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electrical:solar:gentle_complexity [2017/11/09 10:32]
frater_secessus
electrical:solar:gentle_complexity [2017/11/09 16:11]
frater_secessus [Gentle introduction, Pt 2]
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 This is a collection of illustrations that things are more complex than can be revealed in [[electrical:​solar:​gentle_intro|a one-page intro]]. ​ Again, drill down for more info. This is a collection of illustrations that things are more complex than can be revealed in [[electrical:​solar:​gentle_intro|a one-page intro]]. ​ Again, drill down for more info.
  
 +-----
  
 **Solar panel output will almost never be as high as the claimed output.** ​ In fact it will probably hover around 75% of that number under the best conditions; ​ this is called "​[[electrical:​solar:​output#​panel_temperature|derating]]",​ or correcting output to actual conditions. ​ It sounds like fraud but it's not.  A panel'​s power is expressed as a "​nominal"​ rating like 100W as when tested under //​laboratory//​ conditions. ​ Since the roof of your van is unlikely to meet those same lab conditions, if you think you need 200W of panel you probably need 250W. **Solar panel output will almost never be as high as the claimed output.** ​ In fact it will probably hover around 75% of that number under the best conditions; ​ this is called "​[[electrical:​solar:​output#​panel_temperature|derating]]",​ or correcting output to actual conditions. ​ It sounds like fraud but it's not.  A panel'​s power is expressed as a "​nominal"​ rating like 100W as when tested under //​laboratory//​ conditions. ​ Since the roof of your van is unlikely to meet those same lab conditions, if you think you need 200W of panel you probably need 250W.
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 **[[http://​rvwiki.mousetrap.net/​doku.php?​id=electrical:​12v:​deep_cycle_battery#​agm|AGM]] lead-acid batteries are not well suited to solar-only charging**. ​ They cost about 2x that of FLA, have less capacity, require vigourous charging and cannot be charged as high in voltage. ​ They remain popular because people think "$$$ is better"​ and are loathe to vent their banks. **[[http://​rvwiki.mousetrap.net/​doku.php?​id=electrical:​12v:​deep_cycle_battery#​agm|AGM]] lead-acid batteries are not well suited to solar-only charging**. ​ They cost about 2x that of FLA, have less capacity, require vigourous charging and cannot be charged as high in voltage. ​ They remain popular because people think "$$$ is better"​ and are loathe to vent their banks.
  
 +It is possible (though uncommon) to have **one all-purpose battery for both house and starting**. ​ This only works when [[electrical:​solar:​sizing#​your_daily_power_needs|daily power requirements]] are quite low((40-50Ah/​day)) or when [[electrical:​solar:​nonessential|opportunity loads]] are agressively utilized. ​ There are two approaches to such a setup: 
 +  - the premium battery deep-cycling approach as used by Sternwake((http://​www.cheaprvliving.com/​forums/​Thread-Has-anyone-heard-of-Northstar-AGM-batteries?​pid=135811#​pid135811)) ((http://​www.cheaprvliving.com/​forums/​Thread-SternWake-and-other-expert-advice-needed-on-electrical-hookup?​pid=94943#​pid94943)) This requires attention and knowledge. 
 +  - the "make do" [[electrical:​solar:​shallow_cycling|shallow-cycling]] approach. ​ This is more suitable for car dwellers and folks on limited resources.
  
  
electrical/solar/gentle_complexity.txt · Last modified: 2017/11/09 16:11 by frater_secessus