Inserting this here as contrast previous item – The 2.3 tonne Solar Impulse plane is powered by 17,248 solar cells and 4 lithium-ion batteries connected to the electric motors that drive the propellers. It uses the batteries to provide the energy to fly through the night, where it slowly loses altitude. The solar panels provide the power to the electric motors and charge the battery during the day, when the plane regains altitude so it can use less power at night.

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