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--- opinion:solar:sizing [2022/05/08 11:13]
frater_secessus [solar panels]
+++ opinion:solar:sizing [2022/05/24 15:11]
frater_secessus [battery bank]
@@ Line 1: / Line 1: @@
 [[lifestyle:words_of_wisdom|Words of Wisdom]]:  "You have to build for winter, and figure out what to do with the extra electricity in summer." -- timselectric((https://diysolarforum.com/threads/less-than-perfect-off-grid-system.35869/post-450655))
-====== solar sizing - the Big Picture ======
+====== power system sizing - the Big Picture ======
 There are many [[electrical:solar:sizing#calculators|calculators where you can plug in the numbers]].  This page is a 35,000ft view of how choices affect what you will need.
+See [[opinion:solar:sizing.walkthrough|this article]] for a sample walkthrough of the numbers.
@@ Line 20: / Line 22: @@
-===== solar panels =====
+===== solar charging =====
+==== solar panels ====
@@ Line 50: / Line 55: @@
-===== solar charge controller =====
+==== solar charge controller ====
-==== controller choice ====
+=== controller choice ===
-Most people do fine with a PWM controller.  Folks who live off-grid with lead-chemistry batteries can get by with [[electrical:solar:shunt_tweaking|a $10 cheapie]].
+The [[electrical:solar:charge_controller|controller]]'s job is to sit in between the panels and battery bank and regulate charging.  Counterintuitively, its most important job is to //prevent overcharging//.
+Most people do fine with a PWM controller.  Folks who live off-grid with lead-chemistry batteries can get by with even [[electrical:solar:shunt_tweaking|a $10 cheapie]].  Nicer PWM have staged ("smart") charging, more configurabilty, and likely better reliability.
 You may **want an MPPT controller**:
@@ Line 68: / Line 76: @@
-==== controller sizing ====
+=== controller sizing ===
 [[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).
@@ Line 94: / Line 102: @@
-===== battery bank =====
-Having an **undersized bank** means //running out of power// at night.  Sitting in the dark at night with no fan.
-Having an **oversized lead bank** for your charging ability results in [[electrical:batterycide|battery murder]] and replacement.  Having an **oversized lithium bank** is $$$ and can strain the alternator if [[electrical:12v:b2b|a current-limiting isolator]] isn't used.
-IMO, it is better to have an undersized bank you can charge //fully and consistently// rather than a bigger bank you cannot charge.
-You will **need somewhat more Ah capacity**
-      * if you have undersized solar
-You will need **somewhat less Ah capacity**
-    * if you run loads in the daytime instead of at night
-    * if you have [[electrical:solar:overpaneling|oversized solar]]
 ===== alternator charging =====
-For most people living in vehicles [[electrical:12v:alt_and_solar|alternator charging + modest solar]] will be the best-performing system for the dollar.
+For many people living in vehicles [[electrical:12v:alt_and_solar|alternator charging + modest solar]] will be the best-performing system for the dollar.   The ratio of camping //vs// driving((and to some extent what time of day you are driving)) will affect the solar/isolator/[[electrical:generator|generator]] balance.
 You will need **some kind of alternator charging**
@@ Line 134: / Line 126: @@
   * you have a voltage-sensitive battery like gel or lithium
+===== generator charging =====
+You may need a generator if:
+  * you need to run big loads like A/C
+  * you have a lithium battery bank but camp in long stretches with minimal solar.  In this model you would charge the batteries full blast((up to [[electrical:12v:battery_capacity|0.5C]])) for a few hours every few days.
+  * you have enough solar to [[electrical:12v:charging|Absorp/Float your lead batteries but not enough for bulk]].

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