Photovoltaic array module design for solar electric power generation systems

Photovoltaic array module design for solar power generation system

The present invention relates to a thin film multi-junction photovoltaic array module of a solar power concentrator power system.

In the 1990s, most photovoltaic devices with flat silicon photoelectric semiconductor chips produced electricity with a conversion efficiency of 15% to 18% of commercial systems. Since then, the energy and PV manufacturing industries have substantially improved thin-film and multi-junction optoelectronic semiconductor wafers. In 1999, Spectrolab produced a new three-junction optoelectronic semiconductor chip with a commercial efficiency of 34%.

The cost of the new three-junction optoelectronic semiconductor wafer is much higher than that of the traditional optoelectronic semiconductor wafer, so that it is impossible to design a photovoltaic device with a flat panel as a solar receiver that generates electricity.

US Patent No. 5,505,789 to Fraas et al. discloses a linear focus photovoltaic module that uses a solid secondary light element to improve radiation resistance. This invention consists of a linear arched Fresnel lens array with linear photovoltaic cell receivers arranged along the focal line of each lens. The secondary optical element can be parabolic in shape.

The system of the present invention discloses a combination of a Fresnel lens and a parabolic cylindrical mirror. More specifically, they disclose a combination of two or more Fresnel lenses, a compound parabolic cylindrical reflector with an optical collecting glass lens, and a multi-junction optoelectronic semiconductor chip for photovoltaic energy conversion.

Summary of the invention

Design a low-cost, high-efficiency concentrator, which will couple with a smaller area of an expensive optoelectronic semiconductor chip by point focusing. The solar power concentrator is a combination of Fresnel lens and reflector, which can concentrate solar energy 300 to 1000 times within a distance of six inches. The solar power concentrator can be made of low-cost traditional materials, and because its point focusing requires a small area of expensive solar cells, it replaces most of the module surface area.

The invention relates to a thin film multi-junction photovoltaic array module of a solar power generation system. The high-performance photovoltaic (PV) array module has a multi-junction concentrating solar photovoltaic semiconductor chip that converts the received solar energy into electricity.

Photovoltaic optoelectronic semiconductor chips are semiconductor devices that directly convert sunlight into electricity through the photovoltaic effect. One of the important developments in PV applications is to directly convert sunlight into electricity more efficiently through the design of PV array modules, thereby reducing system costs.

The PV array module includes multi-stage solar energy collection with Fresnel lens, CPC reflector and glass lens with a specific shape, which can be used in the system with a smaller multi-junction concentrating solar photovoltaic semiconductor chip. Surface area manufacturing. Solar high-energy-concentration and high-efficiency multi-junction optoelectronic semiconductor chips are important factors in reducing the cost of PV array modules that generate electricity.

The condenser has one or two Fresnel lenses that concentrate sunlight. The second Fresnel lens refracts incoming light by an increased 30°. This larger refraction increases the useful time of the system by four hours. In an embodiment with a two-Fresnel lens, the CPC will also be re-adjusted so that it takes more than eight hours a day to capture the direct sunlight irradiated by the sun. In a system with a Fresnel lens, a photovoltaic module tracking device that follows the sun is useful, but in a solar power system with two Fresnel lenses, the photovoltaic module tracking device may not be used . The total cost of solar power systems can be reduced by 30%. Therefore, it is possible to install low-cost, high-efficiency fixed-energy-collecting photovoltaic solar power generation systems on the roofs or fixed frames of buildings commercially and connect them to the public-scale power grid.

Detailed description of the preferred embodiment

Referring to the drawings, particularly FIGS. 1a and 1b, a fixed built-in PV concentrator 10 is shown, which includes a first optical energy device 11 for focusing sunlight. The second condenser 12 is disposed under the first condenser 11. The third condenser 13 is arranged at the second condenser. The fourth condenser 14 is a glass lens with a special shape, and is arranged at the bottom of the third condenser 13. The concentrating solar photovoltaic semiconductor chip 22 is disposed under the fourth concentrator 14. The fourth concentrator 14 will focus the light to 1000 times the original solar isolation. In addition, the concentrating solar photovoltaic semiconductor wafer 22 can provide 45% conversion efficiency with a four-junction solar photovoltaic semiconductor wafer. The fluid flowing through the radiator 18 is heated by the concentrating solar photovoltaic semiconductor wafer 22.

