"These solar cells are used in concentrator photovoltaics (CPV), a technology which achieves more than twice the efficiency of conventional PV power plants in sun-rich locations. The terrestrial use of so-called III-V multi-junction solar cells, which originally came from space technology, has prevailed to realize highest efficiencies for the conversion of sunlight to electricity. In this multi-junction solar cell, several cells made out of different III-V semiconductor materials are stacked on top of each other. The single subcells absorb different wavelength ranges of the solar spectrum."
If that isn't a reason to be investing in Space, I don't know what is.
"This world record increasing our efficiency level by more than 1 point in less than 4 months..."
I think we may start to see Moore's Law starting to be applied to Solar Cells. Which actually reminds of a chart on the waves of innovation[1] on the Stanford Tech Entrepreneurship course where we are now seeing the tail of IT and computing and beginning of renewable technologies. The same thing can be said about energy density of batteries(According to Tesla batteries).
> If that isn't a reason to be investing in Space, I don't know what is.
To justify government research, the results need to be compared to the alternative. Had NASA scientists not been working for the government, they would have been working for private companies engaged doing useful work. The Soviet Union had similar resources to the US, yet their research budget was spent wholly by government, whereas a large portion of the US research during that time was directed by private companies. If you want to restrict the comparison just to the US, ask yourself what would the massive wealth that was dedicated to NASA had produced had it been directed by private interests? What would NASA engineers have produced had they been employed by in Y-Combinator-style startups? (or even big private companies like Google, Apple, Facebook, Amazon, etc.)
1) It's not like the Soviet Union was a terrible hellhole for research. It had impressive research output for decades.
2) That's almost beside the point, however. Let's take it as a given that more good research, whatever that is, is a worthy goal for a society, and that the market under-invests in it in favor of short term profits. It's obviously not a binary of either 100% government funding or 100% private; it's not even really a one-dimensional continuum, because for the large capital expenditures typically involved in research, the government always has a heavy involvement, either in tax breaks or grants or collaboration. The question is, how do we allocate money to produce the best research? It's undoubtedly at some value that's somewhere between 0% and 100%.
3) There's a whole lot of money floating around now that makes endeavors like SpaceX practicable. That wasn't the case in, say, the Sixties. Even if the arguments for government spending on research were weak now, they'd be stronger in the 1960's, particularly for things like space exploration that required substantial concentrations of capital.
While you're considering alternatives, what would the massive wealth dedicated to the DOD have done in the hands of NASA and private non-military researchers?
The real reason is, all the solar cell numbers are fake. Its dark around here (and everywhere else) an average of 50% of the time. In space, its bright (brighter than on the ground) around 90% of the time.
Terrestrial solar cells MUST account for this when comparing efficiencies. So this new cell is 23% efficient, versus 46% if deployed orbitally, before accounting for the increased solar intensity in space.
Elon Musk is famously quoted as criticizing space-based solar plants because of the supposed inefficiencies in transmitting power to the ground. Somehow he missed this massive difference due to the unavoidable daily 'terrestrial eclipse' e.g. night. Also he failed to consider social/political costs (securing land rights near where the power is needed, the ecological impact of killing millions of acres of vegetation etc) but he's good at ignoring that it appears, recall the HyperLoop plan.
Exactly. So lets talk about a different, important number. Watts per dollar per day. The only one your accountant/investor cares about. Its something like double or triple for space-based solar cells, if you can deploy them efficiently.
Both are VERY debatable points. capital outlay in $56 million per launch for Falcon 9. Is that more or less than buying up hundreds of square miles of urban land? Deployment/construction is also different, and perhaps very much cheaper, under zero-gravity.
As for efficiency losses, I don't know what figures you used but its essentially the same problem to receive photons on the ground from a maser in space as the original task of converting sunlight in the first place. Efficiencies there are in fact very high (re: OP).
It's worse than that. There's no room for a single doubling of 44% efficiency. The theoretical maximum for multi-junction concentrator cells is about 86%:
Which of efficiency or price/watt matters more depends on the application.
For example, I believe something like 4 m^2, 40% efficient, 8 hours of charging is enough to get electricity to drive a Tesla something like 30-40 miles. (In practice, I assume you'd cover all of the outside of the car with 40% efficient solar panels to make this work (or maybe even 80% if you can figure out how to build them), and then 4 m^2 approximates the effective useful area after you take into account suboptimal sun angle, the side of the car facing away from the sun, etc.) The number of people whose commutes could be entirely covered by 40% efficient solar panels built into the car being used to recharge the battery is a lot more than the number of people whose commutes could be covered entirely by 12-15% efficient solar panels. Current mass produced technology doesn't make any variation on this cost effective today, but it seems clear that in the future, a 12% efficient panel array built into a Tesla is never going to be all that attractive for this application no matter how cheap it might become.
I suspect that high rise apartment buildings can cover a much larger percentage of their energy consumption from solar panels mounted on their sides and roof if those solar panels are 40-80% efficient instead of 12-15% efficient. If localized solar right next to the consumer of the power becomes cheaper than paying for electric grid transmission, this may become very relevant in 10 or 20 years.
Even for residential suburban solar installation, where finding adequate space for an adequate quantity 12% efficient solar panels is generally not a problem, the really important thing is not the price per watt of the panels themselves, but the price per watt of the system as a whole. The mechanical support of the panels is a part of the system cost, and the cost of that portion will shrink with more efficient solar panels, though of course there is an open question as to whether that will end up lowering the total system cost or not in the long run.
One way of counting efficiency is by looking at waste. In that view, a 44% efficient process becoming "twice as efficient" means that it's half as wasteful, not that it's 88% efficient.
In other words, a 44% efficient process which doubles in efficiency by this measure is now 72% efficient.
Considering that solar is essentially "free" after you buy the equipment, something like Moore's Law can be applied to the price of solar panels or their longevity. We got plenty of space in our roofs :-)
If that isn't a reason to be investing in Space, I don't know what is.
"This world record increasing our efficiency level by more than 1 point in less than 4 months..."
I think we may start to see Moore's Law starting to be applied to Solar Cells. Which actually reminds of a chart on the waves of innovation[1] on the Stanford Tech Entrepreneurship course where we are now seeing the tail of IT and computing and beginning of renewable technologies. The same thing can be said about energy density of batteries(According to Tesla batteries).
[1] Page 5 https://d2d6mu5qcvgbk5.cloudfront.net/documents/original/69b...