WO2015012772A2

WO2015012772A2 - Glass output coated with a solution

Info

Publication number: WO2015012772A2
Application number: PCT/TR2014/000073
Authority: WO
Inventors: Anil ÖZEN; Can KAPLAN
Original assignee: Türki̇ye Şi̇şe Ve Cam Fabri̇kalari A.Ş.
Priority date: 2013-06-28
Filing date: 2014-03-12
Publication date: 2015-01-29
Also published as: WO2015012772A3

Abstract

The present invention relates to a coating solution applied to glass surfaces for increasing transmittances of cover glasses used in photovoltaic modules and in thermal collectors, the production method of said coating solution, the application thereof onto the glass, and relates to coated glass.

Description

SPECIFICATION

GLASS OUTPUT COATED WITH A SOLUTION TECHNICAL FIELD

The present invention relates to a coating solution applied to the glass surfaces for increasing the transmittance of cover glasses used in photovoltaic modules and in solar thermal collectors, the production method of said coating solution, the application of the coating solution onto the glass, and relates to coated glass.

PRIOR ART

In order to generate the electricity from the sun, glass is used both as a base and as a cover in glass/glass modules, and metal is used as a base and glass is used as a cover in glass/metal modules. The basic principle for increasing module efficiency is to transfer sunlight with minimum loss to the layer where electrical current is formed.

Within this scope, there are 5 basic ways for increasing transmittance. These are as follows: i) Decreasing the amount of iron oxide in the glass batch

ii) Creating the pattern on to the glass surface

iii) Decreasing the glass thickness

iv) Coating the glass surface with a material whose refractive index is lower than the refractive index of glass

v) Minimizing the reflection value by applying multiple layers to the glass surface

The optical properties of glass can be changed by means of coatings applied onto the glass surface. The glasses, whose transmittance value is increased by means of coating thereof with a material whose refractive index is lower than the refractive index of glass, are known as "antireflective coated glasses".

The single layer antireflective coatings, applied onto the glass surface for increasing the transmittance of glass, create two surfaces where the incident light is reflected, namely glass-coating and coating-air surfaces. The theoretical thickness of the coating provided between said two surfaces has to be equal to one fourth of the wavelength (λ/4) of the incident light. In other words, in order to obtain antireflective coating, a coated layer should be created on the glass surface, whose optical thickness (d.n_coating) is equal to one fourth of the wavelength of the incident light and whose refractive index is greater than the refractive index of air and smaller than the refractive index of glass. Antireflective coated glasses can be used both for thermal and solar applications. In thermal applications, mostly the double side antireflective coated patterned glasses having low iron content are used, and in crystalline silicon photovoltaic module applications, usually one side antireflective coated patterned glasses having low iron content are used, and in photovoltaic module applications produced by means of the thin film method, one side antireflective coated float glasses having low iron content are used.

In all applications, where the renewable energy resources are used, each component of the system is expected to provide the maximum performance and to operate the system in the most efficient manner.

The increase in transmittance obtained by means of antireflective coatings, sunlight is transferred to the absorbing layer with lower loss, and so the solar energy is utilized in a more efficient manner. In the present art, the coating solutions are prepared by using the sol-gel method. After the solution is applied onto the glass surface, the pre-curing process is applied to the glass having wet film layer thereon, and afterwards, it is subject to high temperature thermal treatment, and so the glass gains the antireflective property. By means of the pre-curing process, the volatile organics in the composition are moved away from the surface, and the porous silica layer is formed on to the glass surface by means of the thermal treatment at high temperature. This two-step thermal treatment application leads to loss of time and as a result, process efficiency decreases.

