May 7, 2021, C. Stubbs
Notes on making electrical connection to solar cells.
We have found that directly soldering to C60 solar cell tabs reduces the shunt resistance, presumably due to migration of impurities or dopants in the material. We're therefore experimenting with various conductive epoxies.
Some of these require curing at temperatures above room temperature. For the copper bars with three pads, when glued onto the cell, when placed in an oven at 70C for 30 minutes, we found that the differential thermal expansion cracked the cell.
There are two ways around this 1) room temperature (or much lower temperature) curing epoxy, 2) only connect to a single bond pad per side on the C60 cell, rather than all 3. An added complication is when to solder the cable onto the pads. Ideal for this is to do so beforehand, but that puts a strain on the parts when being glued.
Here are some of the epoxies we have on hand:
Specialty Adhesives Catalogue Web.pdf