In some examples, the disclosure relates to solar panels that convert sunlight into electricity. In some examples, the solar panels described herein are constructed to mitigate solar panel heating, to reduce wind loading, and to reduce the environmental impact at the solar panel’s end of life.
Solar power is more affordable, accessible, and prevalent than ever before. In the U.S., installations have grown 35-fold since 2008 to an estimated 62.5 gigawatts (GW) today. This is enough capacity to power the equivalent of 12 million average American homes. Since the beginning of 2014, the average cost of solar photovoltaic (PV) panels has dropped nearly 50%.
The expected growth in solar over the years of 2019 to 2024 is expected to exceed 70 GW, and will be dominated by commercial and industrial applications. This is because economies of scale combined with better alignment of PV panel supply and electricity demand enable more self-consumption and bigger savings on electricity bills in the commercial and industrial sectors. As a result, millions of solar panels each year will be manufactured and installed at large solar farms all over the world. The average service life of solar panels is about 20 to 25 years.
There are four persistent, major, technical, and environmental problems with conventional solar panels.
The first problem is that solar farms destroy environments, lands, and ecological systems. Large scale conventional solar farms using conventional solar panels occupy millions of acres of flat land, forest lands, desert lands, grasslands, and farmlands. Builders of large-scale solar farms cut trees in forests, bulldoze lands, and destroy flora and fauna of vast areas of natural green lands. Damaged ‘bare’ land without trees and vegetation cannot absorb and hold waters from heavy rains. The damaged lands may contribute to massive and uncontrollable floods and landslides. Economically active and fertile farmlands are destroyed for large-scale solar farms.
The second problem is that at end of life, these millions of solar panels are discarded into landfills. The service life of a modern solar panel is about 20 to 25 years. Each year, many millions of large pieces of expired solar panels are discarded somewhere on land. A solar panel is mostly made of non-degrading and non-decomposing materials. When these expired solar panels are buried under ground, the large solar panels block flow of underground water and diffusion of oxygen in soils, kill underground flora and fauna, and pollute underground water with traces of harmful chemicals which leak from expired (and often physically broken) solar panels. Some embodiments of the invention disclosed herein incorporate materials that are readily recyclable and need not find their way into massive landfills.
The third problem is the high temperature of conventional solar cells. Solar cell efficiency is the electrical power delivered by a solar cell divided by the product of the solar irradiance (the power of the sunlight incident on the solar cell) times the area of the cell. Commercially available solar modules are only about 20% efficient in converting sunlight into electricity. That means that 80% of the energy of the incident sunlight is converted to heat. The only heat dissipation mechanisms for a conventional panel are the transfer of heat from the Tedlar backing and the glass front of the panel to air. The thermal conductivity of glass is only 1.7 W/(mK) and that of Tedlar is only 0.16 W/(mK). This results in solar panels getting very hot. Even in subzero ambient temperature below 0° C., the temperature on a solar panel can rise to above 50° C. in strong sunlight. During the hot summer season in tropical regions where the ambient temperature goes up to about 40° C., the temperature on the solar panel rises to 80° C. or even more. It is well known that efficiency of a solar panel reduces as much as 30% at 85° C. as compared to its efficiency at 25° C. In addition, the heat damage the photovoltaic silicon wafers, irreversibly shortens the service life of the solar panels by several years. On a windless, hot, and clear-sky day, thousands of densely packed solar panels of a large-scale solar farm will generate a huge amount heat, and the heat will raise the air temperature of the solar farm. This rise in the air temperature can cause damage to flora and fauna on the ground of the solar farm and its surroundings.
As described further below, some examples of the solar panels disclosed herein mitigate the heat dissipation problem, by transferring the heat generated by solar cells to a heat dissipating backsheet. The backsheet forms a pan that holds a plurality of solar cells that are electrically insulated from the backsheet while still permitting heat transfer. Such a solar panel module may be referred to herein as an “YK-Module.”
