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electrical:solar [2017/10/02 17:45]
frater_secessus [Solar power] 		electrical:solar [2022/06/11 12:17] (current)
frater_secessus [Mounting the panels]
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 ====== Solar power ====== ====== Solar power ======
  
-Solar (photovoltaic or PV) power is an excellent fit for 'dwellers and especially for boondockers.  It is silent, nearly maintenance-free, and requires no infrastructure or [[electrical:shore_power|grid]].+[Note:  a [[electrical:solar:gentle intro|gentle introduction to solar]] is also available] 
 + 
 +Solar (photovoltaic or PV) power is an excellent fit for 'dwellers and especially for boondockers.  It is silent, nearly maintenance-free, and requires no infrastructure or [[electrical:shore_power|grid]].  Downsides include expense, bulky panels, and the requirement for access to direct/unshaded sunlight.
  
 Broadly speaking, **solar power systems consist of** [[electrical:solar:panels|panels]] to collect energy, [[electrical:12v:deep_cycle_battery|house batteries]] to store energy, and [[electrical:solar:charge_controller|charge controllers]] to regulate how those batteries get/stay charged. Broadly speaking, **solar power systems consist of** [[electrical:solar:panels|panels]] to collect energy, [[electrical:12v:deep_cycle_battery|house batteries]] to store energy, and [[electrical:solar:charge_controller|charge controllers]] to regulate how those batteries get/stay charged.
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 The most difficult part of a solar power system (other than [[electrical:solar:frugal|paying for it]]!) is [[electrical:solar:sizing|sizing it correctly]] for your needs.   The most difficult part of a solar power system (other than [[electrical:solar:frugal|paying for it]]!) is [[electrical:solar:sizing|sizing it correctly]] for your needs.  
  
-===== practical considerations =====+ 
 +===== Do you need solar? ===== 
 + 
 +Maybe not. If any of these conditions are met you probably don't need solar: 
 + 
 +  * you stay in campgrounds or other places with access to [[electrical:shore_power|shore power]] 
 +  * you have a [[electrical:12v:deep_cycle_battery#lithium_chemistries|lithium]] or [[electrical:12v:carbon foam|carbon foam]] batteries that do not require [[electrical:12v:charging|smart (multistage) charging]]((carbon foam does require smart charging, but only 1x/month or so)) 
 + 
 + 
 + 
 + 
 +===== Practical considerations =====
  
   * [[electrical:solar:panels|solar panels]] take a lot of room and must not be shaded.  Where will you put them?   * [[electrical:solar:panels|solar panels]] take a lot of room and must not be shaded.  Where will you put them?
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   * how will you ensure your batteries don't run your batteries too low and damage them?   * how will you ensure your batteries don't run your batteries too low and damage them?
  
-===== scheduling your use of solar power =====+===== Scheduling your use of solar power =====
  
 //When// you use power from your system can be as important as //how much// power you use. //When// you use power from your system can be as important as //how much// power you use.
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-===== things that affect solar power =====+===== Things that affect solar power =====
  
   * Insolation (Intensity of sunlight)    * Insolation (Intensity of sunlight) 
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-===== how much solar? =====+===== How much solar? =====
  
 Solar sizing has been moved to [[electrical:solar:sizing|its own page]]. Solar sizing has been moved to [[electrical:solar:sizing|its own page]].
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-===== weather-related issues =====+===== Weather-related issues =====
  
-==== cloudy weather ====+Weather and [[electrical:solar:shading|shading]] have serious effects on [[electrical:solar:output|solar output]]. 
 +==== Cloudy weather ====
  
 **Cloud cover** can have paradoxical effects: **Cloud cover** can have paradoxical effects:
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 Dusty or snowy weather can cause a loss of output due to physical presence on the panels.   Dusty or snowy weather can cause a loss of output due to physical presence on the panels.  
  
-==== temperature ====+==== Temperature ==== 
  
 Panels yield the most power in cold temperatures.  Since panels are dark and get very hot in the sun they are generally raised rather than directly mounted;  this allows air circulation/cooling underneath. Panels yield the most power in cold temperatures.  Since panels are dark and get very hot in the sun they are generally raised rather than directly mounted;  this allows air circulation/cooling underneath.
  
 +===== Mounting the panels =====
 +
 +[based on [[https://www.reddit.com/r/vandwellers/comments/ggxusl/solar_on_a_roof_rack_or_directly_on_the_roof/fq5yvel/|this reddit post]]]
 +
 +
 +There are a few issues to consider:
 +
 +  * solar cells get very hot in sunlight, typically 25deg C hotter than ambient temps. Rating lab tests are performed when the cells are 25deg C (0deg C ambient, freezing)
 +  * [[electrical:solar:output#panel_temperature|Panel output is reduced when the cells get hot]]
 +hot panels re-radiate heat onto the roof of the van. "On my white van (even with a 5" airgap) it is hotter in the 
 +shade under the panels than on the roof in direct sunlight." - secessus
 +  * we prefer fewer holes in the van roof when possible
 +  * "flex" panels cost ~2x as much as rigid panels and last for years rather than decades
 +  * airgapped panels will add height for drive-through adventures
 +  * taller racks will likely increase air drag and MPG, particularly if you drive fast
 +
 +**Mounting hard panels to a rack** increases airflow (thereby reducing heat-related power losses), reduces heat transfer, and minimizes the number of holes in the van roof.
 +
 +**Mounting hard panels directly to the roof** still allows some airgap (the depth of the frame) and the roof corrugations will allow some airflow in the direction of the "valleys". Taller Z-brackets may give a bit more airgap.
 +
 +**Mounting flex panels to the roof** allows some airflow in the corrugations but no airgap. Good news: panel derating won't be so bad because the heat is conducted to your van roof. Which is bad news if it's already hot in your van.
 +
 +**Portable panels** allow the vehicle to be in shade and panels in the sun.  Also can be tilted for maximal yield. 
  
 +Opinion:  [[opinion:frater_secessus:beginner_mistakes#buying_the_wrong_panel|Bonus rant]] on panel/controller selection.
electrical/solar.1506980738.txt.gz · Last modified: 2020/10/11 19:48 (external edit)

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