Title of Invention

MINIATURE SOLAR PHOTOVOLTAIC MODULES AND PROCESS FOR THEIR MANUFACTURE

Abstract

Conventionally solar photovoltaic modules were being made by using hot lamination technology in which major machinery and about 80% raw materials had to be imported. Operation of such machines consumed considerable amount of electricity, which escalated cost of production. Consequently, manufacturers were interested in making only high watt modules. The present invention aims at evolving a low-cost, cold laminated technology for making low or medium watt modules using indigenous raw materials and machinery. The miniature solar photovoltaic module of this invention comprises: (a) monocrystalline solar photovoltaic silicon cells tabbed with a plurality of nickel plated copper ribbons for front and backside on to the bus bar of the cells and stacked to form strings (1); (b) a smooth plain glass or an acrylic sheet (2) on which the strings are arranged as desired; (c) at least one transparent polymeric material layered sandwiches laminated on the arrangement as obtained in (b) to produce modules and (d) anodized aluminum or nylon frames (3) provided at the edges of the laminates, held in place by a suitable sealant. The invention also discloses a process for making the aforesaid modules illustrated by Fig. 1 of the drawings by cold lamination.

Full Text

The present invention relates to miniature solar photovoltaic modules and process for their manufacture. More particularly this invention is concerned with production of solar photovoltaic modules, which find diverse application in our day to day life by harnessing solar energy. With increasing pollution hazards from generation sources based either on fossil fuel or nuclear fuel, search has been going on for the past few years to develop and utilise non- conventional sources of energy, sun being one such source at least in tropical and equatorial countries. Heretofore, solar photovoltaic modules were being produced by using hot lamination technology, not only in India but also in technologically advanced countries like Japan, Korea, Taiwan, the USA and Germany. For following such technology one would require sophisticated machinery and raw materials, 80% of which will have to be imported into India from abroad. These items of machinery are invariably costly and consume considerable amount of energy while in operation, thereby escalating production cost and also manpower cost. Machinery spares are also to be imported from abroad, which pushes up the cost of maintenance and higher investment on inventory. To counteract the high cost of production, almost all the manufacturers are interested in producing modules of high wattage, generating a gap in the demand and supply of low and medium range, say 0.5 volt to 12 volt modules, which have considerable demand among common consumers. The present invention aims at producing modules of low or medium wattage range from indigenously available raw materials and by following a simple, low-cost, cold lamination process technology. The principal object of this invention is to provide miniature solar photovoltaic modules of low wattage, which are easy to make and require very little or no maintenance. A further object of this invention is to provide miniature solar photovoltaic modules made from indigenously available raw materials and using cold lamination technology. A still further object of this invention is to provide a process for manufacturing miniature solar photovoltaic modules, which uses commonly available raw materials and simple items of machinery for ensuring proper quality control. Another object of this invention is to provide a process for producing miniature solar photovoltaic modules, which consumes little or no power at all and is considerably cost effective. Yet another object of this invention is to provide a process for producing miniature solar photovoltaic modules wherein the constituent solar cells are subjected to close scrutiny for their effectiveness and performance by means of a solar cell tester designed and fabricated by the applicant forming a part of the present invention. The foregoing objects are achieved by the present invention which relates to a miniature solar photovoltaic module comprising- (a) monocrystalline solar photovoltaic silicon cells stacked to form strings (1), (b) a smooth transparent, plain glass or an acrylic sheet (2) on which the said strings are arranged as herein described; (c) at least one transparent polymeric material layered sandwich laminated on the arrangement of (b) to produce modules and (d) protective anodized aluminium or nylon frames (3) provided at the edges of the laminates, held in place by a suitable sealant, characterized in that the said silicon cells are tabbed with a plurality of nickel-coated copper ribbons for front and backside on to the bus bar of the cells and stacked to form strings and transparent polymeric material sandwiches are subjected to cold lamination under ambient conditions on the arrangement as at (b) to produce modules. This invention also provides a process for preparing miniature solar photovoltaic modules which comprises the following steps- i) selecting monocrystalline solar photovoltaic silicon cells by using a solar cell tester consisting of a power source, a voltmeter, an ammeter, a sun simulator and a plurality of silver plated contacts ; ii) tabbing the cells with a nickel plated copper ribbon for front and backside on the bus bar of the cells ; iii) coin - stacking the cells to form 'strings' ; iv) cleaning the strings with pure ethanol or isopropyl alcohol and placing the cleaned strings on a plain glass or acrylic sheet; v) applying at least one layer of high - density transparent polymer - based chemical to form a layered sandwich structure ; vi) subjecting the sandwiches to a vacuum treatment to remove any air gap or air bubble; vii) curing the sandwiches from step (iv) at a temperature from around 50 70°C, and viii) fixing anodized aluminum or nylon frames around the laminated sandwiches by means of a silicone sealant. Usually successive layers of high - density transparent polymeric material are used in forming layered materials of desired thickness to give rise to laminated sandwiches. These laminated sandwiches are dispensed within the frame held in place by means of silicone sealant. For the purpose of vacuum treatment, the vacuum is of the order of 0.01mm mercury manometer and the treatment is conducted for about 5-15 minutes. The laminates are then treated in a temperature controlled curing oven and cured at a temperature of around 50°- 70°C for one hour duration. The cured cold laminated sandwiches also known as "modules" are then subjected to finishing and cleaning operations. Anodized aluminium or nylon frames are fixed to the laminated sandwiches by means of a silicone sealant, which is dispensed between the frames and the sandwich to act as a cushion and also to prevent ingress of moisture in the glass-based module. The acrylic-sheet based modules are ready after lamination and usually need no channeling. A finished module is tested with a sun-stimulator for its electrical characteristics under test condition(s) with the help of a calibrated module. The module will be declared 'fit for use' if it passes the tests. The invention will now be further illustrated by means of the accompanying drawings in which— Fig. 1 shows a prototype of solar voltaic module of this invention and Fig. 2 depicts a block diagram of the sequence of steps followed in the process of this invention. Referring to Fig. 1, (1) is the string formed from monocrystalline photovoltaic silicon cells tabbed with a