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Photovoltaics: Difference between revisions
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''If done right,'' this could be a main [[energy]] source for the world. | ''If done right,'' this could be a main [[energy]] source for the world. | ||
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== | {{considerations}} __NOTOC__ | ||
{ | ==Intermittency== | ||
{{sum|Needs [[energy storage]]}} | |||
|Needs [[energy storage]] | |||
The sun only shines during the day. Solar electricity{{x|if used as a main energy source}}would need ''at least'' enough [[energy storage]] to cover a full 24-hour cycle - or maybe a bit more. | The sun only shines during the day. Solar electricity{{x|if used as a main energy source}}would need ''at least'' enough [[energy storage]] to cover a full 24-hour cycle - or maybe a bit more. | ||
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Energy storage is an [[The great battery challenge|ongoing challenge]]. Best candidates for solar might be [[iron-redox flow batteries]] or [[sodium-sulfur batteries]]. | Energy storage is an [[The great battery challenge|ongoing challenge]]. Best candidates for solar might be [[iron-redox flow batteries]] or [[sodium-sulfur batteries]]. | ||
==Rare 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 rare minerals. There's simply no way they could be scaled up enough to replace fossil fuels. <br />{{more|Solar panel minerals}} | ''Thin-film photovoltaics'' are the most common types of solar panels used today. They are relatively efficient, but '''depend heavily''' on rare 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}} | '''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}} | ||
==Need for land== | |||
{{sum|Usually ''not'' a problem}} | |||
[[Solar rooftops]] have enough surface area to power most of the world. Very dense cities are an exception, if they aren't surrounded by enough suburbs. Houses, if the rooftop is fully covered in solar panels, can generally produce ''surplus'' power which could power inner cities. <br />{{more|Rooftop solar}} | [[Solar rooftops]] have enough surface area to power most of the world. Very dense cities are an exception, if they aren't surrounded by enough suburbs. Houses, if the rooftop is fully covered in solar panels, can generally produce ''surplus'' power which could power inner cities. <br />{{more|Rooftop solar}} | ||
[[Solar farms]] would be needed in cases where solar rooftops aren't enough. Some amount of [[land]] would be needed{{qn}}, but far less than what is used for agriculture. Solar panels | [[Solar farms]] would be needed in cases where solar rooftops aren't enough. Some amount of [[land]] would be needed{{qn}}, but far less than what is used for agriculture. Solar panels should best be placed in areas with no fertile soil. They don't play well with agriculture, because (unlike [[wind]] power) solar panels block the sun that plants need to grow. Sure there are some crops that like the shade, but they could have just as well been grown in the shade of full-sun crops. See: [[polyculture]]. | ||
==Energy in production== | |||
{{sum|Fair / maybe needs improvement}} | |||
[[Energy return on investment]]: about 7.5. | [[Energy return on investment]]: about 7.5. | ||
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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]]. | 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]]. | ||
==See also== | |||
* [[Concentrator photovoltaics]] | |||
* [[Energy]] | |||