The present invention relates to the dielectric coating formulation for use in solar modules, method of manufacture of said formulation for a metal integrated solar module. Preferably, the solar module is a light weight metal integrated solar module.
Solar modules are large-area opto-electronic devices that convert solar radiation directly into electrical energy. They are made by interconnecting individually formed and separate solar cells e.g. multi-crystalline or mono-crystalline silicon solar cells and integrating them into a laminated solar module. The laminated modules generally comprise a front transparent, protective panel and a rear metallic panel referred to as backsheet. The main function of backsheet includes acting as barrier against vapour/moisture, UV resistance, electrical insulation, mechanical support and protection and weathering resistance. Generally, backsheet is metallic in nature and is made up of materials selected from stainless steel, galvanized steel, aluminum sheet, brass, copper and any other material which are having excellent heat conducting properties.
A conventional backsheet includes the following layers deposited thereon including a dielectric layer, adhesive layer, barrier layer, and a weather resistant layer, not necessarily in the same order. Commercially available the dielectric coating formulations comprise a polymeric substance filled with fillers such as ceramic and carboneous material. However, it is seen that these readily available formulations do not adhere to the metallic substrates adequately and requires use of additional layers acting as an adhesive.
Available solar modules are very heavy due to use of glass as the solar panel (i.e. the side facing the sun) which accounts for about 80% of the weight of the module which poses practical challenges during handling of modules on manufacturing floor and during installation.
Hence there is a need to develop a dielectric formulation which uses minimum number of layers. Particularly, there is a need to develop a dielectric formulation which obviates the use of adhesive layer and yet is integrated with the metallic backsheet because of its electrically insulative nature. It is also an object of the present invention to provide for a light weight solar module permitting ease of transportation and installation thus reducing costs associated therewith.
The present invention relates to a dielectric coating formulation for a solar module where a separate adhesive layer is not required for applying the formulation to the solar module. Preferably, the solar module is a light weight solar module. The present invention further relates to a method of making said dielectric coating formulation.
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which—
For the purposes of the following detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification are to be understood as being modified in all instances by the term “about” in which “about” is defined as ±10% of the nominal value.
It is noted that, unless otherwise stated, all percentages given in this specification and appended claims refer to percentages by weight of the total composition.
It must be noted that, as used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the content clearly dictates otherwise.
The terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.
As used herein, the terms “comprising”, “including”, “having”, “containing”, “involving” and the like are to be understood to be open-ended, i.e., to mean including but not limited to.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by a person skilled in the art to which this invention pertains. In the case of conflict, the present document, including definitions will control.
In one aspect, the present invention discloses a dielectric coating formulation for solar module (10). The formulation comprises of at least two polymers selected from polyacrylamide, acrylics, epoxy, amides, polyurethane, imides, styrene, polystyrene, high density polyethylene, polyethylene terephthalate, their organic monomers, copolymers, modified polymers thereof. The polymers are used in the ratio of 20-60% w/w:20-30% w/w of the formulation.
The formulation further comprises excipients such as at least one each of initiator, cross-linker, chain transfer agent, catalyst, and insulators, additives selected from organic lubricant, aromatic smells, viscosity controller and stabilizers. Initiator is selected from at least one of benzoyl peroxide, azoisobutyronitrile, MEK peroxide, butyl peroxide, methyl orange. The catalyst for polymerization is selected from chain transfer agent such as N-dodecyl mercaptan, thiol-group consisting compounds and halo carbon-group containing compounds. The cross linker is tannic acid. The insulators include at least one of mica, clay, ceramic oxides selected from silica, calcium carbonate, alumina, gerconia and graphene oxide. The insulator material has particle sizes between 10 nm to 100 micron The additives include organic lubricants to reduce coefficient of friction while forming of being of insulating sheets such as wax, sulphur and phosphorous free compounds for example, naphthalate, oleate, octatate, cabonate etc. The aromatic smells are preferably mineral terpentine oil or pine oil. The viscosity controllers are solvent xylene, butanol, isopropanol including thickenening agents such as butyl-, methyl-, ethyl-cellosov. Stabilizers are selected from BYK 378, 389N.
It is to be noted that the polymers used in the dielectric coating formulation have both dielectric and adhesive properties. As a result, the dielectric coating formulation of present invention is directly applied on the metallic backsheet of the solar module. Therefore, unlike in conventional dielectric coating formulation, a separate adhesive layer is not required for application of dielectric coating formulation of present invention to said metallic backsheet.
Modified polymers provide require performance such as adhesion, corrosion resistance, insulation, flexural strength, free of holidays and post-adhesion etc. It is found that the combination of polymers in the present dielectric coating formulation provides excellent adhesion and corrosion performance as compared to individual polymer. The same formulation may be used with one polymer, for example engineered imide class polymers, but the cost is very high as compared to our claimed formulation.
