View source for Archive:000/Draft:Solar panels

[[Category:Energy sources]]
{{considerations}}

==Scarce minerals==
{{sum|Major problem}}
The most commonly used types of solar panels contain a variety of metals too scarce to scale up (if the goal is to replace all [[fossil fuels]]).
See page on [[solar panel minerals]] for more details. See [[solar mineral challenge]] for requirements & research on less mineral-intensive solar panels.

==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==
{{sum|Needs [[energy storage]]}}
{{empty}}

==Land usage==
{{sum|Reasonable}}
{{dp
|built_up_land
|1500000 km^2
|Urban land, suburbs, industrial areas - global total
|This is home to the vast majority of people on Earth.
<br />Does not include most farm land.<br />
<br />https://ourworldindata.org/land-use
}}
{{dp
|rooftops_area
|(1/4) built_up_land
|Surface area of all rooftops in the world
|Quick estimate based on the assumption that about a quarter of all "urban and build-up land" consists of rooftops or something else suitable for solar panels.
}}
{{dp
|<nowiki>solar_panel.efficiency</nowiki>
|<nowiki>17%</nowiki>
|<nowiki>Efficiency of an average solar panel</nowiki>
|<nowiki>Some solar panels are more efficient than this, but they tend to be expensive and contain more rare metals.</nowiki>
}}
{{dp
|<nowiki>sunlight_average</nowiki>
|<nowiki>200 watts per m^2</nowiki>
|<nowiki>Solar irradiance, averaged over a whole year INCLUDING nights, cloudy days, etc.</nowiki>
|<nowiki>Note: This varies by region.</nowiki><br /><nowiki>
https://www.newport.com/t/introduction-to-solar-radiation</nowiki><br /><nowiki>
http://www.ftexploring.com/solar-energy/insolation.htm</nowiki>
}}
{{dp
|<nowiki>energy.tfc</nowiki>
|<nowiki>9937.70 Mtoe/year</nowiki>
|<nowiki>Global energy usage - total final consumption (TFC)</nowiki>
|<nowiki>Includes: fuel (80.7%) + electricity (19.3%) AFTER it is generated.</nowiki><br /><nowiki>
</nowiki><br /><nowiki>
Does not include the fuel used in generating electricity. See [energy.tes] for that.</nowiki><br /><nowiki>
</nowiki><br /><nowiki>
Citation: "Key World Energy Statistics 2020" IEA</nowiki><br /><nowiki>
- Page 47 - Simplified energy balance table - World energy balance, 2018</nowiki>
}}
<!--

-->
In the simplest average case, [[solar rooftops]] are all that would be needed.

<center><tab name="quick maths">
{{calc
|rooftops_area * solar_panel.efficiency * sunlight_average
|% energy.tfc
|||If all rooftops in the world were covered with solar panels, the energy produced is just about equal to today's global energy demand.
}}
</tab></center>

But of course life is more complicated:
* '''Geography:''' Some regions may need more energy than the ''local'' rooftops can provide, while other regions may be the opposite. Power lines can only reach so far.<small>
** Countries with extreme temperatures need more energy for [[heating and cooling]].
** Local ''industry'' is a major part of energy demand, but it doesn't correlate neatly with local rooftop area.
** Very high-density cities may not have enough rooftop space per capita. Sides of buildings have limited sun when they're obscured by other buildings.</small>
* '''Inequality:''' Most of the world today is in poverty. If every nation was ''developed'', the demand for energy would be a lot higher than the status quo used in the calculation above.
* '''Lower efficiency:''' Since conventional solar panels are too mineral-intensive to scale up, we need some alternative which will probably be less efficient at converting sunlight into electricity.

There is at least one factor that makes this easier:
* [[Electric vehicles]] are more energy-efficient than gasoline or diesel vehicles.

In general, [[rooftop solar]] can almost always provide enough ''electricity'' for a home (and even charge an [[EV]] in many cases), but not always enough for [[heating]]. Burning [[hydrogen gas]] (generated from [[wind]] power) could probably make up the difference in most cases.

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.

<!-- TODO: talk about [[solar farms]], how much land might be needed and how it would interfere with farming or wildlife. -->

==See also==
* [[Solar thermal panels]]
* [[Concentrated solar thermal]]
* [[Concentrator photovoltaics]]