In the invention with publication number EP2197804, a method is disclosed for realizing a coating with low silica amount. In this method, a new upper layer application onto a glass which is previously subject to thermal treatment for duration of 1-10 minutes within the temperature range of 550-700 °C by applying silane or colloidal silica onto the surface is described. The solution, prepared for said upper layer, is applied onto the coated surface and then subjected to thermal treatment. As a result, in said invention, two separate layers are formed and different thermal treatments are separately applied for each of said layers. In the invention with number EP1329433, a sol-gel process is disclosed which is created a layer having the homogeneously distributed pores. The porosity is controlled by the amount of triton added to the solution in concentrations between 5 and 50 g/l. In an exemplary embodiment of said invention, TEOS is hydrolyzed with water in ethanol in the presence of sulfuric acid catalyst. The hydrolysis comprises two steps in different acid and water concentrations. In the first step, pre-hydrolysis process is applied to alkoxysilane for the duration of 90 minutes at 60 °C in a media where the mole ratio of ethanol is between 10-25 moles until the TEOS/H₂SO₄/H₂O ratio becomes 1/0.0002/1. In the second step, the amount of sulfuric acid and water are increased for duration of 60 minutes at 40 °C until TEOS/H₂S0₄/H₂0 ratio becomes 1/0.1/5. When the gel reaches to the room temperature, triton in different concentrations is added to the solution, and then the prepared solution is applied onto a glass. The glass, having the wet film layer thereon, is firstly subjected to a preheating process for the duration of 15 minutes at 60 °C, it is consequently subjected to thermal treatment for the duration of 60 minutes at 500 °C, finally the coated product can be obtained. As a result, both the solution preparation and the thermal treatment are 2-stepped processes.

As a result, because of all of the abovementioned problems, an improvement is required in the related technical field.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a coating solution applied to glass surfaces for providing antireflective property to the glass, the preparation method of said coating solution, the application of the coating solution onto the glass surface, and relates to the obtained glass, for eliminating the above mentioned disadvantages and for bringing new advantages to the related technical field.

The main object of the present invention is to provide a solution enabling the coating of the glass surface by means of a material whose refractive index is smaller than the refractive index of glass in order to increase the transmittance value of glass.

Another object of the present invention is to provide a coating solution enabling the antireflective property to glass surfaces in order to obtain antireflective coated glasses passing the chemical resistance tests described in the EN 1096-2 standard "Glass in Building - Coated glass - Part 2: Requirements and test methods for class A, B and S coatings". Another object of the present invention is to provide an antireflective coated glass whose transmittance value is. increased between 1-5 %.

In order to realize all of the abovementioned objects and the objects which are to be deducted from the detailed description below, the present invention is a coating process enabling the coating of glasses in the form of a thin layer by means of a material whose refractive index is lower than the refractive index of glass in order to increase transmittance of the cover glasses used in photovoltaic modules and/or in solar thermal collectors and where the following steps are applied in order; i) Preparing the solution having the below mentioned component ratios within the total volume,

ii) Applying this solution on to a glass surface,

iii) Subjecting the glass, whereon the said solution as a wet film layer, to a thermal treatment process.

Accordingly, said process is adding of a chemical comprising chemical resistance increasing element to said solution within the range of 1-10 % in volume with respect to the total volume together with the solvent thereof such that Si/Element mole/mole ratio is 1/0.01-0.05 in the coating solution composition in order to increase the chemical resistance of the coating in step (i), and applying the thermal treatment process for the duration of 1-15 minutes at temperature between 500-700 °C without the pre-curing process to the glass whereon the said solution as a wet film layer in order to increase the transmittance value in between 1-5 % with respect to the uncoated glass within 400-1100 nm after the thermal treatment process in step (iii). Thus, the energy is not consumed for the pre-curing process, and the duration of the thermal treatment is shortened. During the thermal treatment, the coating layer providing the antireflective property is formed and the transmittance of the glass is increased.

In a preferred embodiment of the subject matter invention, in step (i), a chemical, comprising the chemical resistance increasing element, is added to said solution within 1-5 % with respect to the total volume together with the solvent thereof. Thus, the glass, coated with said solution, becomes more resistant against to the chemical effects.

In another preferred embodiment of the subject matter invention, the ratio of the polymeric glycol solution to alkoxysilane is within 1.5-3.5 (volume/volume) range.

