Abstract: The present invention pertains to a heating apparatus for heating a defined space which generally comprises at least one heat source, and an enclosure for surrounding both the heat source and a user. The invention provides for a wide variety of heat sources which are suitable for use herewith. The invention also provides for a wide variety of materials which can be used to form the enclosure.

Abstract: A solar collector device for mounting on the outside of a support structure and including a fluid circuit for receiving a fluid for heating by solar radiation, the device further comprising a length of connection piping connected to the fluid circuit and moveable relative to the fluid circuit while thus connected thereto from a protected position to an installation position where the distal end thereof extends to the inside of said support structure.

Abstract: For the production of vacuum elements, which optionally contain fittings in the form of at least one solar module (photovoltaic element) and/or a solar collector or a display element, negative pressure is produced in a space between two flat components, in particular translucent or transparent plates, such as glass panes that are bound together via a bead made of sealing material, such that an arrangement that consists of a first component provided with a bead and at a distance therefrom but parallel to the second component arranged therein, is introduced into a vacuum chamber and pressed under vacuum. In this case, an elevated temperature also optionally can be applied to laminate films provided between the components with the components and optionally present fittings.

Abstract: A portable solar shower includes two detachable water reservoirs. One of the reservoirs may be coupled to a water source and includes a diverter valve regulating the flow and temperature of water spayed by a shower head, and the other reservoir has a port for coupling to the shower head. When the solar shower is not in use, the reservoirs may be separated from one another to form a compact package adapted for storage or transportation.

Abstract: An integrated spa water heating assembly comprising a solar water heater panel, having a water inlet and outlet, an electrical motor/pump unit attached to the panel and having ducting for drawing water from the spa interior for passage to the panel inlet, the panel operating to discharge heated water flowing from the panel back into the spa water, and a solar power panel operatively attached to the heater panel, and electrically connected with the motor to power motor operation.

Abstract: A vacuum solar thermal panel including a vacuum envelope defining a sealed volume and able to withstand atmospheric pressure when evacuated, at least one heat absorber being disposed inside the vacuum envelope, a pipe entering and exiting the envelope and being in contact with the heat absorber, the vacuum envelope including a first plate made of glass, a peripheral frame, a metallic peripheral belt being joined to the first plate by way of a vacuum tight bulk glass-metal seal, including glass material and obtained by fusion and subsequent solidification. The metallic peripheral belt includes at least one elastically deformable portion that prevents the bulk glass-metal seal from getting damaged and is no more vacuum tight when subject to the evacuation process of the envelope and the thermal treatments of the panel and the potential reciprocal displacements of the glass plate and the joined metallic peripheral belt.

Abstract: A panel, for creating a wall/roof of a structure, may consist of a core and an outside lining, and flow-pipes located under corrugations in the lining. Each of a plurality of pipes run from one end of the core to the opposite end, and protrudes outward from those ends. The core may comprise a first side having a female-shaped indentation, and a second side having a corresponding male shaped protrusion, to permit joining together of two or more panels. The ends of alternating flow pipes of one or more panels may be coupled with an adjacent pipe using an elbow, to form a pipe coil in a-heat transfer system. With the help of headers, heat exchangers, and a liquid medium directed to flow through the pipes of a system of rooms, heat management can be accomplished using solar energy.

Abstract: A solar absorber module is described. The module has a housing with a longitudinal axis with a first tapered housing section with a first, free end, and a second end with a reduced cross-sectional area compared to the first end, and with a second housing section adjoining the second end of the first housing section with a substantially constant cross-section over its length. The module also has a ceramic solar absorber element accommodated in the first end of the first housing section with a first surface that can be oriented toward the solar radiation with an axis of symmetry, and a second surface lying across from the first surface, wherein the solar absorber element has a large number of substantially straight channels connecting the first surface to the second surface. The solar absorber module is accommodated in the first end of the first housing section such that the axis of symmetry of the first surface is inclined relative to the longitudinal axis of the housing.

