# US 6,294,723 B1 · Photovoltaic device, photovoltaic module and establishing method of photovoltaic system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,294,723 B1 - Document ID: US6294723B1 - Status: Granted - Kind: B1 - Application number: 09/256,454 - Filed: 1999-02-23 - Published: 2001-07-19 - Granted: 2001-09-25 - Earliest claimed: 1998-02-26 - Assignees: Hitachi, Ltd. - Inventors: Tsuyoshi Uematsu; Terunori Warabisako; Yoshiaki Yazawa; Yoshinori Miyamura; Ken Tsutsui; Shin-ichi Muramatsu; Hiroyuki Ohtsuka; Junko Minemura - Web page: https://patentgrep.com/patent/US6294723B1 ## CPC - G02B 19/0042: {for use with direct solar radiation} - F24S 23/00: Arrangements for concentrating solar-rays for solar heat collectors - G02B 19/0028: {refractive and reflective surfaces, e.g. non-imaging catadioptric systems} - H10F 77/488: {Reflecting light-concentrating means, e.g. parabolic mirrors or concentrators using total internal reflection} - H10F 77/70: Surface textures, e.g. pyramid structures - F24S 23/80: {having discontinuous faces} - Y02B 10/10: Photovoltaic [PV] - Y02B 10/20: Solar thermal - Y02E 10/44: Heat exchange systems - Y02E 10/52: PV systems with concentrators - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - F24S: SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS (for producing mechanical power from solar energy F03G6/00) - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract Disclosed is a photovoltaic module including a plurality of concentrators each having a light-incident plane and a reflection plane, and photo detectors. Each photo detector is in contact with one of the concentrators. The module is capable of effectively trapping light and effectively generating power throughout the year even if the module is established such that sunlight at the equinoxes is made incident on the light-incident planes not in a perpendicular manner but instead obliquely, for example, in the case where the module is established in contact with a curved plane of a roof, or the like. In this module, each concentrator is formed into such a shape as to satisfy a relationship in which the light trapping efficiency of first incident light tilted rightwardly from the normal line of the light-incident plane in the cross-section including the light-incident plane, reflection plane and photo detector is larger than the light trapping efficiency of second incident light tilted leftwardly from the normal line in the above cross-section. Also, these concentrators are arranged in one direction. ## Claims ### Claim 1 A photovoltaic module comprising: a plurality of concentrators each having a light-incident plane and a reflection plane and being connected such that said light-incident planes are continuous; and photo detectors arranged such that at least part of the surface of each of said photo detectors is in contact with one of said concentrators and having a structure which can trap light in the photo detectors of adjacent concentrators after reflecting the incident light from one of said concentrators; wherein the refractive index of said concentrator is larger than that of the environment outside said light-incident plane of said concentrator; said concentrator has such a shape as to make the light trapping efficiency of first incident light different from the light trapping efficiency of second incident light, said first incident light and said second incident light being respectively tilted rightwardly and leftwardly from the normal line of said light-incident plane in a vertical cross-section including said light-incident plane, said reflection plane, and said photo detector; and said plurality of concentrators are arranged such that a large-and-small relationship, in said plurality of concentrators, between the light trapping efficiency of said first incident light and the trapping efficiency of said second incident light corresponds to a large-and-small relationship, in one concentrator, between the light trapping efficiency of said first incident light and the light trapping efficiency of said second incident light. ### Claim 2 (depends on 1) A photovoltaic module according to claim 1, wherein said reflection plane has an interference thin film which enhances the reflectance thereof formed on the surface, on the inner side of said concentrator, of said reflection plane. ### Claim 3 A photovoltaic module comprising: a plurality of concentrators each having a light-incident plane and a reflection plane and being connected such that said light-incident planes are continuous; and photo detectors arranged such that at least part of the surface of each of said photo detectors is in contact with one of said concentrators and having a structure which can trap light in the photo detectors of adjacent concentrators after reflecting the incident light from one of said concentrators; wherein the refractive index of said concentrator is larger than that of the environment outside said light-incident plane of said concentrator; two kinds of incident light, which have been made equiangularly, symmetrically incident on said light-incident plane at two points located equidistant from an arbitrary point on said light-incident plane in a vertical cross-section including said light-incident plane, said reflection plane and said photo detector, go along optical paths in said concentrators asymmetric to each other with respect to said arbitrary point; and said plurality of concentrators are arranged such that a relationship between the two kinds of incident light going along the asymmetric optical paths is given for each of said plurality of concentrators. ### Claim 4 (depends on 3) A photovoltaic module according to claim 3, wherein said light-incident plane of said concentrator has irregularities. ### Claim 5 (depends on 3) A photovoltaic module according to claims 3, wherein the light-receiving plane of said photo