Use of calcium oxide as a water scavenger in solar applications

Abstract

A solar module includes an edge sealant. The sealant composition includes an unsaturated reactive polyolefin, an olefmic polymer, a silane modified polyolefin, inert fillers, calcium oxide, and aging resistors. These components are balanced to produce a sealant having desirable sealing characteristics, high weatherability, desired rheology, low conductivity, and good water absorption.

1 . A sealant composition comprising:
 an olefinic polymer;   a silane modified polyolefin;   at least one filler;   a carbon black;   a calcium oxide included in an amount greater than about 2.5% by weight of the total composition; and   at least one aging resistor.   
     
     
         2 . The sealant composition of  claim 1  further including a molecular sieve included in an amount greater than about 2.5% by weight of the total composition. 
     
     
         3 . The sealant composition of  claim 2  wherein the sealant composition exhibits a water break through time of greater than 5 hr and a steady state moisture vapor transmission rate of less than 40 g·m2/day for a 0.030 inch thick sample of the sealant composition tested at 85 C and 100% relative humidity. 
     
     
         4 . The sealant composition of  claim 2  wherein the sealant composition exhibits a water break through time of greater than 10 hr and a steady state moisture vapor transmission rate of less than 30 g·m2/day for a 0.030 inch thick sample of the sealant composition tested at 85 C and 100% relative humidity. 
     
     
         5 . The sealant composition of  claim 2  wherein a combination of the calcium oxide and the molecular sieve is included in an amount greater than about 10% by weight and the sealant composition exhibits a water break through time of greater than 5 hr and a steady state moisture vapor transmission rate of less than 40 g·m2/day for a 0.030 inch thick sample of the sealant composition tested at 85 C and 100% relative humidity. 
     
     
         6 . The sealant composition of  claim 2  wherein a combination of the calcium oxide and the molecular sieve is included in an amount greater than about 10% by weight and the sealant composition exhibits a water break through time of greater than 10 hr and steady state moisture vapor transmission rate of less than 30 g·m2/day for a 0.030 inch thick sample of the sealant composition tested at 85 C and 100% relative humidity. 
     
     
         7 . The sealant composition of  claim 2  further including at least one of a clay, a calcium sulfate, and a silica gel, and wherein the sealant composition exhibits exhibit a water break through time of greater than 5 hr and a steady state moisture vapor transmission rate of less than 40 g·m2/day for a 0.030 inch thick sample of the sealant composition tested at 85 C and 100% relative humidity. 
     
     
         8 . The sealant composition of  claim 2  further including at least one of a clay, a calcium sulfate, and a silica gel, and wherein a combination of the calcium oxide, the molecular sieve, and the sealant composition exhibits a water break through time of greater than 10 hr and steady state moisture vapor transmission rate of lesser than 30 g·m2/day for a 0.030 inch thick sample of the sealant composition tested at 85 C and 100% relative humidity. 
     
     
         9 . The sealant composition of  claim 2  wherein a combination of the calcium oxide and the molecular sieve is included in an amount from about 10% to about 40% by weight of the total composition. 
     
     
         10 . The sealant composition of  claim 2  wherein a combination of the calcium oxide and the molecular sieve is included in an amount from about 20% to about 40% by weight of the total composition. 
     
     
         11 . The sealant composition of  claim 2  wherein a combination of the calcium oxide and the molecular sieve is included in an amount from about 25% to about 35% by weight of the total composition. 
     
     
         12 . The sealant composition of  claim 1  wherein the olefinic polymer is included in an amount from about 30% to about 60% by weight of the total composition, the silane modified polyolefin is included in an amount from about 10% to about 25% by weight of the total composition, the carbon black is included in an amount from about 2% to about 20% by weight of the total composition, the filler is included in an amount from about 20% to about 60% by weight of the total composition, the calcium oxide is included in an amount from about 2.5% to about 25% by weight of the total composition, and the aging resistor is included in an amount from 0% to about 2% by weight of the total composition. 
     
     
         13 . The sealant composition of  claim 1  wherein the olefinic polymer is included in an amount from about 20% to about 40% by weight of the total composition, the silane modified polyolefin is included in an amount from about 10% to about 20% by weight of the total composition, a combination of the carbon black and the filler is included in an amount from about 30% to about 40% by weight of the total composition, the calcium oxide is included in an amount from about 10% to about 30% by weight of the total composition, and the aging resistor is included in an amount from 0% to about 2% by weight of the total composition. 
     
     
         14 . The sealant composition of  claim 13  further including a molecular sieve included in an amount from about 2.5% to about 25% by weight of the total composition. 
     
     
         15 . The sealant composition of  claim 1  wherein the sealant composition exhibits less than about 15 gm/((m̂2)*day) moisture vapor transmission rate at steady state for a 0.030 inch thick sample of the sealant composition tested at 85 C and 100% relative humidity. 
     
     
         16 . The sealant composition of  claim 1  wherein the sealant composition includes balanced properties that keeps swelling of the sealant to a predetermined amount upon reaction of the calcium oxide with water. 
     
     
         17 . The sealant composition of  claim 1  wherein the calcium oxide does not substantially react with or corrode other components of the sealant. 
     
     
         18 . The sealant composition of  claim 1  wherein the olefinic polymer includes at least one of a polyethylene, a polypropylene, a polybutene, a polyisobutene, a butyl rubber (polyisobutene-isoprene), styrene block copolymers, and modified forms of styrene block copolymers, wherein the olefinic polymers have a number average molecular weight of 100-700,000 Da, wherein the silane modified polyolefins include at least one of an amorphous poly alpha olefin, a silane grafted PE, a moisture curing catalyst, an alkoxy silane, and an amino silane, wherein the fillers include at least one of a ground chalk, a precipitated chalk, a silicate, a silicon oxide, CaCO3, Ca(OH)2, and titanium dioxide, and wherein the silicate is selected from the group comprising talc, kaolin, mica, silicon oxide, silicas, and calcium or magnesium silicates, and wherein the aging resistors include at least one of hindered phenols, hindered amines, thioethers, mercapto compounds, phosphorous esters, benzotriazoles, benzophenones, and antizonants. 
     