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: It is provided a solar energy module for converting solar radiation to thermal energy. The module includes a thermally insulating element transmissive to solar radiation and having low transmissivity to thermal infra-red radiation, an absorbing element, a sealed enclosure, and a variable portion in the envelope of the sealed enclosure. This portion is adapted for varying the volume available to gas enclosed in the enclosure in accordance with changing temperature of the enclosed gas. Also, it is provided a solar energy module which includes a thermally insulating element, an absorbing surface and liquid pipes for absorbing the solar radiation, and an air duct thermally coupled thereof. The heated liquid and the heated air are usable for a variety of thermal applications. A heat storage may be thermally coupled to the absorbing surface and to the liquid pipes. The air duct has several air valves, and is associated with a controller for regulating air flow through the air duct.

Abstract: The invention relates to a solar collector. The collector has a heat regulating medium which defines a cavity therein. An aperture communicates with the cavity so as to allow solar energy incident on the aperture to enter the cavity. An energy collection device is disposed in the cavity and in thermal contact with the heat regulating medium to collect solar energy entering the cavity.

Abstract: A collector system (12) is disclosed that comprises a row of linearly conjoined collector structures (13). The collector system is arranged to be located at a level above a field of reflectors (10) and to receive solar radiation reflected from the reflectors within the field. The collector structure (13) comprises an inverted trough (16) and, located within the trough, a plurality of longitudinally extending absorber tubes (30) that, in use, are arranged to carry a heat exchange fluid. The absorber tubes (30) are supported side-by-side within the trough and each absorber tube has a diameter that is small relative to the aperture of the trough. The ratio of the diameter of each absorber tube to the trough aperture dimension is of the order of 0.01:1.00 to 0.10:1.00 and, thus, the plurality of absorber tubes functions, in the limit, effectively to simulate a flat plate absorber.

Abstract: A solar collector device is provided. The solar collector device includes an evacuated tube and a mini-channel tube mounted within the evacuated tube, the mini-channel tube comprising a first plurality of ports for inflow of a heat-transfer fluid and a second plurality of ports for outflow of the heat-transfer fluid to a heat exchange system. The mini-channel tube may have a hydraulic diameter in a range of approximately 3 millimeters to approximately 200 micrometers. The mini-channel tube may have a hydraulic diameter in a range of approximately 200 micrometers to approximately 10 micrometers.

Abstract: A pavement element is revealed. The pavement element includes a thermally conductive covering element and a solar collector frame. The thermally conductive covering element is a foamed metal disposed with a plurality of through holes for providing slip resistance and drainage function. Moreover, the solar collector frame collects heat and then the heat is transferred to the thermally conductive covering element so as to cause high temperature for killing insect larvae or eggs attached to the thermally conductive covering element.

Abstract: The invention relates to a mounting device (3) for at least one module (400) for recovering power from solar radiation that includes a first (54) and second (56) groove arranged in a stationary manner opposite one another. Each groove (54, 56) is capable of receiving a module edge (402A, 402B) while an opposite module edge (402B, 402A) is received in the other groove. In the configuration for maximum sinking of an edge (402A, 402B) of the module (400) into a groove (54, 56) from among the two grooves, the opposite module edge (402B, 402A) is capable of being extracted from the other edge, and the device contains a means (9) for maintaining the module in a position wherein the two opposite module edges (402A, 402 B) are received in the first (54) and second (56) groove, respectively. The grooves (54, 56) are formed in a section (5) making it possible to completely hold up each module (400).

Abstract: A frame for solar module to fix a solar panel within is disclosed. The frame for solar panel includes two first fastening members arranged at two opposite sides of the solar panel, two second fastening members arranged at another two opposite sides of the solar panel, and plural screws to screw the first fastening members and the second fastening members. Each first fastening member and each second fastening member includes a supporting portion for supporting the solar panel, a base portion, a connecting portion for connecting the supporting portion and the base portion, and a beam disposed between the supporting portion and the base portion.

Abstract: A glazed solar collector with a frame surrounding an absorber (3a), an insulating layer (2) disposed beneath the absorber (3a) and a cover pane (4) spaced above the absorber (3a). Absorber tubing (3b) is connected to an supply header (15) and to an return header (16). The axis (X) of the supply/return header (15,16) is arranged at an angle to a plane (Z) coinciding with the cover pane (4) with the distance between the axis (X) and the plane (2) increasing along the axis (X) in a direction leading away from the collector.

