Solar Cells

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

C60ShuntResistances.pdf

Solar Cell dispositions

Measurements taken in December 2021

Note: for the above measurements, the third sheet has the list of labels corresponding to the good (high impedance) solar cells. 

All high impedance cells are gen 2. These cells were purchased from Sol Go, contact Kirsten Cabanas-Holmen.

Jan. 2022: Solar Cell # 18, a gen 2 solar cell (from page 2 of the Dec 2021 google sheet), with resistance of 1667 Ohms, was shipped to France. 

Solar Cell 18 characterization data:

The data for the QE curve of solar cell 18 can be found here: SC_QE_NewCell_20220401_LongQECurve-2.txt

The raw data used for the above analysis is here: SC_QE_NewCell_20220401.txt

March/April 2022: Solar Cell # 24, a gen 2 solar cell (from page 2 of the Dec 2021 google sheet), with resistance of 3500 Ohms, characterized. 

The angle dependence and temperature dependence measurements were taken and analyzed and can be seen here. The QE curve is here:

The data used for this QE curve can be found here: SC_Cell24_LongQE_20220406_Temp_Dependence.txt

The raw data used for the above analysis is here: SC_Cell24_LongQE_20220406.txt