IIUC it's only half from the Sun's gravity well, the other half of that energy gradient is from the Moon's gravity well. Also IIUC "energy from the sun" is rea

IIUC it's only half from the Sun's gravity well, the other half of that energy gradient is from the Moon's gravity well. Also IIUC "energy from the sun" is really shorthand for "Energy emitted by solar fusion", which tidal would not involve.