In a preferred embodiment, the concentrating solar photovoltaic semiconductor wafer 22 includes a GaInP/GaInAs or GaAs concentrating solar photovoltaic semiconductor wafer connected in series. Moreover, in a preferred embodiment, the first condenser 11 is a Fresnel lens, the second condenser 12 is a Fresnel lens, and the third condenser 13 is a compound parabolic condenser. The fourth condenser 14 is an optical energy-collecting glass lens, which has one of three different possible shapes suitable for different applications.

The second Fresnel lens refracts incoming light by an increased 30°. This larger refraction increases the useful time of the system by four hours. Therefore, the system does not need to use tracking devices and can collect solar energy eight hours a day. The system uses birefringence to efficiently meet its own power requirements. The light will converge at the normal incident focal point 17, below the second condenser 12, which is the second Fresnel lens.

The third condenser 13 is made of a glass mirror containing a reflective surface coating and several layers of protective materials. The reflective surface coating can also be aluminum foil or chrome-coated metal plate.

The third condenser 13 is made of a ceramic material with a glass mirror, and the glass mirror has a silver reflective coating covered by several layers of protective materials. The ceramic pad is used to mount the third concentrator 13 to the concentrator structure with a special adhesive. The protective material reduces the thermal stress at high operating temperatures.

In FIG. 1c, the solar power concentrator 10 is shown as having a first concentrator, a third concentrator 13, and a fourth concentrator 14. This embodiment does not include the second Fresnel lens or the second condenser 12. The light converges at the abnormal incident focal point 19 below the first condenser 11, which is a first Fresnel lens. In a system including a tracking system, an embodiment without a second Fresnel lens is preferably used. For systems that include a second Fresnel lens, no tracking system is required. The system with a single Fresnel lens can be applied to all other embodiments with two Fresnel lenses shown and described in this application.

In another embodiment shown in FIGS. 2a and 2b, the concentrating solar photovoltaic semiconductor wafer 24 includes a photovoltaic film multi-junction concentrating unit. In FIGS. 3a and 3b, the solar power concentrator 10 includes a first condenser 11, a second condenser 12, a third condenser 13, a fourth condenser 14, and an optical fiber 30. The photovoltaic concentrating solar photovoltaic semiconductor chip 26 is arranged under the optical fiber 30. In Figure 3b, the fourth condenser 14 is a glass lens with an anti-reflection coating, connected to an optical fiber 30 with a diameter of less than 3nm, and the optical fiber 30 is connected to a high-efficiency multi-junction concentrator with an energy collection rate of 500 times that of normal sunlight. Type solar photovoltaic semiconductor wafer 26 above.

The function of the device is as follows: The focused sunlight from the first and second condensers 11, 12 will pass through the wider aperture of the third condenser 13 (ie, compound parabolic concentrator (CPC)) (Open upwards). Therefore, even if the parabolic energy collection is not positioned perpendicular to the sunlight, the edge of the circle around the light still allows the maximum amount of sunlight to be concentrated. The focused sunlight will be continuously reflected by the CPC mirror and focused on the bottom of the CPC 13 again, like a three-dimensional halo similar to a doughnut.

In order to further tune and concentrate the light ring, three different shapes of solid glass lenses (lenses with optical fibers) are used as the third condensers 22, 24, and 26.

First, as shown in FIG. 1b, the glass lens 14 located at the bottom of the third condenser 13 has a brassiere-shaped cross-section. The cross-sectional view of the focused light is similar to a crab eye, located on both sides of the base of the CPC 13 cross-section. The cross section of the glass lens 14 is used to tune the light ring and concentrate the incoming light to 1000 times the normal sunlight intensity behind the Fresnel and CPC lens. The light then hits the multi-junction concentrating solar photovoltaic semiconductor wafer 22. The brassiere lens 14 is coated with an anti-reflection coating.