Abstract: A solar thermal panel includes an integrally formed base including a rectangular bottom, four walls, four corners, and a top lip. Four corner brackets each have a leg portion coupled to adjacent walls and a foot portion extending outwardly from the leg portion. A spacer is disposed atop the top lip and a cover is disposed atop the spacer. A trim strip has a first leg that abuts a top edge of the corner bracket and a second leg that overlaps an outer edge of the cover. A layer of sealant is disposed within a space at least partially defined by the trim strip, the cover, the spacer, and the top lip. Parallel supply and return headers extend through an enclosure defined at least partially by the base and the cover, and a plurality of fin-tubes extend between the supply and return headers.

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: To provide the solar cell module retaining structure, the frame for the solar cell module, and the holding member for the solar cell module, which reduces the number of members relating to the solar cell module retaining structure, standardizes the installation process thereof, and reduces the cost of manufacturing and installing.

Abstract: In one embodiment a solar collector is provided. The collector has a modular heat transfer component which includes a heat transfer core to heat up a heat transfer fluid. The collector makes use of the heat transfer fluid itself to prevent heat loss through radiation.

Abstract: A boiler for a solar receiver includes a plurality of boiler walls arranged end to end surrounding a boiler interior space. Each wall includes a plurality of side by side solar receiver panels. The panels are fluidly connected to one another by way of a steam circuit. The boiler also includes a plurality of conduits each forming a portion of the steam circuit fluidly connecting the panels. The panels and conduits form a plurality of heat transfer passes in the steam circuit. In certain embodiments, the steam circuit includes between two and ten passes, inclusively.

Abstract: A solar component for solar thermal installations has an absorber element and at least one tube for a fluid thermal medium, coupled thermally directly or indirectly to the absorber element. At least one solid insulation of foam glass or plastic, in particular a cured plastic foam made of polyurethane or polyisocyanurate, is provided. The solid insulation, when mounted as intended, fixes the at least one tube relative to the absorber element.

Abstract: A water vapor ejector comprises a desiccant disposed in a communication path to a green house enclosure. In the day time and under sunlight exposure, the green house enclosure heats up, which dries the desiccant and generates a flow to the outside ambient through a pressure difference. The moisture trapped in the desiccant is then released to the outside ambient. In the night time, the green house enclosure cools, which generates a flow to the inside of the enclosure. The desiccant traps the moisture within the flow, ensuring a moisture-free enclosure. The cycle re-starts in the next morning when the enclosure heats up. The diurnal cycle removes the water vapor present in the enclosure and delivered to the exterior of the enclosure.

Abstract: A fixing member (3, 40, 43, 50, 53) which fixes a first frame body (1) of a solar battery module main body (9) slides along the first frame body, and the solar battery module main body includes a connecting portion (10) and a to-be connected portion (11) which connects the first frame bodies which are adjacent to each other through the fixing member. With this, a position of the fixing member can freely be moved with respect to the first frame body, the fixing member is slid to a position where there is a structure member (32) which supports a roofboard at predetermined intervals, and the fixing member is mounted at that position. With this, the fixing member can be mounted more strongly, and the adjacent two first frame bodies (31) can be fixed by the fixing member.

Abstract: Apparatus and methods are disclosed for reducing or eliminating the need for an intermediate supporting rack in a solar panel installation, which in turn may lower the cost of the installation. In one exemplary embodiment, a mount design is provided that includes a mounting flange attached to or integrally formed with a first side of a solar panel frame. This first side and flange operate together with a second side of the solar panel frame that is designed to engage with the mounting flange and first side of an adjacent solar panel. The geometry of the first and second sides may be such that they engage upon installation. The engagement may further include pins or similar components protruding from one side of one solar panel to fit into corresponding holes in a side of an adjacent panel.

Abstract: A subterranean solar panel system 10 for collecting solar energy and generating electricity, includes a structure 12 having a building section 14, a roof 16, and rooftop surface 18. A plurality of solar panels forming a solar panel station 30 is provided in an underground space 20. An optical device 50 is provided for capturing and magnifying sunlight in the form of a transparent lens 52 that is either concave or convex, which receives and magnifies the sunlight, or enhances it to be transferred to the solar panel station 30. A system of fiber optic conductors 60 is provided having fiber optic strands contained therein which are connected to the transparent lens 52 and the solar panel station 30 for transferring the collected sunlight from the transparent lens 52 to the solar panel station 30.