In another preferred embodiment of the subject matter invention, the ratio of the polymeric glycol solution to alkoxysilane is within 2-3 (volume/volume) range. In another preferred embodiment of the subject matter invention, in step (iii), thermal treatment is applied at temperature of 600-700 °C for duration of 1-10 minutes. During this thermal treatment, all organic nature in the wet film layer decomposes, and a porous antireflective coating is obtained on to the glass surface. In another preferred embodiment of the subject matter invention, the present invention is an antireflective coated glass produced by means of the abovementioned process and whose transmittance is increased between 1-5 % when compared with the uncoated glass within the wavelength range of 400 - 1100 nm. In order to realize all of the abovementioned objects and the objects which are to be deducted from the detailed description below, the present invention is a Si-based coating solution preparation process for obtaining the solution applied to the glass surface in order to increase the transmittance of cover glasses used in photovoltaic modules and/or in solar thermal collectors, said process comprising the steps of: a) Hydrolysis of alkoxysilane for certain duration by adding the required amount of water for partially or completely hydroxylation in the presence of acid catalyst,

b) Dissolving a polymeric glycol in water and mixing by the hydrolysate in step (a), c) Adding solvents to the mixture and stirring thereof,

d) Adding a strong acid to the mixture and stirring thereof, Accordingly, said coating solution preparation process is characterized by comprising the sub-steps of: e) Dissolving the chemical, comprising chemical resistance increasing element, in the own solvent thereof and afterwards adding to the hydrolysate between step (a) and step (b)

f) Stirring the solution obtained in step (e) for duration of 1-15 minutes

g) Adding the non-ionic surfactant to the mixture after step (d) and stirring thereof In another preferred embodiment of the subject matter invention, the hydarolysate obtained in step (a), is poured on to the polymeric glycol solution in step (b).

In another preferred embodiment of the subject matter invention, the non-ionic surfactant triton is added to the mixture in step (d).

In another preferred embodiment of the subject matter invention, the present invention is a coating solution produced by a preparation process and whose component volumetric ratios are given in below with respect to the total volume. Thus, the resistance of said- glass against to the chemical effects increases while the transmittance value of the glass is increased as coated with said solution.

In order to realize all of the abovementioned objects and the objects which are to be deducted from the detailed description below, the present invention is a coating solution coated on to the glass surface, and whose component ratios in terms of volume are given in below with respect to the total volume, in order to increase the transmittances of cover glasses used in photovoltaic modules and/or in solar thermal collectors.

Accordingly, the coating solution is characterized by comprising a chemical containing chemical resistance increasing element together with the solvent thereof within the range of 1- 0 % in terms of volume with respect to the total volume.

In another preferred embodiment of the subject matter invention, the ratio of the polym glycol solution to alkoxysilane is within the range of 1.5-3.5 (volume/volume).

In another preferred embodiment of the subject matter invention, the amount of alkoxysilane is within 1-5 % in terms of volume with respect to the total volume.

In another preferred embodiment of the subject matter invention, the amount of polymeric glycol aqueous solution is within 5-10 % in terms of volume with respect to the total volume.

In another preferred embodiment of the subject matter invention, a chemical, comprising chemical resistance increasing element, is added to the said solution together with the solvent within 1 -5 % in terms of volume with respect to the total volume.

In another preferred embodiment of the subject matter invention, the mole/mole ratio of Si inside the alkoxysilane with respect to the Al and/or Zr and/or Ti and/or B element inside a chemical comprising chemical resistance increasing element is 1/0.01-0.05.

In another preferred embodiment of the subject matter invention, there are at least two types of monohydric alcohols selected from ethanol, propanol and butanol. In another preferred embodiment of the subject matter invention, there is strong acid within the range of 0-2 % in terms of volume with respect to the total volume. In order to realize all of the abovementioned objects and the objects which are to be deducted from the detailed description below, the present invention is a Si0₂ based antireflective coated glass. Accordingly, the present invention is characterized in that the transmittance value of said glass is increased between 1-5 % with respect to the transmittance value of the uncoated glass within the wavelength range 400 - 1100 nm.

BRIEF DESCRIPTION OF THE FIGURES

The relationship between the refractive indices and the porosity percentage of Ti0₂, Al₂0₃, Si0 is described with the schema in Figure 1.

