ac_coupling:start

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ac_coupling:start [2018-05-30 09:02] mvader [3.1 Lead batteries] |
ac_coupling:start [2021-04-12 03:03] guystewart [Monitoring] |
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===== 1. Introduction to the AC-Coupling concept ===== | ===== 1. Introduction to the AC-Coupling concept ===== | ||

- | Already familiar with the concepts of AC-coupling and regulating PV inverter output power by frequency shifting? Skip to [[:the_10_rulemax_pv_power_must_be_equal_or_less_than_the_va_rating_of_the_multi|the factor 1.0 rule]]. | + | Already familiar with the concepts of AC-coupling and regulating PV inverter output power by frequency shifting? Skip to the requirements and limitations: |

+ | | ||

+ | - [[:the_factor_10_rule|Factor 1.0 rule chapter]] | ||

+ | - [[: | ||

+ | - [[: | ||

+ | | ||

==== 1.1 What is AC-coupling? | ==== 1.1 What is AC-coupling? | ||

+ | |||

+ | {{: | ||

In an AC-coupled system, a grid-tied PV inverter is connected to the output of a Multi, Inverter or Quattro. PV power is first used to power the loads, then to charge the battery, and any excess PV power can be fed back to the grid. | In an AC-coupled system, a grid-tied PV inverter is connected to the output of a Multi, Inverter or Quattro. PV power is first used to power the loads, then to charge the battery, and any excess PV power can be fed back to the grid. | ||

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* Systems with only a grid-tied PV inverter will fail when there is a grid black-out. A micro-grid system will continue to operate, and even keep using solar power. | * Systems with only a grid-tied PV inverter will fail when there is a grid black-out. A micro-grid system will continue to operate, and even keep using solar power. | ||

* It is also possible to run a AC-coupled micro-grid on a generator | * It is also possible to run a AC-coupled micro-grid on a generator | ||

- | * Most brands of PV inverters can be used for these systems, they need to be setup to support frequency shifting, often called the island-mode or micro-grid mode. For Fronius settings, see [[ac_coupling: | + | * Most brands of PV inverters can be used for these systems, they need to be setup to support frequency shifting, often called the island-mode or micro-grid mode. For SolarEdge settings, see [[venus-os:. For Fronius settings, see [[ac_coupling: |

* If power will be fed back into the grid an anti-islanding device may have to be added to the system, depending on local regulations. | * If power will be fed back into the grid an anti-islanding device may have to be added to the system, depending on local regulations. | ||

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- | ===== 2. The 1.0 rule: Max PV power must be equal or less than the VA rating of the Multi ===== | + | ===== 2. The Factor 1.0 rule ===== |

+ | **The max PV power must be equal or less than the VA rating of the inverter/ | ||

==== 2.1 Rule definition ==== | ==== 2.1 Rule definition ==== | ||

- | In both grid-connected and off-grid systems with PV inverters installed on the output of a Multi, Inverter or Quattro, there is a maximum of PV power that can be installed. This limit is called the __factor 1.0 rule__: 3.000 VA Multi = 3.000 Wp installed solar power. So for a 8.000 VA Quattro the maximum is 8.000 Wp, for two paralleled 8000 VA Quattros the maximum is 16.000 Wp, etc. | + | In both grid-connected and off-grid systems with PV inverters installed on the output of a Multi, Inverter or Quattro, there is a maximum of PV power that can be installed. This limit is called the __factor 1.0 rule__: 3.000 VA Multi >= 3.000 Wp installed solar power. So for a 8.000 VA Quattro the maximum is 8.000 Wp, for two paralleled 8000 VA Quattros the maximum is 16.000 Wp, etc. |

==== 2.2 Example and background ==== | ==== 2.2 Example and background ==== | ||

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==== 2.3 Charge current limit ==== | ==== 2.3 Charge current limit ==== | ||

- | Another question frequently asked is how can this factor be 1.0? Since the charger inside a 3000 VA Multi is not 3000 VA but closer to 2000 VA? The explanation lies in the fact that it will regulate . In other words: when there is too much power coming in, causing the charge current to exceed the limit, it will increase the output frequency again and will keep regulating the AC output frequency to charge with the limit. | + | Another question frequently asked is how can this factor be 1.0? Since the charger inside a 3000 VA Multi is not 3000 VA but closer to 2000 VA? The explanation lies in the fact that it will regulate. In other words: when there is too much power coming in, causing the charge current to exceed the limit, it will increase the output frequency again and will keep regulating the AC output frequency to charge with the limit. |

An example, a 3000 VA Multi, with 3000 W of solar power coming out of a PV inverter: | An example, a 3000 VA Multi, with 3000 W of solar power coming out of a PV inverter: | ||

