Abstract: A system for assisting solar power generation contains several racks for fastening power conversion modules. The racks each have a pivot axis and are mounted for pivotal movement about the pivot axis. The racks each have a lever, a movement of the lever causing a respective one of the racks to pivot. A coupling rod is provided on which the levers are each carried for rotation. The coupling rod couple the levers of the racks together and are further coupled to a linear drive unit so that the racks may be caused to pivot together through an action of the linear drive unit. A common mounting configuration mounts the racks so as to have the pivot axis carried on the common mounting configuration. The linear drive unit has a first end hinge-linked to the common mounting configuration and a second end hinge-linked to the coupling rod.

Abstract: An aerospace platform includes a structure having a cavity and a light-transmissive portion that exposes the cavity to sunlight. The aerospace platform further includes a fluid heating system. The fluid heating system includes a fluid-carrying, thermally absorptive structure within the cavity, and a solar collector for collecting light transmitted through the light-transmissive portion and focusing the collected light onto the absorptive structure. The thermally absorptive structure has a high surface absorptivity that retains thermal energy when exposed to solar irradiance and heats fluid contained therein.

Abstract: A solar tracking and concentration device, including a reflecting unit, a receiving unit, a controlling device, and a plurality of photo sensors, is provided. The receiving unit is used to receive the sunlight reflected and reflected by the reflecting unit. The receiving unit and the reflecting unit face each other. The receiving unit is adapted to move along a first direction. According to the position and the time of the reflecting unit, the controlling device controls a rotation angle of a support element and controls a first moving position of the receiving unit moving along the first direction, in which the support element supports the reflecting unit and the receiving unit. The photo sensors are used to detect the sunlight reflected by the reflecting unit to the receiving unit, and are adapted to output a first feedback signal to calibrate a direction of the receiving unit facing the reflecting unit.

Abstract: The present invention provides a solar tracking skylight system for illumination, primarily including a light guide, a solar tracking controller, a two-axis tracking mechanism, an energy converter and energy storage system, and a weather protective cover. The system uses the solar tracking controller to detect the direction of the light, thereby enabling the two-axis tracking mechanism to move toward the light to facilitate the light guide in collecting light and diffusing it indoors for illumination use. The protective cover provides waterproofing, and the energy converter and energy storage system is used to store electrical energy generated by the solar energy panel for system use. External power is not needed for the system to operate and provide indoor lighting, thereby achieving the objective of saving energy and reducing carbon emissions.

Abstract: A solar tracking device for solar panel includes a barrel body, a light transmitting unit, a projecting unit, a photosensor unit, and a lens. The light transmitting unit is disposed at a first end of the barrel body oriented toward the sun. The light transmitting unit has a light-transmittable crossing point provided at a center thereof. The projecting unit is an opaque member arranged between the first end and a second end of the barrel body. The photosensor unit is arranged to one side of the projecting unit, so that the projecting unit is located between the light transmitting unit and the photosensor unit. The photosensor unit has a locating center preset at a center of the projecting unit. The lens is arranged between the projecting unit and the photosensor unit. The barrel body is a telescopic barrel enabling the solar tracking device to switch between different operating angle modes.

Abstract: The present invention provides a solar tracking skylight system for illumination, primarily including a light guide, a solar tracking controller, a two-axis tracking mechanism, an energy converter and energy storage system, and a weather protective cover. The system uses the solar tracking controller to detect the direction of the light, thereby enabling the two-axis tracking mechanism to move toward the light to facilitate the light guide in collecting light and diffusing it indoors for illumination use. The protective cover provides waterproofing, and the energy converter and energy storage system is used to store electrical energy generated by the solar energy panel for system use. External power is not needed for the system to operate and provide indoor lighting, thereby achieving the objective of saving energy and reducing carbon emissions.

Abstract: A high-efficiency, small-scale, combined heat and power, concentrating solar energy system (200), designed specifically for residential and other relatively low-power applications, rendering it cost-effective and economically viable. Two-axis tracking of a dish-like reflector (10) of between 1 and 2 meters in aperture ensures very high concentrating ratios of between 200 and 8-suns or even higher. In consequence very high coolant outlet temperatures, of 120-180° C. may be reached at the outlet of the collector coolant, which may be oil, gas, or pressurized water. The high coolant temperatures are advantageous because they may be used for air-conditioning. The high concentration is advantageous because the efficiency of the photo_voltaic cells is improved with higher concentration. The overall efficiency is greater than 60%.

