Arizona Board of Regents on Behalf of the University of Arizona

Arizona Board of Regents, a Body Corporate

Roger P Angel

Brian M Wheelwright

James H Burge

Justin J Hyatt

Brian Cuerden

Blain H Olbert

Thomas E Stalcup, Jr

Dmitry Reshidko

Robert E Parks

Raymond K Kostuk

Zachary Holman

Warren B Davison

Brian Love

Scott T DeRigne

Andrew R Whiteside

Blake M Coughenour

Nicholas J Didato

Robert A Smythe

Peng Su

An apparatus for generating electricity from solar energy has a large dish reflector with a fly's eye receiver positioned near the focus of the dish reflector, held by a dual axis tracking structure. The fly's eye receiver includes a field lens that concentrates sunlight into an image of the dish reflector, a two-dimensional fly's eye array of contiguous convex lenses extending across the dish image, and a photovoltaic cell behind each convex lens of the fly's eye array. Two imaging stages are provided. First, the dish reflector and the field lens concentrate the sunlight in the form of an image of the dish that is stabilized against pointing errors of the tracking mechanism. Second, the contiguous array of convex lenses divides the sunlight energy of the dish image into portions, one per convex lens, each portion being further concentrated by the respective convex lens onto a corresponding photovoltaic cell.

Solar PV generator with dish reflector and fly's eye receiver

A solar PV module is disclosed having two types of laterally-separated coplanar cells with different bandgaps to improve conversion efficiency. A diffracting entrance window directs sunlight with wavelengths shorter than a separation 5 wavelength ks is directed largely to the first type of wider bandgap cells. Sunlight with wavelengths longer than a separation wavelength ks is directed largely to the second type of narrower bandgap cells. The separation wavelength is chosen so that each cell is illuminated largely by that part of the solar spectrum to which it has the higher conversion efficiency, resulting in an overall conversion efficiency higher than 10 for either type of cell used alone. The wider bandgap cells are configured on a planar support in separated parallel strips, with the narrower bandgap cells largely filling the area between these strips.

Tandem photovoltaic module with diffractive spectral separation

A solar concentrator may have a horizontal circular track on the ground, a tower centered on a vertical axis of the track, and a rotatable structure around the track having an upper, concave mounting surface approximating the shape of part of a sphere centered on the top of the tower. Articulated concave mirrors are attached to the rotatable structure, and the mirrors have a focal length approximately equal to the radius of a sphere portion formed by the concave mounting surface. Sunlight is focused at a receiver mounted atop the tower, and the receiver may convert sunlight into thermal or electrical energy. As the position of the Sun changes, sunlight is maintained on the receiver by turning the rotatable structure toward the Sun, turning the receiver about said vertical axis to face the mirrors, and articulating the mirrors toward the receiver in response to the changing elevation of the Sun.

Solar concentrator for a tower-mounted central receiver

A system for shaping glass or metal sheets or panels for use in solar collectors or microwave antennae may include an oven and an adjustable mold. The adjustable mold may comprise a molding surface located within the oven. The molding surface may be coupled to position actuators located outside of the oven via coupling elements. A sheet or panel may be placed in the oven and heated until the sheet or panel softens and takes the shape of the molding surface. The molding surface may be adjusted to achieve different shapes for glass or metal sheets or panels.

Glass or metal forming mold of adjustable shape

An apparatus is disclosed for generation of electricity using sunlight focused onto multi junction photovoltaic cells having high conversion efficiency. The apparatus includes a large paraboloidal mirror of back-silvered glass, turned to the sun throughout the day, so as to provide an intense focus. Multiple photovoltaic cells are provided at the focus. The optics are configured to distribute sunlight without significant loss into separate regions matched to the photovoltaic cell size. A secondary optical system takes strongly focused sunlight near the focus of a single paraboloidal mirror and distributes it equally between the cells, and regions of equally concentrated sunlight are matched to cell size and are substantially co-planar, so that the cells may be grouped on flat circuit cards.

Solar generator with large reflector dishes and concentrator photovoltaic cells in flat arrays

An apparatus is disclosed for rotating equipment, like solar panels, about an axis. Tension and compression members, in a rigid structure, are employed in the apparatus to minimize weight and to maximize stiffness. The rotating equipment is attached to the upper end of a rotatable elongated compression member, rotatably supported at its lower end by a tri-pod base comprising three additional compression members. Six tension members extending up from the tripod base hold a flange through which passes the rotatable elongated compression member. Lateral forces on the rotatable equipment are transmitted to the tripod base through the six tension members. The apparatus is configured such that wind forces and torques on the rotated equipment are transmitted by the apparatus to ground supports. Solar panels supported by the apparatus may be held at a fixed tilt angle, or an additional mechanism may be provided for rotational about a second orthogonal axis.

