FRONT-FACE SUBSTRATE FOR A SOLAR MODULE

Abstract

The invention relates to a front-face substrate for a solar module, in particular for mobile applications, for example mobile devices, means of transportation, or manned or unmanned flying objects, wherein the front-face substrate has a weight per unit area of under 500 g/m.sup.2 and comprises a material which has a transmission curve T() for a reference thickness of 100 m, said transmission curve forming a transition from a lower transmission T.sub.low to an upper transmission T.sub.up and having a transitional transmission T.sub.tr therebetween of 50% in a wavelength range of 302 nm to 322 nm.

Claims

1-20. (canceled)

21. A frontside substrate for a solar module, wherein the frontside substrate has a surface weight of below 500 g/m.sup.2, and wherein the frontside substrate comprises a material which, at a reference thickness of 100 m, has a transmittance curve T() that forms a transition from a lower transmittance T.sub.low to an upper transmittance T.sub.up and has an intervening intermediate transmittance T.sub.tr=50% in a wavelength range from 302 nm to 322 nm.

22. The frontside substrate of claim 21, wherein the frontside substrate has a surface weight of below 400 g/m.sup.2, and/or wherein the intermediate transmittance T.sub.tr=50% is in a wavelength range from 304 nm to 318 nm.

23. The frontside substrate of claim 21, wherein the frontside substrate has a thickness of less than 150 m.

24. The frontside substrate of claim 21, wherein the transmittance curve T() falls below a value of T.sub.tr=10% at a wavelength in a wavelength range from 288 nm to 312 nm, and/or wherein the transmittance curve T() rises above a value of T.sub.tr=90% at a wavelength in a wavelength range from 322 nm to 400 nm.

25. The frontside substrate of claim 21, wherein the lower transmittance T.sub.low is lower than 5%, and/or wherein the upper transmittance T.sub.up is greater than 85%.

26. The frontside substrate of claim 21, wherein the lower transmittance Tow is at a wavelength of at least 250 nm, and/or wherein the upper transmittance T.sub.up is at a wavelength of at most 375 nm.

27. The frontside substrate of claim 21, wherein the transmittance curve at at least one point has a slope of 2.8 percentage points/nm.

28. The frontside substrate of claim 21, wherein the transmittance curve after irradiation for 7 hours with light in a wavelength range from 250 nm to 600 nm has a shift of less than 5.0 nm, and/or wherein the transmittance curve after irradiation for 100 hours with UV-A light at 210 W/m.sup.2, UV-B light at 170 W/m.sup.2 and UV-C light at 250 W/m.sup.2 has a shift of less than 5.0 nm.

29. The frontside substrate of claim 21, wherein at least one of the following is satisfied: the material of the frontside substrate comprises a glass having a glass composition; the glass is a borosilicate glass and the glass composition contains no Li.sub.2O or contains Li.sub.2O with a proportion of less than 50 ppm; the glass composition contains no CaO or contains CaO with a proportion of less than 50 ppm; the glass composition contains no MgO or contains MgO with a proportion of less than 50 ppm; the glass composition contains no BaO or contains BaO with a proportion of less than 50 ppm; the glass composition contains no SrO or contains SrO with a proportion of less than 50 ppm; the glass composition contains no antimony (Sb) or contains antimony (Sb) with a proportion of less than 50 ppm; or the glass composition contains no arsenic (As) or contains arsenic (As) with a proportion of less than 50 ppm.

30. The frontside substrate of claim 21, wherein the material of the frontside substrate comprises a borosilicate glass having a glass composition that does not contain any cerium oxide or contains cerium oxide with a proportion of less than 500 ppm.

31. The frontside substrate of claim 21, wherein the material of the frontside substrate comprises a glass having a glass composition and at least one of the following is satisfied: the glass composition contains TiO.sub.2 in a proportion of 0.5 to 10 percent by weight; the glass composition contains Al.sub.2O.sub.3 in a proportion of 0 to 15 percent by weight; the glass composition contains SiO.sub.2 in a proportion of 30 to 80 percent by weight; or the glass composition contains B.sub.2O.sub.3 in a proportion of 3 to 20 percent by weight.

32. The frontside substrate of claim 21, wherein the material of the frontside substrate has a density lower than 3.25 g/cm.sup.3.

33. The frontside substrate of claim 21, wherein the material of the frontside substrate has a modulus of elasticity higher than 68 GPa, and/or wherein the material of the frontside substrate has a modulus of elasticity lower than 78 GPa.

34. The frontside substrate of claim 21, wherein the material of the frontside substrate has a coefficient of thermal expansion in a temperature range from 20 C. to 300 C. of greater than 410.sup.6 K.sup.1.

35. The frontside substrate of claim 21, wherein the frontside substrate has a dimension greater than 35 cm, and/or wherein the frontside substrate has a second dimension greater than 65 cm.

36. A frontside unit for a solar module, comprising: a frontside substrate having a surface weight of below 500 g/m.sup.2, wherein the frontside substrate comprises a material which, at a reference thickness of 100 m, has a transmittance curve T() that forms a transition from a lower transmittance T.sub.low to an upper transmittance T.sub.up and has an intervening intermediate transmittance T.sub.tr=50% in a wavelength range from 302 nm to 322 nm; and an adhesive layer applied two-dimensionally atop the frontside substrate.

37. The frontside unit of claim 36, wherein the adhesive layer comprises at least one of the following materials: butyl polymer, EVA, PVB, silyl-modified polymer (SMP), or transparent silicone.

38. A solar module, comprising: a frontside substrate having a surface weight of below 500 g/m.sup.2, wherein the frontside substrate comprises a material which, at a reference thickness of 100 m, has a transmittance curve T() that forms a transition from a lower transmittance T.sub.low to an upper transmittance T.sub.up and has an intervening intermediate transmittance T.sub.tr=50% in a wavelength range from 302 nm to 322 nm; a solar cell; and an adhesive layer that bonds the frontside substrate to the solar cell.

39. The solar module of claim 38, further comprising a backside element, wherein the solar cell is disposed between the backside element and the frontside substrate.

40. The solar module of claim 38, wherein the backside element is in the form of a module frame.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The invention is described in detail hereinafter with reference to the figures. The figures show:

[0057] FIG. 1: a schematic diagram in a top view of a frontside substrate,

[0058] FIG. 2: a schematic diagram in section view of a frontside unit with a frontside substrate and an adhesive layer,

[0059] FIG. 3: a schematic diagram in a section view of a solar module,

[0060] FIG. 4: a graph of the transmittance curve of a frontside substrate with a thickness of 100 m before and after solarization irradiation with a radiation source having an energy distribution according to FIG. 6,

[0061] FIG. 5: a graph of a relative spectral energy distribution of a radiation source for examination of solarization resistance,

[0062] FIG. 6: a graph of a relative spectral energy distribution of a further radiation source for examination of solarization resistance.

DETAILED DESCRIPTION OF THE INVENTION

[0063] FIGS. 1-3 show a frontside substrate 100 (FIG. 1), a frontside unit 10 comprising a frontside substrate 100 and an adhesive layer 110 applied two-dimensionally on one side of the frontside substrate 100 (FIG. 2), and a solar module 1 comprising a solar cell 200 disposed between a frontside substrate 100 (or a frontside unit 10) and a backside element 300, wherein the frontside unit 100 is two-dimensionally bonded to a surface of the solar cell 200 by the adhesive layer 110 (FIG. 3).

[0064] The frontside substrate here has a surface weight of below 500 g/m.sup.2, for example a surface weight of 251 g/m.sup.2, and a thickness of 100 m. Moreover, the frontside substrate has, for example, a glass composition containing the following components in percent by weight:

TABLE-US-00001 SiO.sub.2 63.8-64.8 Al.sub.2O.sub.3 3.2-4.4 B.sub.2O.sub.3 7.4-8.6 Na.sub.2O 5.5-6.7 K.sub.2O 6.3-7.3 ZnO 5.2-6.7 TiO.sub.2 3.6-4.6 Sb.sub.2O.sub.3 0.4-1.2 Cl 0.05-1.3

[0065] FIG. 4 shows transmittance curves of such an illustrative frontside substrate having a thickness of 100 m before and after a solarization test in which the substrate was irradiated for 100 hours with UV-A light at 210 W/m.sup.2, UV-B light at 170 W/m.sup.2 and UV-C light at 250 W/m.sup.2. The irradiation spectrum is shown in FIG. 6. It is found that the transmittance curve and the intermediate transmittance T.sub.tr=50% have a shift of less than 1 nm.

[0066] A further illustrative glass composition comprises the following proportions in percent by weight, where contamination with iron is in the region of 50 ppm:

TABLE-US-00002 SiO.sub.2 63.4-64.4 Al.sub.2O.sub.3 3.3-4.4 B.sub.2O.sub.3 7.2-8.6 Na.sub.2O 5.7-6.7 K.sub.2O 6.4-7.4 ZnO 4.8-6.5 TiO.sub.2 3.2-4.3 Se 0.005-0.1

[0067] For the two glass compositions mentioned, solarization studies were additionally conducted for a frontside substrate having a thickness of 1 mm, with alternative employment of irradiation with a spectrum according to FIG. 5 for 7 hours. Here too, it was found that the transmittance curve and the intermediate transmittance T.sub.tr=50% have a shift of less than 1 nm.

[0068] A further illustrative glass composition comprises the following components in percent by weight:

TABLE-US-00003 SiO2 61.5-65.5 Al2O3 1.8-4.5 B2O3 8.5-10.5 Na2O 6.0-7.0 K2O 6.6-7.7 ZnO 6.0-8.5 TiO2 3.0-4.0

[0069] A further illustrative glass composition comprises the following components in percent by weight:

TABLE-US-00004 SiO.sub.2 61-71 Al.sub.2O.sub.3 5-8 B.sub.2O.sub.3 9-14 Na.sub.2O 9-10 CaO 2-3.5 ZnO 0-1 TiO.sub.2 0.0-6.0 Sb.sub.2O.sub.3 0-1
and it is especially possible to provide a glass composition comprising the following components in percent by weight:

TABLE-US-00005 SiO.sub.2 62.4 Al.sub.2O.sub.3 7.5 B.sub.2O.sub.3 12.7 Na.sub.2O 9.1 CaO 3 ZnO 0.8 TiO.sub.2 4 Sb.sub.2O.sub.3 0.1

[0070] In particular, a glass composition as described above, but also a glass composition irrespective of the other components mentioned above, may comprise a proportion of titanium oxide in the range of 0-6, especially in the range of 3-5, for example 4. In addition, the glass composition, as an alternative or in addition to such a proportion or a proportion of titanium oxide mentioned in the table(s), may comprise a component that preferably acts as a UV absorber.

[0071] Useful examples include a proportion of one or more of the following components that are active with regard to UV absorption: cerium (for example in the form of CeO.sub.2), antimony (for example in the form of Sb.sub.2O.sub.3), where an antimony content should preferably not exceed a proportion of 1 percent by weight, tin (for example in the form of SnO.sub.2), niobium (for example in the form of Nb.sub.2O.sub.5), iron (in the form of Fe.sub.2O.sub.3), especially with an appropriately adjusted Fe.sup.2+/Fe.sup.3+ redox ratio.

[0072] Yet a further illustrative glass composition comprises the following proportions in percent by weight:

TABLE-US-00006 SiO.sub.2 58.0-59.5 Al.sub.2O.sub.3 4.5-5.5 B.sub.2O.sub.3 14.5-15.5 K.sub.2O 9.5-10.5 BaO 9.5-10.5 TiO.sub.2 0.08-0.12 CeO.sub.2 0.5-1.5

[0073] Especially in the case of the illustrative glasses without cerium oxide, it is possible to keep the raw glass costs low, such that a frontside substrate having the properties mentioned is producible inexpensively. In association with a surface weight of below 500 g/m.sup.2, for example below 300 g/m.sup.2, it is thus possible to achieve a reduction both in the weight and in the costs of a solar module, and it is additionally possible, because of the intermediate transmittance, to achieve a suitable protective effect for components of the solar module, for example an adhesive layer, even under conditions of high UV radiation, as a result of which it is possible in turn to use less costly adhesive layers, so as to result overall in a potential for cost savings at several points and in a particularly suitable use for mobile applications, for example mobile devices, modes of transport, modes of transportation or manned or unmanned flying objects.