Just to expand on my earlier comments on energy storage batteries:-
Solar, wind and battery storage now cheapest energy options just about everywhere | RenewEconomy
Utility-scale battery (four-hour storage duration) $145-167 per MWh - if this number is based on a 10 year battery lifetime a simple change to a 20 year lifetime halves that cost.
The whole suite of measures that will be introduced by Battery Day is very likely to halve that cost...
If we apply that reduced battery cost, we can see all other forms of electrcity generation and storage are being challenged by RE+batteries:-
Onshore wind plus storage $41-$104
Fixed-axis PV plus storage $44-$129
Lithium-Ion Energy Storage Cost vs. Pumped Hydro Or Flow Battery Cost Are Dependent On Time | CleanTechnica
If we look at this chart the only bad news for Tesla is that Pumped Hydro and perhaps Sulphur flow batteries out complete Tesla batteries on > 4 hours of energy storage...
But again the halving of the cost probably pushes lithium-ion to break even at around 6-8 hours.
In fact CleanTechnica is more bullish:-
Perhaps there is even a virtuous cycle of Wrights Law allowing ithium-ion to keep lowering costs and unlocking more and more of the market as prices fall. CleanTechnicia has reached a similar conclusion.
The good thing is PV and Wind while being the cheapest for of electricity generation need storage and battery storage can do a lot more than just provide storage, for example it can help maintain stable frequency and voltage and reduce the need for transmission line upgrades.
So how big is the opportunity for Tesla in energy storage batteries?
We might get the answer at Battery Day.
I do hope we see more discussion of Tesla financials and market opportunities in here, fewer arguments and less pseudo-political discussion.