Second, as shown in FIG. 2b, where the solar photovoltaic semiconductor wafer requires less luminosity, a crescent-shaped glass lens can be used as the fourth concentrator 14. This glass lens has a profile similar to a crescent moon. The lens has a convex, upward surface that has a greater curvature than a concave, downward surface. The lens is also coated with an anti-reflective coating.

Third, as shown in Fig. 3b, a small hemispherical solid glass lens can be used, which has a concave upward surface and a flat downward surface. It will be connected to the short length of the optical fiber 30 (less than three diameters, with D<3 mm). At the bottom of the optical fiber 30, the focused light passes through the optical fiber 30 and impinges on the multi-junction solar photovoltaic semiconductor wafer 26 of the concentrator. The lens 14 will also be coated with an anti-reflective coating.

FIG. 4 shows a condenser structure 10 with a first Fresnel lens 11, which is arranged on the second Fresnel lens 12, and the Fresnel lens 12 is arranged above the compound parabolic condenser 14. Fresnel lenses 11 and 12 concentrate the intensity of sunlight. The focused sunlight will be further concentrated 20 to 50 times by the compound parabolic concentrator 14. The enhanced sunlight will be focused on the CPC 13 with the heat exchanger 16. The fluid 18 will flow through the heat exchanger 16 and be heated by the generated energy-collected solar energy and the pressure will increase.

The heat exchanger 16 is configured to be adjacent to the bottom of the CPC 14 and includes a cermet coating of a mixture of ceramic and stainless steel. The cermet coating provides greater heat exchange characteristics with a solar radiation absorption rate of 96%. The cooked heat exchanger can also be designed as a honeycomb type porous metal staggered flow path solar thermal receiver as shown in FIG. 5.

Therefore, although several embodiments of the present invention have been shown and described, it is obvious that many changes and modifications can be made without departing from the spirit and scope of the invention.

<p>10. . . Photovoltaic Concentrator</p><p>11. . . First condenser</p><p>12. . . Second condenser</p><p>13. . . Third concentrator</p><p>14. . . Fourth condenser</p><p>16. . . Heat exchanger</p><p>17. . . Normal incident focal point</p><p>18. . . fluid</p><p>19. . . Abnormal incident focal point</p><p>twenty two. . . Concentrating solar photovoltaic semiconductor wafer</p><p>twenty four. . . Concentrating solar photovoltaic semiconductor wafer</p><p>26. . . Photovoltaic concentrating solar photovoltaic semiconductor wafer</p><p>30. . . optical fiber</p>

From the above detailed description with the accompanying drawings, other objects and features of the present invention can be better understood. However, it should be understood that the drawings are only for illustrative purposes and not for limitation of the invention.

In the diagrams, similar codes in several figures represent similar elements:

Figure 1a shows a solar power concentrator system with a photovoltaic four-junction concentrating solar photovoltaic semiconductor chip with 1000 times the solar intensity energy collection;

Figure 1b shows the AA cross-sectional view of Figure 1a;

Figure 1c shows the solar power concentrator system of Figure 1a with a single Fresnel lens;

Fig. 2a shows the solar power concentrator of Fig. 2b, which has a photovoltaic film multi-junction concentrating solar photovoltaic semiconductor wafer with 400 times the solar energy intensity;

Figure 2b shows the BB cross-sectional view of Figure 2a;

Figure 3a shows another embodiment of a solar power concentrator with optical fiber and photovoltaic concentrator solar photovoltaic semiconductor chip;

Figure 3b shows the CC cross-sectional view of Figure 3a;

Figure 4 shows a solar power concentrator with a heating tube solar thermal receiver;

Figure 5 shows a solar thermal receiver with honeycomb porous metal staggered flow paths.