detector has irregularities. ### Claim 6 (depends on 3) A photovoltaic module according to claim 3, wherein at least each connecting portion between adjacent two pieces of said concentrators is made from an elastic material and capable of being wound. ### Claim 7 (depends on 3) A photovoltaic module according to claim 3, wherein said photo detector is formed into a cylindrical or spherical shape. ### Claim 8 (depends on 3) A photovoltaic module according to claim 3, wherein said photo detector is formed into a hollow shape which is to be filled with a coolant. ### Claim 9 (depends on 3) A photovoltaic module according to claim 3, wherein said reflection plane has irregularities in the direction perpendicular to said vertical cross-section including said light-incident plane, said reflection plane and said photo detector. ### Claim 10 (depends on 9) A photovoltaic module according to claim 9, wherein depressions of said irregularities of said reflection plane have projections, and the projections have convex portions toward the side of said reflection plane, and the convex portions are formed of a curved line or a kinked line similar to the curved line. ### Claim 11 (depends on 9) A photovoltaic module according to claim 9, wherein said projections and depressions of said irregularities of the reflection plane are laterally symmetric to each other with respect to a point positioned in the direction of said projections and depressions. ### Claim 12 (depends on 3) A photovoltaic module according to claim 3, wherein said concentrator has a first medium in contact with said reflection plane and a second medium in contact with said first medium; the refractive index of said first medium is different from that of said second medium; and the interface between said first and second media is formed into a shape with irregularities in the direction perpendicular to said vertical cross-section including said light-incident plane, said reflection plane and said photo detector. ### Claim 13 (depends on 12) A photovoltaic module according to claim 12, wherein depressions of said irregularities on the interface of said first medium and said second medium has a part of projection portions facing on said second medium side, and the projection portions are formed of a curved line or a kinked line similar to the curved line. ### Claim 14 (depends on 12) A photovoltaic module according to claim 12, wherein said projections and depressions of said irregularities on the interface of said first medium and said second medium are laterally symmetric to each other with respect to a point positioned in the direction of said projections and depressions. ### Claim 15 (depends on 3) A photovoltaic system using a photovoltaic module described in claim 3, comprising: said photovoltaic module, wherein said photovoltaic module is established in a state in which sunlight at the equinoxes is tilted from the normal line of said light-incident plane of each of said concentrators; and wherein said first or second incident light side of each of said concentrators, corresponding to the larger one of the different light trapping efficiencies, of first incident light and second incident light, said first incident light and said second incident light being respectively tilted rightwardly and leftwardly from the normal line of said light-incident plane in the vertical cross-section including said light-incident plane, which are different due to said asymmetric optical paths of said two kinds of incident light, is directed in the tilting direction of said sunlight. ### Claim 16 (depends on 3) A photovoltaic module according to claims 3, wherein a part of said photo detectors elongates on the outside of said concentrator and a electrode is formed on the part of said photo detectors elongated on the outside of said concentrator. ### Claim 17 A photovoltaic module comprising: a plurality of concentrators each having a light-incident plane and a reflection plane and being connected such that said light-incident planes are continuous; and photo detectors arranged such that at least part of the surface of each of said photo detectors is in contact with one of said concentrators and having a structure which can trap a light in the photo detectors of adjacent concentrators after reflecting the incident light from one of said concentrators; wherein the refractive index of said concentrator is larger than that of the environment outside said light-incident plane of said concentrator; an angle formed between said light-incident plane and a linear portion of said reflection plane, in a vertical cross-section including said light-incident plane, said reflection plane and said photo detector, is less than 45°; said photo detector is located opposite to a portion, crossing said linear portion of said reflection plane at said angle, of said light-incident plane in said vertical cross-section; and the connection of said plurality of concentrator are arranged such that said portions, each crossing said linear portion of said reflection plane at said angle, of said light-incident planes and said photo detectors are alternately arranged. ### Claim 18 (depends on 17) A photovoltaic module according to claim 17, wherein said photo detector is mounted such that a light-receiving plane of said photo detector is located at a position having a plane portion parallel to said light-incident plane. ### Claim 19 (depends on 17) A photovoltaic module according to claim 17, wherein said photo detector is mounted such that a light-receiving plane of said photo detector is located at a position having a plane portion perpendicular to said light-incident plane. ### Claim 20 (depends on 17) A photovoltaic module according to claim 17, wherein said photo detector is mounted at a position at which a light-receiving plane of said photo detector crosses said light-incident plane at a non-right angle.