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--- electrical:solar:charge_controller [2019/09/02 23:53]
frater_secessus [shunt] holding Vans all day
+++ electrical:solar:charge_controller [2019/10/01 13:04]
frater_secessus [how to choose]
@@ Line 24: / Line 24: @@
 {{ https://media.licdn.com/mpr/mpr/AAEAAQAAAAAAAAwtAAAAJGJhNjE1OGY3LTM3OWQtNGQ2Mi05NWEwLTI2Mzc3MGY3MDk3MA.png?150}}When compared apples-to-apples on identical systems with //only the controller being different//, the "boost" effect is most pronounced:
   * during bulk stage and the early part of absorption stage when the battery can take in the most power
+  * anytime the system is fully loaded down (charging and/or loads)
   * when the battery is most depleted (ie lowest resting voltage).  This is the result of a cascade of factors:
-    * When a battery is deeply discharged it will go into Bulk charging mode until it reaches the Absorption voltage (Vabs).  For the purpose of illustration we will assume the bank is depleted to 12.2v (~50% [[electrical:depth_of_discharge|state of charge]]), a commonly recommended lower limit for deep cycle batteries.
+      * When a battery is deeply discharged it will go into Bulk charging mode until it reaches the Absorption voltage (Vabs).  For the purpose of illustration we will assume the bank is depleted to 12.2v (~50% [[electrical:depth_of_discharge|state of charge]]), a commonly recommended lower limit for deep cycle batteries.
-    * PWM controllers can only run the panel at whatever voltage they are charging at right now.  In our example that is 12.2v.
+      * PWM controllers can only run the panel at whatever voltage they are charging at right now.  In our example that is 12.2v.
-    * Nominal 12v panels usually have max power output (Vmp) around 17v.((https://www.altestore.com/howto/solar-panels-pv-and-voltages-a98/))
+      * Nominal 12v panels usually have max power output (Vmp) around 17v.((https://www.altestore.com/howto/solar-panels-pv-and-voltages-a98/))
-    * when a typical 100w panel((Iop = 5.6A)) is run at 12.2v in lab conditions it puts out **~68.32W**. The same panel run at Vmp (~17v) would put out **100W**.  **MPPT is capturing more power than the PWM when the battery needs it most**.((there are minor inefficiencies not considered here))
+      * when a typical 100w panel((Iop = 5.6A)) is run at 12.2v in lab conditions it puts out **~68.32W**. The same panel run at Vmp (~17v) would put out **100W**.  **MPPT is capturing more power than the PWM when the battery needs it most**.((there are minor inefficiencies not considered here))
   * during times of greatest PV efficiency((i.e. highest voltage)) (clear, cold weather)
   * during times of low irradience (low light levels due to low angle or overcast conditions)((this is a function of higher input voltages))((https://www.victronenergy.com/upload/documents/White-paper-Which-solar-charge-controller-PWM-or-MPPT.pdf Section 7.3))
@@ Line 47: / Line 48: @@
 If more power is needed (and there is physical space) additional PV can be added to match the charging output of an MPPT charger, often at a lower cost.  [There are no prizes for fanciest or most expensive charge controller!  Do what is best for you -- frater secessus]
 MPPT controllers also tend to consume more power to run themselves than PWM models due to additional processing and electronic components.
 **MPPT may be a better fit** when:
   * battery banks are cycled deeply on a regular basis so more time is spent in Bulk
@@ Line 65: / Line 67: @@
 We say "effectively required" because one //can// use 24v panels with PWM and 12v banks -- it just doesn't work very well.  The 24v panels will be run at 12v voltages, yielding about half the power you would get with MPPT.
 **Shunt controllers are useful for [[electrical:solar:shallow_cycling|shallow-cycling configurations]]** or for battery chemistries that are not damaged by [[electrical:depth_of_discharge|partial state of charge (PSoC)]].  Their relative inexpense makes them useful for even very small systems and test configurations.
-Their simple ON and OFF setpoints may also make them useful for charging [[electrical:12v:lifepo4_batteries_thread|lithium]] chemistries.
+Their simple ON and OFF setpoints may also make them useful for charging [[electrical:12v:deep_cycle_battery#lithium_chemistries|lithium]] chemistries.
 Further reading:
 [[https://www.victronenergy.com/upload/documents/White-paper-Which-solar-charge-controller-PWM-or-MPPT.pdf|an excellent and readable whitepaper by Victron]] (PDF).
@@ Line 71: / Line 73: @@
 [[electrical:12v:multipoint_charging|Multiple controllers (with separate arrays) can be used to charge a common bank]].  The controllers should be configured with similar charging setpoints for the greatest efficiency.((http://www.morningstarcorp.com/parallel-charging-using-multiple-controllers-separate-pv-arrays/))
 ===== sizing your charge controller =====
-As with [[electrical:inverter|inverters]], sizing the controller correctly will help system efficiency.  An oversized CC will have unnecessarily high parasitic drains as it powers itself.  An undersized CC will not be able to put all the rated solar wattage to use and will leave no room for expansion.
+As with [[electrical:inverter|inverters]], sizing the controller correctly will help system efficiency and save money.  An oversized CC will have unnecessarily high parasitic drains as it powers itself and will cost more.  An undersized CC will not be able to put all the rated solar wattage to use and will leave no room for expansion.
 For PWM controllers, the formula is something like (panel wattage / 13) * (1.2 oversize for safety) = charge controller amps.((https://www.altestore.com/howto/sizing-pwm-solar-charge-controllers-a91/))
 MPPT controllers have more leeway in sizing since they can control the output of the panels independently of battery voltage.

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