THE DETAILED DESCRIPTION OF THE INVENTION

In this detailed description, the subject matter a coating solution for increasing the transmittance of the cover glasses used in photovoltaic modules and/or in solar thermal collectors is explained with references to examples without forming any restrictive effect in order to make the subject more understandable.

In the present invention, in order to increase the transmittance value of the glass, a solution, that providing the glass surface to be coated by a material whose refractive index is lower than the refractive index of glass, is developed and then coated on to a glass surface.

As described in the patent with number US4271210, for instance, in order to obtain minimum reflection in the desired wavelength, a layer whose refractive index n_c = 1.23 and having the thickness of λ/4 shall be formed on the surface of glass whose refractive index is n_g = 1.52_^7 . In case of using a Si0₂ based layer having the refractive index n_c = 1.23, the porosity percentage has to be 60 %. The relation between the refractive indexes and the porosity of the oxides like Ti0₂, Al₂0₃, Si0₂ is described in literature. As porosity increases, the refractive index decreases. With reference to Figure 1 , when the relation between the porosity and the refractive indexes of the oxides like Ti0₂, Al₂0₃, Si0₂ is examined, the minimum refractive index is obtained in Si0₂ system with an average of 1.15 as described in the patent application US4271210. In the present invention, the Si0₂ system is preferred.

The present invention generally relates to the coating solution prepared by means of a certain preparation method in order to increase transmittance of the cover glasses used in photovoltaic modules and in solar thermal collectors, the application of said coating solution onto a glass, and relates to coated glass. The preparation and the application of said coating solution comprises the following steps. a) Preparing a solution containing a chemical comprising silica, polymeric glycol, chemical comprising the chemical resistance increasing element, at least two monohydric alcohols, a strong acid

b) Applying said solution on to the glass

c) Subjecting said glass, whereon a said solution as a wet film layer is provided, to a thermal treatment process at high temperature and obtaining the coating providing antireflective property to the glass

The coating solution given in step "a" provides antireflective property to the glass by forming a porous coating film, whose refractive index is smaller than the refractive index of glass and greater than the refractive index of air, on the surface of the glass after it is coated onto the glass surface and afterwards thermal treatment is applied. The purpose of each component within the coating solution is described in detail below.

In the coating solution, a chemical is used which will form a coating comprising inorganic oxide like Al₂0₃, Ti0₂, Si0₂ whose refractive index is smaller than the refractive index of glass. Preferably silica is used as a source, in other words, at least one of the alkoxysilane derivatives comprising Si and O and again preferably which can be hydrolyzed preferably by means of the sol-gel method. For instance, like tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), tetrapropoxysilane, triethoxysilane, methyltriethoxysilane, methylpropoxysilane.

Polymeric glycols are used as pore forming agent. They decompose during the thermal treatment and move away from the surfacewith remaning the sapaces left on the coating layer. By this way the porosity is created on the coating layer. In the preferred application, a polymeric glycol having the different molecular weight preferably within .000-20.000 g/moles is used. As polymeric glycol; polyethylene glycol (PEG) derivatives, triton, 1 ,2-propylene- glycol-monomethyl-ether (PGME) can be used. Strong acid is used as a catalyst in order to accelerate the transformation of hybrid structure of alkoxysilane derivatives into Si0₂ during short-term thermal process. The strong acids break the bonds of the alkoxysilane derivatives during the thermal treatment and accelerate to move the organic content from alkoxysilane structure. In case of short-time thermal treatment, the strong acid is particularly required. As the strong acid, acids like HCI, HN0₃ can be used.

Elements like Al, Zr, Ti, B can be used for increasing chemical resistance. The chemical comprising chemical resistance increasing element is added directly to the coating solution or by means of a solvent compatible with the coating solution. Aluminum-acetyl-acetonate (AI.Ac.Ac), zirconium-acetyl-acetonate (Zr.Ac.Ac), titanium-acetyl-acetonate (Ti.Ac.Ac), aluminum sec-butoxide, zirconium sec-butoxide, boron tri-isopropoxide, boron tri-etoxide, etc. can be used for increasing chemical resistance. In the present invention, Al is preferred as a chemical resistance increasing element. In the preferred application, acetic acid is used as a solvent of the chemical resistance increasing element.

