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Discussion in 'Tesla Energy' started by electracity, Oct 28, 2016.
Not a criticism, just a question. It takes a pretty big solar array to charge 14kwh.
(Serious question, I don't know much about solar but interested.)
They probably think people want 24hrs of backup in case of an outage. Plus they figure these folks are nearly all grid connected and it'll make sense to absorb cheap renewable grid juice if we ever get a truly open wholesale market.
Probably helps provide the higher load capability as well.
when you consider that instead of panels that occupy a percentage of a roof, they are now talking about the ENTIRE roof, so hopefully that means more energy created - therefore stored.
I love the way the configurator has two options for lights/fridge or everything
14kWh (I wasn't referring to physical size, but the doubling of capacity). 7kWh is a good size to handle loads after sunset when demand is high. 14kWh with a bigger solar setup would make many homes "net zero".
Could be Anything from 3kW (Sunny SW US desert) to 5.5kW (Seattle) to _average_ 14kW production per day.
That's what she said.
Powerwall 2.0 is bigger perhaps because it has more cells to give it more capacity and because apparently there is an inverter inside the enclosre. Yes, the cells have a higher energy density, but probably the enclosure contains more cells. That is my guess...
Some reference points for our OP:
* On a partial to mostly cloudy October 28th at 34ºN Latitude, our 11kW array produced today 34.7kWh.
* Mid-June, clear sky - it will create 75kWh
* Winter solstice, mostly cloudy: 7.7kWh. If clear: 42kWh
* On a clear mid-summer day at 63ºN Latitude, our 5kW array produces about 24kWh (going by memory here).
US household electricity consumption averages. How much electricity does an American home use? - FAQ - U.S. Energy Information Administration (EIA)
Between about 6000 kWh and 15000 kWh. Divide by 365 and you get between 16 and 41 kWh per day.
Considering that most customers would be in single family houses and higher income, they'd be above those averages.
14 kWh seems to me to be a pretty good estimate of a minimum that would provide one day's backup for minimum use for a small household also not a bad estimate for minimal load shifting.
V 1.0 was clearly too small and it was also clear from early on that there wasn't much separate demand for backup only versions...the Powerwall had to be capable of daily cycling.
This kind of sets the bar for what size solar array is worth installing.
While it isn't intended to take houses "off the grid" this sort of 14 kWh system with solar would provide for necessities indefinitely in power outages.
So when you aggregate 1,000 of the 14kW powerwalls you have a 14 megawatt Virtual Power Plant, and using the smart inverter (built in) these can be aggregated much more for frequency regulation, peaking etc
Also don't forget people may be out of the house for a day or an evening. The solar panels can then charge even more to the battery instead of reaching the daily limit.
Looks like to me that the main sources of powerwall demand are outside of the US. looks like powerwall 1.0 was being shipped to Australia and Germany first.
When looking at powerwall 2.0 I think you need to consider energy demand and pricing of non-US markets. Not just countries like Germany, but also expensive suburbs of countries like Mexico where people have money but intermittent power.
I have a 4 bedroom, 2.5 bath, 3,000 sqft home and it draws roughly 28kwh a day (less in the spring/fall and more in the winter/summer). I'd need 3 of them to power my home for a day if I needed a full backup day.
My 6ksqft home uses ~60-120 kWh/day depending on the season (3 EVs, hybrid heat, pool). I've got a 36 panel array, and it generates anywhere between zero and 69kWh/day.
Of course, if you couple with solar, you'll be offsetting at least some portion of that.
For example: Cloudy/rainy late October day here in Northern California yesterday and I produced 12.83kWh from my 9.5kW array. My gross consumption, including EV charging, was 33.7kWh. I netted out just over 20kWh. In a pinch, I could skip a day of my pool pump (11.12kWh yesterday), or charging (a low 6.68kWh yesterday) and prioritize running the household. With two Powerwalls, I could go for a while, especially if the sun comes out.
You would not need three if you had solar.
With just one powerwall some electricity is far better than no electricity. Maybe leave the xbox off during the outage.
Having bigger storage allows you to charge between 20% to 90% daily without hurting the battery.