Yes there is supposed to be no input.There is no input with the tides if you consider the Earth/moon to be a closed system. It's like a battery-powered fan: self contained and blows continuously without input from outside. But it's not perpetual motion since eventually the battery runs down and the fan stops. Ditto with the tides, which has been steadily draining its energy source (currently at a rate of about 3 TW) for over 4 billion years, slowing the spin of Earth from well under 10 hours to the 24 hours it takes today. The energy from the solar tides comes from the combined angular energy of the Earth/moon system, which is also steadily decreasing.