Energy providers use whatever internet API there is for either chargers or cars. Octopus UK has a list of charger models and car brands they support for their

Energy providers use whatever internet API there is for either chargers or cars. Octopus UK has a list of charger models and car brands they support for their special tariff for cheap off-peak EV charging. The charging cable has a protocol for negotiating power, so either side can pause and restart charging.