Abstract: A suntracking system for a central receiver solar power plant includes a heliostat field for reflecting sunlight to a receiver, cameras directed toward at least a subset of the heliostats, and a controller. The cameras are configured to produce images of sunlight reflected from multiple heliostats. The heliostats include a mirrored surface having a settable orientation and have a geometry modeled by a set of parameters. A method of estimating heliostat parameters for open-loop suntracking includes acquiring pointing samples by setting the direction of reflection of the heliostats and detecting concurrent sunlight reflections into the cameras. The method uses the acquired pointing samples and surveyed locations of the cameras to estimate the heliostat parameters. The method accurately maintains the sun's reflection directed toward the receiver open-loop utilizing the estimated tracking parameters.

Abstract: Systems, methods, and apparatus by which solar energy may be collected to provide electricity, heat, or a combination of heat and electricity are disclosed herein.

Abstract: A man-made island adaptable for land-based operation holds solar energy collection facilities and is rotatable to optimize the angular orientation thereof relative to the position of the sun. A platform includes a large outer ring that floats on a fluid and a flexible cover is attached to the ring to define an airtight volume below the cover. A plurality of rows of solar radiation collector modules are located above the cover and carry steam generating heat pipes. The rows of modules are supported laterally above the cover by an upper support structure, either a space frame, a plurality of cables, or a honeycomb. A compressor creates an over-pressure within the enclosed volume to vertically support the cover and the other components mounted thereabove.

Abstract: It aims to provide a solar heat collecting apparatus that can efficiently collect energy from solar light. The solar heat collecting apparatus comprises an opened container part 22 that accumulates heat, a closed part 25 that closes the container part 22 and has an opening part 26 to let the collected solar light in, and a light absorbing part 36 that absorbs the solar light dispersed by passing through the opening part 26 so that it is converted into heat.

Abstract: An improved solar concentrating system (100) uses a two-stage arrangement of mirrors wherein the rays of the sun are reflected and concentrated to a point focus. The solar concentrator (100) may be used to increase the temperature of a substance such as metal, for use in a variety of applications including the melting of metals in a foundry furnace. The solar concentrating system (100) comprises at least two single-curved parabolic mirrors (10, 20) connected in an operable arrangement. The rays of the sun are reflected from a first single-curved parabolic mirror (10) to a second single-curved parabolic mirror (20). The plane of symmetry of the second single-curved parabolic mirror is arranged substantially orthogonal to the plane of symmetry of the first single-curved parabolic mirror thereby concentrating the rays of the sun to a point focus.

Abstract: A solar servo control tracking device is disclosed. The device includes: an integrated control device having a solar cell sensor unit detecting luminance at a solar azimuth, and an integrated control panel transmitting a control signal at a maximal solar azimuth, calculated by comparing a solar azimuth from the luminance at a solar azimuth; and solar tracking devices, respectively having a tracking device controller receiving the control signal via a wireless link, a high torque driving unit with an AC single phase inductor to generate driving torque by the control signal from the tracking device controller, solar module assemblies driven by the high torque driving unit to track the solar azimuth in accordance with the control signal, and an operating angle sensor unit installed to the high torque driving unit to detect operating angles of the solar module assemblies that track the sun by the control signal.

Abstract: Systems and methods of calibrating heliostat parameters for subsequent open-loop sun-tracking, the calibration based on driving artificial light source reflections from one or more heliostats into one or more image sensors.

Abstract: The invention relates to a solar energy concentrator-collector device including a stationary reflector-concentrator with reflector-concentrator modules joined to a stationary structure forming a matrix. Each reflector-concentrator module includes a frame and at least one reflective surface portion configured to reflect the sun's rays and concentrate them in a linear focus. The stationary structure is formed by frames fixed to supporting profiles. A mobile receiver includes a mobile structure supporting receptor elements parallel to the linear foci. A tracking mechanism is connected to several the supporting profiles and to the mobile structure in order to support and move the mobile structure on the stationary reflector-concentrator so that the receptor elements follow a path of maximum confluence of the sun's rays reflected by the reflective surfaces as the relative position of the sun changes.

