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electrical:solar:pwm_tweaking [2018/04/18 16:52]
frater_secessus [the controller's achilles heel]
electrical:solar:pwm_tweaking [2021/06/26 11:46] (current)
frater_secessus [the controller's achilles heel]
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-===== the controller's achilles heel =====+===== PWM's achilles heel =====
  
 During charging with a PWM controller **the solar panel will be running at the voltage of the battery bank**.  Unfortunately, this is almost never the voltage at which the panel makes its rated power (Vmp).  The panel will make less and less power when battery voltage is low.   During charging with a PWM controller **the solar panel will be running at the voltage of the battery bank**.  Unfortunately, this is almost never the voltage at which the panel makes its rated power (Vmp).  The panel will make less and less power when battery voltage is low.  
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 Since the panels make more power at higher voltages((up to Vmp)) cranking up Vabs and Vfloat to higher-but-still-sane levels will result in more power being harvested.  Since the panels make more power at higher voltages((up to Vmp)) cranking up Vabs and Vfloat to higher-but-still-sane levels will result in more power being harvested. 
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 +Using the above panel as an example, Vabs of 14.7v will yield 3.5% more power than a Vabs of 14.1v.  Vfloat of 13.8v will yield 4.5% more power than a Vfloat of 13.2v. \\
 +Note:  consult the battery manufacturer's recommendations for the actual maximum voltages.  Controller presets often are set too low by the factory since they don't know what battery you will use it with. Better safe than sorry, say their lawyers. 
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 +DO invest in the $10 temperature probe option.
 ==== battery: maintain a higher state of charge ==== ==== battery: maintain a higher state of charge ====
  
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   * keeping your bank as charged as possible will let the panels produce the most power for conditions   * keeping your bank as charged as possible will let the panels produce the most power for conditions
  
-In other words, the lower your battery voltage gets the worse the system works.  There are two courses of action to take that will help reduce this effect.+In other words, the lower your battery voltage gets the worse the pwm charging works.  There are two courses of action to take that will help reduce this effect.
  
   - **Cycle less deeply** - Instead of cycling to 50% state of charge (12.2v) consider cycling to only 75% SoC (12.4v).     - **Cycle less deeply** - Instead of cycling to 50% state of charge (12.2v) consider cycling to only 75% SoC (12.4v).  
-  - [[electrical:12v:alt_and_solar|combine]] your solar charging with even small amounts of [[electrical:12v:alternator|alternator]] or [[electrical:shore_power|shore power]] charging.  Either one of these will help get the bank "out of the mud", particularly if they are added early in the morning.   +  - [[electrical:12v:alt_and_solar|combine]] your solar charging with even small amounts of [[electrical:12v:alternator|alternator]] or [[electrical:shore_power|shore power]] charging.  Either one of these will help get the bank "out of the mud", particularly if they are added early in the morning.  An isolator generally costs less than upgrading to mppt.
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electrical/solar/pwm_tweaking.1524084735.txt.gz · Last modified: 2020/10/11 19:48 (external edit)