Note: This email is written from the perspective of the Enphase terminology, but the concept and question is the same in a general sense.
I am having a hard time understanding the logic and benefit of a power control system that is used for avoiding a main panel upgrade in a typical residence. If you have a 200A main panel bus with a 200A main breaker, the current limit for a backfed breaker is 32A from the PV, no matter what. The PCS will artificially reduce the PV output to 32A when it could be capable of a much higher current for large systems depending on sunlight availability. That would waste a lot of energy if the PV system is significantly larger than a 32A output rating. The PCS standards seem to have missed the mark. Wouldn't it make more sense to limit the total current delivered to the bus from all sources? For example, in the example above, if PV is delivering 40A, why not allow limiting utility input to 120A for a total of 160A continuous delivered to the bus before PV is throttled? If the utility is delivering zero, the PV could deliver all the way up to 160A the the bus if capable. That way, all of the loads would be powered to the maximum extent from PV with the excess exported (if allowed via net metering from the serving utility). Am I missing something about how PCS works? I just don't see many use cases for main panel avoidance that are in customers' best interest. If we can't meet the 120% rule, we just do supply-side interconnections so nothing is wasted. But a backfed breaker would be so much easier if PCS were implemented in the way that I would like it to work. Jason Szumlanski Florida Solar Design Group _______________________________________________ List sponsored by Redwood Alliance Pay optional member dues here: http://re-wrenches.org List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/[email protected]/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
