WO2010118038A1

WO2010118038A1 - Solar panel with lens and reflector

Info

Publication number: WO2010118038A1
Application number: PCT/US2010/030108
Authority: WO
Inventors: Donald S. Stern
Original assignee: Stern Donald S
Priority date: 2009-04-06
Filing date: 2010-04-06
Publication date: 2010-10-14

Abstract

Enclosed herein are embodiments of a design for a system to allow for a more efficient solar panel device to capture energy from solar radiation without having complex mechanical or positional sensitivity, and to use liquids for the capture and transportation of the captured energy to allow a low-pressure, high-temperature system that can be mounted almost anywhere and requires less maintenance than presently available systems.

Description

SOLAR PANEL WITH LENS AND REFLECTOR

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

[0001] The technical field of the invention involves low-cost solar panels offering enhanced efficiency in a solar thermal electrical system optimized to capture the broadest possible band of the solar energy spectrum without requiring complex mechanical positioning systems. The capture, storage and transmission of wide-spectrum solar energy provided by the present invention allows for a low-pressure, high-temperature system that can be mounted virtually anywhere and requires no tracking and significantly reduced mechanical maintenance.

DESCRIPTION OF THE RELATED ART

[0002] Solar panels are designed to capture the sun's energy. Two general types of solar capture designs exist in today's market - direct and reflective. One of the biggest problems with these conventional designs is that a significant portion of the incident light (and, therefore, energy) is reflected off of the various surfaces of these devices, where the amount of reflection (energy loss) is generally dependent on the angle of a given surface relative to the incident radiation. This angular dependence of reflective losses is what typically drives the need for these designs to use complex tracking and mechanical positioning systems to maximize the amount of radiation reaching the device normal to the collector surface. Most current panels also utilize a "sandwich" design with a glass or plastic surface that is responsible for a great deal of the reflective losses, significantly decreasing the overall energy conversion efficiency of such devices. To date, the highest reported energy conversion efficiency for a solar device coupled to a Stirling engine, achieved under highly specific conditions, was slightly more than 30%. Thus, the need clearly exists for more efficient solar collection/conversion designs. [0003] The majority of designs using direct radiation collection serve to focus the sun's energy directly on photovoltaic elements on the device's surface to directly generate electricity. To protect the electronic circuitry of the photovoltaic cells (which generally display a high sensitivity to environmental factors), a cover is used that, in addition to protecting the electronic components of the device, effectively acts to reflect and/or scatter a significant percentage of the light energy so that it never reaches the photovoltaic circuits.

[0004] The alternative, and most commonly used, solar collector design is a parabolic trough collector that channels incident energy through controlled reflection off of mirrored surfaces. These solar collectors are essentially composed of a flat box made up of a transparent cover, an insulated back plate, and tubes containing a liquid that is heated by the channeled incident radiation. Most have an internally mounted cylindrical geometry reflector that focuses the energy into a small-area element that is the primary target of the radiation. Many reflector systems focus the sun's energy into a tube or pipe that carries a liquid with appropriate properties rendering it capable of absorbing the focused radiant energy and, in turn, transforming that energy into other useful forms. In some designs, water serves as the direct absorber of the incident energy in which case the system may be designed to convert the water directly into steam. Generally, the steam is used to drive a turbine connected to a generator to create electricity. In the alternative, other heat transfer fluids may be used, in which case there may be additional heat transfer steps.

[0005] As with the direct design systems, these reflective systems also absorb some of the energy in the reflectors themselves, as well as other components of the design exposed to the direct and reflected radiation, causing the entire panel to experience a local increase in temperature. To protect the panel, a covering is usually added, but this covering can reflect a fairly large amount of energy away from the collector element, acting effectively in the same manner as a mirrored surface, but without contributing to net energy collection and/or conversion.

[0006] The efficiency of an energy capture system is generally measured in terms of the surface area of the panel relative to the amount of electricity that it is capable of producing.

