Clear roofing garage

[joshua-rosen]

It’s called a greenhouse. Put up a greenhouse with a concrete floor and you have an Aptera friendly garage.

[Enceladus]

Yes, thank you for that. Will the glass/clear roof allow for the same solar recharge it would if the Aptera were parked outside? Or does the roofing diminish the amount of sun reaching the Aptera’s solar cells?

[ROMAD]

It would depend on how light transparent the glass was. The clearer the transparency, the more photons will pass through.

[alain-chuzel]

Under the best of conditions, very roughly, about 8% of the sunlight hitting common window glass is reflected away. That means, at best, Aptera’s solar panels can produce only 92% of what they would produce if the common window glass wasn’t there.

[dennis-green]

We should considered solar tubes. I don’t like the idea of parking the Altera outside.

From a Google Bard search: “Solatube is another leading manufacturer of sun tubes and are known for their energy efficiency. They use a patented optical system to direct sunlight into your home, even on cloudy days.”

• This reply was modified 3 weeks ago by  Dennis Green.

[Enceladus]

I don’t want to park my Aptera outside either if I can determine the most efficient material to admit sunlight. I had forgotten about Solartubes, and they’ve been around for a long time. Perhaps engineers have done studies about using them for recharging solar cells indoors?

[dennis-green]

Any tech heads out there want to compare specs? Would it be enough light to make a difference?

Solatube: https://solatube.com/technical-resources/architectural-specifications/

Natural Light Energy Systems:

https://nltubular.com/performance/output/

• This reply was modified 3 weeks ago by  Dennis Green.

[Enceladus]

Thanks for the links! This could be promising.

[alain-chuzel]

The “standard” level of irradiance for sunlight at sea level when impingent at 0 degree angle of incidence is 1000 watts per square meter. The largest “Natural Light Tubular Skylight” (21 inch (I assume that’s a diameter)) has an area of about 346 inches which equates to about 0.22 square meters. Aptera’s got about 3 square meters of solar panels so you’d need 3/.22 or 13 to of these skylights to equal the sun.

[Jeff]

“Would it be enough light to make a difference?”

No.

Looks like the biggest residential skylight on those sites has a 18” diameter tube. Even using optimal assumptions…

0.164 m^2 x 1000 W/m^2 light intensity x 22% solar cell efficiency x 90% charging efficiency = 32 watts.

And that’s a with a lot of unrealistically optimal assumptions thrown in (midday, no clouds, sun directly overhead, 100% of the light transmitted, 100% of the light hitting cells, etc.).

And now that I think of it, I wonder how the Aptera’s solar array will react to spotty shade / inconsistent light intensity across the body of the vehicle. If it acts like a regular solar panel where partial shade on even a small part of a single panel can dramatically reduce output, a bit of light focused on one part of the Aptera while the rest is in shade might not generate hardly any power at all.

[alain-chuzel]

And now that I think of it, I wonder how the Aptera’s solar array
will react to spotty shade / inconsistent light intensity across the
body of the vehicle. If it acts like a regular solar panel where partial
shade on even a small part of a single panel can dramatically reduce
output, a bit of light focused on one part of the Aptera while the rest
is in shade might not generate hardly any power at all.

Aptera’s individual panels (hood, dash, roof and hatch) will each likely have 1 or more MPPT controllers and some number of integral “bypass diodes” to mitigate “mismatch” caused by uneven illumination. This is a common design approach within the solar car racing community (I’m a charter member….).

[gary-greenway]

You’d be better off putting a few solar panels on the roof of the garage and charging that way.

[Enceladus]

Thank you, everyone, for your input. Since I plan to eventually put solar panels on another part of my roof anyway, putting a few more on the existing garage seems to make better sense than adding another garage with a transparent roof.