If every household hooks up, and all the trucks? Currently there is more investment in solar/wind, one is always unreliable and the other is certainly off at night. Now a grid of batteries might be enough to fill up the gaps today, but once that night slum is no longer a slum, who knows how big batteries you'll need.

We're still at low levels of renewable penetration on our grid; once over 50%, all these vehicles become a fantastic source of "negative" demand response. Current demand response asks customers to decrease consumption when there's peak usage and the grid is strained. Negative demand response is a signal to consume electricity when a free-on-the-margin source like solar would otherwise be curtailed.

The massive array of car batteries becomes an absolutely wonderful source of both positive and negative demand response. Currently, almost no one insists on driving around with a 100% full fuel tank. Those with electric cars commonly keep them around 80%. And daily usage of the battery is nearly always far less than 50%. And a decent sized EV battery is 1-2 days of household electricity usage.

If a significant chunk (20%-30%?) of our electrical demand is for battery-powered transport, we've solved a huge problem that comes with high wind and solar penetrance on the grid, without having stationary batteries. As car batteries age and have reduced capacity, they will potentially have a second life as stationary storage, where power density doesn't matter as much.

This means, that if we are able to install chargers at a percentage of workplaces, that car batteries will be able massively smooth out not only the daily duck curve of demand, but also deal with fluctuations where some days have more production and others less.