PV ON LINE SIDE of transfer switch, utility says Generator is connected parallel to utility.

Designer101

Member
Location
California
Occupation
Solar Designer
Attached is the single line diagram.
I tried to convince them that the Utility and generator can be never operated parallel as the automatic transfer switch will only operate the Generator when grid is out.
please help me explaining them or if you have better SLD Can you please upload it., not being from electrical back ground has not helped me much.
 

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SunFish

Member
Location
ID
Seems to me the utility shouldn't be able to tell you where you can and cannot connect anyway. That should be up to the AHJ once it's past the meter. I see in your SLD this is a Generac genny, is the transfer switch also a Generac product? If yes I happen have this attached letter from Generac that says they allow solar to be connected to the conductors on the line side of the transfer switch inside of the ATS. I agree with Texi, ask the utility rep to let you talk to an applications engineer.
 

Attachments

Canton

Senior Member
Location
Virginia
Occupation
Electrical Inspector
Attached is the single line diagram.
I tried to convince them that the Utility and generator can be never operated parallel as the automatic transfer switch will only operate the Generator when grid is out.
please help me explaining them or if you have better SLD Can you please upload it., not being from electrical back ground has not helped me much.
Not sure how they see the generator operating in parallel off your one line.
 

Carultch

Senior Member
Location
Massachusetts
Not sure how they see the generator operating in parallel off your one line.
Unrelated issue first: your fusible disconnect, isn't drawn as a fusible disconnect. I see the fuses, but no blades. The open blade points toward the energy source that it doesn't shut off (i.e. away from the inverter), so that the blade and fuses de-energize in the open position. I recommend drawing this so the open blade points upward, so it reflects the orientation in reality. It should be clear which orientation to wire your disconnects, especially those that require another utility shutdown to correct ex-post-facto.

Only thing I can see, is that the diagram showing the generator neutral solidly tied in to the neutral of the service is throwing them off. Possibly someone who is seeing the term "transfer switch" for the first time, and doesn't care to look up the term. Obviously, that's the way you have to wire this particular generator, so it's not like you can show it any other way if you have to show it in three line form. Perhaps drawing the neutral as gray would help make these connections a lot less vivid, and stand out a lot less to the person reading the drawing. I'd also recommend filling in the words "normal" and "alternate" on the transfer switch, so they can see the two positions.

I'm generally in favor of single lines, as opposed to three lines. For the transfer switch specifically, its purpose is clearer to me on a single line. Less labor to draw, less labor to change, and less drawing elements to distract you from the essential information. I'm aware that the three line may be required by policy that isn't up to you, but if the choice were mine to make, I'd recommend single lines. Some parts of an electrical line drawing might be best communicated in a multiline detail view, but for the overall schematic, I recommend the single line drawing. Examples: phase staggering of 2-pole breakers on a 3-phase panel, details for connecting both DC polarities to a switch, wiring DC through multiple poles of a switch per MFR's requirements, relay instrumentation.
 

Canton

Senior Member
Location
Virginia
Occupation
Electrical Inspector
Unrelated issue first: your fusible disconnect, isn't drawn as a fusible disconnect. I see the fuses, but no blades. The open blade points toward the energy source that it doesn't shut off (i.e. away from the inverter), so that the blade and fuses de-energize in the open position. I recommend drawing this so the open blade points upward, so it reflects the orientation in reality. It should be clear which orientation to wire your disconnects, especially those that require another utility shutdown to correct ex-post-facto.

Only thing I can see, is that the diagram showing the generator neutral solidly tied in to the neutral of the service is throwing them off. Possibly someone who is seeing the term "transfer switch" for the first time, and doesn't care to look up the term. Obviously, that's the way you have to wire this particular generator, so it's not like you can show it any other way if you have to show it in three line form. Perhaps drawing the neutral as gray would help make these connections a lot less vivid, and stand out a lot less to the person reading the drawing. I'd also recommend filling in the words "normal" and "alternate" on the transfer switch, so they can see the two positions.

