On 7/13/19 9:44 AM, Jay Summet via EV wrote:
Also, the PowerWall is able to "fake" the grid well enough that grid tie inverters will "powerup" and start to feed power back into what they believe is the "grid" but is instead the powerwall. (which accepts the power so that the voltage does not climb too high).
I have more PV than my transformer can handle and see high voltages with high PV production. The result is that inverters shut down at around 260. Though each inverter seems to have a different threshold. I have a 15kva transformer, though I'm trying to get a 37.5kva, and my PV might do as much as 30kw.
I believe that when the powerwall is fully charged (can accept no more power) it shifts the frequency of the power from 60 to some other value (62 hz?) that is outside of the standards, which causes the grid tie inverters to stop feeding current into "the grid".
I first figured the PowerWall allowed voltage to rise and inverters to shut themselves down when PV production was too high. That is while off grid. I've since learned that the PW inverter, while grid spoofing, uses a different frequency. While running off grid, I observe old type motor clocks not keeping good time. I have only one PW battery unit but I believe each battery unit has it's own inverter. With more than one battery unit, I suppose one must the the master and the others sync to it. When the PW doesn't have anywhere to go with the PV power (battery charged) it shuts down PV inverters by, I suppose, going to a more different frequency. Something like: 62 hz tells every one that the PW is spoofing but the PV inverters are happy with it. Some other frequency, say 64 hz, is enough to shut down PV inverters.
I've been pondering how one might detect the "I'm about to shut down PV inverters" condition so that some optional loads could be switched on. Any suggestions there?
I haven't done enough off grid experimenting to learn how the PW cycles on a full battery. I suspect it might take the battery down maybe 10% with PV inverters off, then turn them back on until the battery is fully charged again.
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