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electrical:solar:charge_controller [2022/10/12 17:37] frater_secessus [MPPT] wayback link |
electrical:solar:charge_controller [2023/09/10 13:51] frater_secessus [present use] |
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[[lifestyle: | [[lifestyle: | ||
====== Solar charge controllers ====== | ====== Solar charge controllers ====== | ||
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+ | ===== TLDR ===== | ||
+ | |||
+ | * solar panels -> solar charge controller (SCC) -> battery bank | ||
+ | * the SCC's main job is preventing //battery overcharge// | ||
+ | * The two main types of SCC are PWM and MPPT | ||
+ | * PWM - Cheaper, less efficient | ||
+ | * MPPT - More expensive, but more efficient | ||
+ | * SCC LOAD outputs are vestigial features but may be useful for triggering certain loads | ||
+ | |||
+ | |||
+ | [[opinion: | ||
+ | |||
+ | |||
+ | ==== overview ==== | ||
+ | |||
+ | |||
+ | |||
A solar charge controller (CC) regulates the [[electrical: | A solar charge controller (CC) regulates the [[electrical: | ||
Counterintuitively, | Counterintuitively, | ||
Charge controllers are generally **rated by the amount of output they can provide**. This output is shared by charging circuits and [[# | Charge controllers are generally **rated by the amount of output they can provide**. This output is shared by charging circuits and [[# | ||
Controllers operate based on [[electrical: | Controllers operate based on [[electrical: | ||
+ | |||
+ | Cautionary example: | ||
===== specs ===== | ===== specs ===== | ||
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[[https:// | [[https:// | ||
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+ | === panel selection for PWM === | ||
+ | |||
+ | PWM makes the most power when coupled with panels whose operating [[electrical: | ||
+ | |||
+ | Examples: | ||
+ | |||
+ | * 16.28v Vmp panel spec would be optimal for 14.8v Absorption, as we might use for flooded lead acid. 14.8v x 1.1 = 16.28v. | ||
+ | * 15.62v Vmp panel spec would be optimal for 14.2v Absorption, as we might use for Gel or LiFePO4. | ||
+ | |||
+ | |||
+ | Some [[electrical: | ||
==== MPPT ==== | ==== MPPT ==== | ||
[[http:// | [[http:// | ||
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This ability to decouple panel and bank voltage can result in 10%-30% more power harvested from 12v nominal panels than with a PWM controller, depending on conditions. | This ability to decouple panel and bank voltage can result in 10%-30% more power harvested from 12v nominal panels than with a PWM controller, depending on conditions. | ||
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There are some considerations when [[electrical: | There are some considerations when [[electrical: | ||
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+ | == panel selection for MPPT == | ||
+ | |||
+ | MPPT thrives on voltage. | ||
+ | |||
+ | Note that [[electrical: | ||
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+ | |||
+ | == when PWM beats MPPT == | ||
+ | |||
+ | There are edge cases where an optimal PWM setup can make //more// power than MPPT for a time. This can happen because MPPT has DC-DC losses that PWM does not, typically ~5%. Since MPPT harvest from the panel is typically 10-30% greater than PWM the DC-DC losses are hidden. | ||
+ | |||
+ | But when PWM controllers and panels are optimally matched (difference between panel Vmp((actual, | ||
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==== shunt ==== | ==== shunt ==== | ||
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> ....a rather inexpensive piece of equipment but it doesn’t do a terrible job of being a basic solar charge controller. On the whole, it behaves as one may expect – protecting the battery from excessive voltage and overdischarge, | > ....a rather inexpensive piece of equipment but it doesn’t do a terrible job of being a basic solar charge controller. On the whole, it behaves as one may expect – protecting the battery from excessive voltage and overdischarge, | ||
+ | |||
+ | === with Bnn settings === | ||
+ | |||
+ | Units with Bnn settings purport to have Absorption((which they often call Equalization)) profiles for various batteries and configurable Float setpoints. | ||
+ | |||
+ | * B01 - Sealed lead acid (AGM), typically 14.4v | ||
+ | * B02 - Gel, typically 14.2v | ||
+ | * B03 - flooded lead acid, typically 14.6v | ||
+ | * B04 - 4S LiFePO4 <-- like [[electrical: | ||
+ | * B05 - 5S LiFePO4 (uncommon) | ||
+ | * B06 - 3S Li-NMC | ||
+ | * B07 - 4S Li-NMC | ||
+ | |||
+ | Absorption duration is unknown. | ||
+ | |||
+ | Example manual for controller with [[https:// | ||
+ | |||
+ | |||
+ | Further viewing: | ||
+ | |||
+ | |||
+ | * [[https:// | ||
+ | * [[https:// | ||
==== USB converters ==== | ==== USB converters ==== | ||
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**MPPT may be a better fit** when: | **MPPT may be a better fit** when: | ||
- | * the existing PWM system is not providing enough output | + | * the existing PWM system is not providing enough output |
* nominal 12v panels have a relatively high Vmp (>=18v) for [[https:// | * nominal 12v panels have a relatively high Vmp (>=18v) for [[https:// | ||
* battery banks are cycled deeply on a regular basis so more time is spent at low Vbatt where PWM struggles. | * battery banks are cycled deeply on a regular basis so more time is spent at low Vbatt where PWM struggles. | ||
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==== present use ==== | ==== present use ==== | ||
- | In practice the LOAD terminals typically are either ignored((some well-respected controllers don't have them anymore)) or used as [[electrical: | + | In practice the LOAD terminals typically are either ignored((some well-respected controllers don't have them anymore)) or used as [[electrical: |
- | + | ||
- | One benefit to doing this is you can define | + | |
==== why loads aren't powered from LOAD terminals ==== | ==== why loads aren't powered from LOAD terminals ==== | ||
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+ | For an overview of official procedures by manufacturer, | ||