Flexible solar cell interconnection systems and methods
Disclosed is a highly automated method of interconnecting flexible solar cells to form solar modules having a wide variety of sizes and electrical characteristics. The method is fast and economical, providing many attributes of a “pseudo monolithic integration” scheme that has previously been attainable only on rigid substrates.
1. A method for making sheets of interconnected solar cells, comprising:
a) providing a plurality of continuous strips of solar cell material each comprising a flexible substrate, a conductive back contact region, a photoactive region, and a transparent conductive region;
b) adhering the continuous strips of solar cell material to a continuous backing sheet such that the flexible substrate contacts the backing sheet and a gap is formed between adjacent strips;
c) applying an insulating material over a predetermined region of the edge of each of the strips on each side of the gap, said insulating material contacting a region of the top surface of the strips of solar cell and at least a portion of the backing sheet on each side of the gap;
d) forming a plurality of bonding pads on one end of each of the strips disposed on one side of the gap by selectively removing a portion of the insulating material and the photoactive region to expose a portion of the back contact region;
e) providing at least one electrically conductive wire across the plurality of continuous strips of solar cell material such that the at least one electrically conductive wire is in electrical contact with the bonding pads of the plurality of strips of solar cell material and the transparent conductive region and;
f) cutting the at least one electrically conductive wire on one side of each of the bonding pads to form cut regions.
2. The method of claim 1 , further comprising a step of applying an insulating material to the bonding pads and cut regions after the step of cutting the wires.
3. The method of claim 1 , further comprising a step of curing the insulating material after it is applied to the strips.
4. The method of claim 1 , wherein the insulating material is a transparent insulating material.
5. The method of claim 1 , wherein the step of providing at least one electrically conductive wire comprises providing more than one electrically conductive wire further comprising cutting the sheets of interconnected solar cell material in regions between a portion of said electrically conductive wires to form solar cell strings of predetermined width.
6. The method of claim 1 , further comprising a step of attaching the at least one electrically conductive wire to terminal bars at each end of the sheets of interconnected solar cells for connecting to external circuitry.
7. The method of claim 1 , further comprising a step of providing a top transparent flexible sheet over the sheets of interconnected solar cells and laminating said top transparent flexible sheet.
8. The method of claim 1 , further comprising the step of slitting a relatively wide roll or long sheet of flexible solar cell material into the plurality of strips of solar cell material.
9. The method of claim 8 , further comprising a step of treating one or more of the edges of the plurality of strips of solar cell material after the slitting step to remove defects and debris.
10. The method of claim 8 , further comprising rolling the strips of solar cell material onto a reel following the slitting step.
11. The method of claim 1 , further comprising a step of testing the electrical properties along each of the continuous strips of solar cell material.
12. The method of claim 11 , wherein the continuous strips of solar cell material are categorized according to their electrical properties prior to the step of transferring continuous strips of solar cell material to a continuous backing sheet.
13. The method of claim 1 wherein the at least one electrically conductive wire has a diameter and the bonding pad has a size is from 2 to 10 times the diameter of the at least one electrically conductive wire.