The backsheet being metallic is made up of materials selected from stainless steel, galvanized steel, aluminum sheet, brass, copper and any other material which are having excellent heat conducting properties, the thickness of the metal sheet can range from 0.1 mm to 2 mm. The dielectric coating formulation of the present invention adheres to almost any metal providing flexibility in use.
In one aspect depicted in
In one embodiment of the present invention, the dielectric coating formulation is adhered to ethyl vinyl acetate (EVA) which is used for laminating solar cells thus hermetically sealing the solar module. In this embodiment, the solar panel of the present invention comprises 5 layers. The dielectric coating formulation of the present invention is applied on metal backsheet (15) followed by ethyl vinyl acetate layer (EVA) (12) laminating the solar cell (13) with the front panel comprising of ethylene tetraflouroethylene (ETFE) layer (11) (refer
A method of preparation of said dielectric coating formulation for a solar module comprising the steps of—
a. adding chain transfer agent to organic monomers in presence of initiator causing chain transfer polymerisation;
b. adding insulators in the range of 2-30% by weight of the formulation; additives in the range of about 1-10%.
Further wide applicability can be ensured by equally applying the photovoltaic module of the present invention to areas having severe heat or high temperature and high-humidity tropical weather as well as desert areas.
The following example is provided to better illustrate the claimed invention and is not to be interpreted in any way as limiting the scope of the invention. All specific materials, and methods described below, fall within the scope of the invention. These specific compositions, materials, and methods are not intended to limit the invention, but merely to illustrate specific embodiments falling within the scope of the invention. One skilled in the art may develop equivalent materials, and methods
without the exercise of inventive capacity and without departing from the scope of the invention. It is the intention of the inventors that such variations are included within the scope of the invention.
indicates data missing or illegible when filed
The dielectric coating formulation was subjected to following tests—
1. Peel Test: This test is conducted to see the adhesion strength of the dielectric coating with ethyl vinyl acetate (EVA). The peel test tab is made before lamination and a small piece of smooth release sheet is placed under the outer edge of the tab. The area to be peel tested is prepared by making two parallel cuts completely through the encapsulation system to the superstrate or the substrate (depending
on which bond is being tested) at a position perpendicular to the exposed edge in the area between bus bars.
Peel Test Preparation: As seen in
Method: As seen in
Result: This test was conducted for commercially available formulation as well as the formulation of the present invention. It was noted that there was complete peeling of the EVA from backsheet with the adhesion strength coming around 1.6 kg/inch for commercially available formulation whereas with the formulation of present invention, the adhesion strength was higher at 3.7 kg/inch (refer
2. Electrical Performance of coated steel backsheet panel at NOCT and STC: The set up for carrying out NOCT test is depicted in
3. Dielectric Insulation Withstand Voltage Versus Lamination Cycle:
In accordance with
Wet leakage test is done to evaluate the insulation of the module under wet operating conditions and verify that moisture from rain, fog, dew or melted snow does not enter the active parts of the module circuitry, where it might cause corrosion, a ground fault or a safety hazard.
It was concluded that modules with insulation tape around the panels (
With high cycle time (22 min) & temperature (158° C.), the lamination seems to be proper and hence high Insulation Resistanceof 1 Gohm and high voltage (1500V) withstanding capability of the steel backsheet panels
With the lamination cycle of 158° C. and 22 min, the laminate can sustain 1500V for 1 min. It gives both dry and wet IR value of more than 1 Gohm. It clearly shows with higher lamination cycle the dielectric withstand capacity of the laminates increases. In another embodiment of the present invention seen in
Since the modules of the present invention are frameless in which the frames have been replaced with insulating tape sealed around the edges, they can be simply clamped over the roof using conventional clamping methods (see
Advantageously, the dielectric coating formulation of the present invention when used on metal backsheet provides better adhesion and electrical insulation. The frameless light weight module is easier to handle at the manufacturing floor as well as during transportation and handling. Because the modules have a low profile and are light, nearly 3 times the number of modules can be fitted in a standard 40 ft. container as compared to traditional modules. The shipping costs and installation labour reduces drastically.
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.
Number | Date | Country | Kind |
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1581/CHE/2015 | Mar 2015 | IN | national |
The present application is a National Phase entry of PCT Application No. PCT/M2016/051669, filed Mar. 24, 2016, which claims priority from IN Patent Application No. 1581/CHE/2015, filed Mar. 27, 2015, each of which is hereby fully incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/IB16/51669 | 3/24/2016 | WO | 00 |