Abstract: A solar collection apparatus includes a housing with a first opening, a second opening, and a partially-mirrored floor. The device includes fins with first and second end segments and curved bodies. Both sides of the fin bodies have the same curvature, and both sides are mirrored. The curved bodies of the fins all have the same curvature. The floor and the second end segments of the fins together define a light pipe. Light impinging on the first opening of the housing is directed into the light pipe by reflection between adjacent faces of adjacent fins. The second end segments of the fins prevent the light within the light pipe from exiting the light pipe in the first direction. Light within the light pipe exits the light pipe at the second opening, where it may be stored, or may be directed to a solar energy device such as a solar cell, turbine, or vehicle heater.

Abstract: A solar collector comprising an array of solar cells, each of which is spaced-apart from a subset of solar cells adjacent thereto, defining a hiatus therebetween; a first substrate disposed to cover the array of solar cells; and a second substrate disposed to cover the array of solar cells, with the array begin position between the first and second substrates, with a plurality of throughways, each of which extends from an aperture in the first substrate, traversing the hiatus and terminating in an opening in the second substrate.

Abstract: A solar heating apparatus, which includes a panel having one or more layers or a group of such layers, wherein one or more layers among such a group of layers constitutes a transparent medium. The panel includes at least two other layers among the group of layers, which constitute a reflective medium. The panel additionally includes one or more spaces formed between the layers and at least one other space formed between the other layers. A heat transfer fluid can be located within the space between the layers. The heat transfer fluid contains heat-absorbing particles, which are suspended in the heat transfer fluid and subject to a flow-force through the panel in a direction against a force of gravity. The heat-absorbing particles are held in light in the panel via a balance of a flow-force and the force of gravity. The heat-absorbing particles drift to the bottom of the panel when the flow-force stops.

Abstract: The present invention is directed to a device and method for securing optical elements in a solar energy system. Molded securing devices are fixed directly to the front panel of a solar energy system to provide for secure, aligned placement of optical components. In some embodiments, the peripheral edge of a front panel may be encapsulated by the molded device to provide alignment of peripheral optical elements and a secure water resistant seal between the front panel and a backpan. In other embodiments, molded securing devices may be positioned away from the peripheral edge to assist in alignment of central optical elements.

Abstract: The invention relates to a frame assembly for mounting solar modules (1), said frame assembly comprising at least two flat frames which are arranged at a distance, preferably forming a triangle respectively with the frame sides (2, 3, 4) thereof, respectively one frame side (4) being inclined in relation to the surface of the ground or the roof (5). Carrier profiled parts (6, 7) which can be respectively displaced and fixed and are used to support and fix a solar module (1) are respectively arranged on two adjacent frames on the inclined side (4) of the frame. The carrier profiled parts (6, 7) are used to ensure the connection to the adjacently arranged frame sides (2, 3) in such a way that they can be displaced and fixed in relation to each other. The frame sides (2, 3) are also connected in such a way that they can be displaced and fixed in relation to each other and/or comprise at least one length adjustment device.

Abstract: A plug and play solar panel assembly is disclosed. According to one embodiment, an apparatus comprises a substantially rectangular sheet having a first area configured to fit between a first layer and a second layer of a weatherproof surface. The sheet has a second area configured to protrude from the first layer and the second layer of the weatherproof surface. The second area includes a mounting area to attach one or more solar panels.

Abstract: A light wing device for mounting on a window in order to provide light reflection has been disclosed. The light wing device generally has a light wing, a mounting mechanism, and the light wing is configured to rotate away from the application of force to the light wing. This rotating light wing prevents premature breakage of the light wing from force encountering the light wing.

