Yup. I'm surprised toyota has boogered this up. It's a common issue with all gen Prii that have the solar panel roof, with some starting to show discoloration in as little as a year from new.
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Oh geez I didn’t know that!
I’m surprised there’s no recall but there’s probably not enuff of them on the road?
That's mostly it. It's also not a safety critical thing.
doesn't seem to me like glass so thin that isn't highly engineered is gonna do well on such a thing as a car anyway. the harmonics and vibrations can get pretty hard core at times, and if they screwed up the dimensions of it, for sure there would be standing waves that warp the glass constantly when it's running and then it sits in the sun warming up, then at night cooling down, there's no way that you can engineer it to be stable cheaply, at least, not without making it ugly.
to do it right, you'd need to use quartz, i don't think even the best quality borosilicate is going to take the thermal changes and vibrations for very long.
It's not the glass, it's the sealing. Whatever they are using is not flexible enough to handle the exterme temperature expansion differential between glass and the steel of the vehicle.
that's what i'm saying about the type of glass. different types of glass have different expansion coefficients and the sealants also have various expansion properties, and if you don't use materials that can withstand the temperature differentials, the sealants harden or gape, then you will get breaches in the surface.
also, i think the yellowing is probably not so much the glass as the type of polymer and its interaction with water. many kinds of polymers yellow with age and exposure, and consider the guarantee periods they specify on these things. they probably engineered it really tight to those periods so once it fails, a sufficient percentage of the time they were out of warranty and "does washing hands gesture" not our problem anymore.
this kind of thing is really common, you see it with semiconductor devices as well. as soon as the warranty is out a remarkable number of the devices fail.