Abstract: A solar module arrangement for, in particular, solar-thermal and/or photovoltaic energy production, comprising at least three solar module elements (2) which are arranged in a substantially horizontal, flat composite and are each inclined relative to one another with respect to the horizontal plane (H) in such a way that side edges (4) which frame the solar module arrangement (1) are lower or higher than a substantially middle central region (6) relative to the horizontal plane (H). Furthermore, a roof arrangement with a plurality of solar module arrangements of the above-mentioned type, wherein the solar module arrangements (1) are arranged on subsections (22), which run substantially parallel to one another, of the side borders (4) of adjacent solar module arrangements (1) to form an, in particular, diamond-shaped, roof arrangement (30).

Abstract: Concentrating solar collector systems that utilize a concentrating reflector to direct incident solar radiation to a solar receiver are described. In one aspect, the reflective surface is arranged to direct light to the receiver in a non-imaging manner in which the solar rays reflected from the opposing edges of the reflective surface are generally directed towards a central portion of the solar receiver. Rays reflected from selected central portions of the reflective surface are directed closer to the edges of the receiver than the solar rays reflected from the edges of the reflective surface. The described reflectors are generally intended for use in solar collector systems that track movements of the sun along at least one axis.

Abstract: A light concentrator is described, for a device for the conversion of solar radiation into electrical, thermal or chemical energy, capable of conveying the radiation towards a surface of the conversion device. The concentrator comprises at least one portion of Fresnel lens of rotational symmetry, one face of which has a plurality of crests disposed concentrically about a center so as to form a segmented transverse profile of the portion of Fresnel lens. The profile is formed in such a manner that the focal distance of the Fresnel lens is variable in dependence on the radial distance from the center of the lens. The variation of the focal distance is determined such that, when the Fresnel lens is illuminated by polychromatic radiation, the superposition of the distributions of irradiance, produced by the lens at the individual wavelengths constituting the spectrum of the incident radiation, generates a substantially uniform distribution of polychromatic irradiance on the conversion device.

Abstract: An efficient and cost effective system for the collection, concentration, and delivery of disperse solar energy to a central location for use in electrical power generation. The system includes a unique structural design for a strong lightweight parabolic dish heliostat. It couples this heliostat with a small collimating lens (or mirror) and a flat side mirror to redirect the resultant concentrated solar energy beam to a central receiver.

Abstract: The invention discloses a solar concentrator that offers a low-cost option dimensioned for supplying energy to a household. The rays of the sun are reflected and concentrated to a point focus by a combination of fixed and movable reflectors, and the heat concentrated in that manner is directed to a stationary remote absorber from where it is used to generate energy to supply the house. A plurality of safety stoppers and barriers prevent accidental misdirection of the concentrated beam. The shape and geometric arrangement of the fixed portion of the reflector array is designed so that the average amount of light received by the stationary remote absorber is maximized for all solar positions within the system's working range.

Abstract: A solar dish collector system includes a solar dish collector panel for reflecting sunlight, and a conduit adjacent the solar dish collector panel. The conduit includes a supply tube to provide fluid to be heated by the reflected sunlight, and a return tube to return the heated fluid. A collector encloses open ends of the supply and return tubes, and is positioned to receive the reflected sunlight from the solar dish collector panel. The fluid from the supply tube at least partially fills the collector and is heated by the reflected sunlight while circulating therein. The heated fluid is then returned via the return tube.

Abstract: A solar power station includes a plurality of solar panels each connected to a leaf, the leaf including a roof beam; a plurality of bearing plates respectively attached to the roof beams of the leaves; a first supporting structure connected to the bearing plates; a second supporting structure rotatably connected to the first supporting structure and fixedly mounted to a base; and a plurality of hydraulic jacks. One end of each hydraulic jack is fixed with the first supporting structure, and another end of the hydraulic jack is pivotally mounted to the roof beam of one of the leaves.

Abstract: A concentration system or solar concentrator for supplying concentrated solar energy. The system includes a lens array with linear lenses focusing light received on an outer surface onto a number of focal point or focused lines of light. The system includes a light wafer with a substantially planar body formed of a thickness of a light transmissive material. The body includes a top surface facing the lens array and receiving the focused light from at least one the linear lens and further includes a bottom surface opposite the top surface. The light wafer includes a ray splitter, in the form of a triangular air gap, paired to each linear lens at or near a focal point of the paired lens to direct the received focused light into the body or towards edges or sides of the body where a solar collector such as a thermal or photovoltaic collector is positioned.