I'm generally in favor of single lines, as opposed to three lines. For the transfer switch specifically, its purpose is clearer to me on a single line. Less labor to draw, less labor to change, and less drawing elements to distract you from the essential information. I'm aware that the three line may be required by policy that isn't up to you, but if the choice were mine to make, I'd recommend single lines. Some parts of an electrical line drawing might be best communicated in a multiline detail view, but for the overall schematic, I recommend the single line drawing. Examples: phase staggering of 2-pole breakers on a 3-phase panel, details for connecting both DC polarities to a switch, wiring DC through multiple poles of a switch per MFR's requirements, relay instrumentation.
All may be true. This may not be the cleanest drawing, but as in the OP drawing the issue of the generator operating in parallel with the utility is quite clear not possible.

As textie said, go higher up the food chain to get it resolved. Its pretty scary that this is a complex issue for someone at the utility level, nothing more than a run of the mill 200 amp residential service with an ATS.
 

Designer101

Member
Location
California
Occupation
Solar Designer
Seems to me the utility shouldn't be able to tell you where you can and cannot connect anyway. That should be up to the AHJ once it's past the meter. I see in your SLD this is a Generac genny, is the transfer switch also a Generac product? If yes I happen have this attached letter from Generac that says they allow solar to be connected to the conductors on the line side of the transfer switch inside of the ATS. I agree with Texi, ask the utility rep to let you talk to an applications engineer.
yes, the ATS is also Generac product.
the utility is not very friendly For Solar Connection. They always come with some issues though AHJ approved it. The AHJ is ready to approve the drawing but but he just wanted to take the view from utility first as he said THE UTILTY has disapproved such connection before though AHJ approved it.
 

Designer101

Member
Location
California
Occupation
Solar Designer
Unrelated issue first: your fusible disconnect, isn't drawn as a fusible disconnect. I see the fuses, but no blades. The open blade points toward the energy source that it doesn't shut off (i.e. away from the inverter), so that the blade and fuses de-energize in the open position. I recommend drawing this so the open blade points upward, so it reflects the orientation in reality. It should be clear which orientation to wire your disconnects, especially those that require another utility shutdown to correct ex-post-facto.

Only thing I can see, is that the diagram showing the generator neutral solidly tied in to the neutral of the service is throwing them off. Possibly someone who is seeing the term "transfer switch" for the first time, and doesn't care to look up the term. Obviously, that's the way you have to wire this particular generator, so it's not like you can show it any other way if you have to show it in three line form. Perhaps drawing the neutral as gray would help make these connections a lot less vivid, and stand out a lot less to the person reading the drawing. I'd also recommend filling in the words "normal" and "alternate" on the transfer switch, so they can see the two positions.

I'm generally in favor of single lines, as opposed to three lines. For the transfer switch specifically, its purpose is clearer to me on a single line. Less labor to draw, less labor to change, and less drawing elements to distract you from the essential information. I'm aware that the three line may be required by policy that isn't up to you, but if the choice were mine to make, I'd recommend single lines. Some parts of an electrical line drawing might be best communicated in a multiline detail view, but for the overall schematic, I recommend the single line drawing. Examples: phase staggering of 2-pole breakers on a 3-phase panel, details for connecting both DC polarities to a switch, wiring DC through multiple poles of a switch per MFR's requirements, relay instrumentation.
Thank you, i will change the fusible disconnect drawing to show the blades. thank you for your valuable feed back.
 

Designer101

Member
Location
California
Occupation
Solar Designer
Seems to me the utility shouldn't be able to tell you where you can and cannot connect anyway. That should be up to the AHJ once it's past the meter. I see in your SLD this is a Generac genny, is the transfer switch also a Generac product? If yes I happen have this attached letter from Generac that says they allow solar to be connected to the conductors on the line side of the transfer switch inside of the ATS. I agree with Texi, ask the utility rep to let you talk to an applications engineer.
The letter doesn't have word UL Listing of existing equipment will not be compromised. Utility is requesting the letter with that word also at installation the solar is connected via UL tap box outside not in the enclosure itself. So this means its already violating's UL listing??

THE TAP BOX IS THIS ONE https://www.gordonelectricsupply.co...ga_IXUnLT_6qm3BUEwk0jKhlOSZMqP4xoCnI0QAvD_BwE
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
I’m with a utility and see this often on higher end homes with new solar installs.
Usually a double lug on the supply side of the ATS.

Never been an issue...

As mentioned before go higher up the brain stem. Seems you may have asked the utility ass end
 
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