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opinion:solar:sizing [2023/10/22 11:08]
frater_secessus [solar panels] 		opinion:solar:sizing [2023/12/26 11:54]
frater_secessus [battery bank]
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       * if you have undersized solar       * if you have undersized solar
       * you have lead-chemistry battery bank       * you have lead-chemistry battery bank
 +      * if charging is time-limited and you want maximal harvest from the alternator, shore, or other high-current charging source.  **Example: ** If battery specs say you can constant-charge at [[electrical:12v:battery_capacity|0.2C]] (20A per 100Ah of capacity) then((all other things being equal)) a 100Ah bank could take 20A, 200Ah could take 40A, and 300Ah could take 60A.  
  
 You will need **somewhat less Ah capacity** You will need **somewhat less Ah capacity**
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 You will **need somewhat more solar** You will **need somewhat more solar**
  
-    * 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, Northern Europe, etc.
     * 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) or spend long periods [[camping:dispersed|boondocking]]     * if you live offgrid full time (FT) or spend long periods [[camping:dispersed|boondocking]]
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   * overall efficiency of the solar setup (we can ballpark 85% for MPPT setups, 70% for PWM)   * overall efficiency of the solar setup (we can ballpark 85% for MPPT setups, 70% for PWM)
   * [[electrical:solar:pvwatts|average insolation sun power available at the time/place]];  in the northern hemisphere full-timers base this on December since it's the lowest-yield month.  For part-timers, it will be the month of lowest insolation you will camp in.   * [[electrical:solar:pvwatts|average insolation sun power available at the time/place]];  in the northern hemisphere full-timers base this on December since it's the lowest-yield month.  For part-timers, it will be the month of lowest insolation you will camp in.
-  * minimum charging current requirements, if solar is the sole charging source (we can ballpark 0.2C for AGM and 0.1C for FLA)+  * the contribution of any other charging sources 
 +  * minimum charging current requirements, if any.   (we can ballpark 0.2C for AGM and 0.1C for FLA.  Lithium has no minimums)
  
 Let's assume a 200Ah AGM bank depleted to 50% SoC, wintering in [[camping:snowbirding:quartzsite|Quartzsite]] with an MPPT-based solar config and flat-mounted panels.   Let's assume a 200Ah AGM bank depleted to 50% SoC, wintering in [[camping:snowbirding:quartzsite|Quartzsite]] with an MPPT-based solar config and flat-mounted panels.  
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   - So we need **590W of panel** (1568.63Wh / 3.08 hours)   - So we need **590W of panel** (1568.63Wh / 3.08 hours)
  
-You may find it easier in the long-term to model this kind of thing in a spreadsheet.  +In practice you probably won't be drawing your bank to the lowest allowed level each day;  substitute your [[electrical:12v:dailypowerrequirements|actual daily power requirements]].  You may find it easier in the long-term to model this kind of thing in a spreadsheet. 
  
  
 +**Note**:  the numbers are for //average// yields, including average seasonal weather.  Individual days may be better or worse.  **If you have non-negotiable power requirements** you may want to oversize your array to account for days of locally-poor harvest. 
 ==== solar charge controller ==== ==== solar charge controller ====
  
opinion/solar/sizing.txt · Last modified: 2023/12/26 11:57 by frater_secessus

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