YK-Modules are attached to a heat dissipating frame that maintains an empty space between adjacent YK-modules. The space permits the free flow of air, rain, snow, particulates, and sunlight through the array of YK-modules in a direction substantially perpendicular to the plane of the YK-modules. An array of YK-Modules may be referred to herein as an “YK-Panel.”
YK-Panels can be connected to one another to form arrays with spaces between adjacent YK-Panels (analogous with the spaces between YK-Modules within the YK-Panels). The spaces between YK-Panels permit the free flow of air, rain, snow, particulates, and sunlight through the array of YK-Panels in a direction substantially perpendicular to the plane of the YK-Panels.
A fourth problem with conventional solar panels is wind resistance which results in a major stress for the land area that must be used for large-scale solar farms. Modern conventional solar panels are large, e.g., occupying two to several square meters. These large and flat solar panels are typically installed about 1 to 2 meters above the ground. Due to the immense wind pressure (wind load) these large flat solar panels may receive in a strong gusty wind (e.g., 30 meter per second or more of wind speed), these large solar panels cannot practically be installed higher above the ground. Therefore, the land under solar panels cannot be economically used for other purposes. For the same reason, these large solar panels cannot be installed well above treetops of a forest. Accordingly, one must cut down trees of forest and bulldoze the land in order to build a solar farm. Moreover, many lands such as farmlands, land along riverbanks, narrow and long land along highways, and steep hills of mountains cannot be used for conventional solar farms. In summary, construction of large solar farms destroys large areas of environmentally important or economically producing farmlands or ranches. In a country that is covered over 70% with mountains, flat lands are precious.
Some examples of the solar panels described herein mitigate the wind resistance problems described above by introducing porosity to the panel (open spaces within the panel). The porosity permits the free flow of air, rain, and sunlight through the panel. The flow of air dramatically reduces the wind resistance allowing the panel to be installed substantially above ground level, freeing the land under the panels to be used for other purposes. Additional benefits are that rain and sunlight can reach the ground under the panels to sustain plant and animal life without the permanent environmental damage associated with the implementation of traditional solar panels in solar energy farms.
In one aspect, this disclose is directed to solar panel system (“YK-Panel”) configured to convert sunlight to electrical energy. The YK-Panel includes two or more YK-Modules. Each YK-Module of the two or more YK-Modules includes a tray comprising a heat-conductive substrate and a solar cell assembly contained within the tray. The solar cell assembly includes: (i) a solar cell, (ii) an encapsulant, and (iii) a transparent cover. The solar cell is contained within the encapsulant. A bottom surface of the encapsulant faces the tray and a top surface of the encapsulant faces the cover. The YK-Panel also includes a frame assembly attached to each tray of the two or more YK-Modules to provide structural support to the two or more YK-Modules. Open space is defined between adjacent YK-Modules of the two or more YK-Modules.
Such a YK-Panel may optionally include one or more of the following features. The open space may total at least 10% of a total area of the YK-Panel. The open space may total at least 20% of a total area of the YK-Panel. The open space may total 10% to 30% of a total area of the YK-Panel. The YK-Panel may also include one or more interconnectors extending laterally from each tray of the two or more YK-Modules. The one or more interconnectors may connect adjacent trays of the two or more YK-Modules. The frame may include multiple ribs that interlock with each other and with the two or more YK-Modules. The multiple ribs may include tabs that extend through respective slots defined by each tray of two or more YK-Modules. In some embodiments, the two or more YK-Modules may comprise twenty-four YK-Modules.
This disclosure is also directed to a solar farm system comprising a plurality of the YK-Panels. In some embodiments, the two or more of the YK-Panels are elevated at least three meters above ground level. In some embodiments, the two or more of the YK-Panels are elevated at least five meters above the ground level.