[0007] Most currently available systems are, generally, position sensitive so that some mechanism must be utilized to insure that the maximum amount of sunlight strikes the collector surface(s) of the panel at an ideal angle of incidence while minimizing the amount of primary radiation lost to reflection and related optical phenomena. This is typically done using a motorized tracking system that moves, according to a pre-programmed, computer- controlled motion profile (based on data such as geographic position (latitude), and time of day and year), so that the panels always face the sun at an optimal attitude.

[0008] A number of systems in the art have used optical lens constructs to attempt to more effectively focus the incident light energy on appropriate collector elements. These systems use a basic monochromatic approach in that they are optimized for only a small frequency band from the normal solar spectrum, as incident radiation is focused onto a narrow slit or a heated element. These systems generally fail to consider wavelength- dependent effects (such as refraction) and the variation of focal length of a given lens as a function of the different frequencies comprising solar radiation. In addition, many patented designs for panels of this sort use vacuum interfaces between components in order to limit the radiation losses that occur with the heated collector element re-radiating the captured energy at angles where the secondary radiation cannot be captured effectively. These designs are only partially successful at their stated design purposes while, at the same time, significantly increasing the complexity of the structure, the manufacturing costs, and the level of maintenance required to keep the vacuum elements functioning as necessary and desired. SUMMARY OF THE INVENTION

[0009] According to one aspect of the present invention, there is provided a system for the collection of solar radiation, ideally in a process for the conversion of the radiation to alternative forms of energy, wherein the system comprises one or more collector housings; a plurality of lens elements, wherein the lens elements comprise a semi-circular cross-section, a concave inner surface, and a convex outer surface, wherein the plurality of lens elements are generally cylindrical in shape, wherein the plurality of lens elements are arranged in a parallel layout along their long axis and in close spatial proximity to each other creating an array of lens elements, and wherein the array of lens elements comprises an outer surface or external cover for the collector housing; a plurality of energy capture elements arrayed in a one-to-one relationship with the lens elements, concentric with the lens elements, and parallel along their long axis with a long axis of the lens elements; a thermal transfer fluid within the energy capture elements in fluid communication with systems ancillary to the collection system ideally for conversion of captured solar energy to other forms of energy; and a curved reflective surface for each lens element disposed within the housing obverse to the lens elements, substantially parallel therewith and further disposed distal to the energy capture element. Preferably, the configuration and geometry of the lens elements are optimized through use of computer programs or digitally implemented algorithms. [0010] In this embodiment, the lens elements are comprised of one or more materials selected from the group consisting of glass, quartz and plastic. Alternatively, the lens elements are constructed with a plurality of layers. An added option for this embodiment comprises lens elements that comprise two or more lenses.

[0011] In an additional embodiment of the invention, the energy capture elements are cylindrical pipes located obverse to an underside of the lens elements at approximately the refractive focal radius of the lens elements wherein such location optimizes the capture of energy from the solar radiation transmitted through the lens element. Preferably, the energy capture elements are comprised of high temperature steel. Also, in this embodiment, the exterior surfaces of the energy capture elements have been treated so as to optimize absorption of radiation transmitted through the lens element. Preferably, the surfaces of the capture elements are treated by application of a coating designed to optimize absorption of radiation transmitted through the lens element. In one embodiment, the surfaces of the capture elements are treated by application of a film designed to optimize absorption of radiation transmitted through the lens element. Alternately, the surfaces of the capture elements are treated to increase the surface area of the capture elements so as to maximize absorption of radiation transmitted through the lens element. Specifically, this treatment can comprise a sintering of the surface of the capture element. In yet another variant, the coating applied to the surface of the capture element sis Chrome Black™.

[0012] In an alternative embodiment, the collection system of the invention comprises a thermal transfer fluid that is an aqueous fluid, which fluid may further comprise one or more additives designed to improve the function of the fluid. On the other hand, the thermal transfer fluid can be an oil or a non-aqueous fluid. In turn, the non-aqueous fluid also can further comprise one or more additives designed to improve the function of the fluid. In this embodiment, the thermal transfer fluid can be a petroleum oil, or a synthetic petroleum oil. When the embodiment comprises non-aqueous fluids, the additives are polyols, or surfactants, or chemical species comprising organic acid technology (OAT). Alternatively, the heat transfer fluid can be a natural oil, such as a seed oil. Non-aqueous heat transfer fluids may also comprise a combustibility retardant.

[0013] In an embodiment of the collection system of the invention, the curved reflector surfaces within the housing comprise a stainless steel material or aluminum, either material, or others having a surface burnished or otherwise treated to produce a polished, reflective surface. Alternatively, the curved reflector surface can comprise a mirrored glass surface. Preferably, the disposition and geometry of the curved reflector surface is optimized through use of computer programs or digitally implemented algorithms.

[0014] In yet another embodiment, the array of lens elements can comprise an external cover for the one or more housings so that the housing is sealed when the array is in place as a cover. In such an embodiment, the open space within the closed housing can be filled with air, or with an inert gas, or a gaseous mixture comprising components that optimize the energy-transfer processes within the housing and/or preserve the physical integrity of the components within the housing. These one or more gases can fill the housing to a pressure roughly equal to atmospheric pressure, or at higher pressures, in which embodiment additional attention must be paid to maintaining the pressurized status of the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] One or more embodiments, incorporating aspects of the present invention, will now be described by way of example only, with reference to the accompanying drawings in which:

[0016] FIG. 1 is a diagram of a solar panel with a lens assembly and a reflector to focus the sun's energy on a thermal capturing element.

[0017] FIG. 2 illustrates a process of capturing the solar energy using a chromic focusing lens.

[0018] FIG. 3 illustrates a cross section of the panel and how the reflected energy is redirected to adjacent lenses and how the refracted energy is reflected back onto the capture element.

[0019] FIG. 4 illustrates a cross-section of the lens/collector element illustrating the refraction of radiant energy and how it is focused into the capture element. This figure also shows the reflected energy being focused onto the capture element.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Described are embodiments reflecting the best mode of practice known to the present inventor for the practice of a method and system for capturing solar energy using solar panels with a unique lens system to reflect and refract the sun's energy.

[0021] A reflector is also used to capture stray or refracted energy that may have missed the capture element, thus increasing the energy conversion efficiency of the system.

[0022] Existing solar panels normally use a flat glass or plastic cover to protect elements within the panel from elemental effects. Both photovoltaic and thermal panels use this transparent cover to protect the material and system inside from exposure to dust, dirt, rain, pollutants and many other external forces that can cause harm or cause the system to cease functioning, or to degrade system performance.

[0023] Solar panels or solar collectors use two types of thermal panels, movable or fixed. Most of the designs for movable panels require complex and costly tracking systems to program and/or track the sun's movement and, accordingly, reposition the solar panels or collector toward the sun to optimize the panel's attitude with respect to incident radiation. Without this positioning system, a significant portion of the incident energy is reflected away from the panels. In contrast, fixed solar panels are relatively inefficient as, without positioning mechanics, they reflect more than half of the incident energy. As would be recognized by one of skill in the relevant art area, most of the available solar panel designs, of any type, are relatively inefficient, and are capable of capturing, on average, less than half of the incident energy, with many designs averaging less than 30% of the incident energy being converted to other, usable forms of energy, such as electricity.

[0024] According to one aspect of the present invention, there is provided a system for the collection of solar radiation, ideally in a process for the conversion of the radiation to alternative forms of energy, wherein the system comprises one or more collector housings; a plurality of lens elements, wherein the lens elements comprise a semi-circular cross-section, a concave inner surface and a convex outer surface, wherein the plurality of lens elements are generally cylindrical in shape, wherein the plurality of lens elements are arranged in a parallel layout along their long axis and in close spatial proximity to each other creating an array of lens elements, and wherein the array of lens elements comprises an outer surface or external cover for the collector housing; a plurality of energy capture elements arrayed in a one-to-one relationship with the lens elements, concentric with the lens elements, and parallel along their long axis with a long axis of the lens elements; a thermal transfer fluid within the energy capture elements in fluid communication with systems ancillary to the collection system ideally for conversion of captured solar energy to other forms of energy; and a curved reflective surface for each lens element disposed within the housing obverse to the lens elements, substantially parallel therewith and further disposed distal to the energy capture element. Preferably, the configuration and geometry of the lens elements are optimized through use of computer programs or digitally implemented algorithms.

