busbar rating with ESS+Solar

[JoeNorm]

I am wondering if the inverter in the ESS has to be counted as another back-feed source on top of the solar?

This would only be an issue in a "time of use" mode where the battery and solar are dumping onto the busbar while grid connected.

Does the code address this?

 

[Designer101]

yes if its AC coupled battery like Tesla or enphase batteries i am not aware that the code separately address it though but it is treated like a third source
1. Grid
2. Pv
3. Battery

 

[jaggedben]

705 doesn't distinguish between different kinds of interconnected power sources, so a battery inverter counts the same as a solar inverter. The only way around that is for a system to be listed as a Power Control System as mentioned in the 2020 NEC.

Think of it this way. How would a panel busbar know that your battery inverter is in a mode where it doesn't backfeed its max at the same time as the solar?

 

[pv_n00b]

This is why NEC 705.13 was added to the 2020 NEC. Otherwise, equipment would have to be way oversized. But people have been using power control systems for many years, they just had to convince the AHJ it would work. Now that it is in the NEC it should be easier to use.