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electrical:solar:gentle_intro [2023/02/17 11:09]
frater_secessus crvl attribution 		electrical:solar:gentle_intro [2023/11/07 11:18]
frater_secessus
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 > "...trying to take the comfort level you had in a house into your mobile life [is] tough to do for a boondocker." -- akrvbob((http://www.cheaprvliving.com/forums/Thread-Too-much-or-too-little-Solar?pid=116253#pid116253)) (Bob from Cheap RV Living) > "...trying to take the comfort level you had in a house into your mobile life [is] tough to do for a boondocker." -- akrvbob((http://www.cheaprvliving.com/forums/Thread-Too-much-or-too-little-Solar?pid=116253#pid116253)) (Bob from Cheap RV Living)
  
- 
-> The fastest way to bring beginner expectations of solar in line with reality is to **assume you will run //nothing// off an inverter**.   -- secessus 
  
 > Setting up solar that //works// is easy.  Setting up solar that //works well// and //under challenging conditions// is much tougher.  -- secessus  > Setting up solar that //works// is easy.  Setting up solar that //works well// and //under challenging conditions// is much tougher.  -- secessus 
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 +===== TLDR =====
 +
 +  * Making //some// power from solar is easy. 
 +    * Making //sufficient power// from solar to cover your [[electrical:12v:dailypowerrequirements|daily power needs]] is much harder.
 +    * Making sufficient power from solar to cover your daily power needs //in all conditions, seasons, and locations// is so difficult and expensive that few attempt it;  instead we [[electrical:12v:alt_and_solar|augment solar with other forms of charging]].
 +  * panels rarely make their rated output under real conditions
 +  * your //location// will have a huge effect on solar harvest
 +  * shade on the panels will clobber output
 +  * panels still make some power under cloudy skies
 +
 +[[opinion:frater_secessus:pareto|about this summary]]
 ===== Benefits of solar ===== ===== Benefits of solar =====
  
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 Getting //some// power from solar is easy.  Getting //reliable// power from solar alone is challenging (and expensive) because solar harvest is greatly affected by [[electrical:solar:output|real-world conditions]]:  latitude, season, shade, temperature, even battery voltage.  It's bit harsh but you need to hear it early on:  //you won't be getting 100w out of a 100w panel//, and //you won't be getting it for 8 hours a day//.  Getting //some// power from solar is easy.  Getting //reliable// power from solar alone is challenging (and expensive) because solar harvest is greatly affected by [[electrical:solar:output|real-world conditions]]:  latitude, season, shade, temperature, even battery voltage.  It's bit harsh but you need to hear it early on:  //you won't be getting 100w out of a 100w panel//, and //you won't be getting it for 8 hours a day//. 
 A crude rule of thumb might be meaningful solar harvest is possible only when the sun is throwing well-defined shadows on the ground.  A crude rule of thumb might be meaningful solar harvest is possible only when the sun is throwing well-defined shadows on the ground. 
 +
 +Solar must not be shaded;  not by weeds on the the ground or by other objects on the roof.  The panel needs to be the tallest object in the general area.  
  
