Panel for solar concentrators and tandem cell units

A panel for supporting a large group of energy collector lenses together with a corresponding number of solar cell units, comprising:

• a unitary housing having a continuous bottom wall and a plurality of recessed compartments that are defined by upstanding walls that are an integral part of said housing to provide a rigid structure having a low weight to area ratio;
• a plurality of lenses mounted on the housing, one lens for each compartment;
• said upstanding walls being sufficiently rigid to support the lenses at a fixed distance from the bottom wall;
• said bottom wall having a central opening in each compartment aligned with a focal point of the corresponding lens to provide an index position for locating a solar cell unit at the focal point in each compartment;
• a solar cell unit for each compartment mounted on a side of said bottom wall that is remote from said upstanding walls and including upper and lower cells of different semiconductive materials with the lower cell being mounted to receive radiation that has passed through the upper cell;
• and
• said solar cell units being electrically connected together by circuitry located on the bottom wall remote side to be shielded from focused solar energy, said circuitry comprising longitudinally extending strips of conductive material sandwiched between layers of an insulative material that is bonded to the bottom wall remote side and the conductive strips being arranged to provide voltage matching and power collection from the upper and lower cells mounted to said panel.

A heat spreader body comprising a thermally conductive, electrically non-conductive material having parallel faces;

• one of said faces having two islands of conductive material at diametrically opposite sides of a central area;
• the other of said faces having four islands of conductive material with a first two of said four islands being aligned with and electrically connected to the two islands of conductive material on said one face;
• and
• the other two of said four islands being diametrically disposed and positioned between the first two of said four islands to provide four terminals that are substantially coplanar.

A panel supporting a plurality of rows of tandem cell units on a continuous bottom wall that has an aperture for each cell unit;

• a plural number of solar radiation concentrators for focusing solar radiation at said bottom wall apertures, said concentrators being supported by the panel on a side of said bottom wall that is remote from said tandem cell units;
• said tandem cell units comprising:
• upper and lower cells;
• a heat spreader plate having opposed surfaces, said surfaces each having metallization islands that serve as terminals for said cells;
• said upper and lower cells being mounted on opposite surfaces of said plate;
• a circuit carrier having at least three parallel electric current carrying strips and spaced openings that are in registration with the tandem cell units in said row, said openings being sized to expose portions of the current carrying strips;
• and
• means for connecting said exposed strip portions to the metallization islands to provide voltage matching circuitry and means for collecting all of the electrical power generated by said tandem cell units.

A panel supporting a plurality of rows of tandem cell units on a continuous bottom wall that has an aperture for each cell unit;

• a plural number of solar radiation concentrators for focusing solar radiation at said bottom wall apertures, said concentrators being supported by the panel on a side of said bottom wall that is remote from said tandem cell units;
• said tandem cell units each comprising
• an upper cell of a first semiconductor material having upper and lower surfaces;
• a lower cell of a second semiconductive material having upper and lower surfaces;
• a heat spreader comprising a flat plate of thermally conductive, electrically non-conductive material sandwiched between the lower surface of the upper cell and the upper surface of the lower cell;
• and
• metallization on the heat spreader forming electrical circuitry for said unit, said metallization including a first island that engages a lower surface of the upper cell and a second island that is bridged by conductive material to the upper surface of the upper cell, a third island that engages the upper surface of the lower cell and a fourth island that is bridged by conductive material to the lower surface of the lower cell.

A row of tandem cell units interconnected in the form of a string, comprising:

• upper and lower cells mounted on opposite sides of a heat spreader having opposed surfaces each having metallization islands that serve as terminals for said cells;
• a circuit carrier having electric current carrying strips and spaced openings that are in registration with tandem cell units in said row, said openings being sized to expose portions of the current carrying strips;
• and
• means for bonding said exposed strip portions to the metallization islands to provide voltage matching circuitry and means for collecting all of the electrical power generated by said tandem cell units.

A tandem cell unit comprising:

• an upper cell of GaAs having upper and lower surfaces;
• a lower cell of GaSb having upper and lower surfaces;
• a heat spreader sandwiched between the lower surface of the upper cell and the upper surface of the lower cell and having an aperture aligned with photoactive areas of said cells;
• said heat spreader including metallization that forms electrical circuitry for said unit;
• said metallization including a first island that engages the lower surface of the upper cell, a second island that is bridged by conductive material to the upper surface of the upper cell, a third island that engages the upper surface of the lower cell, and a fourth island that is bridged by conductive material to the lower surface of the lower cell.

A panel supporting a large number of solar energy collector lenses together with a corresponding number of tandem solar cell units, comprising:

• a housing;
• at least one lens supported on one side of said housing;
• at least one tape circuit mounted on an opposite side of said housing;
• at least one tandem solar cell unit secured to said housing for receiving solar energy collected by said lens;
• and
• means for connecting current carrying surfaces of said at least one tandem solar cell unit to said tape circuit, including a heat spreader.

A method of making a lightweight honeycomb panel for a solar cell module comprising:

• providing a block of solid material having a thickness related to a focal length for a solar cell lens;
• forming side-by-side compartments by machining each compartment to have a depth slightly less than the block thickness to form a bottom wall and side walls as thin as can be produced that have a rigidity sufficient to support solar cells lenses;
• and
• providing a central opening in each compartment bottom wall that is related to a position of a focal point for the lens that is associated with said compartment to serve as a position reference for a concentrated sunlight solar cell.

A method of fabricating a row of tandem solar cell units interconnected in the form of a string, said tandem cell units each comprising an upper cell and a lower cell of different semiconductive material with the lower cell being mounted to receive radiation that has passed through the upper cell and the upper and lower cells are mounted on opposite sides of a heat spreader body having metallized islands that serve as terminals for said cells, comprising:

• providing a foil of an electrically conductive first material having a predetermined thickness;
• punching the foil to form electric circuit carrying strips;
• providing a coating of an electrically conducting material that is different from the first material on portions of said current carrying strips;
• providing a pair of layers of heat resistant polymer dielectric material in the form of a tape, said tape having prepunched holes to provide spaced openings that are in registration with the row of solar cell units and sized to expose the coated portions of the current carrying strips;
• applying the tape layers on opposite sides of the current carrying strips to form a laminate with the metal coated portions of the current carrying strips exposed in each opening;
• and
• connecting said metal coated portions to the metallized islands on said heat spreader body.