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Discussion Starter · #1 ·
I have an interesting situation. I have a 12k solar PV array for a residential service. There are two interters that is expected to output 22 amps and 30 amps repsectively. They are also to have breaker in the Load Box at 30 amps and 50 amps respectively. According the my HQs read on NEC it states that I would need to install at 400 Amp Load box using 600 mcm wire. The Electric Utility company states that since the residence will not use any more the 200 amp service they would not upgrade the system to 400 amp service even though the code requires a 400 amp load box with xx circuits. Any thoughts?
 

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I have an interesting situation. I have a 12k solar PV array for a residential service. There are two interters that is expected to output 22 amps and 30 amps repsectively. They are also to have breaker in the Load Box at 30 amps and 50 amps respectively. According the my HQs read on NEC it states that I would need to install at 400 Amp Load box using 600 mcm wire. The Electric Utility company states that since the residence will not use any more the 200 amp service they would not upgrade the system to 400 amp service even though the code requires a 400 amp load box with xx circuits. Any thoughts?
You will not win with them, if their conductors are small it's their problem.

Welcome to ET..:thumbup:
 

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200 amp service times 120% means max 40 Amp of PV connected to service panel. To allow your 52 amps of PV you need a bigger panel at least 300 Amps. The load will actually decrease by 52 amps maximum. But try to convince your utility of that.

Downsize PV system to 40 amps and call it a day.
 

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This is a simple and very common problem. You have to do a line tap in the main panel on the feed conductors. Tap onto the wires and go over to a fuses disco and then to a sub panel for the PV breakers from the inverters. Done, Next....
 

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If your utility allows piggyback meters your could use one. Otherwise a tap ahead of the main for a separate service for PV in a residential meter/main will not be allowed by most POCO's. In the west EUSERC rules will not allow it.
 

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FaultCurrent said:
If your utility allows piggyback meters your could use one. Otherwise a tap ahead of the main for a separate service for PV in a residential meter/main will not be allowed by most POCO's. In the west EUSERC rules will not allow it.
Link or I don't buy it.

Nevermind I actually can't even see how a tap
Inside of a meter main would be possible considering its bussing connecting the 2
 

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Discussion Starter · #7 ·
Utility Meter Wire Sizing

200 amp service times 120% means max 40 Amp of PV connected to service panel. To allow your 52 amps of PV you need a bigger panel at least 300 Amps. The load will actually decrease by 52 amps maximum. But try to convince your utility of that.

Downsize PV system to 40 amps and call it a day.
I can get the amp output down to 47 amps. Still leaves me with an issue. The Utility Company demands that we follow NEC but they don't want to comply. This will be interesting as we will install a 250 Amp box and of course it requires 250 mcm. Their Meter only accepts up to 4/0 AWG.

What seems crazy to me is that the customer will be using less of their load by 47 amps. The load box needs to handle 250 amps but the connection to the meter will see a usage less than 200 amps. So does the utility company meter really need a 250 mcm wire size connection? By using 4/0 wire it will handle a 225 amp load that it will never see. In reality the Utility Company will only be supplying 153 amps during the day and a maximum of 200 amps at night.

It seems more like a Catch 22.
 

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I don't grasp the line tap deal either.

Am i reading 690.8 right in that it only addresses certain service components as in panel & main, but not conductors?

~CS~
 

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For some reasons the John C. Wiles of the world seem to think that adding PV is like adding load, when in reality it is reducing load. Hence the 120 % rule. But it will be changing.

I went to a demonstration a while back and saw the actual prototypes. These guys tried like hell to get this approved

http://www.google.com/patents/US7648389

Here's another version

http://www.brooksutility.com/products/42


As far as I know this stuff has never been approved here in California....
 
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