[0025] In FIG. 1, a system 102 is disclosed, which system comprises a plurality of curved lenses 103 that are designed and positioned to focus the energy 101 of the sun 100 onto a capture element 105 that is heated as a result of absorption of the incident solar radiation. The capture element 105 is used to transport the captured energy to a collection and storage system.

[0026] The lens 103 is designed to either reflect the sun's energy 111 or refract 110 and focus it into a non-imaged point to heat the capture element 105.

[0027] Depending upon the frequency or wavelength of the incident radiation (energy), it will be refracted 110 through the lens 103 and into the solar panel 102 unit. This energy can be from a number of regions of the electromagnetic spectrum, such as infrared (IR), ultraviolet (UV), or any of the component frequencies (colors) of visible chromatic light energy (VIS).

[0028] If a portion of the incident radiation 101 is reflected from the primary lens element because of the angle of incidence, then the majority of such reflected radiation will be diverted into an adjacent lens 103. The reflected energy 111 is reflected at an angle such that it is intercepts the adjacent lens 103 within the range of angles where it will be refracted and, ultimately, absorbed into the capture element 105 of that panel 102, either directly or through secondary internal reflection, as explained more fully below.

[0029] If the angle at which the incident radiation is refracted is beyond a certain range of angles, then the energy will be refracted at such an angle as to miss the capture element 105. However, the design of the present invention provides curved, mirrored reflective surfaces 104 at the bottom of the solar panel 106 unit. This secondary reflection will again be focused to cause the majority of the radiant energy to strike the capture element.

[0030] In FIG. 2, a lens 103, with symmetrical, convex surface geometry, is shown that has focal lengths (as a function of wavelength) that allow most of the radiant energy 101 that strikes the lens surface 103 to be refracted 203 and focused to intersect with the absorber or capture element 204.

[0031] As would be recognized by one of skill in the appropriate art, the geometry of any given lens component can be manipulated to achieve the appropriate level of focusing of the incident beam transmitted through the lens onto the radiation collector element 204. Specifically, the angle or shape of the outside surface of the lens (and, also the inner surface of that lens) with respect to the incident radiation will impact the efficiency of focusing of the radiation onto the collector element 204. As discussed infra, the focusing (or collection) efficiency is greatly enhanced through use of the reflective surface 304 that serves to direct refracted light that bypassed the collector element on initial transmission through the lens 103 to the collector 204. The composition of the lens material also has an effect on the angle of refractance that occurs, as many different types of material can be use to construct the lens 103, with each type of material being characterized by a refractive index for that material, the value of which determines the extent of the wavelength-dependent refractive phenomenon for light impinging upon it.

[0032] The lens element 103 can be constructed from glass, plastic, quartz, or any other material sufficiently transparent to the wavelength spectrum of solar radiation. The lens may be a multiple-layer device, or other type of compound design, constructed from layers of material in much the same way as safety glass is made for the windshield of a car. This type of construction allows the lens to have added strength and not crack or break when items like trees, nuts, sand, rocks or other flying debris that may impact the lens surface.

[0033] In one embodiment, the lens can be made of an acrylic resin like polymethylmethacrylate, PMMA, which is one of the preferred lens materials, exhibiting a long lifetime under exposure to sunlight, being transparent to most of the wavelengths within the solar spectrum, and ensuring cost advantageous mass production by means of molding or extrusion.

[0034] The design of the lens is optimized to a single point sometimes called the "circle of least confusion," wherein chromatic aberration can be minimized. The lens can be designed to be very simple by using an achromatic design in which materials with differing dispersion are assembled together to form a compound lens. This is commonly done in an achromatic doublet with some of the lens elements using materials like crown glass and flint glass. This reduces the amount of chromatic aberration over a certain range of wavelengths. By combining two or more lenses of different composition, the degree of aberration can be further minimized. Using these techniques, a lens can be designed to allow for most of the frequencies or wavelengths from the spectrum of solar radiation to be focused to a single collector point or volume. Many other factors must be considered in the design of the lens, such as the temperature operation range, as this is one of the many factors that will cause the lens to shift its focal point (as a function of temperature), as the lens material may display a temperature dependence on density and, consequently, refractance (expressed as refractive index).

