[RE-wrenches] Single phase to three phase interconnect

[Wilco Vercoelen]

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: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Eric Thomas
Sent: April-25-11 14:01
To: re-wrenches at lists.re-wrenches.org
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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