The £80 million greenhouse complex has enough glass to cover 80 football pitches and is expected to also grow tomatoes and peppers out of season.
Philippa Anderson, Tesco's south east regional marketing manager, said: "Until now no British grower has ever been able to grow round-the-year salad produce because of the enormous cost of heating glasshouses.
"The opening of Thanet Earth makes that possible and it will mean cheaper produce for shoppers."
Energy for each of the tree greenhouses is created by an on-site combined heat and power plant (CHP).
Meanwhile, Scottish and Southern Energy has unveiled plans for a multi-fuel CHP plant in Yorkshire.
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