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An interesting blog claiming V2G is a bad idea from @bradtem. But it's not that simple. (thread)
Basically his argument is: using your car battery to discharge from vehicle to grid (V2G) is a bad idea because it wears down your expensive car battery instead of a cheap stationary battery.
I agree with this IF it wears down your car battery before end of life of the car. But I would not be surprised if batteries will already far outlast their Tesla. And degradation is becoming less every year along all brands.
When I started studying this stuff, LFP batteries had 1000 cycles in them. Now they are at 10,000. (that's 30 years of use if you completely deplete the battery every day). I expect NCM and NCA batteries to follow the same path: used to be 1000x, now 2500x, 2020 5000x, 2030 ??
And the kicker: battery calender fade decreases if you store it mostly empty. V2G might prolong battery life if it keeps your battery more empty on average. (The gist of a recent V2G journal article.)
Also Brad claims that V2G will mainly happen during the night when we mainly see "bad baseload" ("coal/nuclear and just little bit of wind"). Actually higher penetration of renewables means large surplusses of wind in the middle of the night in most countries.
Also, many cars are connected at home or work in the middle of the day so the could use solar maximally. And charging when cheapest automatically means the market will favor solar and wind with their lowest marginal costs.
I think in the end the trillion dollar question becomes how cheap stationary batteries can become relative to car batteries. Brad absolutely has a point that they could become much cheaper but at the moment it's mainly the car batteries that are becoming cheaper.
Bottom line: with so many factors in play and battery life increasing this fast, V2G is a better deal than Brad assumes I think.
Future car batteries might well double as your power wall that's using solar&wind to the max while also stabilizing the grid.
Future car batteries might well double as your power wall that's using solar&wind to the max while also stabilizing the grid.
I currently have a master student trying to figure this out (using our SparkCity model). Hopefully his thesis research will enable us to be more specific.
