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electrical:solar:charge_controller [2023/04/17 12:30] frater_secessus [single-stage chargers] |
electrical:solar:charge_controller [2023/09/26 11:25] frater_secessus [how to choose] |
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====== Solar charge controllers ====== | ====== Solar charge controllers ====== | ||
- | ===== Pareto summary | + | ===== TLDR ===== |
* solar panels -> solar charge controller (SCC) -> battery bank | * solar panels -> solar charge controller (SCC) -> battery bank | ||
* the SCC's main job is preventing //battery overcharge// | * the SCC's main job is preventing //battery overcharge// | ||
- | * the two main types of SCC are PWM and MPPT | + | * The two main types of SCC are PWM and MPPT |
- | * SCC LOAD outputs are vestigal | + | * PWM - Cheaper, less efficient |
+ | * MPPT - More expensive, but more efficient | ||
+ | * SCC LOAD outputs are vestigial | ||
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[[https:// | [[https:// | ||
+ | |||
+ | === 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: | ||
+ | |||
+ | == panel selection for MPPT == | ||
+ | |||
+ | MPPT thrives on voltage. | ||
+ | |||
+ | Note that [[electrical: | ||
+ | |||
+ | |||
+ | == 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, | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
==== shunt ==== | ==== shunt ==== | ||
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* B01 - Sealed lead acid (AGM), typically 14.4v | * B01 - Sealed lead acid (AGM), typically 14.4v | ||
- | * B02 - Gel, typicallyt | + | * B02 - Gel, typically |
* B03 - flooded lead acid, typically 14.6v | * B03 - flooded lead acid, typically 14.6v | ||
* B04 - 4S LiFePO4 <-- like [[electrical: | * B04 - 4S LiFePO4 <-- like [[electrical: | ||
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Example manual for controller with [[https:// | Example manual for controller with [[https:// | ||
- | |||
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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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See also [[electrical: | See also [[electrical: | ||
+ | |||
+ | ==== should I upgrade my PWM to MPPT? ==== | ||
+ | |||
+ | If the system has changed and now MPPT is required for one of the reason above, then yes. | ||
+ | |||
+ | But most people consider this switch to make "more power", | ||
+ | |||
+ | So the questions are: | ||
+ | |||
+ | - do you need more power than you are getting now? | ||
+ | - would +15% be enough to meet your needs | ||
+ | - if so, would you pay [whatever the MPPT costs] to get that +15%? | ||
+ | |||
+ | There is a saying in solar circles that " | ||
===== multiple charge controllers | ===== multiple charge controllers | ||
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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, | ||