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Reverse solar panels generate electricity at night by taking advantage of the temperature difference between the ground, through reflecting solar radiation back into space, and the night sky. Right now the technology isn't going to be good enough but can it be in the foreseeable future?
And it says "We experimentally demonstrate electric power generation from the coldness of the universe directly, using the negative illumination effect when an infrared semiconductor diode faces the sky. Our theoretical model, accounting for the experimental results..."
So really it's a much ado about nothing. This is not a new concept, there have been practical applications of extracting energy from the difference in temperatures between a medium (for example, sea water at the surface and sea water at colder greater depths) for decades. As far as I can tell this article is just saying that "we can also do it with these other materials".
Almost two decades ago there was quite a bit of research into INFRARED solar panels.
I was really interested since I could use my wood stove to generate electricity at night for my off grid home.
Like a lot of the solar research that went nowhere.
Look, solar panels were invented in 1939...and during the 60's and 70's had incredible amounts of research due to the space program.
Solar might be at a technological dead end. The $600 solar panel I bought in 1997 now costs $100. BUT it is still the same solar panel....after over 20 years of intensive research.
Solar might be at a technological dead end. The $600 solar panel I bought in 1997 now costs $100. BUT it is still the same solar panel....after over 20 years of intensive research.
Probably not true, unless you now are buying at the absolute bottom.
Some improvements include:
PERC -- internally reflective = higher power production.
Half-Cells -- sounds simple, but fairly clever. Cut the cell(s) in half, wire in parallel, and it cuts the internal resistance in half.
Overall -- a typical 1997 panel may be around 200 Watts. Presently 400 Watts is not uncommon.
Probably not true, unless you now are buying at the absolute bottom.
Some improvements include:
PERC -- internally reflective = higher power production.
Half-Cells -- sounds simple, but fairly clever. Cut the cell(s) in half, wire in parallel, and it cuts the internal resistance in half.
Overall -- a typical 1997 panel may be around 200 Watts. Presently 400 Watts is not uncommon.
509's statement is based on the fact that early solar cells were 10% efficient at converting sunlight to electricity, while modern cells are still only 20% or so efficient. Enthusiasts say that's a 100% improvement; detractors say it's only a 10% improvement. (compare that to 30% efficiency of green plants converting sunlight to chemical potential energy.) edited to add here: you could grow a forest on, say, one acre, providing forest habitat, then harvest the wood and burn it for power (subtracting from the efficiency) while the acre then undergoes ecological succession while the forest re-grows...Or-- you could deforest that one acre and put up solar panels....Which solution is better for the environment?
A problem with power generation based on infrared is that longer wavelengths carry less energy. OTOH, infrared is being radiated 24/7 as opposed to 5 hrs of good sunlight each day.
Maxwell probably wasn't thinking about colored TV when he came up with his equations, and Wilbur & Orville didn't have jumbo jets in mind when they skimmed 3 ft above the beach at Kitty Hawk.
Even a journey of 1000 miles starts with a single step. (Hey-- that's good! someone should write that down.... What's that? Confucius who?)
Last edited by guidoLaMoto; 05-15-2020 at 09:40 PM..
Coal fired plants are about 40-45% efficient. Nuclear about 33%. Efficiency in solar cells only affects the area of the cells required for a given amount of power to be produced. That's rarely a major issue in home based systems.
509's statement is based on the fact that early solar cells were 10% efficient at converting sunlight to electricity, while modern cells are still only 20% or so efficient. Enthusiasts say that's a 100% improvement; detractors say it's only a 10% improvement. (compare that to 30% efficiency of green plants converting sunlight to chemical potential energy.) edited to add here: you could grow a forest on, say, one acre, providing forest habitat, then harvest the wood and burn it for power (subtracting from the efficiency) while the acre then undergoes ecological succession while the forest re-grows...Or-- you could deforest that one acre and put up solar panels....Which solution is better for the environment?
DC makes a good point regarding that "efficiency" is rarely even an issue, let alone a make-believe issue in Solar anymore -- that sort of dropped to irrelevance about 10 years ago or more.
What we now look for is:
1. Effectiveness (as in "Does this work?") and
2. Economics (is this within the budget?).
That is about it. Same as with Coal, Gas, Nukes, on and on.
So at this point Solar has already taken the field, as it is the leading new build as a generation source.
As far as "acres of forest" . . . . Zero Required.
Solar works fine on existing "Man-made Impervious Surface." (fancy name for existing roofs, parking lots, etc.) -- and most such areas already have existing Grid-Tie points and Revenue Meters near by for minimal infrastructure requirements. Just using a fraction of existing Man-Made Impervious Surface -- meets the all the land-use requirements to take the whole US Solar -- including for taking all Ground Transportation Electric.