At least two monohydric alcohols are used as the solvents in the coating solution. In order to arrange the coating application and control the evaporation of the wet film by means of using two different solvents having the different evaporation temperatures. As a solvent, the pair chosen within ethanol, butanol, propanol, etc. can be used.

As a result of the experimental studies, in some cases in order to improve the the efficiency of the coating by means of addition of the non-ionic surfactant comprising mostly ether structures and particularly glycolic ether derivatives into the coating solution, and it is observed to have an effect increasing the transmittance values. Triton can be used as the non-ionic surfantant comprising glycol ether derivatives.

While the coating solution components are selected in suitable ratios, the reflection value of the glass, where the coating solution is applied onto at least one surface thereof, can be decreased. The coating solution subject to this study comprises the components each of which are prepared by adding into the coating solution with the volume ratios are given in Table 1. Table 1 : The volume ratios of the components in the coating solution

In order to achive the hydrolysis of the alkoxysilane, the monohydric alcohol, water and strong acid mixture are added gradually onto the alkoxysilane under the vigorous stirring according to the ratios given in Table 1. After the addition of monohydric alcohol, water and strong acid mixture on to the alkoxysilane , the vigorous stirring shall be continued for the duration of 110-150 minutes. The amount of water used in this step has not to be greater than the stoichiometric amount required for the partial or complete hydrolysis of alkoxysilane. The volume ratio of the hydrolysate in the coating solution is between 1- 0 % and preferably between 1-5 %.

Meanwhile, the chemical, comprising chemical resistance increasing element, is dissolved in a suitable solvent. This solution is added into hydrolysate under the vigorous stirring by adjusting the mole/mole ratio of silicon in the alkoxysilane used as the silica source to the amount of chemical resistance increasing element such that said mole/mole proportion (Si/AI, Zr, Ti, B) is equal to 1/0.01-0.05, thus, the doped hydrolysate is obtained. The volume ratio of the chemical comprising chemical resistance increasing element together with the solvent thereof in the coating solution together with the solvent thereof shall be between 1-10 %, and preferably between 1-5 %. The doping of the coating solution with a chemical resistance increasing element increases the resistance of the coating to the neutral salt sprayjest described in the standard EN 1096-2.

The doped hydrolysate is added onto the aqueous solution of polymeric glycol. The volume ratio of the aqueous solution of polymeric glycol in the coating solution shall be between 1- 20 %, and preferably between 5-10 %. The ratio of the polymeric glycol solution to alkoxysilane in the solution shall be between 1.5-3.5, and preferably between 2-3.

After this step, at least two solvents are added to dilute the coating solution. The volume ratio of the solvents in the coating solution shall be between 50-95 %, and preferably be between 80-95 %.

At the consequent step, the strong acid is added within the volume ratio between 0-5 %, and preferably 0-2 %.

Finally, a non-ionic surfactant, triton is added within the volume ratio between 0-2.5 %.

During preparation of the coating solution, each component shall be added to the coating solution according to the given order and the manner described above. In some different cases, it is observed that there are precipitations in the coating solution. Particularly, the addition order of the polymeric glycol is important after the completion of the hydrolysis of the alkoxysilane. First of all, the hydrolysis and the following condensation reactions of alkoxysilane must be completed because of the sensitivity of the alkoxysilane against the water. Therefore, the aqueous solution of polymeric glycol is added to hydrolysate_afterwards.

The prepared solution can be applied to glass surface by means of the following methods:

- Coating by means of dip coating

- Coating by means of spraying

- Coating by means of spin coating

- Coating by means of roll coating

Prior to the coating process, the surface to be coated shall be clean, dry and dust free. Therefore, prior to coating, the surface shall be cleaned by means of the chemical washing process. During the step of formingjhe wet film by applying the coating solution onto the glass surface, the coating thickness shall be homogeneous. In the same manner, after the thermal treatment, the coating thickness of the final product is also desired to be homogeneous. Every method, where the wet coating film can be applied in homogeneous thickness and where the final coated product is obtained in homogeneous thickness, can be used for the said solution.