plurality of nickel plated copper ribbons for front and backside on to the bus bar of the cells followed by stacking with impregnation with adhesive material. Strings so formed are arranged either longitudinally or transversely as desired on a transparent, smooth plain glass or acrylic sheet (2), which is subjected to cold lamination by using at least one transparent polymeric layered sandwich on the aforementioned arrangement to produce modules. The cold laminated sandwich structure is protected by being provided with a protective frame (3), usually made of anodized aluminium or nylon. As the layers of polymeric material applied to the strings to bring about 'cold lamination' at ambient temperature, it has not been possible to show them separately in the drawings. The invention will be further elaborated by the following Example, which is given by way of illustration and not by way of limitation. Example For producing a representative sample of the module, the following materials and accessories are needed: i) Solar photovoltaic cells (obtained from Webel - SL Energy Systems Ltd.); ii) Short piece nickel - plated copper ribbons ; iii) A cutting tool with diamond bit for cell cutting ; iv) Plain glass having high degree of transparency ; v) Acrylic sheet; vi) Polymer based transparent sealant for hermetic sealing of string with glass or acrylic sheet and for conditioning cold lamination ; vii) Liquid ethyl vinyl acetate for back filling ; viii) Anodized aluminum or nylon frame; ix) Silicon UV resistant wire and x) Isopropyl alcohol or ethanol. The solar photovoltaic cells are selected, tested with solar cell tester mentioned earlier in this specification and then cut to desired size by means of diamond cutter. Then the cells are tabbed with a nickel-plated copper ribbon of predetermined dimensions and coin-stacked forming a cell-string. The string is cleaned with pure ethanol or isopropanol. 100% testing of the string is effected by means of an illuminated magnifying string testing jig for interconnection, soldering of each string with the substrate and also checked for all electrical parameters. The strings are arranged breadth-wise on a transparent acrylic or glass sheet 3 mm thick and measuring 64mm X 60mm. The above arrangement is formed into laminated sandwiches by application of desired number of layers of transparent polymeric material, vacuum treated to remove air gaps or air bubbles, followed by curing in an oven at a temperature of around 50 to 70 C for around 1 (one) hour. This is finished, cleaned with pure ethanol and fitted with anodized aluminum or nylon frame. The frames are fixed to the laminates by means of silicone sealant, dispensed between the frames and the sandwich to act as cushion and also to prevent seepage of moisture. Electrical parameters for 1.5 volt solar module are as follows: Open circuit voltage - 2.12 V Short circuit current - 100mA In conducting tests for solar modules, there is employed solar insulation level of 1000 Watt per meter. By using the process technology as narrated above, it has been possible to make miniature solar photovoltaic modules of varying capacity, e.g. from 0.5 to 12 volts. While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without deviating or departing from the spirit and scope of this invention. Thus the disclosure contained herein includes within its ambit the obvious equivalents and substitutes as well. Having described the invention in detail with particular reference to the example given above and also the accompanying drawings, it will now be more specifically defined by means of claims appended hereafter. I claim: A miniature solar photovoltaic module comprising- (a) monocrystalline solar photovoltaic silicon cells stacked to form strings (1), (b) a smooth transparent, plain glass or an acrylic sheet (2) on which the said strings are arranged as herein described; (c) at least one transparent polymeric material layered sandwich laminated on the arrangement of (b) to produce modules and (d) protective anodized aluminium or nylon frames (3) provided at the edges of the laminates, held in place by a suitable sealant, characterized in that the said silicon cells are tabbed with a plurality of nickel-coated copper ribbons for front and backside on to the bus bar of the cells and stacked to form strings and transparent polymeric material sandwiches are subjected to cold lamination under ambient conditions on the arrangement as at (b) to produce modules. 2. A module as claimed in Claim 1, wherein successive layers of high-density, transparent polymeric materials are used in forming layered materials of desired thickness to obtain laminated sandwiches. 3. A module as claimed in Claim 1, wherein the laminated sandwiches are dispensed within the frames held in place by means of a silicone sealant. 4. A miniature solar photovoltaic module, substantially as hereinbefore described with particular reference to the accompanying drawings. 5. A process for preparing miniature solar photovoltaic modules which comprises the following steps: (i) selecting monocrystalline solar photovoltaic silicon cells by using a solar cell tester consisting of a power source, a voltmeter, an ammeter, a sum simulator and a plurality of silver plated contacts; (ii) tabbing the cells with a nickel-plated copper ribbon for front and backside on to the bus bar of the cells; (iii) coin-stacking the cells to form 'strings'; (iv) cleaning the strings by pure ethanol or isopropanol and placing the cleaned strings on a plain glass or acrylic sheet; (v) applying at least one layer of a high - density transparent polymer - based chemical to form a layered sandwich structure ; (vi) subjecting the sandwiches to a vacuum treatment to remove any air gap or air bubbles; (vii) curing the sandwiches from step (vi) at a temperature of from around 50 to 70 C and (viii) fixing anodized aluminum or nylon frames around the laminated sandwiches by means of silicone sealant 6. A process as claimed in Claim 5, wherein the vacuum is of the order of 0.01mm mercury manometer and the treatment is conducted for from around 5 to 10 minutes. 7. A process as claimed in Claim 5, wherein curing in step (vii) is carried out in an oven for around one hour duration. 8. A process for preparing miniature solar photovoltaic modules, substantially as hereinbefore described with particular reference to the appended Example and also the accompanying drawings. Conventionally solar photovoltaic modules were being made by using hot lamination technology in which major machinery and about 80% raw materials had to be imported. Operation of such machines consumed considerable amount of electricity, which escalated cost of production. Consequently, manufacturers were interested in making only high watt modules. The present invention aims at evolving a low-cost, cold laminated technology for making low or medium watt modules using indigenous raw materials and machinery. The miniature solar photovoltaic module of this invention comprises: (a) monocrystalline solar photovoltaic silicon cells tabbed with a plurality of nickel plated copper ribbons for front and backside on to the bus bar of the cells and stacked to form strings (1); (b) a smooth plain glass or an acrylic sheet (2) on which the strings are arranged as desired; (c) at least one transparent polymeric material layered sandwiches laminated on the arrangement as obtained in (b) to produce modules and (d) anodized aluminum or nylon frames (3) provided at the edges of the laminates, held in place by a suitable sealant. The invention also discloses a process for making the aforesaid modules illustrated by Fig. 1 of the drawings by cold lamination.