[0035] For this embodiment, FIG. 3 depicts a side view, showing the regular, convex shape of the lens 103 that accommodates the movement of the sun 100 across the sky without materially affecting the collection efficiency of the device. As the sun 100 moves across the sky, the incident radiation 101 will strike the panel array 102 at different angles. The light rays striking the convex, curved external surface of the lens, within a range of angles of incidence, will be refracted 301 by the lens 103 and, subsequently, absorbed into the capture element 204. Outside of this range of angles of incidence, the light rays will reflect off of the curved external surface of the lens 103 and will be reflected into the lens element adjacent to it, wherein the vast majority of the secondary incident light rays (redirected by reflection) will be at an angle relative to the external surface of the adjacent lens element so as to now be refracted 305 by that adjacent lens and be directed to the capture element 204 associated with that lens. The inner angle of the lens 103 is designed to focus the maximum amount of the entire range of wavelengths of the solar spectrum onto the capturing element 204 of one or more lens/collector components of the solar panel of the present invention. As also illustrated in FIG. 3, any energy transmitted through the lens that misses the capture element will then strike the reflector surface 304 that is designed to reflect the energy back into the distal side of the capturing element 204. In this manner, as the sun's angle changes throughout the day, and without the aid of tracking systems that include motors and gears to move the capturing units, the solar panel of the present invention will continue to function in a highly efficient and effective energy collection manner.

[0036] Given that the average hours of sunlight throughout the majority of latitudes are in excess of nine hours per day on an annual basis, solar energy provides a potentially large amount of energy, presuming that the efficiency of energy capture/conversion can be maintained at a sufficiently high level. Because of the design of the lens angles and the reflector angles in the system of the present invention, a higher portion of the incident radiation is directed into the capturing element 204 than is achieved with any designs currently available in the art. The solar collection panels currently available in the art generally require an expensive and hard to maintain tracking system to attempt to minimize losses due to reflective phenomena in order to achieve sufficient energy conversion efficiency. Many of these designs are further hampered by the need for flat, protective covers that can reflect more that 60% of the energy as the sun moves across the sky.

[0037] In an embodiment of the present invention, lens elements 103 are provided in a semi-circular, cylindrical shape. In practice, the orientation of the sun 100 with latitude tilt changes during the year, and declination caused by seasonal movements of the earth causes different interceding angles to occur so that the angle of reflection, for fixed panels, is changed. As the sun moves in an east to west orientation with latitude tilt, the sun's energy will cause greater reflection off the surface of the primary lens element, but, according to the design of the present invention, such reflection does not result in significant losses of incident radiation, merely re-direction of the majority of the reflected radiation to an adjacent lens element for collection.

[0038] In addition, using an apochromatic lens design, a broader band of the different wavelengths of the solar spectrum can be focused into a narrow point or volume to allow for maximum energy capture through absorption into the collector element 204.

[0039] The law of refraction, Snell's law (also known as Descartes Law), defines the relationship between the angle of incidence and the angle of refraction for waves passing though a boundary between two isotropically different propagating media, such as the phenomenon that occurs when a light wave passes from the air though a piece of glass, plastic or other transparent media of differing optical density. As one of skill in the appropriate art would recognize, this relationship is used to calculate the diameter and other physical parameters of the lens necessary to result in the sun's energy refracting through the lens to be directed so that the energy either directly impinges on the capture element, or passes the capture element to reflect off the reflector surface 304 and be directed to intersect the distal surface of the capture element 204.

