Wye configuration of Solar Micro Inverters

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EEnergy

Member
I'm trying to hook up a 10kW solar system in a 120/208 3 phase set up. The system consists of 25 Enphase D380 Micro inverters and 50 230 watt solar modules. Enphase has provided me with a drawing, installation guide and engineer confirmation stating that the these inverters are in a Wye configuration. For some reason the LDC is insisting that the it is set up in a delta config. Does anybody have any ideas about to explain that this is wye? Or have an idea how to re draw the diagram to help them understand.

http://enphase.com/wp-uploads/enphase.com/2011/05/Enphase_Field_Wiring_Diagram_D380_208v.pdf

http://enphase.com/wp-uploads/enphase.com/2011/03/Enphase-Microinverter-Model-D380-Installation-Operations-Manual.pdf
 

BillK-AZ

Senior Member
Location
Mesa Arizona
Enphase micro inverters supply current between L1 and L2 of each inverter, there is no current flow in the neutral. The neutral is required for automatic detection of 208 vs 240 service so that the correct voltage limits are used.

The 3-phase cable distributes the micro inverters across the three legs of the 3-phase service. The inverters operate independently, loss of one phase does not affect operation of the 1/3 of the inverters on the other two phases.

The inverters form a DELTA that must be connected to a WYE on the utility side.
 

Smart $

Esteemed Member
Location
Ohio
... Does anybody have any ideas about to explain that this is wye? Or have an idea how to re draw the diagram to help them understand.

...
The wye relies on the service transformer to establish the neutral point. Balancing of the Line-to-Neutral loads minimizes the neutral current having to pass through the service transformer to get back to the PV system.

Consider a delta power system with three identical loads connected in a wye configuration. The common point of the loads acts as a neutral point in the circuit. Now parallell each load with identical power sources and ground the common point connections. These new power sources are representative of the service transformer while the PV system is the original delta system. Two power systems, one delta when isolated operating in tandem with one wye when isolated can power both line-to-line and line-to-neutral loads. The loads do not "care" where the power comes from.
 
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EEnergy

Member
The issue we are having is with regards to weather or not the inverters satisfy measurement Canada's standards for 3 element metering. They want to see each inverter output at 120V. Is this possible with a set up like this? Has anybody had an experience like this?
 

EEnergy

Member
Delta to Wye

Delta to Wye

The issue is that the hydro company needs the output to be a Wye. Would it make sense to connect the lines from the trunk cable to a delta/wye transformer while still referencing of the Utilities neutral?
 

tallgirl

Senior Member
The short answer is "You're okay".

The inverters won't output outside their range, which for a Wye configuration with those inverters will be 208 L-L. I suspect you're getting tripped up because "not producing power" sounds a lot like "0 volts". There will still be 208 L-L and 120 L-N because the grid will be providing power through the transformer -- there just won't be any amps.
 
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