US5076857A — Photovoltaic cell and process

Claim 1

Independent Claim 211 words

An improved photovoltaic cell comprising: (a) a solar cell formed of a semiconductor material having a front surface and a back surface; (b) a front contact grid of a predetermined pattern provided on said front surface of said solar cell; (c) a cover plate formed of a glass material having parallel front and back surfaces and a thermal expansion coefficient matching that of said semiconductor material; (d) said back surface of said cover plate provided with a plurality of V-grooves each formed with facets diverging at a predetermined angle toward a base located at said back surface of said cover plate and mirroring said predetermined pattern of said front contact grid; (e) said back surface of said cover plate being electrostatically bonded to said front surface of said solar cell; (f) said V-grooves serving as clearance slots for said front contact grid such tat said grid is fully contained therein by projecting into said V-grooves from their said respective bases, and said diverging facets thereof serving as reflecting surfaces for light rays incident on said front surface of said cover plate to direct said rays onto said front surface of said solar cell in between said front contact grid; (g) said diverging facets being provided with a layer of reflective material.

Claim 2

Dependent Claim 211 words

An improved photovoltaic cell comprising: (a) a solar cell formed of a semiconductor material having a front surface and a back surface; (b) a front contact grid of a predetermined pattern provided on said front surface of said solar cell; (c) a cover plate formed of a glass material having parallel front and back surfaces and a thermal expansion coefficient matching that of said semiconductor material; (d) said back surface of said cover plate provided with a plurality of V-grooves each formed with facets diverging at a predetermined angle toward a base located at said back surface of said cover plate and mirroring said predetermined pattern of said front contact grid; (e) said back surface of said cover plate being electrostatically bonded to said front surface of said solar cell; (f) said V-grooves serving as clearance slots for said front contact grid such tat said grid is fully contained therein by projecting into said V-grooves from their said respective bases, and said diverging facets thereof serving as reflecting surfaces for light rays incident on said front surface of said cover plate to direct said rays onto said front surface of said solar cell in between said front contact grid; (g) said diverging facets being provided with a layer of reflective material.

Claim 3

Dependent Claim 33 words

The photovoltaic cell of claim 1 wherein said semiconductor material is one of a group consisting of silicon, gallium arsenide, and indium phosphide, and wherein said predetermined angle is less than about 50°.

Claim 4

Dependent Claim 35 words

The photovoltaic cell of claim 1 wherein each of said plurality of V-grooves is formed with a vertex whose radius is smaller than the shortest width of a grid line forming said front contact grid.

Claim 5

Dependent Claim 20 words

The photovoltaic cell of claim 1 wherein said reflective material is one of a group consisting of aluminum and silver.

Claim 6

Dependent Claim 89 words

The photovoltaic cell of claim 1 wherein said front surface of said cover plate is provided with an antireflective coating, and wherein said front contact grid is relatively wide to reduce power loss without significant additional shadow loss due to reflection of light from said plurality of V-grooves, and wherein said front surface of said solar cell also is provided with an antireflective coating before said cover plate is electrostatically bonded thereto, and wherein said plurality of V-grooves have a depth from about 0.02 mm to about 0.05 mm.

Claim 7

Dependent Claim 194 words

A process of making a photovoltaic cell comprising: (a) forming a solar cell from a semiconductor material, including providing a front contact grid of a predetermined pattern on a front surface thereof; (b) forming a cover plate with parallel front and back surfaces of a glass material having a thermal expansion coefficient matching that of said semiconductor material; (c) forming a metal die plate with a surface provided with a plurality of ridges representing a contoured mirror image of said predetermined pattern of said front contact grid; (d) heating said metal die plate to a temperature above the softening point of said glass material; (e) pressing said contoured surface of said heated metal die into said back surface of said cover plate to form a plurality of V-grooves therein with facets diverging at a predetermined angle toward a base located at said back surface of said cover plate; and (f) electrostatically bonding said back surface of said cover plate to said front surface of said solar cell so that said plurality of V-grooves overlie said front contact grid, with said grid fully contained therein by projecting into said V-grooves from their said respective bases.

Claim 8

Dependent Claim 194 words

A process of making a photovoltaic cell comprising: (a) forming a solar cell from a semiconductor material, including providing a front contact grid of a predetermined pattern on a front surface thereof; (b) forming a cover plate with parallel front and back surfaces of a glass material having a thermal expansion coefficient matching that of said semiconductor material; (c) forming a metal die plate with a surface provided with a plurality of ridges representing a contoured mirror image of said predetermined pattern of said front contact grid; (d) heating said metal die plate to a temperature above the softening point of said glass material; (e) pressing said contoured surface of said heated metal die into said back surface of said cover plate to form a plurality of V-grooves therein with facets diverging at a predetermined angle toward a base located at said back surface of said cover plate; and (f) electrostatically bonding said back surface of said cover plate to said front surface of said solar cell so that said plurality of V-grooves overlie said front contact grid, with said grid fully contained therein by projecting into said V-grooves from their said respective bases.

Claim 9

Dependent Claim 22 words

The process of claim 6 wherein said semiconductor material is one of a group consisting of silicon, gallium arsenide, and indium phosphide.

Claim 10

Dependent Claim 32 words

The process of claim 6 wherein said predetermined angle is less than about 50°, said converging facets are smooth, and wherein said converging facets are provided with a layer of reflective material.

Claim 11

Dependent Claim 49 words

The process of claim 8 wherein said reflective material is one of a group consisting of aluminum and silver, and wherein each of said plurality of V-grooves is formed with a vertex whose radius is smaller than the shortest width of a grid line forming said front contact grid.

Claim 12

Dependent Claim 19 words

The process of claim 6 further including providing said front surface of said cover plate with an antireflective coating.

Claim 13

Dependent Claim 19 words

The process of claim 10 further including providing said front surface of said solar cell with an antireflective coating.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1994-12-30	1995-07-01	1995-12-31	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1998-12-30	1999-07-01	1999-12-31	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2002-12-30	2003-07-01	2003-12-31	$7700.00	Window Closed / Lapsed

Photovoltaic cell and process

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