Abstract: A solar air conditioning device (100) includes a solar collector assembly (30), an inlet assembly (10) at an entrance of the solar collector assembly, and an outlet assembly (50) at an exit of the solar collector assembly. The solar collector assembly includes a heat-absorbing set (31) and a transparent panel (38) being assembled to a top of the heat-absorbing set. The heat-absorbing set comprises a plurality of heat-absorbing units (32) engaged with each other. Each of the heat-absorbing units includes two adjacent supporting members (33) and a heat-absorbing plate (35) sandwiched between and buckled with the two supporting members. The heat-absorbing set defines an air channel (314) with the transparent panel and a heat-absorbing channel (315) below the air channel. The inlet and outlet assemblies are in fluidic communication with the heat-absorbing channel.

Abstract: A solar receiver is disclosed and includes a housing having a front, radiation-facing, end and a rear end, the front end being formed with a cavity therein. A window is mounted at the front end of the housing and projects inside the cavity. A receiver chamber is defined within the cavity between the housing and the window. The receiver chamber has a working fluid inlet for ingress of working fluid to be heated therewithin, and a working fluid outlet for egress therethrough of the heated fluid. A solar absorber is within the receiver chamber for absorbing the solar radiation and heating the working fluid. The solar absorber includes at least one tubular member configured for maintaining fluid isolation between contents thereof and contents of the receiver chamber. The solar absorber is configured for heating working fluid within the receiver chamber exterior to the tubular member, and working fluid within the tubular member.

Abstract: A boiler for a solar receiver includes a first receiver panel having a plurality of substantially parallel boiler tubes fluidly connecting an inlet header of the panel to an outlet header of the panel. A second receiver panel has a plurality of substantially parallel boiler tubes fluidly connecting an inlet header of the panel to an outlet header of the panel. The boiler tubes of the second receiver panel are substantially parallel to the boiler tubes of the first receiver panel. The first and second receiver panels are separated by a gap. A panel expansion joint is connected to the first and second receiver panels across the gap, wherein the panel expansion joint is configured and adapted to allow for lengthwise thermal expansion and contraction of the receiver panels along the boiler tubes, and to allow for lateral thermal expansion and contraction of the receiver panels toward and away from one another, while blocking solar radiation through the gap.

Abstract: A boiler for a solar receiver includes a first boiler panel having a plurality of tubes fluidly connecting an inlet header of the first boiler panel to an outlet header of the first boiler panel. The tubes of the first boiler panel form a first solar receiver surface. A second boiler panel has a plurality of tubes fluidly connecting an inlet header of the second boiler panel to an outlet header of the second boiler panel. The tubes of the second boiler panel form a second solar receiver surface. The first and second boiler panels are adjacent to one another with a portion of the first boiler panel and an end of the first solar receiver surface overlapping an end of the second boiler panel to reduce solar radiation passing between the first and second solar receiver surfaces.

Abstract: A boiler for a solar receiver includes a first wall of substantially coplanar side by side boiler panels. A plurality of contiguous panels of the first wall each have an inlet header thereof at a common first wall header elevation. A second wall includes substantially coplanar side by side boiler panels. A plurality of contiguous panels of the second wall each have an inlet header thereof at a common second wall header elevation. The second wall is adjacent to and angled with respect to the first wall so that one end panel of the first wall is adjacent to one end panel of the second wall to form a boiler wall corner. The inlet headers of the two end panels of the boiler wall corner are at different elevations relative to one another.

Abstract: A base body comprises two frames to put lens and solar cells. The working process is simple and the weight and the cost of the base body is reduced.

Abstract: One embodiment relates to an earth-penetrating apparatus. The apparatus includes a pole with a hollow portion therein and a bottom end which is configured to be driven into ground. Anchoring parts are configured to be radially extendable from the pole. In addition, an expansion mechanism is configured to apply a force to the anchoring parts so as to radially extend the anchoring parts from the pole after the pole has been driven into the ground. Another embodiment relates to a solar collector arrangement that includes a plurality of earth-penetrating anchors. Other embodiments, aspects and features are also disclosed.

Abstract: A base body comprises two frames to put lens and solar cells. The working process is simple and the weight and the cost of the base body is reduced.

