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--- projects:blinker:work_logs:8_solar_cells [2022/03/20 01:06] – tjhowse
+++ projects:blinker:work_logs:8_solar_cells [2022/04/17 23:35] – tjhowse
@@ Line 31: / Line 31: @@
 {{ youtube>46e-Z7-262s?large }}
-After I built the tool I trammed in my rubbish drill press as best I could and cut some test pieces. It was harder to control the amount of force required to score the glass to the correct depth. I hooked an ockky strap around the depth crank to provide a constant force. Some tension tuning was required to get it set correctly but it works consistently now.
+After I built the tool I trammed in my rubbish drill press as best I could and cut some test pieces of glass. It was harder to control the amount of force required to score the glass to the correct depth. I hooked an ockky strap around the depth crank to provide a constant force. Some tension tuning was required to get it set correctly but it works consistently now.
 ==== Failure ====
@@ Line 51: / Line 51: @@
 All of this testing was done on a single 125x125 solar cell. I have another nine of them to experiment with. I would like to see how these cells respond to a CO2 laser. I work with people who built solar racing cars, and so have experience with this kind of thing. We also have a water jet cutter at work, which might be worth a try.
-===== Video =====
+==== Unearned success ====
+I was at bunnings (a hardware store) for an unrelated reason and I saw some solar-powered garden lights with various configurations of solar cells. They were mostly under AUD$10 so I grabbed an 8-solar-cell LED light on a stake.
+==== Success again ====
+{{:projects:laser_cutter:pasted:20220331-000734.png}}
+Once I got my [[projects:laser_cutter:overview|laser cutter]] set up, things started to improve again. I collected all of the bigger bits of the failed previous attempts and shot lasers at them at varying intensities, movement speeds and number of passes. I settled on 2 passes at 70% power on my 80W CO2 laser tube moving at 50mm/s, lasering the backside of the cells. This caused the seam to bend upwards slightly providing a guide for the crack.
+{{:projects:blinker:work_logs:pasted:20220403-060140.png}}
+First attempt. Note the cut is approximately parallel to the fine white lines.
+{{:projects:blinker:work_logs:pasted:20220403-060227.png}}
+More success.
+{{:projects:blinker:work_logs:pasted:20220403-060040.png}}
+Repeatable results.
+{{:projects:blinker:work_logs:pasted:20220404-002747.png}}
+Soldered up one five-cell array.
+I used some fine copper wire to join the cells. I used leaded solder, a chisel tip, Chipquik SMD291 flux and 270ºC. I dipped the wire in the flux and laid it across the contact on the panel, wet the iron tip with a good amount of solder then swept across the copper while I held it in place. Once I got my technique sorted it was pretty straightforward.
+Holding this cell in diffuse sunlight gave 2.7V open circuit voltage.
+===== Videos =====
+Failure:
 {{ youtube>s49XNyZ3Eqo?large }}
+Success:
+{{ youtube>lZiL-H9wsoI?large }}
+{{ youtube>E3jePteZ7Yw?large }}
+{{ youtube>DGBrjxjcLxw?large }}
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