Documents:

626-kol-2003-abstract.pdf

626-kol-2003-claims.pdf

626-KOL-2003-CORRESPONDENCE-(12-12-2011).pdf

626-kol-2003-correspondence.pdf

626-kol-2003-description (complete).pdf

626-kol-2003-drawings.pdf

626-kol-2003-examination report.pdf

626-kol-2003-form 1.pdf

626-kol-2003-form 18.pdf

626-kol-2003-form 2.pdf

626-kol-2003-form 3.pdf

626-KOL-2003-FORM-1-(12-12-2011).pdf

626-KOL-2003-FORM-13-(12-12-2011).pdf

626-KOL-2003-FORM-27.pdf

626-kol-2003-granted-abstract.pdf

626-kol-2003-granted-claims.pdf

626-kol-2003-granted-description (complete).pdf

626-kol-2003-granted-drawings.pdf

626-kol-2003-granted-examination report.pdf

626-kol-2003-granted-form 1.pdf

626-kol-2003-granted-form 2.pdf

626-kol-2003-granted-form 3.pdf

626-kol-2003-granted-others.pdf

626-kol-2003-granted-pa.pdf

626-kol-2003-granted-reply to examination report.pdf

626-kol-2003-granted-specification.pdf

626-kol-2003-pa.pdf

626-kol-2003-reply to examination report.pdf

626-kol-2003-specification.pdf