ac_coupling:start

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

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

1,5 kWp installed PV power requires: | 1,5 kWp installed PV power requires: | ||

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

ac_coupling/start.1569927115.txt.gz · Last modified: 2019-10-01 12:51 by guy_stewart