[0040] This relationship is also used to determine the position of each lens element so that the angle of the solar radiation reflected off the exterior surface of the lens is such that it will be reflected at an angle within the range of refractive angles of an adjacent lens element. As can be determined through application of Snell's law, a critical angle of greater that 42.6 degrees for certain kinds of glass will cause the light to reflect off the primary lens and into the adjacent, or secondary, lens. As the solar radiation intersects the curved exterior surface of the lens, the incident angle modifier can be used to calculate how much of the radiation will reflect and how much will be refracted through the lens and focused onto the capture element of the primary lens/collector structure, either directly or after reflecting off the reflector surface 304 and, subsequently, onto the capture element. Using these calculations, it can be shown that this embodiment of the design of the present invention offers a vast improvement over existing solar capturing units that lose over half of the incident radiation to reflective and/or scattering phenomena.

[0041] As would be appreciated by one of skill in the art, lens design software tools like dbOptic™ from Sky Scientific, of Sky Forest, California, 92385, is one of many that can be used to design the lens. These tools provide tracing functions to allow for the different wavelengths to be explored and the lens design adjusted to allow for the maximum intersection of the different frequencies to be focused to the capture element. Other tools like ZEMAX™ optical design software from ZEMAX Development Corporation, of Bellevue, WA, 98004, can be used to allow for many of the design values to be calculated and optimized.

[0042] As stated above, other factors can come into play in the design of an embodiment of this invention, such as temperature increases affecting refractive index in materials absorbing solar energy. This absorption can be measured by the temperature change in the solid collector or in a fluid that may flow through the capture element.

[0043] In one embodiment, an anodized black pipe can be used with a thermal transport liquid that will flow through the pipe to move the captured energy from the panel to a converter unit that will convert the heat energy into other forms of useful energy. The tube may also be coated or have a film applied to increase its ability to capture the radiation. In addition, other types of tubes or pipes, with coatings like silicon carbide, or with optimized surface textures, can be used to allow for increased absorption factors. In the prior art, Chrome Black selective coatings have been also developed for higher temperature operations.

[0044] Additional tube coverings can be used to enhance the absorption of radiant energy and stop or minimize losses through uncontrolled blackbody thermal radiation from the heated collector. Steel boiling tubes that are already used in fossil fuel plants for steam generation systems are well known. They are much less expensive than evacuated tubes in prior art solar reflector trough devices being used today. The absorption of heat and subsequent generation of stream is well know and much less costly.

[0045] Many different types of liquids can be used in the tube or pipe to conduct the absorbed heat from the panel to an energy converter. In one embodiment, water, as is common for many thermal solar collectors, could be used. As is well known, water, when it is heated to about 212° F (at atmospheric pressure), becomes a gas in the form of steam. As the steam is further heated, it goes from saturated steam into superheated steam, accompanied by an increase in pressure, presuming that the volume of the container does not also increase. This requires pipes that are capable of withstanding high temperature and high pressure. Aqueous liquids also can cause corrosion of the pipes, depending on the material composition of the pipes. Both high pressure and corrosion will lead to an increased incidence of system failures, as well as resulting in more complex designs and greater maintenance costs. By way of comparison, in thermal coal- and oil-fueled Rankine cycle generation plants, an ideal operating temperature is maintained between 572° F and 689° F.

[0046] The design and size and shape of the pipes also is an additional factor as flow dynamics and flow rates will have a impact on the efficiency of transport of the thermal transfer fluid and can, consequently, impact energy transfer efficiencies.

[0047] In another embodiment, non-aqueous thermal transfer fluids can be used. Examples are oils and other chemical species that are designed for conductive heat transfer processes and can withstand high temperatures. Examples of the latter are antifreeze products that function to increase the boiling point of aqueous liquids through use of additives like methanol, ethylene glycol, propylene glycol, and organic acids technology (OAT). These compounds, however, can create problems for the liquid containment and transfer systems and can still cause corrosion of tubes or pipes, which phenomena will cause leaks in the system necessitating expensive repairs and/or loss in energy transfer efficiency. There are many problems associated with the use of non-aqueous, synthetic oils at high temperature; some of these are flammability, toxicological effects, thermal stability and high cost. [0048] In another embodiment, a fluid like an oil-based liquid can be used that has a much higher boiling point. For example, automotive engine oil can have a boiling point of 250 to 300° F, wherein synthetic oils have boiling points of 450° F, or above.