As far as "acres of forest" . . . . Zero Required.Solar works fine on existing "Man-made Impervious Surface." (fancy name for existing roofs, parking lots, etc.) -- and most such areas already have existing Grid-Tie points and Revenue Meters near by for minimal infrastructure requirements. Just using a fraction of existing Man-Made Impervious Surface -- meets the all the land-use requirements to take the whole US Solar -- including for taking all Ground Transportation Electric.
Govt stipends & billing regulations, and regulatory impediments to building conventional power generation plants make solar the leader in new installations. Let's not argue that now.
Show me your figures in calculating how existing roof surfaces would provide enough area to replace conventional power generation. (We won't even bring up back up requirements.) Does the roof area of The Empire State Building provide enough surface to provide solar power to the whole building?....If not, who supplies the extra surface needed?
Why do new, industrial installations cover so many acres of desert-- another valuable habitat-- instead of roofs?
You're right about the two main questions- effectiveness & cost. Alternatives aren't ready for prime time yet for all applications. Our highly industrialized society & consumer based economy is made possible by the availability of cheap, reliable power. When carbon-based power generation becomes very expensive due to depletion of supplies, alternatives will appear to have an advantage-- but they still won't be suppling cheap power, only cheaper power. Our life style will take a hit.
Govt stipends & billing regulations, and regulatory impediments to building conventional power generation plants make solar the leader in new installations. Let's not argue that now.
No argument, but your entire premise is now a decade out of date.
New Silicon Solar PV is now the Cheapest, Fastest, Cleanest, and Lowest Risk new build.
$1 per Watt installed and production cost at less than 2.5 Cents per kWh (including Profit, and Operations and Maintenance)
Nothing can compete with this.
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Show me your figures in calculating how existing roof surfaces would provide enough area to replace conventional power generation. (We won't even bring up back up requirements.) Does the roof area of The Empire State Building provide enough surface to provide solar power to the whole building?....If not, who supplies the extra surface needed?
The Math . . . .
Here are general US numbers:
Total Electricity Consumed (US Annual): 4E15 Watt-Hours.
Average US Solar Day (Single Site, non-Tracking) 6 Hours.
Average US Solar Year: 6 Hours X 365 Day = 2190 Hours.
4E15 Watt-Hours / 2190 Hours = 1.8E12 Watts.
Olde skool allowance (from the early 200x) was 250,000 watts per acre -- but improved panels are now closer to 400,000 watts per acre -- but let's go with old school to cover loses, conversions, etc.
1.8E12 Watts / 250,000 Watts per acre => 7.3E6 Acres
But as noted, this is based on older equipment. With newer equipment AND Adding in US Ground Transportation, it still only comes out about 100 X 100 Miles.
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The Practice . . . .
Let's be precise on the language and word choices? The term is Man-Made Impervious Surface -- not just "roof-tops." Very different things, and in terms of space utilization and install costs, often acres of Parking Lots are a better choice than a "roof-top" per se.
But you can background yourself on some of this with this link. Maybe compare the existing Square Miles available compared with those calculated above? >>>
Why do new, industrial installations cover so many acres of desert-- another valuable habitat-- instead of roofs?
Your observation is not so much about Solar, but rather the End-Game battles of the Central Plant Model v. Distributed Renewable Generation.
The Central Plant model (like your industrial example) use a Large Scale Capital "Central Plant" -- whether Nukes, Coal, Gas, or Solar -- to create Wholesale Electricity -- which is then transmitted, distributed and then revenues are created at a retail level through millions of individual meters. That billing then flows upward to support the Central Plant.
Distributed Renewable Generation stands the Capitalist Central Plant model on its head. The locally produced "behind the meter" Electricity is sent up to the local grid during production under-cutting the Central Plant. Even Central Plant Solar PV cannot compete with Distributed Silicon Solar PV in the long run. Presently Local Distributed Generation is still building and will be for years to come. As it reaches more local surplus levels -- it can be exported East-West across time-zones, and create longer-and-longer Solar Days.
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You're right about the two main questions- effectiveness & cost. Alternatives aren't ready for prime time yet for all applications. Our highly industrialized society & consumer based economy is made possible by the availability of cheap, reliable power. When carbon-based power generation becomes very expensive due to depletion of supplies, alternatives will appear to have an advantage-- but they still won't be suppling cheap power, only cheaper power. Our life style will take a hit.
No, you are out-date on this, as well. Oil and Gas are now both Cheap and Surplus -- but now Silicon Solar PV + Electric Transportation (most Oil goes to Transportation) are cheaper, yet.
The "hit" as you say will not be lifestyle -- but rather Economic -- because the Silicon Solar PV + Electric Transportation is so much cheaper than Oil + ICEs (Internal Combustion Engines) -- this can wipe out entire layers of GDP because (here comes the Efficiency part) -- Silicon Solar PV + Electric Motors are so much more efficient than Oil + ICEs. That is the big picture.
But towards Carbon use in Electricity Generation -- Coal is already dying on it's own and now Gas is being overtaken by Renewable Growth.
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