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==== 2.4 Should you look at the total PV array, or the PV inverter rating? ==== | ==== 2.4 Should you look at the total PV array, or the PV inverter rating? ==== | ||

- | The mentioned 3000 Wp and 8000 Wp is the Watt-peak which can be expected from the solar system. So for a oversized PV array, where the total Watt-peak installed PV panels exceeds the power of the PV Inverter, you take the Wp from the inverter. For example 7000 Wp of solar panels installed, with an 6000 Watt PV grid inverter, the figure to be used in the calculations is 6000 Wp. | + | The mentioned 3000 Wp and 8000 Wp is the Watt-peak which can be expected from the solar system. So for an oversized PV array, where the total Watt-peak installed PV panels exceeds the power of the PV Inverter, you take the Wp from the inverter. For example 7000 Wp of solar panels installed, with an 6000 Watt PV grid inverter, the figure to be used in the calculations is 6000 Wp. |

And for an undersized PV array, where the total Wp of installed PV panels is less than the installed PV grid inverter, you use the Wp from the PV panels in your calculation. | And for an undersized PV array, where the total Wp of installed PV panels is less than the installed PV grid inverter, you use the Wp from the PV panels in your calculation. | ||

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==== 3.1 Lead batteries ==== | ==== 3.1 Lead batteries ==== | ||

- | 1 kWp installed PV power requires approximately 5kWh of battery: | + | 1 kWp installed PV power requires approximately 5kWh of lead acid battery: |

- | * 100 Ah accubank 48 Vdc | + | * 100 Ah at 48 Vdc |

- | * 200 Ah accubank 24 Vdc | + | * 200 Ah at 24 Vdc |

- | * 400 Ah accubank 12 Vdc | + | * 400 Ah at 12 Vdc |

+ | Each additional 1 kWp of AC PV will require an additional proportional 5 kWh increase in lead acid battery storage. | ||

==== 3.2 Lithium batteries ==== | ==== 3.2 Lithium batteries ==== | ||

- | 1,5 kWp installed PV power requires: | + | 1,5 kWp installed AC PV power requires 4.8 kWh of battery storage: |

- | * 100 Ah accubank 48 Vdc | + | * 100 Ah at 48 Vdc |

- | * 200 Ah accubank 24 Vdc | + | * 200 Ah at 24 Vdc |

- | * 400 Ah accubank 12 Vdc | + | * 400 Ah at 12 Vdc |

- | ==== 4 Software configuration ==== | + | Each additional 1.5 kWp of AC PV will require an additional proportional 4.8 kWh increase in battery storage. |

+ | ===== 4 Requirement of adding DC-Coupling - MPPT Solar Chargers ===== | ||

- | Multis and Quattros with factory settings will not shift the AC output frequency to regulate charge current. When setting up an AC Coupled system, install either the [[ess:PV Inverter Support Assistant (for off-grid systems). | + | Not required for Energy Storage Systems in Germany or other reliable grid situations. |

+ | | ||

+ | Required for offgrid systems as well as backup systems that need to overcome extended grid failures. | ||

+ | | ||

+ | Reason: recover from deadlock situation of AC-Coupling only situation. | ||

+ | | ||

+ | There is no Factor 1.0 limit that applies for DC coupled PV through a Victron MPPT. Nor is there a specific minimum amount of battery storage capacity, though please follow battery manufacture specifications for maximum charge rates. A rule of thumb is C10 (10% of Ah capacity in A) for lead acid batteries, and C2 (50% of Ah capacity in A) for lithium batteries. | ||

+ | | ||

+ | ===== 5 Software configuration ===== | ||

+ | | ||

+ | Multis and Quattros with factory settings will not shift the AC output frequency to regulate charge current. When setting up an AC Coupled system, install either the [[ess:[[:(for off-grid systems). | ||

+ | | ||

+ | The Inverter RS will automatically shift frequency without any additional configuration required when a surplus/. | ||

Other options, __all deprecated__, | Other options, __all deprecated__, | ||

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- Hub-4 Assistant in combination with the PV Inverter support Assistant | - Hub-4 Assistant in combination with the PV Inverter support Assistant | ||

- Use the Inverter period time settings on the Virtual switch tab. | - Use the Inverter period time settings on the Virtual switch tab. | ||

+ | |||

+ | ===== Monitoring ===== | ||

+ | |||

+ | See [[https:// | ||

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===== DISQUS ===== | ===== DISQUS ===== | ||

~~DISQUS~~ | ~~DISQUS~~ | ||

+ |

ac_coupling/start.txt · Last modified: 2021-04-12 03:03 by guystewart