On 7/13/19 12:03 AM, Robert Bruninga via EV wrote:
When the powerwall battery is selling power to the grid, it is using its
current-source grid-tie circuitry. When it is islanding as a backup power
system without a grid, it is using completely different circuitry as a
stand alone inverter.
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 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".
So in this way a PowerWall attached to a house with a grid tie inverter
(either a single wall mount or microinverters on each panel) can use the
solar power to refill in the power outage as well as to share the load
from the house when the sun is out.
Jay
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