With smarter grids that support dynamic realtime pricing of electricy to end users, I think electric cars, home batteries and even appliances like fridges, refrigerators and washing machines can help balance supply and demand in the grids, using electricity, pausing consumption or pumping it back into the grid as needed.

The UK government recently performed an industry consultation on this subject and has released a plan to:

* remove barriers to smart technologies (such as storage and demand-side response)

* enable smart homes and businesses

* improve access to energy markets for new technologies and business models

https://www.gov.uk/government/publications/upgrading-our-ene...

Home batteries would have to hold more than the car.

This will still put the baseline of the grid higher, just averages it out possibly taking more when its a good time. I think batteries should be hosted/hooked up by the power company, so they can attach them to a power management system. (I think that already exists)

I left out the "where will we get all this power" part, because that is already discussed a lot. I just wonder if the power grid will be able to handle this immense increase in usage, even if spread out. You still need to transport it.

edit: I think the powering down of offices and business makes enough room for the evening to use more.

What reason is there for a home battery to hold more than a car?

You can drive your car empty faster than your home battery might charge (due to supply/demand), and it is possible to give back to grid if there is a peak in your area.