Abstract: Disclosed are a system and methods of control signal generation of a solar panel orientation system with interference reduction using an infrared filter. In one embodiment, a solar panel orientation system includes a sensor that generates a control signal component when the sensor receives an ultraviolet part of a radiation signal. The system further includes an additional sensor coupled to the sensor that generates an additional control signal component when the additional sensor receives an additional ultraviolet part of the radiation signal. The control signal component and the additional control signal component each include one or more of a voltage and a current. In addition, the system includes an infrared filter that reduces an interference caused by an infrared part of the radiation signal.

Abstract: A solar energy collection system comprises a frame for mounting the system on a suitable substrate and a plurality of solar panels disposed adjacent to one another on the frame. A first set of the solar panels are movable relative to a second set of the solar panels, for tracking movement of the sun during the day. Solar panels of the first set are arranged in alternating fashion with solar panels of the second set. In some embodiments of the invention, the panels in the second set of solar panels are stationary. The second set of solar panels, in some embodiments, are disposed substantially flat, relative to the frame and the substrate on which the frame is mounted. In some embodiments, differing from those in which the second set of solar panels are stationary, the second set of solar panels may be arranged to be movable relative to the first set of solar panels.

Abstract: A solar energy power generation system generates AC electrical power from solar radiation through the use of parabolic troughs to capture the energy and a fluid turbine to convert the solar energy to mechanical energy. The turbine is directly coupled to a generator to produce AC electrical power.

Abstract: The invention pertains to a solar sensor that includes a first modulator that is transparent to electromagnetic waves within a spectrum, and an additional modulator that is at best slightly transparent to the electromagnetic waves within the spectrum. The additional modulator features a belt-shaped region of varying widths that is arranged on the outside of the first modulator and partially covers the first modulator, and a photodetector that receives the electromagnetic waves and is covered by the first modulator.

Abstract: This invention deals with the general topic of adaptive non-imaging tracking of the sun. A transmission-mode electro-optical system is presented for solar energy tracking and collection. The scale of the system may range from small portable systems to large-scale industrial power plants used for the production of environmentally benign energy. It maybe integrated directly into buildings and other platforms without the need for heliostats to hold photovoltaic cells or other energy conversion devices above the building or other host platform. It makes solar energy harvesting systems practical by allowing the separation of tracking, collection, concentration, aggregation, distribution, and energy conversion. This novel system is unique and distinct from other sun tracking and energy conversion systems because it allows adaptive solid-state electronics to be used in place of conventional mechanical tracking heliostats.

Abstract: A solar tracking sensor and methods of tracking the sun. In one embodiment, the solar tracking sensor includes a housing, an inclinometer to output a signal indicative of the angle of the housing relative to the gravitational pull of the Earth, and first and second photosensors located on a first plane located within the housing. An opening on one side of the housing allows solar radiation to pass through the housing and reach the first and second photosensors. A difference calculating module is coupled to the first photosensor and the second photosensor. The difference calculating module determines a photosensor difference value using signals from the photosensors and outputs a photosensor difference value. The photosensor difference value can be used by a controller. The controller is coupled to the inclinometer determines whether the opening is aligned with the Sun based on the photosensor difference value and information or signal from the inclinometer.

Abstract: A portable PV modular solar generator. A plurality of wheels are attached to the bottom of a rechargeable battery container. At least one rechargeable battery is contained inside the rechargeable battery container. A power conditioning panel is connected to the rechargeable battery container. At least one photovoltaic panel is pivotally connected. In a preferred embodiment, the rechargeable battery container is a waterproof battery enclosure having a knife switch connection. A mast having a rotation bar is supported by the waterproof battery enclosure. At least one solar panel support brace for supporting the photovoltaic panel is attached to the rotation bar. The power conditioning panel is waterproof, is attached to the mast and has a door. When the door is opened, at least one safety switch is opened, breaking an electric circuit. The waterproof power conditioning panel has a charge controller and an inverter.

Abstract: A positional sensor for a solar energy collection device includes a fine sensing device having first light-sensitive sensors supported above a base so that adjacent first light-sensitive sensors are oriented in mutually orthogonal directions at a sensor height above the base. The first light-sensitive sensors are positioned at oblique angles relative to the base. The sensor also includes a coarse sensing device having a light-opaque shield surrounding the first light-sensitive sensors that extends outwardly from the base to a height that is greater than the sensor height. The shield includes second light sensing devices directed outwardly from the shield and arranged so that adjacent second light-sensitive sensors are oriented in mutually orthogonal directions.

