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0 pointsbglusman3y ago0 comments

The book Critical Mass by Daniel Suarez is my only source, but, the efficiency of rectenna is discussed there, and particularly, though the efficiency of the transmission is somewhat low, the efficiency of solar panels in space is MUCH higher than on earth, and they can operate 24/7, so the overall system efficiency is still substantially higher than the equivalent solar panels on earth... at least, assuming you can build the solar panels in space from mined material as they do in the book, I imagine if you needed to launch all the material from earth, it would probably be a fairly different story, assuming you included that in the calculations.

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giantrobot3y ago· 3 in thread

> the efficiency of solar panels in space is MUCH higher than on earth

Not really. The biggest difference between a panel on Earth and one in space is the space panel is illuminated 23 hours a day. So per panel you're getting 2-3x the illumination over the course of the day.

The drawback is even at the absolute cheapest pie in the sky Musk estimates of cost to orbit ($10/kg), a space solar panel is orders of magnitude more expensive than a ground panel. You could just deploy 3x the number of panels on Earth for 3x the price vs deploying in space at x\^3 the price.

Even with the near constant illumination of panels in space the losses from RF conversion, free space losses, atmospheric losses, and RF rectification eliminate a lot of your power gains. For those losses you also incur significant costs. So SBS is kind of a lose-lose problem. Every technology that would make SBS more practical could be applied on the ground for a tiny fraction of the cost.

dabluecaboose3y ago

>The biggest difference between a panel on Earth and one in space is the space panel is illuminated 23 hours a day

Small nitpick, but as a GEO satellite navigator I want to point out that the solar panels are in sunlight constantly except for "eclipse season" around the equinoxes. During eclipse season it can be in shadow for about an hour.

giantrobot3y ago

Thanks for the correction. So 23.76 hours a day (averaged over a year).

LargoLasskhyfv3y ago

Only if ignoring all externalities. If the panels could be manufactured in space, or on the moon, via some ultrasmall in-situ-utilizer bootstrap gizmothingy, which would then use material from the moon, or asteroids, we'd save much mining and manufacturing here on earth. Which has its own costs. As we all should know, meanwhile?

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