Eric, In order to connect single phase to three phase you probably need phase sensing on all three legs in order to disconnect the inverter from legs connected if one leg fails. Also, in Ontario under microFIT & FIT we typically have to balance power evenly across each leg as far as feeding power into grid on three phase. That is why utility companies basically require three phase inverters on existing three phase lines such as PowerOne or Fronius.
If single phase is only available, you can connect single phase up to 100kW I believe (after connection impact assessment is done of course) Not allowing three phase inverters when three phase is available is a puzzle to me. Not very cost effective and overcomplicating the system. Thanks. Kind regards, Wilco Vercoelen President Dommelvalley Green Power - Solar Energy Solutions Barrie, Ontario Canada _____ From: [email protected] [mailto:[email protected]] On Behalf Of Eric Thomas Sent: April-25-11 14:01 To: [email protected] Subject: [RE-wrenches] Single phase to three phase interconnect While commercial solar work is newer to me, im surprised this hasn't been addressed very much in our forum: Interconnecting single phase inverters to three phase services. We are laying out a 6kW system using Silicon Energy Cascade modules and Aurora PVI inverters (either 2 or 3 PVI 3.0's). The challenge is finding a way to easily tie two of these inverters into the existing 3phase service. I've been reading up on Sunny Boys tech notes and on this forum about imbalance and such, but im still not comfortable enough with tie in. Due to the string configuration options, I can add a third inverter and use a three phase subpanel to aggregate the inverters then tie them in. But adding a third inverter seems like a goofy solution. In looking at available equipment, transformers, phase converters etc, I can't seem to find the right fit. Any ideas? This system does not have a three phase inverter option due to Made in WA req's. Thanks! Eric Thomas Solar Epiphany LLC
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