The solar tracking mechanism is utilized in connection with a solar energy collection system. The collection system includes a light reflective shell shaped to focus solar radiation on a radiation absorbing segment of a tube which carries a heat transfer fluid. The shell is pivotally mounted on a support frame. An actuator mounted between the support frame and the shell rotatably the shell. A solar sensor is mounted deep within a sighting tube which is fixed to the shell such that a line of sight through the sighting tube is at least parallel to the optical axis of the shell. The solar sensor generates a sensor signal which is used as a control input to an actuator control system. End limit switches generate a limit stop signals when the shell reaches maximum angular positions. The actuator control system generates fluid flows to the actuator based the solar sensor signal and the limit stop signals. The method of tracking the sun includes providing a solar cell array, activating the solar collection system when solar radiation illuminating the array exceeds a predetermined threshold, providing a solar sensor shielded from the solar radiation except for direct, aligned radiation, pivotally rotating the shell westward based upon the solar sensor signal, stopping the shell at a maximum angular positions, and rotating the shell westward if the shell does not reach the maximum westward angular orientation during a predetermined daylight time period. The solar energy collection system may be further configured to include a bisected shell, which are hinged together. The shell halves can be collapsed onto each other thereby protecting the light reflective surface and the radiation absorbing segment of the tube carrying heat transfer fluid.

Solar collection system

A low concentration solar array for spacecraft and other uses which has a series of solar panels which can be deployed from a folded stowed configuration to a planar configuration. When the solar panels are stowed, the padding of reflector panels cushions and protects the solar panels from the stresses and vibrations of launch and space flight. Once the solar panels are extended into a deployed planar configuration, the reflector panels are raised to concentrate sunlight upon the solar panels. These reflector panels are constructed from rigid honeycomb substrates and therefore are the active structural members of the solar array, providing the structural rigidity for the solar array.

Foldable low concentration solar array

A light weight photovoltaic concentrator having a foldable, easily deployed structure for concentrating solar rays on solar cells for generating electricity is disclosed. The photovoltaic concentrator features a concentrator which can be inflated, for ease of deployment, to a shape for reflecting sunlight onto solar cells. The solar cells are protected from overheating by a protective infrared coating and by being attached to a heat pipe with a fin for radiating excess heat. The inflatable concentrator is inflated by gas stored in the central arm which supports one end of the concentrator. The concentrator is inflated until the epicenters of the front and rear surfaces reach a specified distance and the concentrator is thereafter maintained at this position by addition of additional gas as needed to compensate for leakage. The concentrator may have a means of stiffening the inflated reflective surface by chemical changes activated after the concentrator is deployed. The concentrator may also be made of a more rigid material rather than be inflatable.

Photovoltaic concentrator system

Systems and materials to improve photovoltaic cell efficiency by implementing a self-cleaning function on photovoltaic cells and on albedo surfaces associated with photovoltaic cell assemblies are provided. Materials for protecting albedo surfaces that surround photovoltaic cell assemblies, thereby maximizing energy input into the photovoltaic cell assemblies, are provided. Materials for self-cleaning photovoltaic cell panels, thereby maintaining their efficiency, are provided. Portable albedo collecting devices associated with photovoltaic cell assemblies are provided.

Self-cleaning protective coatings for use with photovoltaic cells

Flexible, lightweight reflective sheets are positioned to concentrate solar radiation upon spacecraft solar panels. The sheets are held with inner and outer spring members which urge each sheet from a gathered edge-stowed configuration towards a deployed, planar configuration. The outer spring members further urge each fully extended sheet to rotate about an axis along the panel's edge in a direction away from the solar panel's face. Restraint members in the form of tethers limit this rotation to place the sheet in a stable deployed position and orientation chosen by design to reflect solar radiation onto the panel face. The increased incident radiation permits a reduction of the number of solar cells needed to satisfy a power requirement, and allows consequent savings in spacecraft cost and weight. The outer spring members are resilient, elongate members which flex to a stowed position behind a respective panel or inerleavably gather with the flexible sheet into a compact stowed configuration adjacent a panel edge.

Thin-film solar reflectors deployable from an edge-stowed configuration

A lightweight solar cell array for space vehicles powered by solar electric propulsion. The array incorporates a plurality of hinged solar cell units which can be folded for stowage and thereafter extended into a planar configuration. Light is directed onto the solar cell array by a flexible reflector assembly which is carried below the array. The reflector assembly preferably comprises sheets of flexible material stowed on rolls whereby the sheets can be pulled from the rolls into extended positions. The solar cell array and the reflector are carried between two frames, one of which can be moved away from the other to deploy the array and the reflector assembly.

Charlie B. Whitney

Papers

Underwing reflector solar array