Solar can be cheaper for daytime generation before it's cheaper for nighttime generation (when you need to tack on the cost of storage). Electric cars may already have a lower TCO, but if you already have an ICE car, it may not be worth the transaction costs of immediately selling it and buying an electric car instead of waiting until you would have bought a new car anyway, whereas it could be if gas prices were higher. The TCO is also affected by how much you drive, so the gas price that justifies replacing your car depends on how much you drive it.
There isn't a price level where $0.01 below it no one can justify buying an electric car and $0.01 above it everyone can. The higher oil prices get, the more people end up on the other side of the line.
I'm really skeptical of lower TCO for electric cars. My gasoline-powered car is worth $5k. All electric cars with decent range cost more in depreciation alone than my TCO. I think in a few years a Bolt will have a competitive TCO, and maybe a Model 3 will a few years after that.
You're comparing the TCO of a new electric car to a used gasoline car. We all know that used cars have a lower TCO than new ones in general. Nobody is going to crush a perfectly operational two year old gasoline car just because of higher gas prices (though that would obviously cause it to suffer higher depreciation due to the loss in resale value).
The real question is, as the old cars become unreliable and age out of service, how does the TCO compare as between the new cars that will replace them?
I'm comparing the TCO of a good value gasoline car to the best value electric car available (including used models). If you have a ton of disposable income, buying a Tesla could be a good decision, but very few people are in that position. Since we are taking about TCO, I assume we are talking about a financially literate purchaser.
I fully expect that electric cars will have a reasonable TCO in the future.
Which encourages renewable development. Renewables would not be as successful today with oil at $20/bbl.