 [[electrical:12v:alternator|Alternator charging]] helps address these shortcomings of solar charging (and //vice versa//) so it is [[electrical:12v:alt_and_solar|a common combination]]. [[electrical:12v:alternator|Alternator charging]] helps address these shortcomings of solar charging (and //vice versa//) so it is [[electrical:12v:alt_and_solar|a common combination]].
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   * **best-effort** power -  you take what you can get from the sun and [[electrical:solar:rationing|minimize power consumption]] to make do.  No household appliances, at least not often.   * **best-effort** power -  you take what you can get from the sun and [[electrical:solar:rationing|minimize power consumption]] to make do.  No household appliances, at least not often.
-  * **reliable power** - you //need// power to keep insulin refrigerated, keep your external heart bypass machine running, etc.  Prepare yourself for added complexity and/or cost.+  * **reliable power** - you //need// power to keep insulin refrigerated, keep your external heart bypass machine running, etc.  Prepare yourself for added complexity and/or cost because now you have to worry about harvest under poor solar conditions. 
     * **massive solar** - You can still collect usable solar power under very poor conditions if you have [[electrical:solar:overpaneling|a huge amount of panel]].  This may require "maxxing out" your roofspace, tilting the panels, or deploying additional portable panels. Such configurations may be [[electrical:solar:builds#w6|1000w or more]].  One of the pleasant side effects of massive solar is that having //enough panel to meet needs in poor solar conditions// means //lots of bonus power in normal and good conditions//.  You may be able to run [[electrical:solar:nonessential|non-essential loads]] without affecting your battery bank's [[electrical:depth_of_discharge|state of charge]].     * **massive solar** - You can still collect usable solar power under very poor conditions if you have [[electrical:solar:overpaneling|a huge amount of panel]].  This may require "maxxing out" your roofspace, tilting the panels, or deploying additional portable panels. Such configurations may be [[electrical:solar:builds#w6|1000w or more]].  One of the pleasant side effects of massive solar is that having //enough panel to meet needs in poor solar conditions// means //lots of bonus power in normal and good conditions//.  You may be able to run [[electrical:solar:nonessential|non-essential loads]] without affecting your battery bank's [[electrical:depth_of_discharge|state of charge]].
     * **solar + other forms of charging** - Solar can work much better when augmented by [[electrical:12v:alt_and_solar|additional sources of charging]].  It can work so well that less solar might be required and overall cost reduced.     * **solar + other forms of charging** - Solar can work much better when augmented by [[electrical:12v:alt_and_solar|additional sources of charging]].  It can work so well that less solar might be required and overall cost reduced.
  
  
 +
 +===== What about portable panels? =====
 +
 +Pro
 +
 +  * can be set in sun while vehicle is in shade
 +  * can add more power when mounted panels are insufficient
 +  * can be tilted easily
 +
 +Con
 +
 +  * panels made to be portable tend to be expensive per-watt. 
 +  * **they have to be deployed in order to work**
 +
 +On the last point:  many people believe they will [[opinion:frater_secessus:beginner_mistakes#believing_they_will_set_out_portable_panels|set out their portables any time they are stopped]];  far fewer actually do it.  
 +
 +
 +===== What about flexible panels? =====
 +
 +Flex panels are very expensive by the watt.  They are a great fit for people who need to mount on a curved surface (boat hull, teardrop trailer, etc) or store/lift a portable.  
 +
 +Otherwise framed panels are the standard for many good reasons. 
 ===== How much solar do I need? ==== ===== How much solar do I need? ====
  
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 ==== Why daily? ==== ==== Why daily? ====
  
-Power requirements are calculated **daily** because the solar feeds the batteries((and [[electrical:12v:loads|loads]])) only in daylight.  Then at night the system pulls power back out of the batteries. This is natural rhythm of a solar-powered system. +Power requirements are calculated **daily** because the solar feeds the batteries((and [[electrical:12v:loads|loads]])) only in daylight.  Then at night the system pulls power back out of the batteries. This is natural rhythm of a solar-powered system and the reason why deep-cycle batteries are used. 
  
 A **minimal solar configuration** will  A **minimal solar configuration** will 
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 **Pro:** some of the product selection is outsourced for you **Pro:** some of the product selection is outsourced for you
  
-**Con:** likely could get better quality and better-matched components for less money with DIY.  Packages are often put together by marketing teams instead of engineering or support teams.  +**Con:** likely could get better quality and better-matched components for less money with DIY.  Packages are often put together by marketing teams instead of engineering or support teams and sometimes [[https://mouse.mousetrap.net/blog/2019/11/13/pwm-loves-poly/|the combinations don't work as well as they could]].
  
  
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 +===== rack mounting =====
 +
 +It is common to mount framed panels on a rack.  This accomplishes a few things:
 +
 +  * allows the panels to always be deployed 
 +  * where they won't fall over, walk off, or be urinated on by loose dogs
 +  * allows underside cooling to minimize [[electrical:solar:output#panel_temperature|heat-related losses]] and re-radiation from superheated panels into the van interior
 +  * to keep from drilling extra holes in the roof
 +  * allow changes later; drill new holes in the rack 
 +
 +Note:  avoid racks with "ladder retainers" or other vertical elements.  [[electrical:solar:output#shade|Partial shading]] is brutal on solar harvest, and //carrying around your own shade// is an "unforced error".  If you have inherited a rack with uprights consider cutting them off. 
 +
 +
 ===== Is my solar working? ===== ===== Is my solar working? =====
  
electrical/solar/gentle_intro.txt ยท Last modified: 2023/11/07 11:19 by frater_secessus

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