The solar panel systems described herein address the above-described four major problems associated with large solar farms of conventional solar panels. The solar panel systems described herein can use existing photovoltaic materials such as silicon wafers, and new photovoltaic materials can be incorporated into new types of solar modules and solar panels so that the new solar modules and solar panels will become instruments for solution of the four major problems. For convenience, we will call the newly invented solar modules described herein, “YK-Modules,” and the newly invented solar panels described herein, “YK-Panels.”
The YK-Panel includes an array of two or more YK-Modules. In some embodiments, each YK-Module is a single solar cell comprised of a heat-conductive substrate that is designed to contain or otherwise support solar cells, such as silicon wafers, and other requisite materials that convert sunlight into electricity. The YK-Module is designed to be attached to a frame that can support a plurality of YK-Modules. Such a plurality of YK-Modules are electrically interconnected one to another to form a YK-Panel. The electrical interconnections of the YK-Modules in the YK-Panel form a circuit that can deliver electricity from the YK-Panel to provide power to an external load.
A first example embodiment is shown in
Each tray 101 contains one crystalline silicon wafer 106 capable of converting sunlight into electricity. A unique feature of this YK-Panel 100 is that the YK-Modules 110 are separated from one another by empty/open space gaps 104 that permit the free flow of air (wind), sunlight, and water (e.g., rainwater) through the YK-Panel 100 in a direction substantially perpendicular to the plane of the YK-Panel 100.
Individual solar cells that are contained in the YK-Modules 110 are electrically connected to one another by electrical conductors supported by the YK-Module interconnectors 102 shown in
A second example embodiment of the solar panel systems described herein is shown in
In some embodiments, the photovoltaic cells 502 are electrically connected to one another (electrical connection not shown) by a standard tabbing and stringing circuit common to the solar energy industry. In this particular example, the edges of the top surface of the heat-conductive substrate 501 are raised to provide a dish to hold photovoltaic cells and other materials required to form a working solar module.
Electrical connections between the YK-Modules 500 are established through the channels 603 that culminate in a junction box 604. The YK-Panel 600 is connected to other YK-Panels or to an electrical load by means of the junction box 604.
The frame 601 both supports the YK-Modules 500 and provides a ribbed structure with a large-surface-area that can transfer heat from the YK-Modules 500 to the surrounding atmosphere. The design pays special attention to providing structures for large heat dissipation of the YK-Panel 600 via to the large surface areas of both the heat conducting substrate of the YK-Module 500 and to the material of the frame 601.
In
In some embodiments of the YK-Panels 100/300/600 described above, the heat conductive substrate of the tray and/or frame is aluminum that has a thickness of 0.5 mm to 2 mm. The choice of aluminum and the thickness thereof are not limiting. That is, other materials and other thicknesses of materials may be used. For example, the substrate may be a heat conductive metal such as copper, steel, titanium, or magnesium. Moreover, the substrate need not be a metal at all, it could be chosen to be a polymer such as a polyester, or acrylic that is appropriately filled with a ceramic material such as boron nitride or aluminum nitride to enhance the thermal conductivity. The choice of material for the substrate and its thickness may require trade-offs in the thermal conductivity versus other factors such as electrical resistance, strength and weight. Such considerations will need to be considered depending on the specifications for the final product.
In some embodiments described herein, the photovoltaic cells are single crystal silicon wafers, but this choice is not limiting. Other choices for photovoltaic cells include, but are not limited to, amorphous silicon wafers, thin film constructions, CdTe, or perovskite materials. Any type of photovoltaic cell appropriate to the final application can be used.
In some embodiments, the encapsulant used is EVA (Ethyl Vinyl Acetate), but other types of encapsulating materials such as silicone rubber, polyurethanes, or epoxies can also be used. The electrical insulator is an optional component of the construction. If the encapsulant is something like EVA that has only a moderate electrical resistance, an insulator such as fiberglass, nylon, polyimide, a ceramic-filled polyester, or a ceramic-filled acrylic. These choices are not limiting to the scope of the disclosure. For a ceramic-filled plastic as the insulator, materials such as boron nitride or aluminum nitride can be used as the filler ceramic. The insulator should be chosen to have high electrical resistance but also be a good heat conductor. The above-mentioned materials have those characteristics.
The unique features of the YK-Modules and YK-Panels described herein address the four problems associated with conventional solar panels mentioned above. For example, the photovoltaic silicon wafer (or other photovoltaic materials) is encapsulated in a flat and shallow tray made of aluminum sheet (or metal alloy sheet). As shown in
Another unique feature of the YK-Modules and YK-Panels described herein is that the YK-Modules are attached to the aluminum (or metal alloy) frame of YK-Panel in such a way that each YK-Module is separated from its neighboring YK-Modules with empty gaps between them. The empty gaps let air, rainwater, and sunlight pass through the YK-Panel. For example,
These unique features of the YK-Modules and YK-Panels can address the four problems described above that are associated with conventional solar panels as follows.
The first problem (the destruction of environments, lands, and ecological systems) and the fourth problem (wind resistance or loading) are strongly tied to one another. Traditional solar panels are large flat panels that must bear immense wind pressure in strong and gusty winds. To prevent the panels from being destroyed, the panels are typically mounted within one or two meters of the ground surface. Unfortunately, the close proximity of the panels to the ground in the solar farms and the fact that rain, sunlight, and gentle breezes cannot reach the ground beneath the conventional solar panels causes permanent damage to the land underneath the panels. Builders of solar farms cut trees, bulldoze land, and destroy flora and fauna to install the panels for a solar farm. As a result, the land under the panels cannot be used for agricultural or commercial purposes. Ultimately, the land is destroyed by erosion, and by the growth of noxious weeds and undesirable insects and other animals.
The YK-Panels described herein mitigate the problems of wind resistance and ecological damage by allowing air, rain and sunlight to freely pass through YK-Panels via its empty gaps between adjacent YK-Modules.
Regarding wind loading, a conventional solar panel does not have any empty gaps (open space) and, therefore, wind cannot pass through it. The surface area of a conventional solar panel is several square meters, and there are no holes or empty gaps in conventional solar panels, through which air can pass. Therefore, the total force that wind pressure (wind load) exerts on a large conventional solar panel in a strong gusty wind (e.g., 30 meters per second of wind speed) is very large (e.g., on the order of several hundred to a few thousand kilograms). Wind load on a YK-Panel with its empty gaps which cover about 10% to 30% of the total surface of the YK-Panel is significantly less than the wind load on a conventional solar panel of the same size. The fraction of total area represented by the gaps or open space is called “porosity.”
A number of wind tunnel studies conducted on porous plates (such as shown in
It can be assumed that a large plate such as a radar antenna that has many uniformly distributed holes through which air can pass is representative of the effect of wind loads on the YK-Panels described herein.
If the percentage of empty gaps of the YK-Panels described herein is made larger than 30%, the mechanical/structural integrity of the aluminum frame may become too weak. The percentage of total area of empty gaps (% of porosity) of the YK-Panels described herein is in the range of 10% ~ 30%. The actual percentage of porosity of particular YK-Panels can be selected depending on the average wind speed and annual weather patterns of a geographic region where the particular YK-Panels will be installed.
The drastically lower wind load on YK-Panels compared to conventional solar panels allows YK-Panels to be installed several meters (3 meters or higher) above the ground.
When the YK-Panels are installed sufficiently above ground level, people and/or vehicles can move around freely under the installed YK-Panels. This concept is depicted in
It is difficult to install conventional large solar panels high above the ground (e.g., at a height of 3 meters or higher) due to the immense wind load on the conventional large solar panels in strong wind. It is anticipated that the wind load on a conventional solar panel of 2 meter-square of surface area may be about 30 times more than wind load on a YK-Panel of the same surface area in the same wind speed of about 30 meters per second.
