Keep in mind that 7.5kW is max charge/discharge for 10 sec...it is NOT the continuous rate. This comes into play in the following scenario:
Let’s say a single Powerwall 2 is at 50% SOC and there is a utility outage on a sunny day. The inverter is outputting 7kW AC and loads in the house are below 2kW. The Powerwall will force the PV inverter to turn off via frequency shift and the inverter sit in a holding pattern, trying to reconnect every 5 minutes. If PV continues to be above 5 kW, then it will be turned off until the battery shuts off at its designated cut off %. Not an ideal scenario. This is why I like to use 5kW of PV per Powerwall as a general rule, to avoid this worst case scenario. Best, Chris On Sun, Apr 18, 2021 at 1:53 PM Barton Churchill <[email protected]> wrote: > You can just land the new PV to the same "generation" panel that already > hosts the 3 Powerwalls and existing PV inverter output breakers. There > should be no loads on this panel. The Powerwall AC coupled solar limit is > 7.5 KW AC per Powerwall, note AC not DC. The DC rating is irrelevant here. > If the combined PV AC inverter output is less than 22.5 kW the system will > work fine. Tesla does have a list of approved PV inverters but unless > you're looking to connect something over 3 years old it should be fine. > > *Barton Churchill* > *Director, Power Division* > 2042 Stadium Drive Suite 2 • Bozeman, MT 59715 > <https://www.google.com/maps/search/2042%0D%0A+Stadium+Drive+Suite+2+%E2%80%A2+Bozeman,+MT+59715?entry=gmail&source=g> > • (O) 406-587-2917 • (D) 406-589-4493 > 235 E. Broadway • Jackson, WY 83001 • (O) 307-200-2210 > [email protected] <[email protected]> | www.energy-1.net > > ------------------------------ > *From:* RE-wrenches <[email protected]> on behalf > of Kirk Herander, VSE <[email protected]> > *Sent:* Friday, April 16, 2021 9:13 AM > *To:* [email protected] <[email protected] > > > *Subject:* [RE-wrenches] Powerwall 2 AC PV regulation > > 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 / **[email protected] <[email protected]>* > > *Owner|Principal, VT Solar, LLC* > > *Celebrating our 30th Anniversary 1991-2021!!* > > *www.vermont.solar* > <https://us-west-2.protection.sophos.com?d=outlook.com&u=aHR0cHM6Ly9uYW0wMi5zYWZlbGlua3MucHJvdGVjdGlvbi5vdXRsb29rLmNvbS8_dXJsPXd3dy52ZXJtb250c29sYXJub3cuY29tJmRhdGE9MDIlN0MwMSU3QyU3QzlmMDMzMGQ3NWEyNDQ4NzAxMTI0MDhkNjg1MzExODQxJTdDODRkZjllN2ZlOWY2NDBhZmI0MzVhYWFhYWFhYWFhYWElN0MxJTdDMCU3QzYzNjg0Mjg0MzIzMzQ3NzY0NSZzZGF0YT0wTmp5dUtlUWJFSzYyNDVTTm5rOFg0WG5QOVElMkIlMkJxdHZjQUxrZERnaHZrNCUzRCZyZXNlcnZlZD0w&i=NWY3Yjg4NTEwMTMzZWYwZjc4ZDZiZjM0&t=T0V4VmVuWVp1a3A2UUVZOTRNRitLRWViVk1TM1o4Wll0MDNtSTg5WndOTT0=&h=257d32539c424fbdb09425b1e02ea242> > > dba Vermont Solar Engineering > > 802.863.1202 > _______________________________________________ > 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 > > -- Chris Sparadeo C_802-369-4458 H_802-728-3059
_______________________________________________ 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
