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Photovoltaics: Difference between revisions
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Photovoltaics (PV) are any '''solar panels''' that produce electricity. | Photovoltaics (PV) are any '''solar panels''' that produce electricity. | ||
<!--: {{minor|''Not to be confused with [[solar thermal panels]] (non-electric) which just heat air or water in the sun.''}}--> | |||
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====Status quo==== | ====Status quo==== | ||
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{{considerations}} __NOTOC__ | {{considerations}} __NOTOC__ | ||
==Scarce metals== | |||
{{sum|Major problem}} | |||
''Thin-film photovoltaics'' are the most common types of solar panels used today. They are relatively efficient, but '''depend heavily''' on scarce minerals. There's simply no way they could be scaled up enough to replace fossil fuels. <br />{{more|Solar panel minerals}} | |||
'''Solution:''' Find some other photovoltaic tech based on more abundant minerals. Sacrificing some efficiency is okay, for the sake of making cheaper, more scalable solar panels. <br />{{more|solar/challenge 1}} | |||
==Recycling== | |||
{{sum|Possible problem}} | |||
Status quo: Most solar panels are not recycled. Existing recycling plants can't recover very much of the rare metals in the panels. {{en}} | |||
As mentioned in the section above, we'll need to use some alternative solar panel tech anyway (one that is less dependent on scarce minerals). Whichever tech we choose, there will still be ''some'' metals involved, so it's more important than ever to make sure it can be recycled in a way that recovers those metals. | |||
==Intermittency== | ==Intermittency== | ||
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''So if solar were to be '''scaled up enough''' to phase out fossil fuels,'' | ''So if solar were to be '''scaled up enough''' to phase out fossil fuels,'' | ||
* We'd need ''at least'' enough battery [[energy storage]] to cover a full 24-hour cycle - or maybe a bit more. | * We'd need ''at least'' enough '''battery''' [[energy storage]] to cover a full 24-hour cycle - or maybe a bit more. | ||
** Energy storage is an [[The great battery challenge|ongoing challenge]]. Best candidates for solar batteries might be... | |||
*** [[iron-redox flow batteries]] | |||
*** [[sodium-sulfur batteries]] | |||
*** [[sodium-ion batteries]] | |||
*** {{light|The above battery types are not on the market yet. Innovations are needed.}} | |||
* ''Some'' excess summer daytime energy may be worth storing by producing [[hydrogen gas]] (which could be burned in the winter for [[heating]]). | * ''Some'' excess summer daytime energy may be worth storing by producing [[hydrogen gas]] (which could be burned in the winter for [[heating]]). | ||
* To reduce the need for energy storage, it would help if people were to charge their [[electric vehicles]] mostly during the day, and if factories were to run only during the day (and maybe even temporarily shut down in the winter). <sup>[new economics needed]</sup> | |||
* To reduce the need for energy storage, it would help if people were to charge their [[electric vehicles]] mostly during the day, and if factories were to run only during the day (and maybe even temporarily shut down in the winter). | |||
==Energy in production== | |||
{{sum|Fair / needs improvement}} | |||
[[Energy return on investment]]: about 7.5. | |||
Solar panels are estimated to have an "energy payback" of about 4 years.{{cn}} In other words, for all the [[energy]] it takes to manufacture a solar panel, the solar panel will generate the same amount of energy after about 4 years of being installed. Since a solar panel is expected to last about 30 years, this comes out to an [[EROI]] ratio of 7.5. | |||
{{ | |||
4 years is a long time, which means that switching to solar might need a lot of fossil fuels to "get the ball rolling". A shorter energy payback time is a worthwhile goal, mentioned in: [[solar/challenge 1]]. This becomes even more important if there turns out to be a lot of energy losses in [[energy storage]]. | |||
==Land usage== | ==Land usage== | ||
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In the simplest average case, [[solar rooftops]] are all that would be needed. | In the simplest average case, [[solar rooftops]] are all that would be needed. | ||
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Compared to [[wind power]], solar is far less land-intensive {{x|about 50x less, based on the fact that the atmosphere converts about 2% of the sun's energy (that hits the Earth) into winds}} but far more invasive to the land it ''does'' use. | Compared to [[wind power]], solar is far less land-intensive {{x|about 50x less, based on the fact that the atmosphere converts about 2% of the sun's energy (that hits the Earth) into winds}} but far more invasive to the land it ''does'' use. | ||
==See also== | ==See also== | ||
* [[Solar thermal panels]] | * [[Solar thermal panels]] - {{light|Not electric, only for heating water & air.<!--[[hot water|water]] and [[heating|air]].-->}} | ||
* [[Concentrated solar thermal]] | * [[Concentrated solar thermal]] | ||
* [[Concentrator photovoltaics]] | * [[Concentrator photovoltaics]] | ||
* [[Energy]] | * [[Energy]] | ||
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