The figures I've heard Elon talking of for stationary batteries seem incredibly high to me. To me it looks like a very expensive device for a home owner (maybe I'm missing something?) and the farmers around here who get huge subsidies to turn Grade I agricultural land into PV arrays <sigh> laugh at the Battery Barns that are mentioned (to store Day until Night), so my thinking is that Commercial use of stationary batteries is not a market that is imminent; when it has come up in discussion before the thought seems to be that there is no need for (commercial) stationary storage until output from renewables gets to a level where we can't use it all, there & then.
I believe the commercial stationary storage business is where the money is. And it isn't just renewables. Many utilities are now offering deals on electricity on non-peak hours. In some places in Texas electric rates in the middle of the night are free. A business could potentially save a ton of money storing energy when it's cheap and then running off of batteries during the day when it's expensive. This is a huge savings in places where electric rates vary wildly throughout the day.
The utilities can take advantage of it too. They have a daily headache balancing loads, which spike sky high in the day, especially in the afternoons in hot climates, and crash to near zero at night. It's a lot of effort to completely shut down a major power plant, so they need to keep those plants idling through the night. During the day at the peaks they need to run their most expensive plants to meet demand. If they charge large battery arrays during the night and use those during peak hours, then they can decommission some of the most expensive plants and keep the cheaper ones.
As solar is getting more popular, utilities are finding they are getting too much electricity from solar customers put on the grid on sunny days with mild temperatures. That will become a more pressing issue as more solar comes online.
I believe the first customers for Tesla energy are commercial customers, not home users.
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It takes decades to get approval, and construct, Nuclear over here, so no quick-fix there; government / local authorities are putting up all sorts of planning reasons to decline applications for wind turbines (and, indeed, other PV too) on agricultural land, so if we have to phase out our old / polluting generating capacity before we have replacements in place perhaps we will need stationary storage to smooth out supply when the whole nation turns on a kettle during an advert break! but when that moment comes perhaps there wll be enough plug-in car BEVs to cover me, and the nation, for power-requirement smoothing rather than buying stationary storage.
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There are some next gen nuclear plant designs that would consume all the nuclear waster we have lying around and produce inert ash which is environmentally safe. They also run inherently safer, by design it's impossible for them to melt down. But resistance to anything nuclear in the US is so strong that these next generation plants may never get built.
The problem the world has with nuclear power plants is most land based nuclear plants are an old design that was based on what was used on nuclear ships (only subs and carriers today, but there were some other experimental ship designs). Those reactors were built to be compact and portable. This required partially enriched fuel so you could get a critical mass in a compact space. With a terrestrial reactor, you can make the reaction chamber as big as it needs to be and use fuel with much lower radioactivity. Nuclear waste is the ideal source for these types of reactors, they are still radioactive enough to heat something that can be run through a turbine, and you wouldn't want to be around it, but it's not hot enough to work in an old design reactor.
With the old reactor designs, they need water circulating all the time to keep within a safe temperature (hot enough to boil water at one end, but still cool enough that the machinery doesn't melt). If circulation is lost, bad things start happening. That's what happened at 3 Mile Island. New designs force the reactor into a shut down state if circulation stops and this happens by gravity. Basically everything has to be nominal for the reactor to keep working and if anything goes wrong, gravity slams it down.
The reactors that would use nuclear waste also can't get as hot as the old design reactors. With a larger amount of lower quality fuel, the potential top end temperature is much lower.
There is a young nuclear engineer who built a home made reactor in his garage using uranium he mined himself when he was 14 has designed one of these reactors and I believe he claims the thing just can't get hot enough to melt down.
But the public is pretty dead set against nuclear so it probably won't happen unless they manage to sell this reactor type as a nuclear waste disposal facility that just happens to generate electricity as a by product.
I am poorly educated on these points, but unless someone puts me straight it seems to me that Elon's proportion of stationary storage is high, and thus he has a higher percentage available for cars. If he can sell a car, why would he sell a battery, surely more added value in a car and accelerated land-grab penetration in the BEV marketplace? (albeit slower payback for his gigafactory, maybe)
Elon has been saying for over a year that the potential value of Tesla Energy is higher than the car business. It's also a business that's easier to get into so there will be more competition and Tesla might get edged out by cheaper rivals over the long term, but short term they have the turf to themselves, and over the long term they will probably be the premium stationary storage company. When you want rock solid stationary storage, you buy Tesla and only buy the other guys if you can't afford the best.
That said, at work we have several UPS boxes, one for each server / critical device, and their lifetime seems very short. A single Powerwall that would power the whole company for a modest period might well be a considered purchase. Power supply quality may be more fickle in other countries / states.
Experience with EVs has shown that well managed Li-ion cells with sophisticated charging firmware and good temperature management systems can last a long time with very little degradation. Very few Teslas have lost more than 5% of their battery capacity and there are some out there with 200 KM on the odometer. Even Nissan Leafs, which have poorer battery management systems have had very few batteries that have essentially died, though many have seen more severe degradation.
UPSs usually use lead acid batteries which are the oldest rechargeable battery technology and UPS makers probably don't do a very good job of managing the battery charging. I have UPSs on all the equipment in the house and I have to replace the batteries in at least one every year. It is a pain. I notice the new generation of UPSs have Li-ion batteries. I hope they manage them for better life.
, but will check responses at some point), if you haven't read this epic takedown of Nissan's LEAF marketing, communications, and dealers, I HIGHLY encourage it:
