BI-FACIAL SOLAR PANELS INCORPORATING SILICON FORMED ON A SUBSTRATE
Systems and methods for fabricating a bi-facial solar cell are presented. Among many possible applications for a bi-facial solar cell described herein, a particularly interesting one is its application on the south pole region of the Moon. In this region, rather than rising and setting, the Sun travels in a complete circle, skimming low over the Moon's horizon. The bi-facial solar cell may be oriented vertically so that either one or the other side of the solar cell will be positioned to receive solar radiation to generate electricity. The bi-facial solar cell may include p-type regions adjacent to n-type regions on each side of the solar cell. The p-n junctions are between the p-type regions and the n-type regions and on or near the surface of each side of the solar cell.
1 - 10 . (canceled)
11 . A bi-facial solar cell comprising:
a substrate having a first surface and a second surface opposite the first surface;
a first silicon sheet on the first surface and a second silicon sheet on the second surface;
p-type regions and n-type regions in each of the first and the second silicon sheets, wherein the p-type regions and the n-type regions are arranged side by side with one another; and
electrical contacts on the p-type and the n-type regions that are in each of the first and the second silicon sheets.
12 . The bi-facial solar cell of claim 11 , wherein the substrate comprises iron-depleted lunar regolith.
13 . The bi-facial solar cell of claim 12 , wherein the iron-depleted lunar regolith comprises an electrolyte of a molten electrolysis process.
14 . The bi-facial solar cell of claim 11 , further comprising:
boron silicate glass on the p-type regions in each of the first and the second silicon sheets; and
phosphor silicate glass on the n-type regions in each of the first and the second silicon sheets.
15 . The bi-facial solar cell of claim 11 , wherein the electrical contacts on each of the p-type regions and the n-type regions comprise both busbars and fingers.
16 . The bi-facial solar cell of claim 11 , wherein the electrical contacts on the p-type regions and the n-type regions that are in each of the first and the second silicon sheets comprise both a positive junction and a negative junction for an external circuit.
17 . The bi-facial solar cell of claim 11 , wherein the melting temperature of the substrate is greater than the melting temperature of silicon.
18 . The bi-facial solar cell of claim 11 , further comprising p-n junctions between the p-type and the n-type regions, wherein top surfaces of the p-n junctions and the p-type and the n-type regions are configured to be exposed to the sun.
19 . The bi-facial solar cell of claim 11 , wherein the first and the second silicon sheets are each crystalline.
20 . The bi-facial solar cell of claim 11 , wherein the substrate is configured to support the bi-facial solar cell on the lunar surface.
21 . A bi-facial solar cell comprising:
a substrate having a first surface and a second surface opposite the first surface;
a first silicon sheet on the first surface and a second silicon sheet on the second surface, each silicon sheet comprising a crystalline or polycrystalline silicon layer;
in each of the first and second silicon sheets, alternating p-type and n-type regions arranged laterally with respect to one another to define surface p-n junctions positioned at or near an outer surface of the corresponding silicon sheet;
dopant-containing layers disposed on the p-type and n-type regions to establish the surface p-n junctions; and
electrical contacts coupled to the p-type and n-type regions of each silicon sheet, the electrical contacts of each silicon sheet being interconnected to form respective positive and negative terminals that are independently accessible from opposite sides of the substrate.
22 . The bi-facial solar cell of claim 21 , wherein the dopant-containing layers comprise boron silicate glass on the p-type regions and phosphor silicate glass on the n-type regions.
23 . The bi-facial solar cell of claim 21 , wherein each of the first and second silicon sheets has a thickness between 10 μm and 200 μm, and the substrate has a thickness between 2 mm and 10 mm.
24 . The bi-facial solar cell of claim 21 , wherein the substrate comprises iron-depleted lunar regolith or an electrolyte of a molten electrolysis process.
25 . The bi-facial solar cell of claim 21 , further comprising an interfacial buffer layer between the substrate and each of the first and second silicon sheets, the buffer layer comprising silicon nitride (SiN), silicon carbide (SiC), or boron nitride (BN).
26 . The bi-facial solar cell of claim 21 , further comprising coverglass disposed over outward-facing surfaces of the first and second silicon sheets, the coverglass comprising a transparent silicate derived from lunar in-situ resources.
27 . The bi-facial solar cell of claim 21 , wherein the p-type and n-type regions in each silicon sheet form laterally alternating stripes extending across the sheet, and top surfaces of the p-n junctions are substantially coplanar with outer surfaces of the silicon sheets.
28 . The bi-facial solar cell of claim 21 , wherein the electrical contacts on each silicon sheet comprise a grid of busbars and fingers configured to reduce optical shadowing of the silicon sheet.
29 . The bi-facial solar cell of claim 21 , wherein the substrate includes a portion extending beyond the perimeters of the first and second silicon sheets to provide a mechanical support or mounting interface for the solar cell.
30 . The bi-facial solar cell of claim 21 , wherein each of the first and second silicon sheets comprises n-type silicon, and the n-type regions are more heavily doped than a background doping concentration of the corresponding silicon sheet.