Help with de-rating center fed panel.

[ShastaDuke]

I've recently finished installing a 6.2kw system with a SolarEdge SE6000A-US inverter. I have a center-fed 200A panel.

The inspector came today for final and informed me that I'd need to de-rate the service breaker to accommodate the new PV circuit.

I'm having trouble determining if I can use a 175A service breaker or 150A. The max continuous output current of the inverter is 25A + 20%=30A, so am I correct in my assumption that the 175A breaker would not meet the requirement(175+30=205)?

I've checked my other circuits and 150A would be overly sufficient, but I'd like to use a 175A if at all possible.

Thanks in advance for any advice.

[silversaver]

What City and State are you in? I have not heard anyone ever needed to de-rating a 200A service panel for just a 6.2kW system....

[sensij]

Yes, the rules for center-fed panels are more stringent than the typical end-fed design. The PV breaker is sized 125% of the inverter's rated output, so a 30 A breaker would be too small. Derating the main to 150 A is the way to go if you want stay with a load-side connection.

[ShastaDuke]

Yes, the rules for center-fed panels are more stringent than the typical end-fed design. The PV breaker is sized 125% of the inverter's rated output, so a 30 A breaker would be too small. Derating the main to 150 A is the way to go if you want stay with a load-side connection.

I have a 40a breaker installed on the new pv circuit. Thanks for the advice on the 150a, I think that's my only option at this point if I want to keep the current configuration.

[ShastaDuke]

What City and State are you in? I have not heard anyone ever needed to de-rating a 200A service panel for just a 6.2kW system....

Tehama county, ca. Evidently this is a common issue with center fed panels, I was totally unaware until the inspection today...

[inetdog]

Tehama county, ca. Evidently this is a common issue with center fed panels, I was totally unaware until the inspection today...

What NEC cycle (year) are you on?
For 2011 and earlier you must use the breaker size when doing the 120% calculation, and I believe for the 100% (center fed) calculation too. For 2014 you must use the rated inverter output times 125% instead. That will usually give you a little more headroom if you fall just a fraction above a standard breaker size and have to go to the next one up.

[silversaver]

Tehama county, ca. Evidently this is a common issue with center fed panels, I was totally unaware until the inspection today...

Got ya. I did not read about the center fed...

[ShastaDuke]

What NEC cycle (year) are you on?
For 2011 and earlier you must use the breaker size when doing the 120% calculation, and I believe for the 100% (center fed) calculation too. For 2014 you must use the rated inverter output times 125% instead. That will usually give you a little more headroom if you fall just a fraction above a standard breaker size and have to go to the next one up.

Thanks for the info, I believe it's 2011 NEC. I'm moving forward with the 150A service breaker, should be here mid week.