Feed In Breaker Sizing

What options do I have to feed in large arrays into residential main circuit panels. Most residential are only 200 amp and the array calls for 50 amp feed in breaker. What is the sub panel feed in rule. Sub is feed by a 70 amp at main, sub panel is rated at 125 amp, my solar feed in breaker is a 50 amp, so does the breaker feeding the sub panel become a feed in breaker also to the main?


  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: Feed In Breaker Sizing

    IMO, 690.64(B)(2) indicates that you use the 50A breaker closest to the inverter for the calculation on the main bus bar. You can go up to 120% of the busbar rating in the main panel.

    You can

    A) Keep the main service panel you have. You can go up to 240A on that bus bar, so if you drop the main breaker to anything 190A or below (probably will be 175A) you will be ok. I don't know what you do at your house, but it's really really unlikely that you'd ever trip a main 175A breaker or even close.

    B) Upgrade the equipment. You could keep a 200A main and upgrade the panel/busbar to 225A. I've done this before and the utility was fine with keeping the same service conductors.

    C) Really upgrade to a larger service.

    D) Line tap. - This isn't complicated, except most service equipment won't make this easy or possible, so it usually involves changing service equipment too.

    I'd generally go with A.
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