     
         19 . A solar module comprising:
 a first substrate;   a second substrate;   at least one photovoltaic cell disposed between the first and second substrates;   a sealant in contact with the first and second substrates to form a moisture vapor barrier to hinder moisture vapor from reaching the at least one photovoltaic cell, wherein the sealant includes:
 an olefinic polymer; 
 a silane modified polyolefin; 
 at least one filler; 
 a carbon black; 
 a calcium oxide included in an amount greater than about 2.5% by weight of the total composition; and 
 at least one aging resistor. 
   
     
     
         20 . The solar module of  claim 19  wherein the sealant composition includes a molecular sieve included in an amount greater than about 2.5% by weight of the total composition. 
     
     
         21 . The solar module of  claim 20  wherein a combination of the calcium oxide and the molecular sieve is included in an amount from about 10% to about 40% by weight of the total composition. 
     
     
         22 . The solar module of  claim 20  wherein a combination of the calcium oxide and the molecular sieve is included in an amount from about 20% to about 40% by weight of the total composition. 
     
     
         23 . The solar module of  claim 20  wherein a combination of the calcium oxide and the molecular sieve is included in an amount from about 25% to about 35% by weight of the total composition. 
     
     
         24 . The solar module of  claim 19  wherein the olefinic polymer is included in an amount from about 30% to about 60% by weight of the total composition, the silane modified polyolefin is included in an amount from about 10% to about 25% by weight of the total composition, the carbon black is included in an amount from about 2% to about 20% by weight of the total composition, the filler is included in an amount from about 20% to about 60% by weight of the total composition, the calcium oxide is included in an amount from about 2.5% to about 25% by weight of the total composition, and the aging resistor is included in an amount up to about 2% by weight of the total composition. 
     
     
         25 . The solar module of  claim 20  wherein the olefinic polymer is included in an amount from about 30% to about 40% by weight of the total composition, the silane modified polyolefin is included in an amount from about 10% to about 20% by weight of the total composition, a combination of the carbon black and the filler is included in an amount from about 30% to about 40% by weight of the total composition, the calcium oxide is included in an amount from about 10% to about 30% by weight of the total composition, and the aging resistor is included in an amount up to about 2% by weight of the total composition. 
     
     
         26 . The solar module of  claim 25  wherein the sealant includes a molecular sieve included in an amount from about 2.5% to about 25% by weight of the total composition. 
     
     
         27 . The solar module of  claim 20  wherein the sealant composition exhibits less than about 15 gm/((m̂2)*day) moisture vapor transmission rate at steady state for a 0.030 inch thick sample of the sealant composition tested at 85 C and 100% relative humidity. 
     
     
         28 . The solar module of  claim 20  wherein the sealant includes balanced properties that keep swelling of the sealant to a predetermined amount upon reaction of the calcium oxide with water. 
     
     
         29 . The solar module of  claim 20  wherein the calcium oxide does not substantially react with or corrode the sealant or the first and second substrates. 
     
     
         30 . The solar module of  claim 20  wherein the olefinic polymer includes at least one of a polyethylene, a polypropylene, a polybutene, a polyisobutene, a butyl rubber (polyisobutene-isoprene), styrene block copolymers, and modified forms of styrene block copolymers, and wherein the olefinic polymers have a Number average molecular weight of 100-700,000 Da. 
     
     
         31 . The solar module of  claim 20  wherein the silane modified polyolefins include at least one of an amorphous poly alpha olefin, a silane grafted PE, a moisture curing catalyst, an alkoxy silane, and an amino silane. 
     
     
         32 . The solar module of  claim 20  wherein the fillers include at least one of a ground chalk, a precipitated chalk, a silicate, a silicon oxide, CaCO3, Ca(OH)2, and titanium dioxide, and wherein the silicate is selected from the group comprising talc, kaolin, mica, silicon oxide, silicas, and calcium or magnesium silicates. 
     
     
         33 . The solar module of  claim 20  wherein the aging resistors include at least one of hindered phenols, hindered amines, thioethers, mercapto compounds, phosphorous esters, benzotriazoles, benzophenones, and antizonants. 
     
     
         34 . A sealing compound for use in a solar module having a first substrate and a second substrate, wherein the sealing compound is disposed between the first substrate and the second substrate, the sealing compound comprising:
 an olefinic polymer in an amount greater than about 30% by weight of the total composition;   at least one of a silane modified APAO and a silane modified polymer in an amount less than 35% by weight of the total composition;   a filler;   a carbon black having a primary particle size of less than about 60 nm;   a calcium oxide included in an amount greater than about 2.5% by weight of the total composition;   a molecular sieve included in an amount greater than about 2.5% by weight of the total composition; and   an aging resistor.   
     
     
         35 . The sealing compound of  claim 34  wherein the olefinic polymer includes a polyisobutylene in an amount from about 30% to about 60% by weight of the total composition, the at least one of the silane modified APAO and the silane modified polyisobutylene is included in an amount from about 2% to about 35% by weight of the total composition, the filler is included in an amount from about 3% to about 47% by weight of the total composition, a combination of the molecular sieve and the calcium oxide is included in an amount of about 10% to about 40% by weight of the total composition, and the aging resistor is included in an amount from 0.1% to about 3% by weight of the total composition.