Encapsulant with Modified Refractive Index
The present invention provides an encapsulant material with a modified index of refraction for increasing the acceptance angle of a concentrated photovoltaic system. The encapsulant material may include filler material of a higher index of refraction than the encapsulant. The filler material may be particulates that are smaller than the wavelength of light converted to electricity by a solar cell.
1 . An apparatus comprising:
an optical element having a first refractive index;
a solar cell, wherein the solar cell converts light associated with a range of wavelengths to electrical energy, the range having a minimum wavelength of light;
an encapsulant having a second refractive index, wherein the encapsulant is disposed between the optical element and the solar cell; and
wherein the second refractive index of the encapsulant is modified to approach the value of the first refractive index.
2 . The apparatus of claim 1 , wherein the optical element is a non-imaging concentrator.
3 . The apparatus of claim 1 , wherein the second refractive index is modified to match the first refractive index.
4 . The apparatus of claim 1 , wherein the encapsulant comprises silicone and a filler material.
5 . The apparatus of claim 4 , wherein the filler material comprises titania.
6 . The apparatus of claim 4 , wherein the filler material comprises particulates smaller than the minimum wavelength.
7 . The apparatus of claim 4 , wherein the filler material comprises particulates smaller than 300 nm in diameter.
8 . The apparatus of claim 4 , wherein the filler material comprises 10-20% volume of the encapsulant.
9 . The apparatus of claim 1 , further comprising an anti-reflective layer between the optical element and the solar cell.
10 . A method of increasing the acceptance angle of an optical system, wherein the optical system comprises an optical element having a first refractive index and an encapsulant having a second refractive index, the method comprising:
modifying the encapsulant to cause the second refractive index to approach the value of the first refractive index;
applying the encapsulant to the optical element; and
coupling a solar cell to the encapsulant, wherein the solar cell converts light associated with a range of wavelengths to electrical energy, the range having a minimum wavelength of light.
11 . The method of claim 10 , wherein the step of modifying comprises adding a filler material to the encapsulant.
12 . The method of claim 11 , wherein the filler material is titanium dioxide.
13 . The method of claim 11 , wherein the filler material is associated with an index of refraction greater than 1.4.
14 . The method of claim 11 , wherein the filler material comprises particulates smaller than the minimum wavelength.
15 . The method of claim 11 , wherein the filler material comprises particulates smaller than 300 nm in diameter.
16 . The method of claim 11 , wherein the filler material is 10-20% volume of the encapsulant.
17 . The method of claim 10 , further comprising the step of applying an anti-reflective layer to the solar cell.