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ac_coupling:start [2019-01-22 10:15]
127.0.0.1 external edit
ac_coupling:start [2020-06-18 16:13] (current)
marmour [2.4 Should you look at the total PV array, or the PV inverter rating?]
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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 [[:ac_coupling:start#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: 
 + 
 +  - [[:ac_coupling:start#the_factor_10_rule|Factor 1.0 rule chapter]] 
 +  - [[:ac_coupling:start#minimum_battery_capacity|Minimum battery capacity chapter]] 
 +  - [[:ac_coupling:start#requirement_of_adding_dc-coupling_-_mppt_solar_chargers|Requirement of adding DC-Coupling]] (MPPT Solar Chargers)  
 + 
 ==== 1.1 What is AC-coupling? ==== ==== 1.1 What is AC-coupling? ====
 +
 +{{:ac_coupling:ac_couple.jpg?direct&400|}}
  
 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:fronius|AC-coupled PV with Fronius PV Inverters]].+  * 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:gx_solaredge|]]. For Fronius settings, see [[ac_coupling:fronius|AC-coupled PV with Fronius PV Inverters]].
   * 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/charger**
 ==== 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 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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   * 400 Ah accubank 12 Vdc   * 400 Ah accubank 12 Vdc
  
-==== 4 Software configuration ====+===== 4 Requirement of adding DC-Coupling - MPPT Solar Chargers ===== 
 + 
 +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. 
 + 
 +===== 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:start|ESS Assistant]] (for grid-connected systems) or the [[:assistants:pv-inverter-support]] (for off-grid systems). 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:start|ESS Assistant]] (for grid-connected systems) or the [[:assistants:pv-inverter-support]] (for off-grid systems).
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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 [[ccgx:start|section 1.5 in the GX manual]].
  
 ===== DISQUS ===== ===== DISQUS =====
 ~~DISQUS~~ ~~DISQUS~~
  
ac_coupling/start.1548148552.txt.gz · Last modified: 2019-01-22 10:15 by 127.0.0.1