Abstract: A horizontal solar tracker is provided for solar tracker and solar moduli. The horizontal solar tracker uses a truss device to enhance bending moment endurance. The truss device has good stress strength. Thus the present invention can resist deformation.

Abstract: A solar energy collection and conversion system includes at least one mirror array, with each array including a multiplicity of mirrors, and each array of mirrors reflecting incident sunlight onto a common target. The common target serves as a collection point where the reflected sunlight energy converges and is thereby concentrated. The target comprises an energy to electricity conversion device, for example, a photovoltaic device, and/or a reservoir of material which can be heated by the incident light energy such that the energy may be subsequently extracted to generate electricity.

Abstract: Lower heat-collection efficiency and a much smaller amount of solar heat may result from the providing of only a single receiver on a supporting post to collect lights coming from both heliostats located at nearby positions and heliostats located at faraway positions. A solar heat power generation device to be provided by the invention can avoid such problems. The solar heat power generation device has the following characteristic features. The solar heat power generation device comprises: a supporting post 4 including a receiver 1 that receives sunlight; and a plurality of heliostats 6 which are provided concentrically around the supporting post 4 and which reflect the sunlight towards the receiver 1. The supporting post 4 includes at least two receivers 1a and 1b that are arranged in the up-and-down direction.

Abstract: A system is provided for converting thermal energy derived from a solar field into electricity.

Abstract: Concentrating solar collector systems that utilize a concentrating reflector to direct incident solar radiation to a solar receiver are described. In one aspect, the reflective surface is arranged to direct light to the receiver in a non-imaging manner in which the solar rays reflected from the opposing edges of the reflective surface are generally directed towards a central portion of the solar receiver. Rays reflected from selected central portions of the reflective surface are directed closer to the edges of the receiver than the solar rays reflected from the edges of the reflective surface. The described reflectors are generally intended for use in solar collector systems that track movements of the sun along at least one axis.

Abstract: A free-floating, integrated, solar operated water heater appliance, for heating the body of water includes a flotation device for buoyantly supporting the appliance in the body of water. A water heater element, fueled by solar energy, heats water pumped through the heater element by an integral pump, driven by solar energy. A solar energy reflector/container supports the heater element and concentrates solar energy onto the outer surface of the heater element. A parabolic dish reflector concentrates solar energy onto the inner surface of the heater element. Water is circulated through the heater element and returned, in elevated temperature, to the body of water.

Abstract: The present invention is directed to an apparatus and method for improving the total power output from a field of solar energy systems. The invention provides a field level tracker controller which calculates an improved positioning of individual solar energy systems and communicates those configurations to trackers in the field. An algorithm stored in the controller calculates the improved configuration for the solar energy systems based on factors such as solar movement, shade patterns generated by surrounding structures, and measured output of the energy systems. Improved positioning may include individual energy systems being directed to a stowed position to maximize the power output of the field as a whole.

Abstract: The present invention relates to a sun tracking sensor unit and a sun tracking apparatus having the same.

Abstract: A solar powered aerial vehicle includes an elongated airframe incorporating lifting and control surfaces, a mechanism for propelling the airframe through the air such that lift developed by the lifting surface is equal to or greater than the weight of the aerial vehicle, a planar solar sail coupled to the airframe and having at least one surface adapted to collect solar energy during the day and to power the propelling mechanism with a first portion of the energy collected, and an apparatus such as a fuel cell/electrolyzer for storing a second portion of the solar energy collected by the solar sail during the day and for powering the propelling mechanism with the second portion of energy during the night. The vehicle is capable of continuous operation at northern latitudes and during the winter months for extended periods without landing or refueling.

Abstract: In one embodiment, a solar energy collection system that includes an array of collectors to track movements of the sun, each collector having a plurality of reflector panels, a support structure that supports the reflector panels, wherein the support structure supports the reflector panels in a manner that defines a trough, a pair of reflective side walls and a trough aperture suitable for receiving incident sunlight during operation of the collector, a plurality of solar receivers, each solar receiver being positioned generally adjacent an edge of an associated trough and including at least one photovoltaic cell, wherein the reflector panels are arranged to direct incident sunlight towards the solar receivers using a single reflection during operation of the collector, and a tracking mechanism to rotate the collector about an axis perpendicular to the longitudinal axis to track movements of the sun and direct incident sunlight along the longitudinal axis.

