Mobil Solar Energy Corporation

Rwe Schott Solar Gmbh

Other

Ronald C Gonsiorawski

Jeffrey T Borenstein

Douglas A Yates

Michael J Kardauskas

Christopher E Dube

Grace Xavier

George Czernienko

A photovoltaic module comprises electrically interconnected and mutually spaced photovoltaic cells that are encapsulated by a light-transmitting encapsulant between a light-transparent front cover and a back cover, with the back cover sheet being an ionomer/nylon alloy embossed with V-shaped grooves running in at least two directions and coated with a light reflecting medium so as to provide light-reflecting facets that are aligned with the spaces between adjacent cells and oriented so as to reflect light falling in those spaces back toward said transparent front cover for further internal reflection onto the solar cells, whereby substantially all of the reflected light will be internally reflected from said cover sheet back to the photovoltaic cells, thereby increasing the current output of the module. The internal reflector improves power output by as much as 67%.

Photovoltaic module with light reflecting backskin

In the manufacture of a wafer-type silicon solar cell having on its front side a silicon nitride AR coating and an electrical contact that is formed by printing a thick film metal ink onto the silicon nitride in the form of a grid-like pattern having narrow fingers and then firing that ink to convert it to a bonded metal contact, a surface treatment method is provided to adjust the condition of the surface of the silicon nitride coating in a manner that substantially improves the adherence of the thick film ink to the silicon nitride coating, thereby eliminating or substantially inhibiting the tendency of the narrow fingers of the unfired ink to peel away before the ink has been fired to produce the electrical contact. The surface treatment method comprises subjecting the silicon nitride layer to a corona discharge using a plasma jet and is readily incorporated into the manufacturing process sequence without requiring any modification of existing stages of that sequence.

Surface modification of silicon nitride for thick film silver metallization of solar cell

A laminated solar cell module comprises a front light transmitting support, a plurality of interconnected solar cells encapsulated by a light-transmitting encapsulant material, and an improved backskin formed of an ionomer/nylon alloy. The improved backskin has a toughness and melting point temperature sufficiently great to avoid any likelihood of it being pierced by any of the components that interconnect the solar cells.

Solar cell modules with improved backskin

Photovoltaic cells with silver-rich thick film electrical contacts having superior thermal aging properties are disclosed. The silver-rich contacts are formed by firing a silver ink or paste wherein substantially all of the silver in the ink or paste before firing is in the form of spherical particles. Preferably inter-cell connections to the contacts are accomplished using a tin and silver solder paste comprising between about 96% tin/4% silver and 98% tin/2% silver. Solar cells having contacts incorporating the present invention exhibit the capability of withstanding temperatures in the range of 150.degree. C. with little or no thermal degradation of contact peel strength in the region of the solder bonds.

Method for forming solar cell contacts and interconnecting solar cells

Photovoltaic cells with silver-rich thick film electrical contacts and superior thermal aging properties are disclosed. Electrical wires are bonded to the silver-rich thick film contacts using a tin and silver solder paste comprising between about 96% tin/4% silver and 98% tin/2% silver. Solar cells having soldered connections incorporating the present invention exhibit the capabilty of withstanding temperatures in the range of 150.degree. C. with little or no deterioration of the solder bonds for periods far longer than conventionally prepared cells.

Photovoltaic cells with improved thermal stability

A method of applying metallized contacts to a solar cell substrate, the front surface of which is covered with a dielectric layer. The method involves forming a plurality of apertures extending through the dielectric layer using a laser beam and defining a grid-shaped electrode. The apertures comprise a plurality of microscopically-sized holes that are arranged in a series of rows, with the holes being spaced a relatively short distance from one another. Nickel is plated onto the portions of the substrate exposed through the apertures. The nickel plating is then overcoated with copper which is preferably applied by a contactless light-induced plating process. The copper plating process causes copper to be deposited so that it bridges over the dielectric layer between the holes so as to form an integrated grid electrode structure.

Dotted contact solar cell and method of making same

A method of forming a metallization pattern on a solar cell substrate having an outer layer of a selected dielectric such as silicon nitride, silicon dioxide, or glass, by removing selected portions of the dielectric layer with a laser beam. This laser exposure drives portions of the P/N junction positioned beneath the exposed regions of the substrate more deeply into the substrate. Removal of selected portions of the dielectric layer exposes regions of the silicon substrate on which conductors may be deposited by conventional immersion plating methods. This laser removal of the dielectric layer is effected in an environment substantially free of chemical etching substances. Following removal of the selected portions of the dielectric layer, the substrate is preferably immersed in a buffered oxide etch solution to remove residual silicon dioxide and is then preferably immersed in a high ratio (nitric acid to hydrofluoric acid) etch solution to remove residual silicon nitride. The method of forming a metallization pattern may be incorporated into a comprehensive solar cell fabrication process.

Method of fabricating solar cells

A process of manufacturing silicon solar cells with efficiencies of between about 12.5% and about 16.0% is described, the method being characterized by forming a P/N junction adjacent the front surface of a silicon substrate, subjecting the front surface of the substrate to a selected plasma surface etch treatment, and then forming a polysilazane coating on the etched front surface by (a) first subjecting the substrate to an ammonia plasma treatment for a predetermined period of time so as to produce hydrogen implantation and (b) subjecting the subtrate to a silane and ammonia plasma treatment to obtain additional hydrogen implantation and formation of a polysilazane (hydrogenated silicon nitride) coating. The polysilazane coating is etched to form a grid electrode pattern. An aluminum coating is applied to the rear side of the substrate so as to form a back electrode. The aluminum coating is heated so as to alloy with the silicon substrate and thereby form an ohmic contact. The alloying step also densifies the polysilazane so that it is more nearly silicon nitride. The exposed silicon on the front side of the substrate is coated with an adherent coating of a highly conductive metal so as to form a grid electrode.

Method of fabricating solar cells with silicon nitride coating

A solar cell fabrication procedure is described which is characterized by (1) forming a front surface mask in the configuration of the front surface electrodes, (2) a passivation step which, inter alia, results in the formation of an altered silicon substrate surface layer in the areas not covered by the front surface mask, (3) removal of the front surface mask, and (4) the use of the altered surface layer as a plating mask for subsequent metallization steps.

Growing community of inventors

Danvers, MA, United States of America

Ronald C Gonsiorawski