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this post was submitted on 09 Apr 2024
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Science Memes
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That's why Photovoltaic Cells got the Nobel Prize, imo. The only new way to generate electricity actually put to use AFAIK.
Of course it's completely inefficient at large scale and they just revert back to mirroring light into a collection tower where steam happens.
Wasn't the main appeal of the mirror installations that you can store the heat somewhat efficiently? Rooftop solar is cost effective even here in Germany, where darkness and shadows loom around every corner.
The nonchalant poetry of your reply made me look up and appreciate your username.
These numbers change every year, but: solar panels on roofs don't track so they'd be lucky to get 20%, average closer to 12%, efficiency and slowly degrade over a few years. Sun tracking panels can reach a maximum of around 40%, theoretically, but on average more like 20%-30%. You have to subtract the negative impact of creating and assembling the materials from it's lifetime effectiveness, in Germany I believe Hydrogen Steel exists which is much greener than other types of smelting, or otherwise Aluminum is the higher grade material used for such things, and Photovoltaic Panels have a very specialized Glass in most cases that has to be exceptionally clear and strong. If the capacitance of the system is not enough to hold the produced power then an electrical failure will occur, so you must also include large commercial and industrial batteries.
Meanwhile, a Heliostat (a Collection Tower and Mirror Array) out in the desert has a theoretical efficiency just below 70%. Furthermore, if the capacity of the grid fills up then the array can be disable by adjusting the mirrors and excess power can be stored for extremely long periods of time by utilizing molten salt beneath the tower.
These efficiency numbers refer to how much of the heat energy from full spectrum light hitting the array is converted into electricity. Home panels are nice because you can put them on your home
Yeah, but PV is dirt cheap nowadays. Also
If by "few" you mean like 30-50 then sure, they degrade. But it certainly beats anything with a spinning turbine. Or anything with moving parts really. PV is purely solid state physics, you can't get more longevity than that.
That's not true. You can also simply turn PV off. The inverters only run when they sense 50 Hz on their output terminals, it's easy to have them turn off when it's 50.2 instead. Basically all big powerplants follow that rule already, ordered by things like shutoff time etc.
Funny that you specified in the desert. The appeal of PV is not only that it's cheap and easy, it also scales down to small investments and local power generation. If base load actually becomes a problem concentrated solar power will be relevant. But for now, slapping a few solar panels on your roof just makes sense.
lmao your consumer grade photovoltaic panels will not last 50 years.
The solar panels I just bought have a manufacturer warranty for 87% power output after 30 years.
That's much more realistic, I like that.
My dad is still using the first 60w panel he bought in 1986, for 600$. Obvs added many more to his system, and who knows how efficient it is, but it does work, haven't put a ampmeter on it though.
Mind you it was made in the USA, probably better materials than nowadays.
The mass market has really pushed solar panel production. I expect the material quality even of the cheap china panels to be better than what anyone was able to produce almost 40 years ago. That's a long time to understand degradation processes and develop countermeasures.
it's both, but i'm not sure if these large solar concentrators (ivanpah or these things in spain) are more efficient than current pv panels
I mean, if they're dramatically cheaper, they don't have to be efficient.
That being said, solar cells get around 20% efficiency, steam generators maybe 50% on a good day, subtract the reflection, collection and storage inefficiencies and you might get roughly in the same ballpark as solar cells.
Non-tracking solar panels are closer to 12% actual efficiency, 20% would be a theoretical efficiency. I only mention this because you used an actual efficiency estimate for the steam generator but not the solar panel.
That's because I'm so smart I completely ignored that the sun moves around during the day.
There’s also wind. But that just skips the steam
There is an argument to be made that the wind power is technically steam power, given the moist gaseous fluid turning a turbine, but that's silly.
Right. We all know it's generated by trees. It's why cutting trees down is so bad for the environment, it stops the wind and everything gets more hot. Leading to global warming.
I am now picturing a line of trees rocking back and forth to generate air and wind for us.
Buy it's all better than the old smoky steam we used to use
Cost per MWh is what tends to matter more than efficiency. Photovoltaics have become dirt cheap. Mirror collection systems haven't been able to keep up, and the projects for them are basically defunct at this point.
Was worth trying, though. It wasn't obvious that photovoltaics would get so damn cheap 10 or 20 years ago.
great for satellites tho
Is it that they're inefficient or harder to maintain?
Yes. Heliostat's max efficiency estimates are like 70%, sun tracking panels 40%, static panels 20%.
20% for static panels is fine though because they are spamable. They are cheap and you can just put them on roofs and parking lots.
Nobody was arguing anything otherwise, I was just answering questions about why we swap back to steam power for largescale. If you're powering some LEDs and a Toaster then yeah it's fine, if you're powering 10,000 then heliostat time.