Solar cells encapsulated with poly(vinyl butyral)

• US 20080185035A1
• Filed: 02/07/2007
• Published: 08/07/2008
• Est. Priority Date: 02/07/2007
• Status: Active Grant

• Current Assignee: Dow Global Technologies LLC (Dow, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Hayes, Richard Allen
• Granted Patent: US 7,943,845 B2
• Time in Patent Office: Days
• US Class Current: 136/251
• CPC Class Codes: B32B 17/10018 comprising only one glass sheet
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10743 containing acrylate (co)polymers or salts thereof
• CPC Class Codes: B32B 17/10761 containing vinyl acetal
• CPC Class Codes: B32B 17/10853 the membrane being bag-shaped
• CPC Class Codes: B32B 17/10862 using pressing-rolls
• CPC Class Codes: B32B 2327/12 containing fluorine
• CPC Class Codes: H01L 31/02168 the coatings being antireflective or having enhancing optical properties for the solar cells
• CPC Class Codes: H01L 31/0481 characterised by the composition of the encapsulation material
• CPC Class Codes: Y02E 10/542 Dye sensitized solar cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A solar cell pre-laminate assembly comprising (i) a solar cell component comprising one or a plurality of solar cells and having a light-receiving side and a back side, and (ii) stiff poly(vinyl butyral) sheet as an encapsulant layer, wherein the stiff poly(vinyl butyral) sheet is positioned next to the light-receiving or the back side of the solar cell component and comprises a poly(vinyl butyral) composition containing about 10 to about 23 wt % of a plasticizer based on the total weight of the composition.

A process of preparing solar cell assembly comprising (i) providing a solar cell component and a stiff poly(vinyl butyral) sheet comprising a poly(vinyl butyral) composition containing about 10 to about 23 wt % of a plasticizer based on the total weight of the poly(vinyl butyral) composition, and (ii) encapsulating the solar cell component in a polymer matrix comprising the poly(vinyl butyral) composition.

Claims

1. A solar cell pre-laminate assembly comprising (i) a solar cell component comprising one or a plurality of solar cells and having a light-receiving side and a back side, and (ii) stiff poly(vinyl butyral) sheet as an encapsulant layer, wherein the stiff poly(vinyl butyral) sheet is positioned next to the light-receiving or the back side of the solar cell component and comprises a poly(vinyl butyral) composition containing about 10 to about 23 wt % of a plasticizer based on the total weight of the composition.

2. The solar cell pre-laminate assembly of claim 1, wherein the poly(vinyl butyral) composition contains about 15 to about 18 wt % of the plasticizer based on the total weight of the composition.

3. The solar cell pre-laminate assembly of claim 1, wherein the stiff poly(vinyl butyral) sheet has a thickness of equal to or less than about 60 mils (1.52 mm).

4. The solar cell pre-laminate assembly of claim 2, wherein the stiff poly(vinyl butyral) sheet has a thickness of about 10 to about 20 mils (about 0.25 to about 0.51 mm).

5. The solar cell pre-laminate assembly of claim 1, wherein the stiff poly(vinyl butyral) sheet has a glass transition temperature (Tg) of about 35°

C. to about 60°

C.

6. The solar cell pre-laminate assembly of claim 4, wherein the stiff poly(vinyl butyral) sheet has a glass transition temperature (Tg) of about 50°

C. to about 55°

C.

7. The solar cell pre-laminate assembly of claim 1 wherein the plasticizer is selected from the group consisting of triethylene glycol di-2-ethylhexanoate, tetraethylene glycol di-n-heptanoate, dibutyl sebacate, and mixtures thereof.

8. The solar cell pre-laminate assembly of claim 6, wherein the poly(vinyl butyral) used to make the stiff poly(vinyl butyral) sheet has a weight average molecular weight of about 30,000 to about 600,000, and contains about 12 to about 23 wt % of hydroxyl groups calculated as polyvinyl alcohol (PVOH).

9. The solar cell pre-laminate assembly of claim 6, wherein the poly(vinyl butyral) used to make the stiff poly(vinyl butyral) sheet has a weight average molecular weight of about 200,000 to 300,000, and contains about 15 to about 19 wt % of hydroxyl groups calculated as polyvinyl alcohol (PVOH), and wherein the plasticizer is selected from the group consisting of triethylene glycol di-2-ethylhexanoate, tetraethylene glycol di-n-heptanoate, dibutyl sebacate, and mixtures thereof.

10. The solar cell pre-laminate assembly of claim 1, further comprising a second polymeric layer that is positioned next to the solar cell component on the opposite side from the stiff poly(vinyl butyral) sheet, wherein the second polymeric layer comprises a polymeric composition selected from the group consisting of poly(vinyl butyral), ionomers, ethylene vinyl acetate, acoustic poly(vinyl acetal), polyurethane, polyvinylchloride, polyethylenes, polyolefin block elastomers, ethylene acrylate ester copolymers, acid copolymers, silicone elastomers and epoxy resins.