Frame with compression and tension members to rotate equipment about an axis

A non-contact metrology system utilizes a display that can be programmed with a plurality of targets. The display targets shine on a specular surface and the reflected targets are detected by an imaging device. Based on the display pattern and the expected location of the reflected pattern, it is possible to characterize the reflective surface. The displayed pattern can be a regular array of targets and the reflected pattern detected by the imaging device is an irregular display of targets whose locations are based on the particular display pattern, the location of the display system and imaging device and the nature of the surface. Deviations of the actual location of targets from the expected location of targets is indicative of unexpected variations in the surface. Alternatively, the display has an irregular pattern of targets such that the reflected signals result in a regularly spaced array detected by the imaging device.

System and method for non-contact metrology of surfaces

Glass reflectors for concentrating sunlight in a solar energy system are disclosed. A concave mold is used to shape the glass reflectors in which the surface of the mold that contacts the float glass has a grooved surface profile comprising a plurality of cusps. The surface of the mold also has a plurality of concave valleys. Glass reflectors are preferably manufactured by heating a sheet of float glass positioned over the mold until the sheet of glass sags to contact the mold. If necessary, the glass may also stretch to conform to the shape of the mold. In the case of large monolithic glass reflectors, the edges of the dish-shaped glass are rolled around the periphery of the mold. The glass reflector is then silvered to create a dish-shaped mirror that reflects solar radiation to a focus.

Method of manufacturing reflectors for a solar concentrator apparatus

A two-axis solar tracker apparatus is disclosed having multiple dish-shaped monolithic reflectors for concentrating sunlight. The dish-shaped monolithic reflectors are co-axially aligned in an array supported by a moveable frame. The moveable frame forms the elevation structure of a two-axis tracker that has control means for following the movement of the sun across the sky. Each dish-shaped monolithic reflector produces a region of concentrated sunlight suitable for generation of solar energy. A generator is positioned at the focus of each reflector. A preferred generator uses photovoltaic cells to generate electricity at a high output power due to the high solar power input that is directed to the generator by the dish-shaped monolithic reflector.

Solar concentrator apparatus with large, multiple, co-axial dish reflectors

The invention is a generator for photovoltaic conversion of concentrated sunlight into electricity. A generator according to the invention incorporates a plurality of photovoltaic cells and is intended for operation near the focus of a large paraboloidal reflector pointed at the sun. Within the generator, the entering concentrated light is relayed by secondary optics to the cells arranged in a compact, concave array. The light is delivered to the cells at high concentration, consistent with high photovoltaic conversion efficiency and low cell cost per unit power output. Light enters the generator, preferably first through a sealing window, and passes through a field lens, preferably in the form of a full sphere or ball lens centered on the paraboloid focus. This lens forms a concentric, concave and wide-angle image of the primary reflector, where the intensity of the concentrated light is stabilized against changes in the position of concentrated light entering the generator. Receiving the stabilized light are flat photovoltaic cells made in different shapes and sizes and configured in a concave array corresponding to the concave image of a given primary reflector. Photovoltaic cells in a generator are also sized and interconnected so as to provide a single electrical output that remains high and stable, despite aberrations in the light delivered to the generator caused by, for example, mispointing or bending of the primary reflector. In some embodiments, the cells are set back from the image formed by the ball lens, and part of the light is reflected onto each cell small secondary reflectors in the form of mirrors set around its perimeter.

Photovoltaic generator with a spherical imaging lens for use with a paraboloidal solar reflector

A method of manufacturing monolithic glass reflectors for concentrating sunlight in a solar energy system is disclosed. The method of manufacturing allows large monolithic glass reflectors to be made from float glass in order to realize significant cost savings on the total system cost for a solar energy system. The method of manufacture includes steps of heating a sheet of float glass positioned over a concave mold until the sheet of glass sags and stretches to conform to the shape of the mold. The edges of the dish-shaped glass are rolled for structural stiffening around the periphery. The dish-shaped glass is then silvered to create a dish-shaped mirror that reflects solar radiation to a focus. The surface of the mold that contacts the float glass preferably has a grooved surface profile comprising a plurality of cusps and concave valleys. This grooved profile minimizes the contact area and marring of the specular glass surface, reduces parasitic heat transfer into the mold and increases mold lifetime. The disclosed method of manufacture is capable of high production rates sufficiently fast to accommodate the output of a conventional float glass production line so that monolithic glass reflectors can be produced as quickly as a float glass production can make sheets of float glass to be used in the process.

Method of manufacturing large dish reflectors for a solar concentrator apparatus

An impact micro-positioning actuator. In one aspect of the invention, a threaded shaft is threadably received in a nut and the nut is impacted by an impacting device, causing the nut first to rotate relative to the shaft by slipping as a result of shaft inertia and subsequently to stick to the shaft as a result of the frictional force therebetween. The nut is returned to its initial position by a return force provided by a return mechanism after impact. The micro-positioning actuator is further improved by controlling at least one and preferably all of the following: the friction, the impact provided by the impacting device, the return force provided by the return mechanism, and the inertia of the shaft. In another aspect of the invention, a threaded shaft is threadably received in a nut and the shaft is impacted by an impacting device, causing the shaft to rotate relative to the nut.

Growing community of inventors

Tucson, AZ, United States of America

Roger P Angel