Hi Kirk, the maximum actual charge rate is 5kW per Powerwall. When you exceed that, or start getting full batteries, the Gateway tells the Powerwalls to frequency shift to 62-66 Hz.
This takes the UL 1741 listed inverters out of the sweet spot, and they stop or curtail production. However, predictably other sensitive electronics don't love being at 66 Hz. The newer inverters with more advanced grid profiles are able to partially curtail production based on slight variations in frequency. Older SMA are unlikely to be compliant, so behavior of those will be PV production on or off. This can especially be a problem when cold starting batteries, older inverters may overload the ability of a morning cold battery to even take a charge. In those situations you will get absolutely no PV production until the batteries are warm enough to take the full charge. It can be devastating for a winter day where you may get only 3 hours of good production. If you add PV to the backup side, it will need to run through a new or existing CT dedicated to PV production. If you put the new PV in the service panel you should put a new PV production CT around it, but you wouldn't have to depending on the current CT configuration. It would not produce during a grid outage. If you don't add the PV Production CT, the Powerwalls cannot use that PV to charge or see it in the app. If you have to land the new PV breaker on the non-backup side, but still in a location metered by the whole home consumption CTs, you will need PV production CTs. Also if there is a discrete "generation" and "essential loads" panel, the generation panel can have a maximum of 200A of generation pass through the gateway, as it is a 200A device. *With Regard,* *Vince Jolissaint* *Cobalt Power Systems Inc. |* *Director of CAD Services*2557 Wyandotte St. | Mountain View CA 94043 Office: 650.938.9574 | E-Mail vince...@cobaltpower.com <vince...@cobaltpower.com> > Hello all, > I am adding more PV to an orphaned Powerwall 2 AC system (which is all new > to me), -3- PW's stacked to total about 40kwh of usable storage. it > presently has about 13kw of PV, though -2- SMA inverters, feeding into it > through a common subpanel between the PW gateway and the main panel. I'm > wondering if there is a limit to the amount of PV the powerwall can > regulate/backoff (or use for battery charging) during a utility outage. > What is the max PW charge rate? I need to add about 10 kw of PV to produce > the owners goal of 100% coverage of electrical demand.? > If necessary for safety, i assume the extra pv inverter can be routed to > the main panel, and then won't participate in battery charging if the grid > goes down. Am I correct? Thanks. The PW manuals are of little use here. > > > Kirk Herander /?kirkh@vermont.solar [mailto:kirkh@vermont.solar] > Owner|Principal, VT Solar, LLC >
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