When the prepared coating solution is applied onto the glass surface, firstly, solvents like ethanol, butanol, water evaporates from the surface, and, only the compound, polymeric material and strong acid comprising Si and O remain on the surface. Thus, the glass, whereon the wet coating film is formed, is subject to thermal treatment for the duration of 1- 10 minutes on the average and in the range of 600-700 °C without applying any pre-curing process. The compound, comprising Si and O, is transformed into silica with the help of the effect of heat and with the help of the strong acid catalyst, and meanwhile, polymeric glycol is decomposed and leaves from the surface and creates a porous structure on the glass surface. Thus, on the glass surface, a porous silica film is formed whose refractive index is smaller than the refractive index of glass, and as a result of this effect, the transmittance of the glass increases between 1-5 %, and antireflective coated glass is obtained.

The resistance of the antireflective coated glass, coated by means of the coating solution doped with aluminium, to the neutral salt spray test described in EN1096-2 standard, and the transmittance measurements taken by means of the haze meter are monitored and the results thereof are given in Table 2 and Table 3. The transmittances are measured by means of haze meter with trademark BYK Gardner, model Haze-Gard Dual.

Table-2: Salt spray test resistances of 3 different antireflective coated glasses whose one surface is coated by means of a coating solution which does not comprise Al

* Δ T = Transmittance value of the coated glass - Transmittance value of the uncoated glass

Table-3: Salt spray test resistances of 3 different antireflective coated glasses whose one surface is coated by means of a coating solution which comprises Al

EN 1096-2 Standard / Neutral Salt Spray resistance test results

Antireflective coated glasses whose one surface is coated by

Test samples means of a coating solution which comprises Al

Measurement time % Δ T * Prior to test 1.8

Example-1

21^st day 1.9

Prior to test 1.7

Example-2

21^st day 2.0

Prior to test 1.6

Example-3

21^st day 1.6

When Table 2 and Table 3 are examined, it is observed that: · The salt spray test resistance of the coated glass is increased by means of Al doping processwith a compromise in the transmittance value

• The salt spray test resistances of the antireflective coated glasses whose one surface is coated with the solution which does not comprise Al do not give suitable and repeatable results,

· The salt sprayjest resistances of the antireflective coated glasses whose one surface is coated with the solution which comprises Al give repeatable results.

As may be seen from Table 2 and Table 3, by means of the transmittance measurements, it is observed that the difference between the transmittance values is significantly decreased on 12^th day in Example-1 , on 6^th day in Example 2, and on 13^th day in Example-3 for the glass samples coated with the solution which does not comprise Al. This shows that the transmittance value of the coated glass decreases by time. More stable and repeatable results are obtained from the salt spray resistance tests of glasses coated with antireflective solution comprising Al. This shows that the Al doping process increases salt spray test resistances of the antireflective coated glasses.

The protection scope of the present invention is set forth in the annexed Claims and cannot be restricted to the illustrative disclosures given above, under the detailed description. It is because a person skilled in the relevant art can obviously produce similar embodiments under the light of the foregoing disclosures, without departing from the main principles of the present invention.

Claims

1. A coating process providing coating of glasses in the form of a thin layer by means of a material whose refractive index is lower than the refractive index of glass in order to increase transmittance of the cover glasses used in photovoltaic modules and/or in solar thermal collectors and where the following steps are applied in order; i) Preparing the solution having the below mentioned component ratios within the total volume,

ii) Applying this solution on to a glass surface,

iii) Subjecting the glass, whereon the said solution as a wet film layer form is applied, to a thermal treatment process. characterized in that said process is the addition of a chemical comprising chemical resistance increasing element to said solution within the range of 1-10 % in volume with respect to the total volume together with the solvent thereof such that Si/Element mole/mole ratio is 1/0.01-0.05 in the coating solution composition in order to increase the chemical resistance of the coating in step (i), and the application of the thermal treatment process for the duration of 1-15 minutes at temperature between 500-700 °C without procuring process to the glass whereon the said solution as a wet film layer, in order to increase the transmittance value in between of 1-5 % with respect to the uncoated glass within 400-1100 nm after the thermal treatment process in step (iii).

