Octopus Energy has launched the UK’s first mass market vehicle-to-grid (V2G) tariff, which will allow drivers to charge their electric vehicle for free, provided they keep it plugged for long enough. The Octopus Power Pack tariff will use V2G charging technology and Octopus’ Kraken platform to charge vehicles with cheap green electricity during off-peak periods and then export it back to the grid when demand and prices are high.