Abstract: A grid support system for tracker-mounted solar panel array for rooftop applications includes a base frame having a plurality of interconnected lateral members which define a generally planar area substantially parallel with the rooftop. The system also includes a set of support legs corresponding to each one of the tracker devices. The set of support legs are secured to the lateral members and extend upward and inward toward one another to a respective tracker mounting plate. The tracker mounting plate supports a tracker device and associated solar panel(s). A plurality of ballast trays are secured to the base frame and are adapted to hold a plurality of ballast weights for applying a downward force on the base frame to stabilize and resist movement of the base frame.

Abstract: Embodiments relate to solar energy systems and methods of operating the same. In some embodiments, the solar energy system comprising: a plurality of heliostats configured to reflect sunlight to a target mounted on a tower, each heliostat including a respective heliostat controller, the target, the target being selecting from the group consisting of an energy conversion target and/or a secondary reflector; and a macro-array of light-intensity sensors characterized by a maximum sensor-sensor distance and mounted on the tower such that when any heliostat of the plurality of heliostats reflects a beam of light onto the macro-array of light-intensity sensors, the maximum dimension of the reflected beam's projection on the macro-array is at most twice the maximum sensor-sensor distance, wherein each heliostat controller is operative to control its respective heliostat so that the light beam reflected by the heliostat traverses the macro-array of light-intensity sensors.

Abstract: A sun tracing device includes a power unit having an elevating element, a supporting plate carrying a photoelectric transformation unit, and an adjusting unit coupled to the power unit and the supporting plate. The power unit is used to lift/lower the adjusting unit, so that the adjusting unit can rotate and/or lift/lower the supporting plate.

Abstract: A solar tracking and concentration device, including a reflecting unit, a receiving unit, a controlling device, and a plurality of photo sensors, is provided. The receiving unit is used to receive the sunlight reflected and reflected by the reflecting unit. The receiving unit and the reflecting unit face each other. The receiving unit is adapted to move along a first direction. According to the position and the time of the reflecting unit, the controlling device controls a rotation angle of a support element and controls a first moving position of the receiving unit moving along the first direction, in which the support element supports the reflecting unit and the receiving unit. The photo sensors are used to detect the sunlight reflected by the reflecting unit to the receiving unit, and are adapted to output a first feedback signal to calibrate a direction of the receiving unit facing the reflecting unit.

Abstract: Provided is a high-effective concentration photovoltaic solar tracking device and method; and, more particularly, to a concentration photovoltaic solar tracking device and method, which maximize concentration efficiency by concentrating solar light using a Fresnel lens and moving a solar panel based on focus information formed when the concentrated solar light is irradiated on a photodiode.

Abstract: Systems and methods of calibrating heliostat parameters for subsequent open-loop sun-tracking, the calibration based on driving artificial light source reflections from one or more heliostats into one or more image sensors.

Abstract: A system may include determination of solar tracking error associated with a solar collector, and determination of a fault associated with the solar collector based on the determined solar tracking error. In some aspects, determination of the fault includes fitting a tracking error vs. time function to the determined solar tracking error and the plurality of previously-determined solar tracking errors, and determining that a derivative of the function exceeds a threshold value.

Abstract: A solar power generating system employing a solar battery includes a two-dimensional reflector comprising a holder and a sheet-like first solar battery held on the holder. The sheet forms a partially absorptive and partially reflective surface of the reflector. The two-dimensional reflector has a focal line and a mirror axis plane extending along the direction of its length. The system further includes a sun-tracking unit to detect the direction of the sun and to control the two-dimensional reflector to point the mirror axis plane toward the sun. The system further includes a thermally conductive tube extending along the focal line of the two-dimensional reflector, a second solar battery held on an outer surface of the tube with its photo-sensitive surface facing outward, and a cooling and heat supplying unit for circulating fluid through the tube and for supplying obtained heat externally.

Abstract: Solar concentrators are arranged in an array to define an input aperture such that the solar collector is positionable to face the input aperture of the concentrators skyward. An input axis of rotation extends through the aperture in the skyward direction, and a focus region is smaller than the aperture. Each concentrator includes at least one optical arrangement that is supported for rotation about the input axis for tracking the sun within a predetermined range of positions of the sun using no more than the rotation of the optical arrangement around the input axis. An optical concentrator is described in which a receiving direction extends at an acute angle from an optical axis and in one azimuthal direction outward from the optical axis such that a component of the concentrator is rotatable about the optical axis for alignment to receive input light. A previously unknown inverted off-axis lens is described.