2. A coating process according to Claim 1 , characterized in that in step (i), a chemical, comprising the chemical resistance increasing element, is added to said solution within 1-5 % with respect to the total volume together with the solvent thereof.

3. A coating process according to Claim 1 , characterized in that the ratio of the polymeric glycol solution to the alkoxysilane is within 1.5-3.5 (volume/volume) range.

4. A coating process according to Claim 1 , characterized in that the ratio of the polymeric glycol solution to the alkoxysilanejs within 2-3 (volume/volume) range.

5. A coating process according to Claim 1 , characterized in that in step (iii), thermal treatment is applied at temperature of 600-700 °C for duration of 1-10 minutes.

6. An antireflective coated glass produced by means of a process according to any of the preceding claims between Claim 1 and Claim 5, and whose transmittance is increased between 1-5 % when compared with the uncoated glass within the wavelength range of 400 - 1100 nm.

7. A Si-based coating solution preparation process for obtaining the solution applied to the glass surface in order to increase the transmittances of cover glasses used in photovoltaic modules and/or in solar thermal collectors, said process comprising the steps of: a) Hydrolysis of alkoxysilane for certain duration by adding the required amount of water for partially or completely hydrolysation in the presence of acid catalyst, b) Dissolving a polymeric glycol in water and mixing by the hydrolysatejn step (a), c) Adding solvents to the mixture and stirring thereof,

d) Adding a strong acid to the mixture and stirring thereof, characterized by comprising the sub-steps of: e) Dissolving the chemical, comprising chemical resistance increasing element, in the own solvent thereof and afterwards adding to hydrolysate between step (a) and step (b)

f) Stirring the solution obtained in step (e) for duration of 1-15 minutes

g) Adding the non-ionic surfactant to the mixture after step (d) and stirring thereof

8. A coating solution production process according to Claim 7, characterized in that the hydrolysate, obtained in step (a), is poured on to the polymeric glycol solution in step (b).

9. A coating solution production process according to Claim 7, characterized in that the non-ionic surfactant triton, is added to the mixture in step (d).

10. A coating solutipn produced by a preparation process according to any one of the preceding claims between Claim 7 and Claim 9, and whose component volumetric ratios are given in below with respect to the total volume.

11. A coating solution coated to the glass surface and whose component ratios in terms of volume are given in below with respect to the total volume, in order to increase the transmittances of cover glasses used in photovoltaic modules and/or in solar thermal collectors;

characterized by comprising a chemical containing chemical resistance increasing element together with the solvent thereof within the range of 1-10 % in terms of volume with respect to the total volume.

12. A coating solution according to Claim 1 1 , characterized in that the ratio of the polymeric glycol solution to the alkoxysilane is within the range of 1.5-3.5 (volume/volume).

13. A coating solution according to Claim 11 , characterized in that the amount of alkoxysilane is within 1-5 % in terms of volume with respect to the total volume.

14. A coating solution according to Claim 11, characterized in that the amount of polymeric glycol aqueous solution is within 5-10 % in terms of volume with respect to the total volume.

15. A coating solution according to Claim 11 , characterized by comprising a chemical, comprising chemical resistance increasing element, which is added to the said solution together with the solvent within 1-5 % in terms of volume with respect to the total volume.

16. A coating solution according to Claim 11 , characterized in that the mole/mole ratio of the amount of Si inside the alkoxysilane with respect to the Al and/or Zr and/or Ti and/or B element inside a chemical comprising chemical resistance increasing element is 1/0.01-0.05.

17. A coating solution according to Claim 11 , characterized by comprising at least two types of monohydric alcohols selected from ethanol, propanol and butanol.

18. A coating solution according to Claim , characterized by comprising strong acid within the range of 0-2 % in terms of volume with respect to the total volume.

19. A Si0₂ based antireflective coated glass , characterized in that the transmittance value of said glass is increased between 1-5 % with respect to the transmittance value of the uncoated glass within the wavelength range 400 - 1100 nm.