class 320 csed and solar (pv) panels

ylmzmSeptember 15, 2013

We are about to upgrade our electric service to 400 Amps and we plan to install a class 320 CSED (320 Amps continuous, 400 Amps max) ( Square D, Model #: SU3040D400CB ). It has two 200 Amp disconnects, one driving its own 200 Amp buss bar, another one for a remote 200 Amp subpanel.

I have some confusion about how to find the max breaker amps for a solar panel installation. As far as I know, we can install a circuit breaker (CB) for the solar system that is 20% of the service panel�s buss rating. Is that the case? If that is the case, how to I calculate the max CB size for solar? We don't want to be limited by 40 Amps when we have 400 Amp service. Is it 40 Amps or 80 Amps in our case?

Should we select a different meter combo? For instance, how about installing a 400 Amp meter + two 200 Amp solar ready subpanels?

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Who is doing the solar install?
Where are you getting this info from?

    Bookmark   September 15, 2013 at 1:38PM
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Solar installation will not be done now, it will be done in 2 years, but we want to be ready for it.

Regarding limitation of 20% limitation: I just learned about it online.

One example:

"For residential applications, the NEC 690-64 allows the total supply (utility plus PV) to the busbar of the service panel to equal 120% of the busbar rating (100-amps x 1.2 = 120-amps). This means that a 100-amp service panel can have a 100-amp main breaker and a 20-amp PV breaker."

    Bookmark   September 15, 2013 at 1:48PM
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Hi ylmzm,

very curious if you ever finished this install and what equipment you ended up using?

we are starting to do the very same right now and available info on is scetchy to say the least

thanks - hope to see you post back

    Bookmark   April 10, 2014 at 12:26PM
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