11. The solar cell pre-laminate assembly of claim 10, wherein the stiff poly(vinyl butyral) sheet is positioned next to the light-receiving side of the solar cell component and serves as a front-sheet encapsulant layer and the second polymeric layer is positioned next to the back side of the solar cell component and serves as a second encapsulant layer.

12. The solar cell pre-laminate assembly of claim 11, wherein the second encapsulant layer is formed of a second layer of the stiff poly(vinyl butyral) sheet.

13. The solar cell pre-laminate assembly of claim 1, wherein the one or a plurality of solar cells are selected from the group consisting of multi-crystalline solar cells, thin film solar cells, compound semiconductor solar cells, dye sensitized solar cells, and amorphous silicon solar cells.

14. The solar cell pre-laminate assembly of claim 1, further comprising an incident layer that is formed of a transparent material and serves as an outer layer at the light-receiving side of the assembly.

15. The solar cell pre-laminate assembly of claim 14, wherein the transparent material is glass or a plastic film or sheet.

16. The solar cell pre-laminate assembly of claim 1, further comprising a back-sheet that serves as an outer layer at the back side of the assembly.

17. The solar cell pre-laminate assembly of claim 16, wherein the back-sheet is formed of glass, plastic sheets or films, or metal sheets or films.

18. The solar cell pre-laminate assembly of claim 12, wherein (a) the poly(vinyl butyral) composition contains about 15 to about 18 wt % of the plasticizer based on the total weight of the composition;

(b) each of the two stiff poly(vinyl butyral) sheets has a thickness of about 10 to about 20 mils;

(c) each of the two stiff poly(vinyl butyral) sheets has a glass transition temperature (Tg) of about 50°

C. to about 55°

C.;

(d) the poly(vinyl butyral) used to make the two stiff poly(vinyl butyral) sheet has a weight average molecular weight of about 200,000 to 300,000, and contains about 15 to about 19 wt % of hydroxyl groups calculated as polyvinyl alcohol (PVOH), and (e) the plasticizer is selected from the group consisting of triethylene glycol di-2-ethylhexanoate, tetraethylene glycol di-n-heptanoate, dibutyl sebacate, and mixtures thereof.

21. A process of manufacturing a solar cell module comprising:

(i) providing a solar cell pre-laminate assembly as described in claim 1; and

(ii) laminating the pre-laminate assembly to form the solar cell module.

23. The process of claim 21, wherein the step (ii) of lamination is conducted by subjecting the assembly to heat.

24. The process of claim 23, wherein the step (ii) of lamination further comprising subjecting the assembly to vacuum.

19. A solar cell pre-laminate assembly consisting essentially of, from top to bottom, (i) an incident layer formed of a transparent material, which is positioned next-to, (ii) a front-sheet encapsulant layer that is positioned next to, (iii) a solar cell component comprising one or a plurality of solar cells, which is positioned next to, (iv) an optional second encapsulant layer that is positioned next to, (v) a back-sheet, wherein at least one of the two encapsulant layers is formed of a stiff poly(vinyl butyral) sheet that comprises a poly(vinyl butyral) composition containing about 10 to about 23 wt % of a plasticizer, based on the total weight of the composition.

20. The solar cell pre-laminate assembly of claim 19, wherein (a) the poly(vinyl butyral) composition contains about 15 to about 18 wt % of the plasticizer based on the total weight of the composition;

(b) the stiff poly(vinyl butyral) sheet has a thickness of about 10 to about 20 mils;

(c) the stiff poly(vinyl butyral) sheet has a glass transition temperature (Tg) of about 50°

C. to about 55°

C.;

(d) the poly(vinyl butyral) used to make the stiff poly(vinyl butyral) sheet has a weight average molecular weight of about 200,000 to 300,000, and contains about 15 to about 19 wt % of hydroxyl groups calculated as polyvinyl alcohol (PVOH), and (e) the plasticizer is selected from the group consisting of triethylene glycol di-2-ethylhexanoate, tetraethylene glycol di-n-heptanoate, dibutyl sebacate, and mixtures thereof.

22. A process of manufacturing a solar cell module comprising:

(i) providing a solar cell pre-laminate assembly as described in claim 20; and

(ii) laminating the pre-laminate assembly to form the solar cell module.

25. A process of preparing solar cell assembly comprising (i) providing a solar cell component and a stiff poly(vinyl butyral) sheet comprising a poly(vinyl butyral) composition containing about 10 to about 23 wt % of a plasticizer based on the total weight of the poly(vinyl butyral) composition, and (ii) encapsulating the solar cell component in a polymer matrix comprising the poly(vinyl butyral) composition.

26. The process of claim 25 comprising (a) providing a second interlayer sheet, (b) placing the solar cell component between the stiff poly(vinyl butyral) sheet and the second interlayer sheet to form a pre-laminate, and (c) wherein the encapsulating comprise heating the pre-laminate so that the solar cell component is encapsulated.

27. The process of claim 26 wherein the second interlayer sheet is a stiff poly(vinyl butyral) sheet.

28. The process of claim 25 further comprising forming a solar cell module comprising the encapsulated solar cell component with an incident layer and a back sheet layer.