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electrical:solar:pwm_tweaking [2018/04/18 16:38] frater_secessus [Tweaking a PWM controller for maximum power] |
electrical:solar:pwm_tweaking [2019/05/09 21:09] frater_secessus [battery: maintain a higher state of charge] |
====== Tweaking a PWM controller for maximum power ====== | ====== Tweaking a PWM controller for maximum power ====== |
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[[electrical:solar:charge_controller#pwm|PWM controllers]] are inexpensive and durable. Their chief downside is they usually can't make as much power from a given panel as the more expensive [[electrical:solar:charge_controller#mppt|MPPT]] can. This page is intended to help people get the most out of their PWM system. It assumes the 'dweller owns [[electrical:solar:pwm configurable|a configurable PWM controller]]. | [[electrical:solar:charge_controller#pwm|PWM controllers]] are inexpensive and durable. Their chief downside is their ability to generate power is limited when battery voltage is low ([[electrical:solar:charge_controller#mppt|MPPT]] output is unaffected by battery voltage). This page is intended to help people get the most out of their PWM system. It assumes the 'dweller owns [[electrical:solar:pwm configurable|a configurable PWM controller]]. |
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Note: much of this information also applies to [[electrical:solar:shunt_tweaking|tweaking shunt controllers]]. | Note: much of this information also applies to [[electrical:solar:shunt_tweaking|tweaking shunt controllers]]. |
12.1v x 5.6A = 67.76W <-- power at 50% state of charge; bulk charging | 12.1v x 5.6A = 67.76W <-- power at 50% state of charge; bulk charging |
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This last number shows how far off PWM output can fall when battery voltage is at its lowest.((The last number is also the source of the "30% boost!!!" claims some MPPT makers make. Yes, at that point MPPT at 94.69w (after 5% MPPT efficiency penalty) is 40.2% more than PWM's 67.76w but that is when the disparity is the widest. Most of the time the MPPT charging advantage is lower, perhaps 15%.)) It's also when the battery needs the most current to get out of that deep cycle trough. | This last number shows how far off PWM output can fall when battery voltage (Vbatt) is at its lowest.((The last number is also the source of the "30% boost!!!" claims some MPPT makers make. Yes, at that point MPPT at 94.69w (after 5% MPPT efficiency penalty) is 40.2% more than PWM's 67.76w but that is when the disparity is the widest. Most of the time the MPPT charging advantage is lower, perhaps 15%.)) It's also when the battery needs the most current to get out of that deep cycle trough. |
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===== the plan ===== | ===== the plan ===== |
* 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 |
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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. |
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- **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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