50k Solar interconnect 120/240 3phase 4wire

Status
Not open for further replies.
S

SolarBri

Member
Interesting and the first time for a commercial install that we have come across this configuration, 120/240 3phase 4wire with a 208 High leg.
So... any advice on interconnecting? First thought is a sub panel for 240 phase to phase with 2/3 of the system and a separate subpanel for the 208 high leg, all run as separate taps..... would this avoid an unbalanced system? we can vary up to 6k per phase, but shoot for a harmonius situation.
Thanks in advance.

Brian
 
If your are in the U.S, I'm thinking a transformer is sounding like a cheap option. If you feed the Delta end of an xfmr the high-leg becomes a moot (spelling?) point.

My 2?
Doug S.
 
A three phase 4 wire service as described is intended for 120 volt lighting and small appliance loads, and for 240 volt single phase loads, and for 240 volt three phase loads.
Although 208 volts is available between the high phase and the neutral, the intention is not to feed 208 volt loads since this increases losses and gives poor voltage regulation. (the connection of very small 208 volt loads is sometimes regarded as acceptable)

If the drawing of significant load at 208 volts is considered unwise, then I would presume that any significant backfeeding of PV would be equally unwise.

I would therefore obtain three identical backfeed inverters, each rated for 240 volt service.
Connect between A/B , B/C , and A/C.
The fact that the mid point of one phase is earthed is of no consequence, the grid tie inverters, simply require a 240 volt connection, they dont "know" if the mid point of one phase is grounded or not.

Many grid tie inverters are listed for operation at 208 volts, 240 volts, and 277 volts.
 
Status
Not open for further replies.
Top