I'm ignorant as to existing implementations but the system I heard of to solve this is: Your car or charger module has electricity spot prices available to it

I'm ignorant as to existing implementations but the system I heard of to solve this is: Your car or charger module has electricity spot prices available to it and you can select a strategy for it to automatically follow. E.g. * Rapid charge (charge battery, ignore price) * Economise (charge battery at low price) * Make money (charge/discharge according to price to profit from the difference)