series; the Thermoelectric generators (140) are placed on the heat sink (150); an array of water circulating copper tubes (160) are placed in the heat sink along its width to facilitate faster cooling; the Thermoelectric generators (140) utilize the Seebeck effect to generate voltage; the excess heat is converted into electricity. , Description:DETAILED DESCRIPTION OF THE INVENTION
Fig. 1 illustrates a schematic of the overall hybrid energy harvesting system. The system according to the present invention consists of a photovoltaic (PV) cell (120), a first solar irradiation concentrator (110) placed on the photovoltaic cell (120), an array of Thermoelectric generators (140), a second solar irradiation concentrator (130) placed on the array of Thermoelectric generators, a heat sink (150) and an array of water circulating copper tubes (160) which are placed in the heat sink (150). The solar irradiation concentrator further consists of a set of a mosaic set of mirrors. A large proportion of solar energy is converted to waste heat in a photovoltaic (PV) cell, due to thermalization of excited, high energy electrons and absorption of low energy photons, raising the temperature of the photovoltaic cell. The photovoltaic cell (120) is made of different materials, ranging from monocrystalline, polycrystalline silicon. The system consists of an array of Thermoelectric generators (140) which are connected electrically in series. The Thermoelectric generators (140) placed beneath the base of the photovoltaic cell (120) to trap the maximum available energy of the sun. Thermoelectric generators (140) are selected semiconductor materials such as Bismuth Telluride, Bi2Te3 and lead telluride, PbTe. The First irradiating concentrator (110) and the second irradiating concentrator (130) are selected from an anti-reflecting glass. The Thermocouple generators (140) according to the present invention is disposed of between the Photovoltaic cell (120) and the heat sink (150). Thermoelectric generators (140) are placed on the heat sink (150). An array of water circulating copper tubes (160) is placed in the heat sink along its width to facilitate faster cooling.
Fig 2 illustrates a schematic of the Thermoelectric generator (140). A thermoelectric generator (140) according to the current invention is used to convert heat energy directly into electrical energy. A thermoelectric generator (140) is used to capture waste heat energy from the ambient. The Thermoelectric generator (140) in this system is SP-1848 27145 which is based on bismuth telluride (Bi2Te3). This type of Thermoelectric generator (140) can hold out at a maximum temperature of 200oC. The Thermoelectric generator (140) consists of upper and lower substrates (141) made of ceramic material. It further consists of several p-type semiconductors (143) and n-type semiconductor (144) and these thermo-elements are connected in series by highly conducting metal strips (142) and sandwiched between two ceramic plates (143). Due to the properties of semiconductors, p-type (143) and n-type (144) have Seebeck coefficients of opposing signs. These semiconductors are connected using positive terminal (145) and negative terminals (146). When DC is passed through the Thermoelectric generator (140), heat is absorbed in the cold side junction (147) and heat is released at the hot side junction (148). The cold side is cooled by air or water. Heat exchangers (not shown in the figure) are used on both sides of the modules to supply this heating and cooling. The hot side junction (148) of the Thermoelectric Generator (140) at midday has a temperature of around 200°C, and the cold side is approximately 50°C. The cooling system was designed to absorb the heat passing through the array of Thermoelectric generator (140) and provide optimal working conditions. The system according to the present invention generates 20 W of electrical energy and 200 W of thermal energy stored in water with a temperature of around 50°C. The cooling capacity scales are directly proportional to the number of Thermoelectric generators in the system. These Thermoelectric generators (140) can be connected electrically in parallel or series-parallel to reduce the electrical resistance of the module.
Fig. 3 illustrates the method (200) of working of hybrid energy harvesting system (100). The system according to the present invention consists of a first solar irradiation concentrator (110) which is placed above the photovoltaic cell (120) of the system. The solar irradiation concentrator further consists of a set of a mosaic set of mirrors. The first solar irradiation concentrator (110) collects the sun lights and helps the light to concentrate on the photovoltaic cell (120). The photovoltaic cell (120) which is made of semiconductor materials absorb the photons emitted by the sun and generate a flow of electrons thus converting a part of incident light (photon energy (hγ) ≥ energy gap (Eg)) into electricity. The remaining part of light energy wasted in the form of heat. The generated heat is further concentrated on the second solar irradiation concentrator (130) and passes on to the array of Thermoelectric generators (140) which are connected electrically in series. The Thermoelectric generators (140) utilize the Seebeck effect to generate voltage. The heat is directed to the array of six Thermoelectric generators in which the thermal energy is partially converted into electricity. Thermoelectric generators (140) are placed on the heat sink (150). An array of water circulating copper tubes (160) is placed in the heat sink along its width to facilitate faster
cooling. Thermoelectric generators (140) are semiconductor-based solid-state thermocouple device consisting of p-type (143) and n-type (144) junction and generates the electrical energy by converting temperature differences of the cold and hot junction of the Thermoelectric generators (140) which is available in form of heat into voltage by using the Seebeck effect. Thus, the waste energy produced in the Photovoltaic cell (120) conversion is further processed in the array of Thermoelectric generators (140) and converts the remaining waste and un-utilized energy into electricity.