Hacker News Reader

Comment by FreeFull | Hacker News Reader

How quickly would a protective coating on the glass wear out? Or the green/brown colouring that gets added to beer bottle glass.

View on HN

Mineral coloration has literally a dozen different explanations. Most of them do not "wear out", but some of them change colors under irradiation.

Green glass is green because of iron (II) oxide (FeO), which is usually a naturally occurring contaminant of the sand used for glassmaking. Amber glass is amber because of FeS2. Neither change color under normal weathering conditions.

The duration of a protective coating depends on the coating, and its thickness. If you layer a glass pane under a synthetic sapphire pane, that would probably be better than a protective coating. The sapphire would protect the glass, and the glass would block UV-A.

How much would such a coating reduce the efficiency of the panel though? I’m seriously asking btw, I don’t know the answer or very much about PV panels.

That seems to be the fantastic part of this motor. Even if you traded off almost all efficiency in order for protectiveness of the material instead, this machine runs on such a low power you could make those trade offs. What you could use this motor for I am unsure.

The energy required is so small, I wonder if you could use a thermoelectric generator utilizing some tinfoil half in the sun and half in the shade. Maybe such a design could last longer than a solar panel based one.

Too cool. Hey, could these bearings be used in something like a water wheel or windmill? I realize the technology isn’t there yet, but if it could then really you’d could have lowered maintenance costs, slightly increased efficiency, and probably a lot less noise.

>technology isn't there yet

In what sense?

>lowered maintenance costs

Not really, actually - hydrodynamic bearings already work on the "zero wear due to zero surface contact" principle. The reason this is using magnetic bearings is just because it needs super-super low friction, under super-tiny loads, in order to work.

>Probably a lot less noise

Bearings aren't generally noisy. If they were, they wouldn't be very good bearings!

I stand massively corrected on all fronts, thanks!

Only about 5% of the Sun's energy, as filtered by Earth's atmosphere, is ultraviolet. You can block it all with negligible efficiency loss at your solar panel.

I'm not sure about UV filters that will be stable for 1000 years. Regular glass blocks most UV, but lets through about 25% of the frequencies close to blue.

For museum and artwork protection time frames acrylic is popular. It blocks almost all UV and is still stable after 25 years. I don't know how that extrapolates to 1000 years.

The glass isn't the thing that wears out, the PV cells are. And if you're keeping light from reaching those, then you're really defeating the purpose of the whole thing.

It's using so little power that this should not be a problem. In the accompanying video it is stated that

...the most surprising thing probably is that it was being powered off a small solar cell under this dark blue plastic box. Any more power than that and the motor would spin up, lose control and fly out of stability. , https://youtu.be/wNcgnooayDc?t=129

Reply on news.ycombinator.com