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--- ac_coupling:start [2022-04-12 06:47] – [1.1 What is AC-coupling?] bob
+++ ac_coupling:start [2026-09-01 10:41] (current) – [2.4 Should you look at the total PV array, or the PV inverter rating?] sloges
@@ Line 37: / Line 37: @@
 ===== 2. The Factor 1.0 rule =====
-**The max PV power must be equal or less than the VA rating of the inverter/charger**
+**The max PV power must be equal to or less than the continuous output power at 25 °C of the inverter/charger**
 ==== 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. That maximum is the continuous output power of the inverter/charger at 25 °C, as stated in its datasheet.
+A MultiPlus-II 48/3000 is rated 2400 W continuous at 25 °C, so the maximum is 2400 Wp of installed solar power. A Quattro 48/8000 is rated 6400 W, so the maximum is 6400 Wp. For paralleled units, add the continuous ratings of the individual units.
 ==== 2.2 Example and background ====
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 ==== 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.
+A question frequently asked is how PV power up to the full continuous output rating can be allowed, since the charger inside a 3000 VA Multi is not 2400 W but closer to 2000 W? 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, MultiPlus-II 48/3000, with 2400 W of solar power coming out of a PV inverter:
-  - When the Multi is connected to the grid, all 3000 W can be fed back to the grid through the Multi, no problem.
+  - When the Multi is connected to the grid, all 2400 W can be fed back to the grid through the Multi, no problem.
-  - In case the Multi is not connected to the grid, the 3000 Wp is more than the charger in a Multi 3000 VA can handle. The charger is around 2000 W. Therefore the grid inverter assistant will automatically increase the frequency to reduce the output of the grid inverter, to match maximum charge current.
+  - In case the Multi is not connected to the grid, the 2400 Wp is more than the charger in a Multi 3000 VA can handle. The charger is around 2000 W. Therefore the grid inverter assistant will automatically increase the frequency to reduce the output of the grid inverter, to match maximum charge current.
 ==== 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 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.
+The mentioned 2400 Wp and 6400 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.
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 ===== 3. Minimum battery capacity =====
-Besides the relation between installed PV Power and the inverter/charger VA rating, it is also important to have a sufficiently sized battery. The minimum battery capacity depends on the type of battery, lead or lithium.
+Besides the relation between installed PV Power and the continuous output power of the inverter/charger, it is also important to have a sufficiently sized battery. The minimum battery capacity depends on the type of battery, lead or lithium.
 Note that, besides the minimum battery capacity, the mentioned sizes are often also the most economical battery size. In case used for self-consumption purposes that is. In case the goal is to increase autonomy, of course installing a large battery increases the system autonomy in case of a grid failure.