wheisenburg
Independent Solar Consultant
Sol Arc and the new EG4 18,000 both recommend connecting AC coupled solar to the Gen port.
Normally when your system is grid tied excess PV is routed to the grid. In a grid down situation that is not an option. The Hybrid inverter will then become the grid forming inverter and the PV inverters will couple to that an begin exporting power to the Hybrid inverter. The Hybrid inverter will need to store the power in the batteries. When the batteries are full the hybrid inverter can use frequency shifting to shut down or curtail the PV inverters
My understanding of why Sol Arc uses the Gen input is that managing the curtailment of the AC coupled inverters is not instantaneous and it is not perfect. It depends on having some room left in the batteries so that you can dump the excess power into them. Sol Arc, I know suggests that you setup your installation so that it cycles between 80% and 90% SOC. So when the SOC <= 80% it will close the GEN connections and keep it connected until SOC >= 90%. The gen input will then stay off until SOC <= 80%.
My assumption is that they are doing this because they feel allowing the AC coupled inverters to operate above 90% SOC could cause the system to become unstable. After 1.5 years of not having to worry about this because the PV inverters would not turn on when not connected to the grid, that problem was finally solved
My question is why does Connect WX Pro not use this same method? They have no way to disconnect the PV inverters from the micro grid. Is there a potential instability issue because of the inability to quickly turn PV generation off when operating with batteries that are fully charged?
Normally when your system is grid tied excess PV is routed to the grid. In a grid down situation that is not an option. The Hybrid inverter will then become the grid forming inverter and the PV inverters will couple to that an begin exporting power to the Hybrid inverter. The Hybrid inverter will need to store the power in the batteries. When the batteries are full the hybrid inverter can use frequency shifting to shut down or curtail the PV inverters
My understanding of why Sol Arc uses the Gen input is that managing the curtailment of the AC coupled inverters is not instantaneous and it is not perfect. It depends on having some room left in the batteries so that you can dump the excess power into them. Sol Arc, I know suggests that you setup your installation so that it cycles between 80% and 90% SOC. So when the SOC <= 80% it will close the GEN connections and keep it connected until SOC >= 90%. The gen input will then stay off until SOC <= 80%.
My assumption is that they are doing this because they feel allowing the AC coupled inverters to operate above 90% SOC could cause the system to become unstable. After 1.5 years of not having to worry about this because the PV inverters would not turn on when not connected to the grid, that problem was finally solved
My question is why does Connect WX Pro not use this same method? They have no way to disconnect the PV inverters from the micro grid. Is there a potential instability issue because of the inability to quickly turn PV generation off when operating with batteries that are fully charged?
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