Hi,
All of us in Northern California are aware that power is no longer something we can take for granted. If a home has a Powerwall how long can it provide power for basic support like minimal lighting, fridge, fans for furnace?
Thanks.
I live in south of Fort Worth, TX. My full home has 48 Solar Panels and 2x Powerwalls supporting 4000 sq feet of living space across two floors. There are two central AC units with an open floor plan. We got our Solar System installed in February and got PTO (permission to operate) in March.
During March & April, allowing my Powerwalls to deplete down to 40%, I was 99% self-powered. Most nights the 2x Powerwalls even running 2x AC units sporadically didn't deplete more than 60%.
As the months got hotter May-June, I found that they started depleting up to 40% and start drawing from grid before sun is back the next day to start powering home and recharging the Powerwalls.
Jul-Aug-Sep, I was lucky if the Powerwalls wouldn't get depleted to 40% even before midnight.
In Oct, things are finally getting cooler and now Powerwalls are back to being able to last night without even using up 50%.
All of this while we also charge one Tesla Model 3, mostly during day between 11am-3pm (peak sun hours). If we ever have to charge Tesla in evening / night, the Powerwalls get depleted super fast (within 1-2 hours). Sometime I think it would have been good to isolate the Tesla Wall Connector circuit as not being supported by Powerwalls and always pull from Grid or Solar only, but I didn't think of it to ask during install design / implementation or know if that is even possible.
Long story short, it basically depends on the load. The faster you are drawing power from them, the faster they deplete. If you can exclude your AC or you don't have high heat to combat, like you might have in CA year round, you can leave full home supported by the PowerWalls for days on end if you also have Solar during day to keep your home running plus re-charge your Powerwalls.
I think my situation would be better if I had 3x Powerwalls for my home size and the amount of heat we get in Summer to cool for even during night, but 2x is all that was minimally required to support both my AC units along with everything else. We have net metering and produce more during day than we are pulling at night so our electric bill is basically $0 and earning credits for future.
The only days we pull more from grid than we produce during day are hot days that are also cloudy.