[0049] In an alternative embodiment, natural oils, such as seed oils, can be used to obtain higher temperatures. Breakdown temperatures for these natural oils can be quite high, such as, for example, 450° F for sunflower oil, 468° F for olive oil, and 475° F for canola oil. These oils provide a higher temperature for transferring heat energy from the collector to an energy converter or storage unit. These natural oils also provide for safe, nontoxic processes that will not cause additional pollution. In addition, these natural oils can be easily disposed of when the solar panels are removed, unlike other oils or synthetic liquids that cause pollution in their creation, use and cleanup. Before use in systems of the present invention, these oils need to be processed to remove waxes and other material that, when exposed to high temperatures, will cause build-up or other flow issues in the system.

[0050] The higher temperatures of operation with these types of non-aqueous heat transfer fluids can avoid some of the problems associated with high pressure when using water as the thermal transfer fluid and, therefore, simpler pumping systems can be used, with less cost and lower risk of failure. The higher temperature also allows for a more efficient transfer of the thermal energy. However, use of these high temperature oils can result in other problems such as an increased risk of fire from increased volatility. Fortunately, this combustibility issue can easily be resolved by adding other compounds like a soap-based surfactant that can inhibit the oil from burning. Alternatively, a small pipe can be installed and connected to a fire suppression system that can fill the panel and pipes with water or a fire suppression chemical that will quickly extinguish any fires that are detected. [0051] Using natural oils, such as processed seed oil, as thermal transfer fluids allows for higher temperatures and lower viscosity of the liquid to be used. Consequently, requirements and costs for pumps and related plumbing are greatly reduced. Possible oxidization or burning of the oil at high operating temperatures can be control by adding compounds that, again, increase the temperature transfer efficiency and prohibit the flash point or breakdown temperature of the oil from being reached within the temperature range of operation.

[0052] In an alternative embodiment, the heat storage or heat exchange unit can contain a molten salt compound that will allow for higher temperature range transfer or storage units.

[0053] Some prior art discloses the use of a vacuum or containment area for reducing blackbody radiation losses from the heated capture element, resulting in many different types of designs, many of high complexity. See, for example, U.S. Patent No. 7,412,976 (the '"976 patent"), the disclosure of which is specifically incorporated herein by reference in its entirety. In comparison, the solar panel of the present invention comprises a lens 103 and a reflector 304 that surrounds the capture element 204. The dead space (preferably at atmospheric pressure) between the capture element 204 and the lens 103 and reflector 304 provides a thermal barrier to minimize blackbody thermal radiation from the panel and, instead, reflect this radiation back into the capture element 204. This enclosure also keeps the panel housing 106 from reaching excessively high temperatures, with the added advantage of incorporating relative simplicity of design and manufacture. In other reflector systems that do not provide an insulated enclosure, part of the energy that is absorbed is radiated back into the surrounding environment, which process causes a temperature rise in that environment. This can be harmful to plants and animals in the environment near the thermal collectors. In prior art systems, thermal radiation loss has been caused by both convection and conduction. In prior art designs, such as the '976 patent, referenced above, the heat loss from glass-covered tubes or pipes is generally released back into the surrounding environment. With other prior art designs, wind and air humidity can increase convection of the captured energy back into the environment, with potentially harmful effects.

[0054] In the design of the present invention, heat loss from convection is reduced as both the lens and the reflector provide a barrier from the outside environment and cause the majority of the convected energy to be reflected back into the capture element. As the capture element is isolated from the other parts of the panel and insulated where it leaves the panel to the energy transfer unit, losses from conduction are greatly reduced.

[0055] As discussed above, the curved reflector 304 is used to reflect radiant energy that bypasses the capture element 204 back toward the capture element 204. In one embodiment, this reflector is a thin metal sheet made from stainless steel, high temperature aluminum, or any other metal that can be curved at an angle to cause the reflection of wavelengths like infrared, ultraviolet or visible light, and plated or laminated with a highly reflective material, and, optionally, with a composite or backing layer obverse to the reflective surface to add additional insulation or reflection of the different wavelengths of energy incident on the panel structure.

