RV and vandwellers wiki

User Tools

Site Tools

Trace:
opinion:solar:sizing

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision 		Previous revision
opinion:solar:sizing [2022/05/24 15:16]
frater_secessus [solar panels] 		opinion:solar:sizing [2023/06/13 21:13] (current)
frater_secessus [solar charge controller] examples
Line 64: Line 64:
     * if you live in an area with relatively little sun, like the American Northwest.     * if you live in an area with relatively little sun, like the American Northwest.
     * if you want to run more [[electrical:12v:loads|loads]]     * if you want to run more [[electrical:12v:loads|loads]]
-    * if you live offgrid full time (FT) +    * if you live offgrid full time (FT) or spend long periods [[camping:dispersed|boondocking]] 
-    * to run things off [[electrical:inverter|inverter]] rather than 12v+    * to run things off [[electrical:inverter|inverter]] rather than 12v((due to inversion losses, typically at least 10%))
     * to charge a bigger [[electrical:12v:deep_cycle_battery|battery bank]]     * to charge a bigger [[electrical:12v:deep_cycle_battery|battery bank]]
-    * to charge lead-chemistries (FLA, AGM, Gel) rather than lithium+    * to charge lead-chemistry (FLA, AGM, Gel) banks
  
 You will **need somewhat less solar** You will **need somewhat less solar**
Line 73: Line 73:
     * if you live in an area with a great deal of sun, like the American Southwest.     * if you live in an area with a great deal of sun, like the American Southwest.
     * if you camp recreationally mainly in the summer when solar harvest is easier     * if you camp recreationally mainly in the summer when solar harvest is easier
-    * if you [[electrical:12v:alt_and_solar|augment solar]] with [[electrical:generator|generator]],  [[electrical:12v:alternator|isolator]], etc+    * if you [[electrical:12v:alt_and_solar|augment solar]] with [[electrical:generator|generator]],  [[electrical:12v:alternator|isolator]], [[electrical:converter|shore power]] etc
     * if you live in the vehicle part time (PT) and can charge consistently from [[electrical:converter|shore power]] when not camping.      * if you live in the vehicle part time (PT) and can charge consistently from [[electrical:converter|shore power]] when not camping. 
     * if you voluntarily reduce your power consumption     * if you voluntarily reduce your power consumption
     * if you time-shift loads to periods like the afternoon when [[electrical:solar:nonessential|excess power]] is available     * if you time-shift loads to periods like the afternoon when [[electrical:solar:nonessential|excess power]] is available
 +    * to charge lithium banks
  
 ==== solar charge controller ==== ==== solar charge controller ====
Line 104: Line 104:
 [[electrical:solar:charge_controller|Controllers]] are rated by the Amps they can pump out.  A 20A controller can handle up to 20 Amps (about 250w incoming power, depending on battery voltage).   [[electrical:solar:charge_controller|Controllers]] are rated by the Amps they can pump out.  A 20A controller can handle up to 20 Amps (about 250w incoming power, depending on battery voltage).  
  
-A common **rule of thumb for sizing PWM controllers** is to divide [[electrical:solar:panels|panel]] wattage by 10;  300w((rated power)) of panel on a 30A PWM controller. They are cheap enough that a little oversizing is not a big deal, and they need a bit of headroom since they do not throttle incoming current to protect themselves.((they do use PWM switching to throttle current to hold a given setpoint))  +A common **rule of thumb for sizing PWM controllers** is to divide [[electrical:solar:panels|panel]] wattage by 10;  300w((rated power)) of panel on a 30A PWM controller. They are cheap enough that a little oversizing is not a big deal, and they need a bit of headroom since they do not throttle incoming current to protect themselves.((they do use PWM switching to throttle current to hold a given setpoint))   See [[https://mouse.mousetrap.net/blog/2023-06-13-backchannel---comments-on-solar-advice.html#fn:amps|these examples]].
  
 MPPT sizing is less straightforward. These tend to cost 2-3x as much for a given rating as PWM, so oversizing can get $$$.  MPPT have the ability to [[electrical:solar:overpaneling#vs_charge_controller|clip power]] during unusually-high harvest to limit current to their rated capacity.  For this reason they are often **sized to the power the panels make under normal circumstances** rather than the panels' lab rated power.  MPPT sizing is less straightforward. These tend to cost 2-3x as much for a given rating as PWM, so oversizing can get $$$.  MPPT have the ability to [[electrical:solar:overpaneling#vs_charge_controller|clip power]] during unusually-high harvest to limit current to their rated capacity.  For this reason they are often **sized to the power the panels make under normal circumstances** rather than the panels' lab rated power. 
Line 113: Line 113:
   * 300w of panel might make 249w under good conditions.  25A controllers are rare, so they might be put on a 20A mppt controller   * 300w of panel might make 249w under good conditions.  25A controllers are rare, so they might be put on a 20A mppt controller
   * MPPT smaller than 10A are rare, so 100w-150w of panel are usually put on 10A mppt.   * MPPT smaller than 10A are rare, so 100w-150w of panel are usually put on 10A mppt.
 +  * [[https://mouse.mousetrap.net/blog/2023-06-13-backchannel---comments-on-solar-advice.html#sizing-an-mppt-controller|more examples with explanation]]
  
  
Line 232: Line 233:
   * disadvantages - in-place camping makes DC-DC charging less cost-effective.  Entire life must be powered, not just recreational loads while camping. [[electrical:solar:sizing#your_reserve_needs|Days of autonomy]] == forever.   * disadvantages - in-place camping makes DC-DC charging less cost-effective.  Entire life must be powered, not just recreational loads while camping. [[electrical:solar:sizing#your_reserve_needs|Days of autonomy]] == forever.
  
-This isn't a game or vacation anymore;  //this is your life//. You need power every day and under all conditions.  The most reliable way to do this is by [[electrical:solar:overpaneling|overpaneling]] (having massive solar to account for all weather conditions), although you could do it with smaller solar [[electrical:12v:alt_and_solar|combined with]] a [[electrical:generator|generator]]. +FT boondocking game or vacation anymore;  //this is your life//. You need power every day and under all conditions.  The most reliable way to do this is by [[electrical:solar:overpaneling|overpaneling]] (having massive solar to account for all weather conditions), although you could do it with smaller solar [[electrical:12v:alt_and_solar|combined with]] a [[electrical:generator|generator]]. 
  
 Battery banks tend to be either lithium or flooded 6v golf cart((CG2)) batteries in series, both of which have lifetime $/kAh costs under $2.   Battery banks tend to be either lithium or flooded 6v golf cart((CG2)) batteries in series, both of which have lifetime $/kAh costs under $2.  
opinion/solar/sizing.1653419796.txt.gz · Last modified: 2022/05/24 15:16 by frater_secessus

Page Tools

Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution-Noncommercial-Share Alike 4.0 International
CC Attribution-Noncommercial-Share Alike 4.0 International Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki