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Make sure electronics are podded potted or protected in a water resistant enclosure
Make everything assuming that things will be completely soaked
Get waterproof heat shrink
RTV PV-804 (have to use special acetate-free rtv)
Have a hole underneath driver so person is not sitting in a puddle haha
Front sheets could use fluorinated polymers
use deionised water and microfibre to clean and keep it cool
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Really great for troubleshooting
Feb 26
Question 7: Is Silicon still competitive when so many teams are using GaAs?
Depends on the rules
GaAs is thicker, SunPower has copper on the back and is a little more resistant
Looking at regs -
Smart diodes - TI smart diodes - Gochermann was laminating them into the arrays of other teams for bypass diodes
25mV drop - FETs and ideal diode controller in one package
What is your team good at - can tradeoff in other areas to make this better
2008, (2010), 2012 and 2013 went well
Wh per mile for each speed - see if other teams are willing to share info?
Single person 3-wheel cars is ~3/4 of power loss for
Berkeley is really nice
Stanford
Minnesota
Are all really nice to talk to
Question 8: Testing the array
Each module - do curve tracing - tilted towards the sun, preferably between 10 and 2.
Oregon they just couldn’t test the array
Good to have an irradiance meter - use a reference cell
Electoluminesce - 1200nm or 1170nm
Can’t see them with camera of FLIR IR camera either
Working on making one out of a Raspberry
Monosilicon cells will generally crack on
point crack will look like an X
Copper on back side - sunpower cells
Gray ish areas - voltage differences
RPi HQ Camera - EL with a raspberry pi
Remove the IR filter
Power supply into cell - + to +, - to -
Put approx Voc and 1/2 or 1 Isc into the array - votlage must be above the VoC
Current will affect the exposure time
Exactly what components to purchase in the presentation tomorrow
Add in a visible light filter
Just call FLIR for an IR camera - $200 for a FLIR One
FLIR module in a cell phone
Even a crappy one on hand is so much better
At Intel
Old Caterpillar cell phone had a FLIR camera
Turned it off immediately and fixed backwards component
Question 9: Copper on the back of SunPower cells
Interdigitated - one top of each other
Front contact cells- silver frit material
SEM images show that these are not crystalline metal - they crack super easily
Back contact - aluminum frit material
Silver FRIT - glass and silver mixed together
Copper on the Sunpower cells is a solid matter
A lot of metal compared to the rest of the industry
Copper instead of silver - can get away with it due to a complicated layering
In lines on the back side - PN junction
White backsheet - reflects stray light back
Question 10: Cell characteristics for reliability
Module design, not just electrical geometry
Front sheets - we don’t really need to worry
Are the solder joints good? Will they last through the race?
EL and IR works really well.
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You made an ideal design - now what’s going to happen in the real world - performance analysis and expected
Power trackers - buck is higher efficiency
GaAs - tiny bodies with too many different angles