The porosity of YK-Panels not only allows wind to pass through the YK-Panel, but it allows sunlight and rainwater to pass through the YK-Panel as well. This advantageously enables the construction of solar farms with HelioTowers of YK-Panels on economically active farmlands. The farmlands stay as economically productive farmlands, and at the same time are a solar farm to produce electricity from sunlight. That is, the land can be used doubly as farmland and as a solar farm. There are many millions of acres of farmlands in the US which are ideal places for construction of solar farms with H-Type or T-Type HelioTowers of YK-Panels. Construction of solar farms with H-Type or T-Type HelioTowers of YK-Panels will not damage the environment and ecology of the land.
The YK-Modules described herein also mitigate or solve the third problem (the high temperature of conventional solar cells). Temperatures of conventional solar panel rises high above ambient temperature under strong sunlight. Temperatures of YK-Modules under the same strong sunlight are significantly lower than conventional solar modules or solar panels. The surfaces of the YK-Modules are covered with heat-conductive aluminum (or metal alloy) except for the top sunlight receiving surface. In addition, there are empty gaps between neighboring YK-Modules in a YK-Panel. In some embodiments, YK-Module and YK-Panels are made of aluminum which has a very high thermal conductivity. This is because the aluminum removes heat of YK-Modules to the air far more efficiently that typical polymeric materials, such as Tedlar used for conventional solar panels. The empty gaps allow air pass through YK-Panel freely. Under strong sunlight, convective air flows through the empty gaps of YK-Panel remove heat from YK-Modules to the air highly efficiently. Conventional solar panels have no similar empty gaps and there is no convective air flow passing through conventional solar panels. In addition, the aluminum frames of the YK-Panels have a large surface area.
The combined effects of high thermal conductivity of the aluminum surfaces of the YK-Modules, the large surface area of aluminum frames of the YK-Panels, and the convective air flow through empty gaps on YK-Panel keep the temperature of YK-Module and YK-Panel significantly lower than the temperature on conventional solar panel under the same exposure to sunlight at the same ambient temperature.
In some embodiments, the YK-Modules and YK-Panels described herein can mitigate problem two described above by using recyclable materials. For example, the YK-Modules can be covered by aluminum sheet (or metal alloy sheet) entirely except its sunlight-receiving surface. In some embodiments, the YK-Panel has a 100% aluminum (or metal alloys) frame which holds a number of YK-Modules which are electrically connected. The aluminum of YK-Modules and YK-Panels are easily recovered or recycled after the service life of the YK-Modules and/or YK-Panels.
The top sunlight-receiving surface of a YK-Module is covered with solar glass plate. The glass plate is only slightly larger than typical size of a photovoltaic silicon wafer. The glass plates on each of YK-Modules can be easily removed from expired YK-Modules. The glass plates can be cleaned and reused for YK-Modules again. Therefore, most of the materials of the YK-Modules and YK-Panels (which are aluminum and solar glass plates, for example) can be easily recycled or reused. Therefore YK-Modules and YK-Panels will not create huge amounts of solid wastes like expired conventional solar panels. In this way, the YK-Modules and YK-Panels described herein solve or mitigate problem two described above.
The YK-Panel shown in
The devices, systems, materials, compounds, compositions, articles, and methods described herein may be understood by reference to the above detailed description of specific aspects of the disclosed subject matter. It is to be understood, however, that the aspects described above are not limited to specific devices, systems, methods, or specific agents, as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.
A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the claim scope here. Accordingly, other embodiments are within the scope of the following claims.
This application claims the benefit of U.S. Provisional Application Serial No. 62/968,460, filed Jan. 31, 2020, and U.S. Provisional Application Serial No. 63/062,866, filed Aug. 7, 2020. The disclosures of the prior applications are considered part of (and are incorporated by reference in) the disclosure of this application.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/US2021/015373 | 1/28/2021 | WO |
Number | Date | Country | |
---|---|---|---|
62968460 | Jan 2020 | US | |
63062866 | Aug 2020 | US |