connection to service

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keith gigabyte

Senior Member
Location
New Kensington, Pa
My background is residential rewires, commercial new construction, and industrial controls install and troubleshooting

I recently looked at a job to install a new service at a residence. Existing conditions...old entrance cable, old meter base, new load side wire form meter base, new 100 amp plug on panel, solar inverter and 30 amp disconnect switch (maybe 1-4 years old) greenfield from inverter outside to existing panel in basement. wires from inverter are stuffed under the same lugs as the load side wires from meter socket. How does the synchronizing of phases occur from solar unit and power company?
I am familiar with synchroscopes and synchronizing multiple generators from my industrial background. so just tying wires together with spilt bolts doesn't seem right to me.

My question is how do I go about replacing the service; line side and meter base, tie the solar inverter into the new panel.
 
keith gigabyte said:
My background is residential rewires, commercial new construction, and industrial controls install and troubleshooting

I recently looked at a job to install a new service at a residence. Existing conditions...old entrance cable, old meter base, new load side wire form meter base, new 100 amp plug on panel, solar inverter and 30 amp disconnect switch (maybe 1-4 years old) greenfield from inverter outside to existing panel in basement. wires from inverter are stuffed under the same lugs as the load side wires from meter socket. How does the synchronizing of phases occur from solar unit and power company?
I am familiar with synchroscopes and synchronizing multiple generators from my industrial background. so just tying wires together with spilt bolts doesn't seem right to me.

My question is how do I go about replacing the service; line side and meter base, tie the solar inverter into the new panel.
Click to expand...
Phase synchronization is done by the inverter, so you don't need to worry about that, but from your description the solar interconnection sounds a bit sketchy. It needs to be compliant with either 705.11 or 705.12 as well as with POCO rules.
 
keith gigabyte said:
update: there are CT's on the line side feed from POCO to main breaker in panel.
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And possibly on the conductors from the inverter as well. These are for monitoring so the customer can tell how much the PV system is contributing to their energy consumption.
 
The double luggin is obviously a hack, otherwise there's nothing wrong in theory with a supply side connection. I agree with electrofelon that if you are upgrading the service a backfed breaker connection might make more sense.

The CTs need to go back on the same phase at the same schematic point and pointing the same direction they are installed now. Inverter connection phasing also needs to stay consists. If you don't want to be responsible for that then maybe the solar company is still around and can come back out to check it after you're done. But it would be nice of you to ensure there's a place to put the CTs.

The synchronization algorithms are proprietary trade secrets but tested to a UL standard.
 
jaggedben said:
The CTs need to go back on the same phase at the same schematic point and pointing the same direction they are installed now. Inverter connection phasing also needs to stay consists. If you don't want to be responsible for that then maybe the solar company is still around and can come back out to check it after you're done.
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For monitoring to work not only the phasing and direction must be correct; the position they occupy in the system must be correct for the calculations to work. If the system is converted from a line side to a load side connection, the CTs most likely have to be moved or the calculation changed. Moving the point of interconnection from the line side of the CT's on the service conductors to the load side will change the math.
 
ggunn said:
For monitoring to work not only the phasing and direction must be correct; the position they occupy in the system must be correct for the calculations to work. If the system is converted from a line side to a load side connection, the CTs most likely have to be moved or the calculation changed. Moving the point of interconnection from the line side of the CT's on the service conductors to the load side will change the math.
Click to expand...
Yeah that's what I meant by "same schematic point". Thanks for elaborating.
 
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