Abstract: A heliostat includes a pedestal, a transmission system, a heliostat frame assembly, and a mirror assembly. The heliostat frame assembly generally includes a first heliostat frame set and a second heliostat frame set mounted to the transmission system which is mounted upon the pedestal. Each heliostat frame set includes a stackable heliostat inner frame assembly and a stackable heliostat outer frame assembly. Each stackable heliostat inner frame assembly is identical and each stackable heliostat outer frame assembly is identical such that a multiple of heliostat inner frames and a multiple of heliostat outer frames are readily stackable in a nested arrangement for storage and transport.

Abstract: Disclosed is a fixture for external frame sections (1) of solar modules on a profiled support (2). Said fixture comprises a clamping piece support (3) which can be moved in a guided manner on the profiled support (2) in the longitudinal direction of the profiled support (2) and can be braced with the profiled support (2) so as to enclose a frame section (1) of the solar module and a clamping piece (4) that is guided within the clamping piece support (3). The clamping piece (4) is designed as a double-angled profiled element which has legs (4.1, 4.2) extending in opposite directions. The upper leg (4.1) embraces the frame section (1) of the solar module while the lower leg (4.2) is disposed in and on the clamping piece support (3) so as to be vertically adjustable in a guided manner in the moving direction (7).

Abstract: Solar collectors heat and self pump heat transfer fluid at reduced system pressure without mechanical intervention for heat exchange with hot water in a storage tank. Slugs of hot fluid are pumped by steam bubbles formed in solar collector tubes through an upper manifold and an exit-tube into an upper hot fluid reservoir. Hot fluid flows downward through a heat exchanger at the tank. Cold fluid returns to a lower reservoir. Vapor flows from the upper reservoir and is condensed by cooler water and walls of the lower reservoir. The cool fluid returns from the lower reservoir to a lower manifold supplying the collector tubes. Below ambient pressure is automatically established in the system. When heat build-up increases pressure in the system, fluid flows to a third closed variable volume reservoir. A float valve in the bottom of the third reservoir allows liquid to return to the system when it cools.

Abstract: The invention relates to a system for converting solar energy into mechanical or electrical energy, comprising: means for concentrating the solar radiation from the sun at a given focal point, collector means for receiving and accumulating the solar radiation originating from the concentration means in order to accumulate thermal energy, and means for converting the thermal energy accumulated in the collector means into mechanical energy. Subsequently, the mechanical energy can be converted into electrical energy using a conventional generator.

Abstract: A solar panel array support system including a plurality of removable, interengaged adjacent support modules of similar configuration. Each support module mounts a PV solar panel, and also a DC-AC inverter electrically connected to the solar panel. The DC-AC inverter is also electrically connectable to additional DC-AC inverters mounted to the adjacent solar panel support modules. Each support module includes flexible male connector elements that enter a slot forming a female connector element in an adjacent support module to pivotally and removably engage each support module to another. Individual modules or a plurality of solar panel support modules can be readily removed from and replaced in a solar panel array, and can be readily removed and installed to form a second modular solar panel array.

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: A collector includes a convergent lens (2) having a focal distance f and an image focal plane (PFI). The convergent lens (2) defines one of the walls of a casing (1) defined by two pairs of side walls (4a, 4c), a bottom wall (3) and a front wall defined by the lens (2), the side and bottom walls on the inside of the casing being reflective, and the depth p of the casing being lower than the focal distance f of the lens so that after multiple reflections, the ray beam (R1, R2) thus reflected is concentrated on a final image focus (I?) located inside the casing, the collector including a mobile receptor (6a) held inside the concentrated beam or in a position at least intersecting the beam by elements controlling the movement of the collector (6a) with that of the beam.

Abstract: The present invention provides a solar collector comprising a collector device and a heat-transfer device which includes a heat conductive conduit for heat-transfer fluid, the conduit being in physical contact with the collector device, characterized in that: the collector device comprises flexible metallic foil of which at least one side is adapted for exposure to solar radiation by the presence thereon of a heat absorptive coating; and the physical contact is maintained by tension effective to stretch the foil over the conduit. In an embodiment of the invention the tubes 5 of the conduit are arranged in one plane, the tension is maintained by bars 10 arranged in another plane, substantially parallel to the plain of the tubes. Foil 8 is placed so as to contact alternately with the tubes and with tension-maintaining bars 5.