NEC Article 964 Small Wind Systems - What size main panel to use?

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SGEI

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Phelan CA USA
Hello all,

Thanks for offering this great forum. I've browsed around here quite a bit over the last few months and have gained quite a bit of info.

I understand that the 2011 NEC includes provisions for small wind energy systems, article 964.


However, I can't figure this problem out.
I have a question relating to what size the main should be for a 10 kW 240v grid tie wind system.

Is it okay to have the wind system on a 60 amp breaker with the main being a 200 amp panel?

I understand that section 690? states that solar energy system breaker size is not to exceed 20% of the main panel amperage. Is this the same story for small wind systems too?


Thanks in advance,

Steve
 
Y
Hello all,

Thanks for offering this reat forum. I've browsed around here quite a bit over the last few months and have gained quite a bit of info.

I understand that the 2011 NEC includes provisions for small wind energy systems, article 964.


However, I can't figure this problem out.
I have a question relating to what size the main should be for a 10 kW 240v grid tie wind system.

Is it okay to have the wind system on a 60 amp breaker with the maintaining being a 200 amp panel?

I understand that section 690? states that solar energy system breaker size is not to exceed 20% of the main panel amperage. Is this the same story for small wind systems too?


Thanks in advance,

Steve
If the 200A panel has only a 200A busbar, then the maximum size for the backfed breaker is 240A minus the size of the main breaker.
Put in a 100A main and you can use up to 140A for the RE breakers. (Not that that would make a lot if sense.)

The calculation should apply to any GTI whether solar, wind, or water powered.

The 120% only applies if there are other loads on the pa el. If it is e.timely a backfeed combiner, a different calculation applies.
 
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My local utility states that since the system breaker ( its a 60 amp ) exceeds 20 % of the main bus amperage its not to NEC code.
Assuming that the panel bus is rated at 200 amps and there is a 200 amp main breaker, they are correct.
 
Looks like the panel has a 225 amp bus with a 200 amp main breaker. So if my calculations are correct, I should be okay up to 70 amps line feed from the turbine.
 
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