[0056] Optimization of elements of the design of the reflector can also be accomplished through the use of software programs such as those mentioned above. This process is used to calculate the diameter of the reflector to optimize reflection from the different angles of the refracted energy transmitted through the lens and any uncontrolled blackbody radiation emerging from the capture element.

[0057] In an advantageous aspect of the solar panel design of the present invention, low cost per panel, minimal loss of incident energy through reflection and blackbody emissions from collector elements, and significant reduction of other factors that reduce the efficiency (expressed as cost per watt-area), can be achieved that are far greater than possible with the current panels in the market today.

Claims

I claim:

1. A system for the collection of solar radiation, wherein the system comprises: a) one or more collector housings; b) a plurality of lens elements, wherein the lens elements comprise a semi-circular cross-section, a concave inner surface, and a convex outer surface, wherein the plurality of lens elements are generally cylindrical in shape, wherein the plurality of lens elements are arranged in a parallel layout along their long axes and in close spatial proximity to each other creating an array of lens elements, and wherein the array of lens elements comprises an outer surface or external cover for the collector housing; c) a plurality of energy capture elements arrayed in a one-to-one relationship with the lens elements, concentric with the lens elements, and parallel along their long axis with a long axis of the lens elements; d) a thermal transfer fluid within the energy capture elements in fluid communication with systems ancillary to the collection system ideally for conversion of captured solar energy to other forms of energy; and e) a curved reflective surface for each lens element disposed within the housing obverse to the lens elements, substantially parallel therewith and further disposed distal to the energy capture element.

2. The collection system of claim 1, wherein the configuration and geometry of the lens elements are optimized through use of computer programs or digitally implemented algorithms.

3. The collection system of claim 1, wherein the lens element is comprised of one or more materials selected from the group consisting of glass, quartz and plastic.

4. The collection system of claim 3, wherein the lens element is constructed with a plurality of layers.

5. The collection system of claim 3, wherein the lens element comprises two or more lenses.

6. The collection system of claim 1, wherein the energy capture element is a cylindrical pipe located obverse to an underside of the lens element at approximately the refractive focal radius of the lens element, wherein such location optimizes the capture of energy from the solar radiation transmitted through the lens element.

7. The collection system of claim 6, wherein an exterior surface of the energy capture element has been treated so as to optimize absorption of radiation transmitted through the lens element.

8. The collection system of claim 7, wherein the surface of the capture element is treated by application of a coating designed to optimize absorption of radiation transmitted through the lens element.

9. The collection system of claim 7, wherein the surface of the capture element is treated by application of a film designed to optimize absorption of radiation transmitted through the lens element.

10. The collection system of claim 1, wherein the thermal transfer fluid is an aqueous fluid.

11. The collection system of claim 10, wherein the aqueous fluid further comprises additives.

12. The collection system of claim 1, wherein the thermal transfer fluid is an oil or a non-aqueous fluid.

13. The collection system of claim 12, wherein the non-aqueous fluid further comprises one or more additives.

14. The collection system of claim 13, wherein the one or more additives are selected from the group consisting of polyols, surfactants, and chemical species comprising organic acid technology.

15. The collection system of claim 12, wherein the heat transfer fluid is a natural oil.

16. The collection system of claim 12, wherein the heat transfer fluid further comprises a combustibility retardant.

17. The collection system of claim 1, wherein the curved reflector surface comprises stainless steel.

18. The collection system of claim 1, wherein the array of lens elements comprises an external cover for the one or more housings so that the housing is sealed when the array is in place as a cover.

19. The collection system of claim 18, wherein the open space within the closed housing is filled with an inert gas.

20. The collection system of claim 18, wherein the open space within the closed housing is filled with a gaseous mixture comprising components that optimize the energy- transfer processes within the housing and/or preserve the physical integrity of the components within the housing.